/*
 * Copyright (c) 2008-2025, Dave Benson and the protobuf-c authors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*! \file
 * Support library for `protoc-gen-c` generated code.
 *
 * This file implements the public API used by the code generated
 * by `protoc-gen-c`.
 *
 * \authors Dave Benson and the protobuf-c authors
 *
 * \copyright 2008-2025. Licensed under the terms of the [BSD-2-Clause] license.
 */

/**
 * \todo 64-BIT OPTIMIZATION: certain implementations use 32-bit math
 * even on 64-bit platforms (uint64_size, uint64_pack, parse_uint64).
 *
 * \todo Use size_t consistently.
 */

#include <config.h>

#include <stdlib.h>	/* for malloc, free */
#include <string.h>	/* for strcmp, strlen, memcpy, memmove, memset */
#if defined(HAVE_ENDIAN_H)
# include <endian.h>
#elif defined(HAVE_SYS_ENDIAN_H)
# include <sys/endian.h>
#elif defined(HAVE_MACHINE_ENDIAN_H)
# include <machine/endian.h>
#else
# include <compat/endian.h>
#endif

#include <protobuf-c/protobuf-c.h>

#if BYTE_ORDER == BIG_ENDIAN
# define WORDS_BIGENDIAN
#endif

#define TRUE				1
#define FALSE				0

#define PROTOBUF_C__ASSERT_NOT_REACHED() assert(0)

/* Workaround for Microsoft compilers. */
#ifdef _MSC_VER
# define inline __inline
#endif

/**
 * \defgroup internal Internal functions and macros
 *
 * These are not exported by the library but are useful to developers working
 * on `libprotobuf-c` itself.
 */

/**
 * \defgroup macros Utility macros for manipulating structures
 *
 * Macros and constants used to manipulate the base "classes" generated by
 * `protobuf-c`. They also define limits and check correctness.
 *
 * \ingroup internal
 * @{
 */

/** The maximum length of a 64-bit integer in varint encoding. */
#define MAX_UINT64_ENCODED_SIZE		10

#ifndef PROTOBUF_C_UNPACK_ERROR
# define PROTOBUF_C_UNPACK_ERROR(...)
#endif

#if !defined(_WIN32) || !defined(PROTOBUF_C_USE_SHARED_LIB)
const char protobuf_c_empty_string[] = "";
#endif

/**
 * Internal `ProtobufCMessage` manipulation macro.
 *
 * Base macro for manipulating a `ProtobufCMessage`. Used by STRUCT_MEMBER() and
 * STRUCT_MEMBER_PTR().
 */
#define STRUCT_MEMBER_P(struct_p, struct_offset) \
    ((void *) ((uint8_t *) (struct_p) + (struct_offset)))

/**
 * Return field in a `ProtobufCMessage` based on offset.
 *
 * Take a pointer to a `ProtobufCMessage` and find the field at the offset.
 * Cast it to the passed type.
 */
#define STRUCT_MEMBER(member_type, struct_p, struct_offset) \
    (*(member_type *) STRUCT_MEMBER_P((struct_p), (struct_offset)))

/**
 * Return field in a `ProtobufCMessage` based on offset.
 *
 * Take a pointer to a `ProtobufCMessage` and find the field at the offset. Cast
 * it to a pointer to the passed type.
 */
#define STRUCT_MEMBER_PTR(member_type, struct_p, struct_offset) \
    ((member_type *) STRUCT_MEMBER_P((struct_p), (struct_offset)))

/* Assertions for magic numbers. */

#define ASSERT_IS_ENUM_DESCRIPTOR(desc) \
	assert((desc)->magic == PROTOBUF_C__ENUM_DESCRIPTOR_MAGIC)

#define ASSERT_IS_MESSAGE_DESCRIPTOR(desc) \
	assert((desc)->magic == PROTOBUF_C__MESSAGE_DESCRIPTOR_MAGIC)

#define ASSERT_IS_MESSAGE(message) \
	ASSERT_IS_MESSAGE_DESCRIPTOR((message)->descriptor)

#define ASSERT_IS_SERVICE_DESCRIPTOR(desc) \
	assert((desc)->magic == PROTOBUF_C__SERVICE_DESCRIPTOR_MAGIC)

/**@}*/

/* --- version --- */

const char *
protobuf_c_version(void)
{
	return PROTOBUF_C_VERSION;
}

uint32_t
protobuf_c_version_number(void)
{
	return PROTOBUF_C_VERSION_NUMBER;
}

/* --- allocator --- */

static void *
system_alloc(void *allocator_data, size_t size)
{
	(void)allocator_data;
	return malloc(size);
}

static void
system_free(void *allocator_data, void *data)
{
	(void)allocator_data;
	free(data);
}

static inline void *
do_alloc(ProtobufCAllocator *allocator, size_t size)
{
	return allocator->alloc(allocator->allocator_data, size);
}

static inline void
do_free(ProtobufCAllocator *allocator, void *data)
{
	if (data != NULL)
		allocator->free(allocator->allocator_data, data);
}

/*
 * This allocator uses the system's malloc() and free(). It is the default
 * allocator used if NULL is passed as the ProtobufCAllocator to an exported
 * function.
 */
static ProtobufCAllocator protobuf_c__allocator = {
	.alloc = &system_alloc,
	.free = &system_free,
	.allocator_data = NULL,
};

/* === buffer-simple === */

void
protobuf_c_buffer_simple_append(ProtobufCBuffer *buffer,
				size_t len, const uint8_t *data)
{
	ProtobufCBufferSimple *simp = (ProtobufCBufferSimple *) buffer;
	size_t new_len = simp->len + len;

	if (new_len > simp->alloced) {
		ProtobufCAllocator *allocator = simp->allocator;
		size_t new_alloced = simp->alloced * 2;
		uint8_t *new_data;

		if (allocator == NULL)
			allocator = &protobuf_c__allocator;
		while (new_alloced < new_len)
			new_alloced += new_alloced;
		new_data = do_alloc(allocator, new_alloced);
		if (!new_data)
			return;
		memcpy(new_data, simp->data, simp->len);
		if (simp->must_free_data)
			do_free(allocator, simp->data);
		else
			simp->must_free_data = TRUE;
		simp->data = new_data;
		simp->alloced = new_alloced;
	}
	memcpy(simp->data + simp->len, data, len);
	simp->len = new_len;
}

/**
 * \defgroup packedsz protobuf_c_message_get_packed_size() implementation
 *
 * Routines mainly used by protobuf_c_message_get_packed_size().
 *
 * \ingroup internal
 * @{
 */

/**
 * Return the number of bytes required to store the tag for the field. Includes
 * 3 bits for the wire-type, and a single bit that denotes the end-of-tag.
 *
 * \param number
 *      Field tag to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
get_tag_size(uint32_t number)
{
	if (number < (1UL << 4)) {
		return 1;
	} else if (number < (1UL << 11)) {
		return 2;
	} else if (number < (1UL << 18)) {
		return 3;
	} else if (number < (1UL << 25)) {
		return 4;
	} else {
		return 5;
	}
}

/**
 * Return the number of bytes required to store a variable-length unsigned
 * 32-bit integer in base-128 varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
uint32_size(uint32_t v)
{
	if (v < (1UL << 7)) {
		return 1;
	} else if (v < (1UL << 14)) {
		return 2;
	} else if (v < (1UL << 21)) {
		return 3;
	} else if (v < (1UL << 28)) {
		return 4;
	} else {
		return 5;
	}
}

/**
 * Return the number of bytes required to store a variable-length signed 32-bit
 * integer in base-128 varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
int32_size(int32_t v)
{
	if (v < 0) {
		return 10;
	} else if (v < (1L << 7)) {
		return 1;
	} else if (v < (1L << 14)) {
		return 2;
	} else if (v < (1L << 21)) {
		return 3;
	} else if (v < (1L << 28)) {
		return 4;
	} else {
		return 5;
	}
}

/**
 * Return the ZigZag-encoded 32-bit unsigned integer form of a 32-bit signed
 * integer.
 *
 * \param v
 *      Value to encode.
 * \return
 *      ZigZag encoded integer.
 */
static inline uint32_t
zigzag32(int32_t v)
{
	// Note:  Using unsigned types prevents undefined behavior
	return ((uint32_t)v << 1) ^ -((uint32_t)v >> 31);
}

/**
 * Return the number of bytes required to store a signed 32-bit integer,
 * converted to an unsigned 32-bit integer with ZigZag encoding, using base-128
 * varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
sint32_size(int32_t v)
{
	return uint32_size(zigzag32(v));
}

/**
 * Return the number of bytes required to store a 64-bit unsigned integer in
 * base-128 varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
uint64_size(uint64_t v)
{
	uint32_t upper_v = (uint32_t) (v >> 32);

	if (upper_v == 0) {
		return uint32_size((uint32_t) v);
	} else if (upper_v < (1UL << 3)) {
		return 5;
	} else if (upper_v < (1UL << 10)) {
		return 6;
	} else if (upper_v < (1UL << 17)) {
		return 7;
	} else if (upper_v < (1UL << 24)) {
		return 8;
	} else if (upper_v < (1UL << 31)) {
		return 9;
	} else {
		return 10;
	}
}

/**
 * Return the ZigZag-encoded 64-bit unsigned integer form of a 64-bit signed
 * integer.
 *
 * \param v
 *      Value to encode.
 * \return
 *      ZigZag encoded integer.
 */
static inline uint64_t
zigzag64(int64_t v)
{
	// Note:  Using unsigned types prevents undefined behavior
	return ((uint64_t)v << 1) ^ -((uint64_t)v >> 63);
}

/**
 * Return the number of bytes required to store a signed 64-bit integer,
 * converted to an unsigned 64-bit integer with ZigZag encoding, using base-128
 * varint encoding.
 *
 * \param v
 *      Value to encode.
 * \return
 *      Number of bytes required.
 */
static inline size_t
sint64_size(int64_t v)
{
	return uint64_size(zigzag64(v));
}

/**
 * Calculate the serialized size of a single required message field, including
 * the space needed by the preceding tag.
 *
 * \param field
 *      Field descriptor for member.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
required_field_get_packed_size(const ProtobufCFieldDescriptor *field,
			       const void *member)
{
	size_t rv = get_tag_size(field->id);

	switch (field->type) {
	case PROTOBUF_C_TYPE_SINT32:
		return rv + sint32_size(*(const int32_t *) member);
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		return rv + int32_size(*(const int32_t *) member);
	case PROTOBUF_C_TYPE_UINT32:
		return rv + uint32_size(*(const uint32_t *) member);
	case PROTOBUF_C_TYPE_SINT64:
		return rv + sint64_size(*(const int64_t *) member);
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		return rv + uint64_size(*(const uint64_t *) member);
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
		return rv + 4;
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
		return rv + 8;
	case PROTOBUF_C_TYPE_BOOL:
		return rv + 1;
	case PROTOBUF_C_TYPE_FLOAT:
		return rv + 4;
	case PROTOBUF_C_TYPE_DOUBLE:
		return rv + 8;
	case PROTOBUF_C_TYPE_STRING: {
		const char *str = *(char * const *) member;
		size_t len = str ? strlen(str) : 0;
		return rv + uint32_size(len) + len;
	}
	case PROTOBUF_C_TYPE_BYTES: {
		size_t len = ((const ProtobufCBinaryData *) member)->len;
		return rv + uint32_size(len) + len;
	}
	case PROTOBUF_C_TYPE_MESSAGE: {
		const ProtobufCMessage *msg = *(ProtobufCMessage * const *) member;
		size_t subrv = msg ? protobuf_c_message_get_packed_size(msg) : 0;
		return rv + uint32_size(subrv) + subrv;
	}
	}
	PROTOBUF_C__ASSERT_NOT_REACHED();
	return 0;
}

/**
 * Calculate the serialized size of a single oneof message field, including
 * the space needed by the preceding tag. Returns 0 if the oneof field isn't
 * selected or is not set.
 *
 * \param field
 *      Field descriptor for member.
 * \param oneof_case
 *      Enum value that selects the field in the oneof.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
oneof_field_get_packed_size(const ProtobufCFieldDescriptor *field,
			    uint32_t oneof_case,
			    const void *member)
{
	if (oneof_case != field->id) {
		return 0;
	}
	if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
	    field->type == PROTOBUF_C_TYPE_STRING)
	{
		const void *ptr = *(const void * const *) member;
		if (ptr == NULL || ptr == field->default_value)
			return 0;
	}
	return required_field_get_packed_size(field, member);
}

/**
 * Calculate the serialized size of a single optional message field, including
 * the space needed by the preceding tag. Returns 0 if the optional field isn't
 * set.
 *
 * \param field
 *      Field descriptor for member.
 * \param has
 *      True if the field exists, false if not.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
optional_field_get_packed_size(const ProtobufCFieldDescriptor *field,
			       const protobuf_c_boolean has,
			       const void *member)
{
	if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
	    field->type == PROTOBUF_C_TYPE_STRING)
	{
		const void *ptr = *(const void * const *) member;
		if (ptr == NULL || ptr == field->default_value)
			return 0;
	} else {
		if (!has)
			return 0;
	}
	return required_field_get_packed_size(field, member);
}

static protobuf_c_boolean
field_is_zeroish(const ProtobufCFieldDescriptor *field,
		 const void *member)
{
	protobuf_c_boolean ret = FALSE;

	switch (field->type) {
	case PROTOBUF_C_TYPE_BOOL:
		ret = (0 == *(const protobuf_c_boolean *) member);
		break;
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_SINT32:
	case PROTOBUF_C_TYPE_INT32:
	case PROTOBUF_C_TYPE_UINT32:
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
		ret = (0 == *(const uint32_t *) member);
		break;
	case PROTOBUF_C_TYPE_SINT64:
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
		ret = (0 == *(const uint64_t *) member);
		break;
	case PROTOBUF_C_TYPE_FLOAT:
		ret = (0 == *(const float *) member);
		break;
	case PROTOBUF_C_TYPE_DOUBLE:
		ret = (0 == *(const double *) member);
		break;
	case PROTOBUF_C_TYPE_STRING:
		ret = (NULL == *(const char * const *) member) ||
		      ('\0' == **(const char * const *) member);
		break;
	case PROTOBUF_C_TYPE_BYTES:
	case PROTOBUF_C_TYPE_MESSAGE:
		ret = (NULL == *(const void * const *) member);
		break;
	default:
		ret = TRUE;
		break;
	}

	return ret;
}

/**
 * Calculate the serialized size of a single unlabeled message field, including
 * the space needed by the preceding tag. Returns 0 if the field isn't set or
 * if it is set to a "zeroish" value (null pointer or 0 for numerical values).
 * Unlabeled fields are supported only in proto3.
 *
 * \param field
 *      Field descriptor for member.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
unlabeled_field_get_packed_size(const ProtobufCFieldDescriptor *field,
				const void *member)
{
	if (field_is_zeroish(field, member))
		return 0;
	return required_field_get_packed_size(field, member);
}

/**
 * Calculate the serialized size of repeated message fields, which may consist
 * of any number of values (including 0). Includes the space needed by the
 * preceding tags (as needed).
 *
 * \param field
 *      Field descriptor for member.
 * \param count
 *      Number of repeated field members.
 * \param member
 *      Field to encode.
 * \return
 *      Number of bytes required.
 */
static size_t
repeated_field_get_packed_size(const ProtobufCFieldDescriptor *field,
			       size_t count, const void *member)
{
	size_t header_size;
	size_t rv = 0;
	unsigned i;
	void *array = *(void * const *) member;

	if (count == 0)
		return 0;
	header_size = get_tag_size(field->id);
	if (0 == (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED))
		header_size *= count;

	switch (field->type) {
	case PROTOBUF_C_TYPE_SINT32:
		for (i = 0; i < count; i++)
			rv += sint32_size(((int32_t *) array)[i]);
		break;
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		for (i = 0; i < count; i++)
			rv += int32_size(((int32_t *) array)[i]);
		break;
	case PROTOBUF_C_TYPE_UINT32:
		for (i = 0; i < count; i++)
			rv += uint32_size(((uint32_t *) array)[i]);
		break;
	case PROTOBUF_C_TYPE_SINT64:
		for (i = 0; i < count; i++)
			rv += sint64_size(((int64_t *) array)[i]);
		break;
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		for (i = 0; i < count; i++)
			rv += uint64_size(((uint64_t *) array)[i]);
		break;
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		rv += 4 * count;
		break;
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		rv += 8 * count;
		break;
	case PROTOBUF_C_TYPE_BOOL:
		rv += count;
		break;
	case PROTOBUF_C_TYPE_STRING:
		for (i = 0; i < count; i++) {
			size_t len = strlen(((char **) array)[i]);
			rv += uint32_size(len) + len;
		}
		break;
	case PROTOBUF_C_TYPE_BYTES:
		for (i = 0; i < count; i++) {
			size_t len = ((ProtobufCBinaryData *) array)[i].len;
			rv += uint32_size(len) + len;
		}
		break;
	case PROTOBUF_C_TYPE_MESSAGE:
		for (i = 0; i < count; i++) {
			size_t len = protobuf_c_message_get_packed_size(
				((ProtobufCMessage **) array)[i]);
			rv += uint32_size(len) + len;
		}
		break;
	}

	if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED))
		header_size += uint32_size(rv);
	return header_size + rv;
}

/**
 * Calculate the serialized size of an unknown field, i.e. one that is passed
 * through mostly uninterpreted. This is required for forward compatibility if
 * new fields are added to the message descriptor.
 *
 * \param field
 *      Unknown field type.
 * \return
 *      Number of bytes required.
 */
static inline size_t
unknown_field_get_packed_size(const ProtobufCMessageUnknownField *field)
{
	return get_tag_size(field->tag) + field->len;
}

/**@}*/

/*
 * Calculate the serialized size of the message.
 */
size_t protobuf_c_message_get_packed_size(const ProtobufCMessage *message)
{
	unsigned i;
	size_t rv = 0;

	ASSERT_IS_MESSAGE(message);
	for (i = 0; i < message->descriptor->n_fields; i++) {
		const ProtobufCFieldDescriptor *field =
			message->descriptor->fields + i;
		const void *member =
			((const char *) message) + field->offset;
		const void *qmember =
			((const char *) message) + field->quantifier_offset;

		if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
			rv += required_field_get_packed_size(field, member);
		} else if ((field->label == PROTOBUF_C_LABEL_OPTIONAL ||
			    field->label == PROTOBUF_C_LABEL_NONE) &&
			   (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF))) {
			rv += oneof_field_get_packed_size(
				field,
				*(const uint32_t *) qmember,
				member
			);
		} else if (field->label == PROTOBUF_C_LABEL_OPTIONAL) {
			rv += optional_field_get_packed_size(
				field,
				*(protobuf_c_boolean *) qmember,
				member
			);
		} else if (field->label == PROTOBUF_C_LABEL_NONE) {
			rv += unlabeled_field_get_packed_size(
				field,
				member
			);
		} else {
			rv += repeated_field_get_packed_size(
				field,
				*(const size_t *) qmember,
				member
			);
		}
	}
	for (i = 0; i < message->n_unknown_fields; i++)
		rv += unknown_field_get_packed_size(&message->unknown_fields[i]);
	return rv;
}

/**
 * \defgroup pack protobuf_c_message_pack() implementation
 *
 * Routines mainly used by protobuf_c_message_pack().
 *
 * \ingroup internal
 * @{
 */

/**
 * Pack an unsigned 32-bit integer in base-128 varint encoding and return the
 * number of bytes written, which must be 5 or less.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
uint32_pack(uint32_t value, uint8_t *out)
{
	unsigned rv = 0;

	if (value >= 0x80) {
		out[rv++] = value | 0x80;
		value >>= 7;
		if (value >= 0x80) {
			out[rv++] = value | 0x80;
			value >>= 7;
			if (value >= 0x80) {
				out[rv++] = value | 0x80;
				value >>= 7;
				if (value >= 0x80) {
					out[rv++] = value | 0x80;
					value >>= 7;
				}
			}
		}
	}
	/* assert: value<128 */
	out[rv++] = value;
	return rv;
}

/**
 * Pack a signed 32-bit integer and return the number of bytes written,
 * passed as unsigned to avoid implementation-specific behavior.
 * Negative numbers are encoded as two's complement 64-bit integers.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
int32_pack(uint32_t value, uint8_t *out)
{
	if ((int32_t)value < 0) {
		out[0] = value | 0x80;
		out[1] = (value >> 7) | 0x80;
		out[2] = (value >> 14) | 0x80;
		out[3] = (value >> 21) | 0x80;
		out[4] = (value >> 28) | 0xf0;
		out[5] = out[6] = out[7] = out[8] = 0xff;
		out[9] = 0x01;
		return 10;
	} else {
		return uint32_pack(value, out);
	}
}

/**
 * Pack a signed 32-bit integer using ZigZag encoding and return the number of
 * bytes written.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
sint32_pack(int32_t value, uint8_t *out)
{
	return uint32_pack(zigzag32(value), out);
}

/**
 * Pack a 64-bit unsigned integer using base-128 varint encoding and return the
 * number of bytes written.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
uint64_pack(uint64_t value, uint8_t *out)
{
	uint32_t hi = (uint32_t) (value >> 32);
	uint32_t lo = (uint32_t) value;
	unsigned rv;

	if (hi == 0)
		return uint32_pack((uint32_t) lo, out);
	out[0] = (lo) | 0x80;
	out[1] = (lo >> 7) | 0x80;
	out[2] = (lo >> 14) | 0x80;
	out[3] = (lo >> 21) | 0x80;
	if (hi < 8) {
		out[4] = (hi << 4) | (lo >> 28);
		return 5;
	} else {
		out[4] = ((hi & 7) << 4) | (lo >> 28) | 0x80;
		hi >>= 3;
	}
	rv = 5;
	while (hi >= 128) {
		out[rv++] = hi | 0x80;
		hi >>= 7;
	}
	out[rv++] = hi;
	return rv;
}

/**
 * Pack a 64-bit signed integer in ZigZag encoding and return the number of
 * bytes written.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
sint64_pack(int64_t value, uint8_t *out)
{
	return uint64_pack(zigzag64(value), out);
}

/**
 * Pack a 32-bit quantity in little-endian byte order. Used for protobuf wire
 * types fixed32, sfixed32, float. Similar to "htole32".
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
fixed32_pack(uint32_t value, void *out)
{
#if !defined(WORDS_BIGENDIAN)
	memcpy(out, &value, 4);
#else
	uint8_t *buf = out;

	buf[0] = value;
	buf[1] = value >> 8;
	buf[2] = value >> 16;
	buf[3] = value >> 24;
#endif
	return 4;
}

/**
 * Pack a 64-bit quantity in little-endian byte order. Used for protobuf wire
 * types fixed64, sfixed64, double. Similar to "htole64".
 *
 * \todo The big-endian impl is really only good for 32-bit machines, a 64-bit
 * version would be appreciated, plus a way to decide to use 64-bit math where
 * convenient.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
fixed64_pack(uint64_t value, void *out)
{
#if !defined(WORDS_BIGENDIAN)
	memcpy(out, &value, 8);
#else
	fixed32_pack(value, out);
	fixed32_pack(value >> 32, ((char *) out) + 4);
#endif
	return 8;
}

/**
 * Pack a boolean value as an integer and return the number of bytes written.
 *
 * \todo Perhaps on some platforms *out = !!value would be a better impl, b/c
 * that is idiomatic C++ in some STL implementations.
 *
 * \param value
 *      Value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
boolean_pack(protobuf_c_boolean value, uint8_t *out)
{
	*out = value ? TRUE : FALSE;
	return 1;
}

/**
 * Pack a NUL-terminated C string and return the number of bytes written. The
 * output includes a length delimiter.
 *
 * The NULL pointer is treated as an empty string. This isn't really necessary,
 * but it allows people to leave required strings blank. (See Issue #13 in the
 * bug tracker for a little more explanation).
 *
 * \param str
 *      String to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
string_pack(const char *str, uint8_t *out)
{
	if (str == NULL) {
		out[0] = 0;
		return 1;
	} else {
		size_t len = strlen(str);
		size_t rv = uint32_pack(len, out);
		memcpy(out + rv, str, len);
		return rv + len;
	}
}

/**
 * Pack a ProtobufCBinaryData and return the number of bytes written. The output
 * includes a length delimiter.
 *
 * \param bd
 *      ProtobufCBinaryData to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
binary_data_pack(const ProtobufCBinaryData *bd, uint8_t *out)
{
	size_t len = bd->len;
	size_t rv = uint32_pack(len, out);
	memcpy(out + rv, bd->data, len);
	return rv + len;
}

/**
 * Pack a ProtobufCMessage and return the number of bytes written. The output
 * includes a length delimiter.
 *
 * \param message
 *      ProtobufCMessage object to pack.
 * \param[out] out
 *      Packed message.
 * \return
 *      Number of bytes written to `out`.
 */
static inline size_t
prefixed_message_pack(const ProtobufCMessage *message, uint8_t *out)
{
	if (message == NULL) {
		out[0] = 0;
		return 1;
	} else {
		size_t rv = protobuf_c_message_pack(message, out + 1);
		uint32_t rv_packed_size = uint32_size(rv);
		if (rv_packed_size != 1)
			memmove(out + rv_packed_size, out + 1, rv);
		return uint32_pack(rv, out) + rv;
	}
}

/**
 * Pack a field tag.
 *
 * Wire-type will be added in required_field_pack().
 *
 * \todo Just call uint64_pack on 64-bit platforms.
 *
 * \param id
 *      Tag value to encode.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
tag_pack(uint32_t id, uint8_t *out)
{
	if (id < (1UL << (32 - 3)))
		return uint32_pack(id << 3, out);
	else
		return uint64_pack(((uint64_t) id) << 3, out);
}

/**
 * Pack a required field and return the number of bytes written.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
required_field_pack(const ProtobufCFieldDescriptor *field,
		    const void *member, uint8_t *out)
{
	size_t rv = tag_pack(field->id, out);

	switch (field->type) {
	case PROTOBUF_C_TYPE_SINT32:
		out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		return rv + sint32_pack(*(const int32_t *) member, out + rv);
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		return rv + int32_pack(*(const int32_t *) member, out + rv);
	case PROTOBUF_C_TYPE_UINT32:
		out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		return rv + uint32_pack(*(const uint32_t *) member, out + rv);
	case PROTOBUF_C_TYPE_SINT64:
		out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		return rv + sint64_pack(*(const int64_t *) member, out + rv);
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		return rv + uint64_pack(*(const uint64_t *) member, out + rv);
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		out[0] |= PROTOBUF_C_WIRE_TYPE_32BIT;
		return rv + fixed32_pack(*(const uint32_t *) member, out + rv);
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		out[0] |= PROTOBUF_C_WIRE_TYPE_64BIT;
		return rv + fixed64_pack(*(const uint64_t *) member, out + rv);
	case PROTOBUF_C_TYPE_BOOL:
		out[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		return rv + boolean_pack(*(const protobuf_c_boolean *) member, out + rv);
	case PROTOBUF_C_TYPE_STRING:
		out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		return rv + string_pack(*(char *const *) member, out + rv);
	case PROTOBUF_C_TYPE_BYTES:
		out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		return rv + binary_data_pack((const ProtobufCBinaryData *) member, out + rv);
	case PROTOBUF_C_TYPE_MESSAGE:
		out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		return rv + prefixed_message_pack(*(ProtobufCMessage * const *) member, out + rv);
	}
	PROTOBUF_C__ASSERT_NOT_REACHED();
	return 0;
}

/**
 * Pack a oneof field and return the number of bytes written. Only packs the
 * field that is selected by the case enum.
 *
 * \param field
 *      Field descriptor.
 * \param oneof_case
 *      Enum value that selects the field in the oneof.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
oneof_field_pack(const ProtobufCFieldDescriptor *field,
		 uint32_t oneof_case,
		 const void *member, uint8_t *out)
{
	if (oneof_case != field->id) {
		return 0;
	}
	if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
	    field->type == PROTOBUF_C_TYPE_STRING)
	{
		const void *ptr = *(const void * const *) member;
		if (ptr == NULL || ptr == field->default_value)
			return 0;
	}
	return required_field_pack(field, member, out);
}

/**
 * Pack an optional field and return the number of bytes written.
 *
 * \param field
 *      Field descriptor.
 * \param has
 *      Whether the field is set.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
optional_field_pack(const ProtobufCFieldDescriptor *field,
		    const protobuf_c_boolean has,
		    const void *member, uint8_t *out)
{
	if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
	    field->type == PROTOBUF_C_TYPE_STRING)
	{
		const void *ptr = *(const void * const *) member;
		if (ptr == NULL || ptr == field->default_value)
			return 0;
	} else {
		if (!has)
			return 0;
	}
	return required_field_pack(field, member, out);
}

/**
 * Pack an unlabeled field and return the number of bytes written.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The field member.
 * \param[out] out
 *      Packed value.
 * \return
 *      Number of bytes written to `out`.
 */
static size_t
unlabeled_field_pack(const ProtobufCFieldDescriptor *field,
		     const void *member, uint8_t *out)
{
	if (field_is_zeroish(field, member))
		return 0;
	return required_field_pack(field, member, out);
}

/**
 * Given a field type, return the in-memory size.
 *
 * \todo Implement as a table lookup.
 *
 * \param type
 *      Field type.
 * \return
 *      Size of the field.
 */
static inline size_t
sizeof_elt_in_repeated_array(ProtobufCType type)
{
	switch (type) {
	case PROTOBUF_C_TYPE_SINT32:
	case PROTOBUF_C_TYPE_INT32:
	case PROTOBUF_C_TYPE_UINT32:
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
	case PROTOBUF_C_TYPE_ENUM:
		return 4;
	case PROTOBUF_C_TYPE_SINT64:
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		return 8;
	case PROTOBUF_C_TYPE_BOOL:
		return sizeof(protobuf_c_boolean);
	case PROTOBUF_C_TYPE_STRING:
	case PROTOBUF_C_TYPE_MESSAGE:
		return sizeof(void *);
	case PROTOBUF_C_TYPE_BYTES:
		return sizeof(ProtobufCBinaryData);
	}
	PROTOBUF_C__ASSERT_NOT_REACHED();
	return 0;
}

/**
 * Pack an array of 32-bit quantities.
 *
 * \param[out] out
 *      Destination.
 * \param[in] in
 *      Source.
 * \param[in] n
 *      Number of elements in the source array.
 */
static void
copy_to_little_endian_32(void *out, const void *in, const unsigned n)
{
#if !defined(WORDS_BIGENDIAN)
	memcpy(out, in, n * 4);
#else
	unsigned i;
	const uint32_t *ini = in;
	for (i = 0; i < n; i++)
		fixed32_pack(ini[i], (uint32_t *) out + i);
#endif
}

/**
 * Pack an array of 64-bit quantities.
 *
 * \param[out] out
 *      Destination.
 * \param[in] in
 *      Source.
 * \param[in] n
 *      Number of elements in the source array.
 */
static void
copy_to_little_endian_64(void *out, const void *in, const unsigned n)
{
#if !defined(WORDS_BIGENDIAN)
	memcpy(out, in, n * 8);
#else
	unsigned i;
	const uint64_t *ini = in;
	for (i = 0; i < n; i++)
		fixed64_pack(ini[i], (uint64_t *) out + i);
#endif
}

/**
 * Get the minimum number of bytes required to pack a field value of a
 * particular type.
 *
 * \param type
 *      Field type.
 * \return
 *      Number of bytes.
 */
static unsigned
get_type_min_size(ProtobufCType type)
{
	if (type == PROTOBUF_C_TYPE_SFIXED32 ||
	    type == PROTOBUF_C_TYPE_FIXED32 ||
	    type == PROTOBUF_C_TYPE_FLOAT)
	{
		return 4;
	}
	if (type == PROTOBUF_C_TYPE_SFIXED64 ||
	    type == PROTOBUF_C_TYPE_FIXED64 ||
	    type == PROTOBUF_C_TYPE_DOUBLE)
	{
		return 8;
	}
	return 1;
}

/**
 * Packs the elements of a repeated field and returns the serialised field and
 * its length.
 *
 * \param field
 *      Field descriptor.
 * \param count
 *      Number of elements in the repeated field array.
 * \param member
 *      Pointer to the elements for this repeated field.
 * \param[out] out
 *      Serialised representation of the repeated field.
 * \return
 *      Number of bytes serialised to `out`.
 */
static size_t
repeated_field_pack(const ProtobufCFieldDescriptor *field,
		    size_t count, const void *member, uint8_t *out)
{
	void *array = *(void * const *) member;
	unsigned i;

	if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED)) {
		unsigned header_len;
		unsigned len_start;
		unsigned min_length;
		unsigned payload_len;
		unsigned length_size_min;
		unsigned actual_length_size;
		uint8_t *payload_at;

		if (count == 0)
			return 0;
		header_len = tag_pack(field->id, out);
		out[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		len_start = header_len;
		min_length = get_type_min_size(field->type) * count;
		length_size_min = uint32_size(min_length);
		header_len += length_size_min;
		payload_at = out + header_len;

		switch (field->type) {
		case PROTOBUF_C_TYPE_SFIXED32:
		case PROTOBUF_C_TYPE_FIXED32:
		case PROTOBUF_C_TYPE_FLOAT:
			copy_to_little_endian_32(payload_at, array, count);
			payload_at += count * 4;
			break;
		case PROTOBUF_C_TYPE_SFIXED64:
		case PROTOBUF_C_TYPE_FIXED64:
		case PROTOBUF_C_TYPE_DOUBLE:
			copy_to_little_endian_64(payload_at, array, count);
			payload_at += count * 8;
			break;
		case PROTOBUF_C_TYPE_ENUM:
		case PROTOBUF_C_TYPE_INT32: {
			const int32_t *arr = (const int32_t *) array;
			for (i = 0; i < count; i++)
				payload_at += int32_pack(arr[i], payload_at);
			break;
		}
		case PROTOBUF_C_TYPE_SINT32: {
			const int32_t *arr = (const int32_t *) array;
			for (i = 0; i < count; i++)
				payload_at += sint32_pack(arr[i], payload_at);
			break;
		}
		case PROTOBUF_C_TYPE_SINT64: {
			const int64_t *arr = (const int64_t *) array;
			for (i = 0; i < count; i++)
				payload_at += sint64_pack(arr[i], payload_at);
			break;
		}
		case PROTOBUF_C_TYPE_UINT32: {
			const uint32_t *arr = (const uint32_t *) array;
			for (i = 0; i < count; i++)
				payload_at += uint32_pack(arr[i], payload_at);
			break;
		}
		case PROTOBUF_C_TYPE_INT64:
		case PROTOBUF_C_TYPE_UINT64: {
			const uint64_t *arr = (const uint64_t *) array;
			for (i = 0; i < count; i++)
				payload_at += uint64_pack(arr[i], payload_at);
			break;
		}
		case PROTOBUF_C_TYPE_BOOL: {
			const protobuf_c_boolean *arr = (const protobuf_c_boolean *) array;
			for (i = 0; i < count; i++)
				payload_at += boolean_pack(arr[i], payload_at);
			break;
		}
		default:
			PROTOBUF_C__ASSERT_NOT_REACHED();
		}

		payload_len = payload_at - (out + header_len);
		actual_length_size = uint32_size(payload_len);
		if (length_size_min != actual_length_size) {
			assert(actual_length_size == length_size_min + 1);
			memmove(out + header_len + 1, out + header_len,
				payload_len);
			header_len++;
		}
		uint32_pack(payload_len, out + len_start);
		return header_len + payload_len;
	} else {
		/* not "packed" cased */
		/* CONSIDER: optimize this case a bit (by putting the loop inside the switch) */
		size_t rv = 0;
		unsigned siz = sizeof_elt_in_repeated_array(field->type);

		for (i = 0; i < count; i++) {
			rv += required_field_pack(field, array, out + rv);
			array = (char *)array + siz;
		}
		return rv;
	}
}

static size_t
unknown_field_pack(const ProtobufCMessageUnknownField *field, uint8_t *out)
{
	size_t rv = tag_pack(field->tag, out);
	out[0] |= field->wire_type;
	memcpy(out + rv, field->data, field->len);
	return rv + field->len;
}

/**@}*/

size_t
protobuf_c_message_pack(const ProtobufCMessage *message, uint8_t *out)
{
	unsigned i;
	size_t rv = 0;

	ASSERT_IS_MESSAGE(message);
	for (i = 0; i < message->descriptor->n_fields; i++) {
		const ProtobufCFieldDescriptor *field =
			message->descriptor->fields + i;
		const void *member = ((const char *) message) + field->offset;

		/*
		 * It doesn't hurt to compute qmember (a pointer to the
		 * quantifier field of the structure), but the pointer is only
		 * valid if the field is:
		 *  - a repeated field, or
		 *  - a field that is part of a oneof
		 *  - an optional field that isn't a pointer type
		 * (Meaning: not a message or a string).
		 */
		const void *qmember =
			((const char *) message) + field->quantifier_offset;

		if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
			rv += required_field_pack(field, member, out + rv);
		} else if ((field->label == PROTOBUF_C_LABEL_OPTIONAL ||
			    field->label == PROTOBUF_C_LABEL_NONE) &&
			   (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF))) {
			rv += oneof_field_pack(
				field,
				*(const uint32_t *) qmember,
				member,
				out + rv
			);
		} else if (field->label == PROTOBUF_C_LABEL_OPTIONAL) {
			rv += optional_field_pack(
				field,
				*(const protobuf_c_boolean *) qmember,
				member,
				out + rv
			);
		} else if (field->label == PROTOBUF_C_LABEL_NONE) {
			rv += unlabeled_field_pack(field, member, out + rv);
		} else {
			rv += repeated_field_pack(field, *(const size_t *) qmember,
				member, out + rv);
		}
	}
	for (i = 0; i < message->n_unknown_fields; i++)
		rv += unknown_field_pack(&message->unknown_fields[i], out + rv);
	return rv;
}

/**
 * \defgroup packbuf protobuf_c_message_pack_to_buffer() implementation
 *
 * Routines mainly used by protobuf_c_message_pack_to_buffer().
 *
 * \ingroup internal
 * @{
 */

/**
 * Pack a required field to a virtual buffer.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes packed.
 */
static size_t
required_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
			      const void *member, ProtobufCBuffer *buffer)
{
	size_t rv;
	uint8_t scratch[MAX_UINT64_ENCODED_SIZE * 2];

	rv = tag_pack(field->id, scratch);
	switch (field->type) {
	case PROTOBUF_C_TYPE_SINT32:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		rv += sint32_pack(*(const int32_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		rv += int32_pack(*(const int32_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_UINT32:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		rv += uint32_pack(*(const uint32_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_SINT64:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		rv += sint64_pack(*(const int64_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		rv += uint64_pack(*(const uint64_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_32BIT;
		rv += fixed32_pack(*(const uint32_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_64BIT;
		rv += fixed64_pack(*(const uint64_t *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_BOOL:
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_VARINT;
		rv += boolean_pack(*(const protobuf_c_boolean *) member, scratch + rv);
		buffer->append(buffer, rv, scratch);
		break;
	case PROTOBUF_C_TYPE_STRING: {
		const char *str = *(char *const *) member;
		size_t sublen = str ? strlen(str) : 0;

		scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		rv += uint32_pack(sublen, scratch + rv);
		buffer->append(buffer, rv, scratch);
		buffer->append(buffer, sublen, (const uint8_t *) str);
		rv += sublen;
		break;
	}
	case PROTOBUF_C_TYPE_BYTES: {
		const ProtobufCBinaryData *bd = ((const ProtobufCBinaryData *) member);
		size_t sublen = bd->len;

		scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		rv += uint32_pack(sublen, scratch + rv);
		buffer->append(buffer, rv, scratch);
		buffer->append(buffer, sublen, bd->data);
		rv += sublen;
		break;
	}
	case PROTOBUF_C_TYPE_MESSAGE: {
		const ProtobufCMessage *msg = *(ProtobufCMessage * const *) member;
		
		scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		if (msg == NULL) {
			rv += uint32_pack(0, scratch + rv);
			buffer->append(buffer, rv, scratch);
		} else {
			size_t sublen = protobuf_c_message_get_packed_size(msg);
			rv += uint32_pack(sublen, scratch + rv);
			buffer->append(buffer, rv, scratch);
			protobuf_c_message_pack_to_buffer(msg, buffer);
			rv += sublen;
		}
		break;
	}
	default:
		PROTOBUF_C__ASSERT_NOT_REACHED();
	}
	return rv;
}

/**
 * Pack a oneof field to a buffer. Only packs the field that is selected by the case enum.
 *
 * \param field
 *      Field descriptor.
 * \param oneof_case
 *      Enum value that selects the field in the oneof.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes serialised to `buffer`.
 */
static size_t
oneof_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
			   uint32_t oneof_case,
			   const void *member, ProtobufCBuffer *buffer)
{
	if (oneof_case != field->id) {
		return 0;
	}
	if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
	    field->type == PROTOBUF_C_TYPE_STRING)
	{
		const void *ptr = *(const void *const *) member;
		if (ptr == NULL || ptr == field->default_value)
			return 0;
	}
	return required_field_pack_to_buffer(field, member, buffer);
}

/**
 * Pack an optional field to a buffer.
 *
 * \param field
 *      Field descriptor.
 * \param has
 *      Whether the field is set.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes serialised to `buffer`.
 */
static size_t
optional_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
			      const protobuf_c_boolean has,
			      const void *member, ProtobufCBuffer *buffer)
{
	if (field->type == PROTOBUF_C_TYPE_MESSAGE ||
	    field->type == PROTOBUF_C_TYPE_STRING)
	{
		const void *ptr = *(const void *const *) member;
		if (ptr == NULL || ptr == field->default_value)
			return 0;
	} else {
		if (!has)
			return 0;
	}
	return required_field_pack_to_buffer(field, member, buffer);
}

/**
 * Pack an unlabeled field to a buffer.
 *
 * \param field
 *      Field descriptor.
 * \param member
 *      The element to be packed.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes serialised to `buffer`.
 */
static size_t
unlabeled_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
			       const void *member, ProtobufCBuffer *buffer)
{
	if (field_is_zeroish(field, member))
		return 0;
	return required_field_pack_to_buffer(field, member, buffer);
}

/**
 * Get the packed size of an array of same field type.
 *
 * \param field
 *      Field descriptor.
 * \param count
 *      Number of elements of this type.
 * \param array
 *      The elements to get the size of.
 * \return
 *      Number of bytes required.
 */
static size_t
get_packed_payload_length(const ProtobufCFieldDescriptor *field,
			  unsigned count, const void *array)
{
	unsigned rv = 0;
	unsigned i;

	switch (field->type) {
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		return count * 4;
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		return count * 8;
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32: {
		const int32_t *arr = (const int32_t *) array;
		for (i = 0; i < count; i++)
			rv += int32_size(arr[i]);
		break;
	}
	case PROTOBUF_C_TYPE_SINT32: {
		const int32_t *arr = (const int32_t *) array;
		for (i = 0; i < count; i++)
			rv += sint32_size(arr[i]);
		break;
	}
	case PROTOBUF_C_TYPE_UINT32: {
		const uint32_t *arr = (const uint32_t *) array;
		for (i = 0; i < count; i++)
			rv += uint32_size(arr[i]);
		break;
	}
	case PROTOBUF_C_TYPE_SINT64: {
		const int64_t *arr = (const int64_t *) array;
		for (i = 0; i < count; i++)
			rv += sint64_size(arr[i]);
		break;
	}
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64: {
		const uint64_t *arr = (const uint64_t *) array;
		for (i = 0; i < count; i++)
			rv += uint64_size(arr[i]);
		break;
	}
	case PROTOBUF_C_TYPE_BOOL:
		return count;
	default:
		PROTOBUF_C__ASSERT_NOT_REACHED();
	}
	return rv;
}

/**
 * Pack an array of same field type to a virtual buffer.
 *
 * \param field
 *      Field descriptor.
 * \param count
 *      Number of elements of this type.
 * \param array
 *      The elements to get the size of.
 * \param[out] buffer
 *      Virtual buffer to append data to.
 * \return
 *      Number of bytes packed.
 */
static size_t
pack_buffer_packed_payload(const ProtobufCFieldDescriptor *field,
			   unsigned count, const void *array,
			   ProtobufCBuffer *buffer)
{
	uint8_t scratch[16];
	size_t rv = 0;
	unsigned i;

	switch (field->type) {
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
#if !defined(WORDS_BIGENDIAN)
		rv = count * 4;
		goto no_packing_needed;
#else
		for (i = 0; i < count; i++) {
			unsigned len = fixed32_pack(((uint32_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
#endif
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
#if !defined(WORDS_BIGENDIAN)
		rv = count * 8;
		goto no_packing_needed;
#else
		for (i = 0; i < count; i++) {
			unsigned len = fixed64_pack(((uint64_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
#endif
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		for (i = 0; i < count; i++) {
			unsigned len = int32_pack(((int32_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
	case PROTOBUF_C_TYPE_SINT32:
		for (i = 0; i < count; i++) {
			unsigned len = sint32_pack(((int32_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
	case PROTOBUF_C_TYPE_UINT32:
		for (i = 0; i < count; i++) {
			unsigned len = uint32_pack(((uint32_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
	case PROTOBUF_C_TYPE_SINT64:
		for (i = 0; i < count; i++) {
			unsigned len = sint64_pack(((int64_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		for (i = 0; i < count; i++) {
			unsigned len = uint64_pack(((uint64_t *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
			rv += len;
		}
		break;
	case PROTOBUF_C_TYPE_BOOL:
		for (i = 0; i < count; i++) {
			unsigned len = boolean_pack(((protobuf_c_boolean *) array)[i], scratch);
			buffer->append(buffer, len, scratch);
		}
		return count;
	default:
		PROTOBUF_C__ASSERT_NOT_REACHED();
	}
	return rv;

#if !defined(WORDS_BIGENDIAN)
no_packing_needed:
	buffer->append(buffer, rv, array);
	return rv;
#endif
}

static size_t
repeated_field_pack_to_buffer(const ProtobufCFieldDescriptor *field,
			      unsigned count, const void *member,
			      ProtobufCBuffer *buffer)
{
	char *array = *(char * const *) member;

	if (count == 0)
		return 0;
	if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED)) {
		uint8_t scratch[MAX_UINT64_ENCODED_SIZE * 2];
		size_t rv = tag_pack(field->id, scratch);
		size_t payload_len = get_packed_payload_length(field, count, array);
		size_t tmp;

		scratch[0] |= PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED;
		rv += uint32_pack(payload_len, scratch + rv);
		buffer->append(buffer, rv, scratch);
		tmp = pack_buffer_packed_payload(field, count, array, buffer);
		assert(tmp == payload_len);
		(void)tmp;
		return rv + payload_len;
	} else {
		size_t siz;
		unsigned i;
		/* CONSIDER: optimize this case a bit (by putting the loop inside the switch) */
		unsigned rv = 0;

		siz = sizeof_elt_in_repeated_array(field->type);
		for (i = 0; i < count; i++) {
			rv += required_field_pack_to_buffer(field, array, buffer);
			array += siz;
		}
		return rv;
	}
}

static size_t
unknown_field_pack_to_buffer(const ProtobufCMessageUnknownField *field,
			     ProtobufCBuffer *buffer)
{
	uint8_t header[MAX_UINT64_ENCODED_SIZE];
	size_t rv = tag_pack(field->tag, header);

	header[0] |= field->wire_type;
	buffer->append(buffer, rv, header);
	buffer->append(buffer, field->len, field->data);
	return rv + field->len;
}

/**@}*/

size_t
protobuf_c_message_pack_to_buffer(const ProtobufCMessage *message,
				  ProtobufCBuffer *buffer)
{
	unsigned i;
	size_t rv = 0;

	ASSERT_IS_MESSAGE(message);
	for (i = 0; i < message->descriptor->n_fields; i++) {
		const ProtobufCFieldDescriptor *field =
			message->descriptor->fields + i;
		const void *member =
			((const char *) message) + field->offset;
		const void *qmember =
			((const char *) message) + field->quantifier_offset;

		if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
			rv += required_field_pack_to_buffer(field, member, buffer);
		} else if ((field->label == PROTOBUF_C_LABEL_OPTIONAL ||
			    field->label == PROTOBUF_C_LABEL_NONE) &&
			   (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF))) {
			rv += oneof_field_pack_to_buffer(
				field,
				*(const uint32_t *) qmember,
				member,
				buffer
			);
		} else if (field->label == PROTOBUF_C_LABEL_OPTIONAL) {
			rv += optional_field_pack_to_buffer(
				field,
				*(const protobuf_c_boolean *) qmember,
				member,
				buffer
			);
		} else if (field->label == PROTOBUF_C_LABEL_NONE) {
			rv += unlabeled_field_pack_to_buffer(
				field,
				member,
				buffer
			);
		} else {
			rv += repeated_field_pack_to_buffer(
				field,
				*(const size_t *) qmember,
				member,
				buffer
			);
		}
	}
	for (i = 0; i < message->n_unknown_fields; i++)
		rv += unknown_field_pack_to_buffer(&message->unknown_fields[i], buffer);

	return rv;
}

/**
 * \defgroup unpack unpacking implementation
 *
 * Routines mainly used by the unpacking functions.
 *
 * \ingroup internal
 * @{
 */

static inline int
int_range_lookup(unsigned n_ranges, const ProtobufCIntRange *ranges, int value)
{
	unsigned n;
	unsigned start;

	if (n_ranges == 0)
		return -1;
	start = 0;
	n = n_ranges;
	while (n > 1) {
		unsigned mid = start + n / 2;

		if (value < ranges[mid].start_value) {
			n = mid - start;
		} else if (value >= ranges[mid].start_value +
			   (int) (ranges[mid + 1].orig_index -
				  ranges[mid].orig_index))
		{
			unsigned new_start = mid + 1;
			n = start + n - new_start;
			start = new_start;
		} else
			return (value - ranges[mid].start_value) +
			    ranges[mid].orig_index;
	}
	if (n > 0) {
		unsigned start_orig_index = ranges[start].orig_index;
		unsigned range_size =
			ranges[start + 1].orig_index - start_orig_index;

		if (ranges[start].start_value <= value &&
		    value < (int) (ranges[start].start_value + range_size))
		{
			return (value - ranges[start].start_value) +
			    start_orig_index;
		}
	}
	return -1;
}

static size_t
parse_tag_and_wiretype(size_t len,
		       const uint8_t *data,
		       uint32_t *tag_out,
		       uint8_t *wiretype_out)
{
	unsigned max_rv = len > 5 ? 5 : len;
	uint32_t tag = (data[0] & 0x7f) >> 3;
	unsigned shift = 4;
	unsigned rv;

	/* 0 is not a valid tag value */
	if ((data[0] & 0xf8) == 0) {
		return 0;
	}

	*wiretype_out = data[0] & 7;
	if ((data[0] & 0x80) == 0) {
		*tag_out = tag;
		return 1;
	}
	for (rv = 1; rv < max_rv; rv++) {
		if (data[rv] & 0x80) {
			tag |= (data[rv] & 0x7f) << shift;
			shift += 7;
		} else {
			tag |= data[rv] << shift;
			*tag_out = tag;
			return rv + 1;
		}
	}
	return 0; /* error: bad header */
}

/* sizeof(ScannedMember) must be <= (1UL<<BOUND_SIZEOF_SCANNED_MEMBER_LOG2) */
#define BOUND_SIZEOF_SCANNED_MEMBER_LOG2 5
typedef struct ScannedMember ScannedMember;
/** Field as it's being read. */
struct ScannedMember {
	uint32_t tag;              /**< Field tag. */
	uint8_t wire_type;         /**< Field type. */
	uint8_t length_prefix_len; /**< Prefix length. */
	const ProtobufCFieldDescriptor *field; /**< Field descriptor. */
	size_t len;                /**< Field length. */
	const uint8_t *data;       /**< Pointer to field data. */
};

static inline size_t
scan_length_prefixed_data(size_t len, const uint8_t *data,
			  size_t *prefix_len_out)
{
	unsigned hdr_max = len < 5 ? len : 5;
	unsigned hdr_len;
	size_t val = 0;
	unsigned i;
	unsigned shift = 0;

	for (i = 0; i < hdr_max; i++) {
		val |= ((size_t)data[i] & 0x7f) << shift;
		shift += 7;
		if ((data[i] & 0x80) == 0)
			break;
	}
	if (i == hdr_max) {
		PROTOBUF_C_UNPACK_ERROR("error parsing length for length-prefixed data");
		return 0;
	}
	hdr_len = i + 1;
	*prefix_len_out = hdr_len;
	if (val > INT_MAX) {
		// Protobuf messages should always be less than 2 GiB in size.
		// We also want to return early here so that hdr_len + val does
		// not overflow on 32-bit systems.
		PROTOBUF_C_UNPACK_ERROR("length prefix of %lu is too large",
			(unsigned long int)val);
		return 0;
	}
	if (hdr_len + val > len) {
		PROTOBUF_C_UNPACK_ERROR("data too short after length-prefix of %lu",
			(unsigned long int)val);
		return 0;
	}
	return hdr_len + val;
}

static size_t
max_b128_numbers(size_t len, const uint8_t *data)
{
	size_t rv = 0;
	while (len--)
		if ((*data++ & 0x80) == 0)
			++rv;
	return rv;
}

/**@}*/

/**
 * Merge earlier message into a latter message.
 *
 * For numeric types and strings, if the same value appears multiple
 * times, the parser accepts the last value it sees. For embedded
 * message fields, the parser merges multiple instances of the same
 * field. That is, all singular scalar fields in the latter instance
 * replace those in the former, singular embedded messages are merged,
 * and repeated fields are concatenated.
 *
 * The earlier message should be freed after calling this function, as
 * some of its fields may have been reused and changed to their default
 * values during the merge.
 */
static protobuf_c_boolean
merge_messages(ProtobufCMessage *earlier_msg,
	       ProtobufCMessage *latter_msg,
	       ProtobufCAllocator *allocator)
{
	unsigned i;
	const ProtobufCFieldDescriptor *fields =
		latter_msg->descriptor->fields;
	for (i = 0; i < latter_msg->descriptor->n_fields; i++) {
		if (fields[i].label == PROTOBUF_C_LABEL_REPEATED) {
			size_t *n_earlier =
				STRUCT_MEMBER_PTR(size_t, earlier_msg,
						  fields[i].quantifier_offset);
			uint8_t **p_earlier =
				STRUCT_MEMBER_PTR(uint8_t *, earlier_msg,
						  fields[i].offset);
			size_t *n_latter =
				STRUCT_MEMBER_PTR(size_t, latter_msg,
						  fields[i].quantifier_offset);
			uint8_t **p_latter =
				STRUCT_MEMBER_PTR(uint8_t *, latter_msg,
						  fields[i].offset);

			if (*n_earlier > 0) {
				if (*n_latter > 0) {
					/* Concatenate the repeated field */
					size_t el_size =
						sizeof_elt_in_repeated_array(fields[i].type);
					uint8_t *new_field;

					new_field = do_alloc(allocator,
						(*n_earlier + *n_latter) * el_size);
					if (!new_field)
						return FALSE;

					memcpy(new_field, *p_earlier,
					       *n_earlier * el_size);
					memcpy(new_field +
					       *n_earlier * el_size,
					       *p_latter,
					       *n_latter * el_size);

					do_free(allocator, *p_latter);
					do_free(allocator, *p_earlier);
					*p_latter = new_field;
					*n_latter = *n_earlier + *n_latter;
				} else {
					/* Zero copy the repeated field from the earlier message */
					*n_latter = *n_earlier;
					*p_latter = *p_earlier;
				}
				/* Make sure the field does not get double freed */
				*n_earlier = 0;
				*p_earlier = 0;
			}
		} else if (fields[i].label == PROTOBUF_C_LABEL_OPTIONAL ||
			   fields[i].label == PROTOBUF_C_LABEL_NONE) {
			const ProtobufCFieldDescriptor *field;
			uint32_t *earlier_case_p = STRUCT_MEMBER_PTR(uint32_t,
								     earlier_msg,
								     fields[i].
								     quantifier_offset);
			uint32_t *latter_case_p = STRUCT_MEMBER_PTR(uint32_t,
								    latter_msg,
								    fields[i].
								    quantifier_offset);
			protobuf_c_boolean need_to_merge = FALSE;
			void *earlier_elem;
			void *latter_elem;
			const void *def_val;

			if (fields[i].flags & PROTOBUF_C_FIELD_FLAG_ONEOF) {
				if (*latter_case_p == 0) {
					/* lookup correct oneof field */
					int field_index =
						int_range_lookup(
							latter_msg->descriptor
							->n_field_ranges,
							latter_msg->descriptor
							->field_ranges,
							*earlier_case_p);
					if (field_index < 0)
						return FALSE;
					field = latter_msg->descriptor->fields +
						field_index;
				} else {
					/* Oneof is present in the latter message, move on */
					continue;
				}
			} else {
				field = &fields[i];
			}

			earlier_elem = STRUCT_MEMBER_P(earlier_msg, field->offset);
			latter_elem = STRUCT_MEMBER_P(latter_msg, field->offset);
			def_val = field->default_value;

			switch (field->type) {
			case PROTOBUF_C_TYPE_MESSAGE: {
				ProtobufCMessage *em = *(ProtobufCMessage **) earlier_elem;
				ProtobufCMessage *lm = *(ProtobufCMessage **) latter_elem;
				if (em != NULL) {
					if (lm != NULL) {
						if (!merge_messages(em, lm, allocator))
							return FALSE;
						/* Already merged */
						need_to_merge = FALSE;
					} else {
						/* Zero copy the message */
						need_to_merge = TRUE;
					}
				}
				break;
			}
			case PROTOBUF_C_TYPE_BYTES: {
				uint8_t *e_data =
					((ProtobufCBinaryData *) earlier_elem)->data;
				uint8_t *l_data =
					((ProtobufCBinaryData *) latter_elem)->data;
				const ProtobufCBinaryData *d_bd =
					(ProtobufCBinaryData *) def_val;

				need_to_merge =
					(e_data != NULL &&
					 (d_bd == NULL ||
					  e_data != d_bd->data)) &&
					(l_data == NULL ||
					 (d_bd != NULL &&
					  l_data == d_bd->data));
				break;
			}
			case PROTOBUF_C_TYPE_STRING: {
				char *e_str = *(char **) earlier_elem;
				char *l_str = *(char **) latter_elem;
				const char *d_str = def_val;

				need_to_merge = e_str != d_str && l_str == d_str;
				break;
			}
			default: {
				/* Could be has field or case enum, the logic is
				 * equivalent, since 0 (FALSE) means not set for
				 * oneof */
				need_to_merge = (*earlier_case_p != 0) &&
						(*latter_case_p == 0);
				break;
			}
			}

			if (need_to_merge) {
				size_t el_size =
					sizeof_elt_in_repeated_array(field->type);
				memcpy(latter_elem, earlier_elem, el_size);
				/*
				 * Reset the element from the old message to 0
				 * to make sure earlier message deallocation
				 * doesn't corrupt zero-copied data in the new
				 * message, earlier message will be freed after
				 * this function is called anyway
				 */
				memset(earlier_elem, 0, el_size);

				if (field->quantifier_offset != 0) {
					/* Set the has field or the case enum,
					 * if applicable */
					*latter_case_p = *earlier_case_p;
					*earlier_case_p = 0;
				}
			}
		}
	}
	return TRUE;
}

/**
 * Count packed elements.
 *
 * Given a raw slab of packed-repeated values, determine the number of
 * elements. This function detects certain kinds of errors but not
 * others; the remaining error checking is done by
 * parse_packed_repeated_member().
 */
static protobuf_c_boolean
count_packed_elements(ProtobufCType type,
		      size_t len, const uint8_t *data, size_t *count_out)
{
	switch (type) {
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		if (len % 4 != 0) {
			PROTOBUF_C_UNPACK_ERROR("length must be a multiple of 4 for fixed-length 32-bit types");
			return FALSE;
		}
		*count_out = len / 4;
		return TRUE;
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		if (len % 8 != 0) {
			PROTOBUF_C_UNPACK_ERROR("length must be a multiple of 8 for fixed-length 64-bit types");
			return FALSE;
		}
		*count_out = len / 8;
		return TRUE;
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
	case PROTOBUF_C_TYPE_SINT32:
	case PROTOBUF_C_TYPE_UINT32:
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_SINT64:
	case PROTOBUF_C_TYPE_UINT64:
		*count_out = max_b128_numbers(len, data);
		return TRUE;
	case PROTOBUF_C_TYPE_BOOL:
		*count_out = len;
		return TRUE;
	case PROTOBUF_C_TYPE_STRING:
	case PROTOBUF_C_TYPE_BYTES:
	case PROTOBUF_C_TYPE_MESSAGE:
	default:
		PROTOBUF_C_UNPACK_ERROR("bad protobuf-c type %u for packed-repeated", type);
		return FALSE;
	}
}

static inline uint32_t
parse_uint32(unsigned len, const uint8_t *data)
{
	uint32_t rv = data[0] & 0x7f;
	if (len > 1) {
		rv |= ((uint32_t) (data[1] & 0x7f) << 7);
		if (len > 2) {
			rv |= ((uint32_t) (data[2] & 0x7f) << 14);
			if (len > 3) {
				rv |= ((uint32_t) (data[3] & 0x7f) << 21);
				if (len > 4)
					rv |= ((uint32_t) (data[4]) << 28);
			}
		}
	}
	return rv;
}

static inline uint32_t
parse_int32(unsigned len, const uint8_t *data)
{
	return parse_uint32(len, data);
}

static inline int32_t
unzigzag32(uint32_t v)
{
	// Note:  Using unsigned types prevents undefined behavior
	return (int32_t)((v >> 1) ^ -(v & 1));
}

static inline uint32_t
parse_fixed_uint32(const uint8_t *data)
{
#if !defined(WORDS_BIGENDIAN)
	uint32_t t;
	memcpy(&t, data, 4);
	return t;
#else
	return data[0] |
		((uint32_t) (data[1]) << 8) |
		((uint32_t) (data[2]) << 16) |
		((uint32_t) (data[3]) << 24);
#endif
}

static uint64_t
parse_uint64(unsigned len, const uint8_t *data)
{
	unsigned shift, i;
	uint64_t rv;

	if (len < 5)
		return parse_uint32(len, data);
	rv = ((uint64_t) (data[0] & 0x7f)) |
		((uint64_t) (data[1] & 0x7f) << 7) |
		((uint64_t) (data[2] & 0x7f) << 14) |
		((uint64_t) (data[3] & 0x7f) << 21);
	shift = 28;
	for (i = 4; i < len; i++) {
		rv |= (((uint64_t) (data[i] & 0x7f)) << shift);
		shift += 7;
	}
	return rv;
}

static inline int64_t
unzigzag64(uint64_t v)
{
	// Note:  Using unsigned types prevents undefined behavior
	return (int64_t)((v >> 1) ^ -(v & 1));
}

static inline uint64_t
parse_fixed_uint64(const uint8_t *data)
{
#if !defined(WORDS_BIGENDIAN)
	uint64_t t;
	memcpy(&t, data, 8);
	return t;
#else
	return (uint64_t) parse_fixed_uint32(data) |
		(((uint64_t) parse_fixed_uint32(data + 4)) << 32);
#endif
}

static protobuf_c_boolean
parse_boolean(unsigned len, const uint8_t *data)
{
	unsigned i;
	for (i = 0; i < len; i++)
		if (data[i] & 0x7f)
			return TRUE;
	return FALSE;
}

static protobuf_c_boolean
parse_required_member(ScannedMember *scanned_member,
		      void *member,
		      ProtobufCAllocator *allocator,
		      protobuf_c_boolean maybe_clear)
{
	unsigned len = scanned_member->len;
	const uint8_t *data = scanned_member->data;
	uint8_t wire_type = scanned_member->wire_type;

	switch (scanned_member->field->type) {
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
			return FALSE;
		*(int32_t *) member = parse_int32(len, data);
		return TRUE;
	case PROTOBUF_C_TYPE_UINT32:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
			return FALSE;
		*(uint32_t *) member = parse_uint32(len, data);
		return TRUE;
	case PROTOBUF_C_TYPE_SINT32:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
			return FALSE;
		*(int32_t *) member = unzigzag32(parse_uint32(len, data));
		return TRUE;
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_32BIT)
			return FALSE;
		*(uint32_t *) member = parse_fixed_uint32(data);
		return TRUE;
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
			return FALSE;
		*(uint64_t *) member = parse_uint64(len, data);
		return TRUE;
	case PROTOBUF_C_TYPE_SINT64:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_VARINT)
			return FALSE;
		*(int64_t *) member = unzigzag64(parse_uint64(len, data));
		return TRUE;
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		if (wire_type != PROTOBUF_C_WIRE_TYPE_64BIT)
			return FALSE;
		*(uint64_t *) member = parse_fixed_uint64(data);
		return TRUE;
	case PROTOBUF_C_TYPE_BOOL:
		*(protobuf_c_boolean *) member = parse_boolean(len, data);
		return TRUE;
	case PROTOBUF_C_TYPE_STRING: {
		char **pstr = member;
		unsigned pref_len = scanned_member->length_prefix_len;

		if (wire_type != PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED)
			return FALSE;

		if (maybe_clear && *pstr != NULL) {
			const char *def = scanned_member->field->default_value;
			if (*pstr != def)
				do_free(allocator, *pstr);
		}
		*pstr = do_alloc(allocator, len - pref_len + 1);
		if (*pstr == NULL)
			return FALSE;
		memcpy(*pstr, data + pref_len, len - pref_len);
		(*pstr)[len - pref_len] = 0;
		return TRUE;
	}
	case PROTOBUF_C_TYPE_BYTES: {
		ProtobufCBinaryData *bd = member;
		const ProtobufCBinaryData *def_bd;
		unsigned pref_len = scanned_member->length_prefix_len;

		if (wire_type != PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED)
			return FALSE;

		def_bd = scanned_member->field->default_value;
		if (maybe_clear &&
		    bd->data != NULL &&
		    (def_bd == NULL || bd->data != def_bd->data))
		{
			do_free(allocator, bd->data);
		}
		if (len > pref_len) {
			bd->data = do_alloc(allocator, len - pref_len);
			if (bd->data == NULL)
				return FALSE;
			memcpy(bd->data, data + pref_len, len - pref_len);
		} else {
			bd->data = NULL;
		}
		bd->len = len - pref_len;
		return TRUE;
	}
	case PROTOBUF_C_TYPE_MESSAGE: {
		ProtobufCMessage **pmessage = member;
		ProtobufCMessage *subm;
		const ProtobufCMessage *def_mess;
		protobuf_c_boolean merge_successful = TRUE;
		unsigned pref_len = scanned_member->length_prefix_len;

		if (wire_type != PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED)
			return FALSE;

		def_mess = scanned_member->field->default_value;
		if (len >= pref_len)
			subm = protobuf_c_message_unpack(scanned_member->field->descriptor,
							 allocator,
							 len - pref_len,
							 data + pref_len);
		else
			subm = NULL;

		if (maybe_clear &&
		    *pmessage != NULL &&
		    *pmessage != def_mess)
		{
			if (subm != NULL)
				merge_successful = merge_messages(*pmessage, subm, allocator);
			/* Delete the previous message */
			protobuf_c_message_free_unpacked(*pmessage, allocator);
		}
		*pmessage = subm;
		if (subm == NULL || !merge_successful)
			return FALSE;
		return TRUE;
	}
	}
	return FALSE;
}

static protobuf_c_boolean
parse_oneof_member (ScannedMember *scanned_member,
		    void *member,
		    ProtobufCMessage *message,
		    ProtobufCAllocator *allocator)
{
	uint32_t *oneof_case = STRUCT_MEMBER_PTR(uint32_t, message,
					       scanned_member->field->quantifier_offset);

	/* If we have already parsed a member of this oneof, free it. */
	if (*oneof_case != 0) {
		const ProtobufCFieldDescriptor *old_field;
		size_t el_size;
		/* lookup field */
		int field_index =
			int_range_lookup(message->descriptor->n_field_ranges,
					 message->descriptor->field_ranges,
					 *oneof_case);
		if (field_index < 0)
			return FALSE;
		old_field = message->descriptor->fields + field_index;
		el_size = sizeof_elt_in_repeated_array(old_field->type);

		switch (old_field->type) {
	        case PROTOBUF_C_TYPE_STRING: {
			char **pstr = member;
			const char *def = old_field->default_value;
			if (*pstr != NULL && *pstr != def)
				do_free(allocator, *pstr);
			break;
	        }
		case PROTOBUF_C_TYPE_BYTES: {
			ProtobufCBinaryData *bd = member;
			const ProtobufCBinaryData *def_bd = old_field->default_value;
			if (bd->data != NULL &&
			   (def_bd == NULL || bd->data != def_bd->data))
			{
				do_free(allocator, bd->data);
			}
			break;
	        }
		case PROTOBUF_C_TYPE_MESSAGE: {
			ProtobufCMessage **pmessage = member;
			const ProtobufCMessage *def_mess = old_field->default_value;
			if (*pmessage != NULL && *pmessage != def_mess)
				protobuf_c_message_free_unpacked(*pmessage, allocator);
			break;
	        }
		default:
			break;
		}

		memset (member, 0, el_size);
	}
	if (!parse_required_member (scanned_member, member, allocator, TRUE))
		return FALSE;

	*oneof_case = scanned_member->tag;
	return TRUE;
}


static protobuf_c_boolean
parse_optional_member(ScannedMember *scanned_member,
		      void *member,
		      ProtobufCMessage *message,
		      ProtobufCAllocator *allocator)
{
	if (!parse_required_member(scanned_member, member, allocator, TRUE))
		return FALSE;
	if (scanned_member->field->quantifier_offset != 0)
		STRUCT_MEMBER(protobuf_c_boolean,
			      message,
			      scanned_member->field->quantifier_offset) = TRUE;
	return TRUE;
}

static protobuf_c_boolean
parse_repeated_member(ScannedMember *scanned_member,
		      void *member,
		      ProtobufCMessage *message,
		      ProtobufCAllocator *allocator)
{
	const ProtobufCFieldDescriptor *field = scanned_member->field;
	size_t *p_n = STRUCT_MEMBER_PTR(size_t, message, field->quantifier_offset);
	size_t siz = sizeof_elt_in_repeated_array(field->type);
	char *array = *(char **) member;

	if (!parse_required_member(scanned_member, array + siz * (*p_n),
				   allocator, FALSE))
	{
		return FALSE;
	}
	*p_n += 1;
	return TRUE;
}

static unsigned
scan_varint(unsigned len, const uint8_t *data)
{
	unsigned i;
	if (len > 10)
		len = 10;
	for (i = 0; i < len; i++)
		if ((data[i] & 0x80) == 0)
			break;
	if (i == len)
		return 0;
	return i + 1;
}

static protobuf_c_boolean
parse_packed_repeated_member(ScannedMember *scanned_member,
			     void *member,
			     ProtobufCMessage *message)
{
	const ProtobufCFieldDescriptor *field = scanned_member->field;
	size_t *p_n = STRUCT_MEMBER_PTR(size_t, message, field->quantifier_offset);
	size_t siz = sizeof_elt_in_repeated_array(field->type);
	void *array = *(char **) member + siz * (*p_n);
	const uint8_t *at = scanned_member->data + scanned_member->length_prefix_len;
	size_t rem = scanned_member->len - scanned_member->length_prefix_len;
	size_t count = 0;
#if defined(WORDS_BIGENDIAN)
	unsigned i;
#endif

	switch (field->type) {
	case PROTOBUF_C_TYPE_SFIXED32:
	case PROTOBUF_C_TYPE_FIXED32:
	case PROTOBUF_C_TYPE_FLOAT:
		count = (scanned_member->len - scanned_member->length_prefix_len) / 4;
#if !defined(WORDS_BIGENDIAN)
		goto no_unpacking_needed;
#else
		for (i = 0; i < count; i++) {
			((uint32_t *) array)[i] = parse_fixed_uint32(at);
			at += 4;
		}
		break;
#endif
	case PROTOBUF_C_TYPE_SFIXED64:
	case PROTOBUF_C_TYPE_FIXED64:
	case PROTOBUF_C_TYPE_DOUBLE:
		count = (scanned_member->len - scanned_member->length_prefix_len) / 8;
#if !defined(WORDS_BIGENDIAN)
		goto no_unpacking_needed;
#else
		for (i = 0; i < count; i++) {
			((uint64_t *) array)[i] = parse_fixed_uint64(at);
			at += 8;
		}
		break;
#endif
	case PROTOBUF_C_TYPE_ENUM:
	case PROTOBUF_C_TYPE_INT32:
		while (rem > 0) {
			unsigned s = scan_varint(rem, at);
			if (s == 0) {
				PROTOBUF_C_UNPACK_ERROR("bad packed-repeated int32 value");
				return FALSE;
			}
			((int32_t *) array)[count++] = parse_int32(s, at);
			at += s;
			rem -= s;
		}
		break;
	case PROTOBUF_C_TYPE_SINT32:
		while (rem > 0) {
			unsigned s = scan_varint(rem, at);
			if (s == 0) {
				PROTOBUF_C_UNPACK_ERROR("bad packed-repeated sint32 value");
				return FALSE;
			}
			((int32_t *) array)[count++] = unzigzag32(parse_uint32(s, at));
			at += s;
			rem -= s;
		}
		break;
	case PROTOBUF_C_TYPE_UINT32:
		while (rem > 0) {
			unsigned s = scan_varint(rem, at);
			if (s == 0) {
				PROTOBUF_C_UNPACK_ERROR("bad packed-repeated enum or uint32 value");
				return FALSE;
			}
			((uint32_t *) array)[count++] = parse_uint32(s, at);
			at += s;
			rem -= s;
		}
		break;

	case PROTOBUF_C_TYPE_SINT64:
		while (rem > 0) {
			unsigned s = scan_varint(rem, at);
			if (s == 0) {
				PROTOBUF_C_UNPACK_ERROR("bad packed-repeated sint64 value");
				return FALSE;
			}
			((int64_t *) array)[count++] = unzigzag64(parse_uint64(s, at));
			at += s;
			rem -= s;
		}
		break;
	case PROTOBUF_C_TYPE_INT64:
	case PROTOBUF_C_TYPE_UINT64:
		while (rem > 0) {
			unsigned s = scan_varint(rem, at);
			if (s == 0) {
				PROTOBUF_C_UNPACK_ERROR("bad packed-repeated int64/uint64 value");
				return FALSE;
			}
			((int64_t *) array)[count++] = parse_uint64(s, at);
			at += s;
			rem -= s;
		}
		break;
	case PROTOBUF_C_TYPE_BOOL:
		while (rem > 0) {
			unsigned s = scan_varint(rem, at);
			if (s == 0) {
				PROTOBUF_C_UNPACK_ERROR("bad packed-repeated boolean value");
				return FALSE;
			}
			((protobuf_c_boolean *) array)[count++] = parse_boolean(s, at);
			at += s;
			rem -= s;
		}
		break;
	default:
		PROTOBUF_C__ASSERT_NOT_REACHED();
	}
	*p_n += count;
	return TRUE;

#if !defined(WORDS_BIGENDIAN)
no_unpacking_needed:
	memcpy(array, at, count * siz);
	*p_n += count;
	return TRUE;
#endif
}

static protobuf_c_boolean
is_packable_type(ProtobufCType type)
{
	return
		type != PROTOBUF_C_TYPE_STRING &&
		type != PROTOBUF_C_TYPE_BYTES &&
		type != PROTOBUF_C_TYPE_MESSAGE;
}

static protobuf_c_boolean
parse_member(ScannedMember *scanned_member,
	     ProtobufCMessage *message,
	     ProtobufCAllocator *allocator)
{
	const ProtobufCFieldDescriptor *field = scanned_member->field;
	void *member;

	if (field == NULL) {
		ProtobufCMessageUnknownField *ufield =
			message->unknown_fields +
			(message->n_unknown_fields++);
		ufield->tag = scanned_member->tag;
		ufield->wire_type = scanned_member->wire_type;
		ufield->len = scanned_member->len;
		ufield->data = do_alloc(allocator, scanned_member->len);
		if (ufield->data == NULL)
			return FALSE;
		memcpy(ufield->data, scanned_member->data, ufield->len);
		return TRUE;
	}
	member = (char *) message + field->offset;
	switch (field->label) {
	case PROTOBUF_C_LABEL_REQUIRED:
		return parse_required_member(scanned_member, member,
					     allocator, TRUE);
	case PROTOBUF_C_LABEL_OPTIONAL:
	case PROTOBUF_C_LABEL_NONE:
		if (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_ONEOF)) {
			return parse_oneof_member(scanned_member, member,
						  message, allocator);
		} else {
			return parse_optional_member(scanned_member, member,
						     message, allocator);
		}
	case PROTOBUF_C_LABEL_REPEATED:
		if (scanned_member->wire_type ==
		    PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED &&
		    (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED) ||
		     is_packable_type(field->type)))
		{
			return parse_packed_repeated_member(scanned_member,
							    member, message);
		} else {
			return parse_repeated_member(scanned_member,
						     member, message,
						     allocator);
		}
	}
	PROTOBUF_C__ASSERT_NOT_REACHED();
	return 0;
}

/**
 * Initialise messages generated by old code.
 *
 * This function is used if desc->message_init == NULL (which occurs
 * for old code, and which would be useful to support allocating
 * descriptors dynamically).
 */
static void
message_init_generic(const ProtobufCMessageDescriptor *desc,
		     ProtobufCMessage *message)
{
	unsigned i;

	memset(message, 0, desc->sizeof_message);
	message->descriptor = desc;
	for (i = 0; i < desc->n_fields; i++) {
		if (desc->fields[i].default_value != NULL &&
		    desc->fields[i].label != PROTOBUF_C_LABEL_REPEATED)
		{
			void *field =
				STRUCT_MEMBER_P(message, desc->fields[i].offset);
			const void *dv = desc->fields[i].default_value;

			switch (desc->fields[i].type) {
			case PROTOBUF_C_TYPE_INT32:
			case PROTOBUF_C_TYPE_SINT32:
			case PROTOBUF_C_TYPE_SFIXED32:
			case PROTOBUF_C_TYPE_UINT32:
			case PROTOBUF_C_TYPE_FIXED32:
			case PROTOBUF_C_TYPE_FLOAT:
			case PROTOBUF_C_TYPE_ENUM:
				memcpy(field, dv, 4);
				break;
			case PROTOBUF_C_TYPE_INT64:
			case PROTOBUF_C_TYPE_SINT64:
			case PROTOBUF_C_TYPE_SFIXED64:
			case PROTOBUF_C_TYPE_UINT64:
			case PROTOBUF_C_TYPE_FIXED64:
			case PROTOBUF_C_TYPE_DOUBLE:
				memcpy(field, dv, 8);
				break;
			case PROTOBUF_C_TYPE_BOOL:
				memcpy(field, dv, sizeof(protobuf_c_boolean));
				break;
			case PROTOBUF_C_TYPE_BYTES:
				memcpy(field, dv, sizeof(ProtobufCBinaryData));
				break;

			case PROTOBUF_C_TYPE_STRING:
			case PROTOBUF_C_TYPE_MESSAGE:
				/*
				 * The next line essentially implements a cast
				 * from const, which is totally unavoidable.
				 */
				*(const void **) field = dv;
				break;
			}
		}
	}
}

/**@}*/

/*
 * ScannedMember slabs (an unpacking implementation detail). Before doing real
 * unpacking, we first scan through the elements to see how many there are (for
 * repeated fields), and which field to use (for non-repeated fields given
 * twice).
 *
 * In order to avoid allocations for small messages, we keep a stack-allocated
 * slab of ScannedMembers of size FIRST_SCANNED_MEMBER_SLAB_SIZE (16). After we
 * fill that up, we allocate each slab twice as large as the previous one.
 */
#define FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2 4

/*
 * The number of slabs, including the stack-allocated ones; choose the number so
 * that we would overflow if we needed a slab larger than provided.
 */
#define MAX_SCANNED_MEMBER_SLAB			\
  (sizeof(unsigned int)*8 - 1			\
   - BOUND_SIZEOF_SCANNED_MEMBER_LOG2		\
   - FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2)

#define REQUIRED_FIELD_BITMAP_SET(index)	\
	(required_fields_bitmap[(index)/8] |= (1UL<<((index)%8)))

#define REQUIRED_FIELD_BITMAP_IS_SET(index)	\
	(required_fields_bitmap[(index)/8] & (1UL<<((index)%8)))

ProtobufCMessage *
protobuf_c_message_unpack(const ProtobufCMessageDescriptor *desc,
			  ProtobufCAllocator *allocator,
			  size_t len, const uint8_t *data)
{
	ProtobufCMessage *rv;
	size_t rem = len;
	const uint8_t *at = data;
	const ProtobufCFieldDescriptor *last_field = desc->fields + 0;
	ScannedMember first_member_slab[1UL <<
					FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2];

	/*
	 * scanned_member_slabs[i] is an array of arrays of ScannedMember.
	 * The first slab (scanned_member_slabs[0] is just a pointer to
	 * first_member_slab), above. All subsequent slabs will be allocated
	 * using the allocator.
	 */
	ScannedMember *scanned_member_slabs[MAX_SCANNED_MEMBER_SLAB + 1];
	unsigned which_slab = 0; /* the slab we are currently populating */
	unsigned in_slab_index = 0; /* number of members in the slab */
	size_t n_unknown = 0;
	unsigned f;
	unsigned j;
	unsigned i_slab;
	unsigned last_field_index = 0;
	unsigned required_fields_bitmap_len;
	unsigned char required_fields_bitmap_stack[16];
	unsigned char *required_fields_bitmap = required_fields_bitmap_stack;
	protobuf_c_boolean required_fields_bitmap_alloced = FALSE;

	ASSERT_IS_MESSAGE_DESCRIPTOR(desc);

	if (allocator == NULL)
		allocator = &protobuf_c__allocator;

	rv = do_alloc(allocator, desc->sizeof_message);
	if (!rv)
		return (NULL);
	scanned_member_slabs[0] = first_member_slab;

	required_fields_bitmap_len = (desc->n_fields + 7) / 8;
	if (required_fields_bitmap_len > sizeof(required_fields_bitmap_stack)) {
		required_fields_bitmap = do_alloc(allocator, required_fields_bitmap_len);
		if (!required_fields_bitmap) {
			do_free(allocator, rv);
			return (NULL);
		}
		required_fields_bitmap_alloced = TRUE;
	}
	memset(required_fields_bitmap, 0, required_fields_bitmap_len);

	/*
	 * Generated code always defines "message_init". However, we provide a
	 * fallback for (1) users of old protobuf-c generated-code that do not
	 * provide the function, and (2) descriptors constructed from some other
	 * source (most likely, direct construction from the .proto file).
	 */
	if (desc->message_init != NULL)
		protobuf_c_message_init(desc, rv);
	else
		message_init_generic(desc, rv);

	while (rem > 0) {
		uint32_t tag;
		uint8_t wire_type;
		size_t used = parse_tag_and_wiretype(rem, at, &tag, &wire_type);
		const ProtobufCFieldDescriptor *field;
		ScannedMember tmp;

		if (used == 0) {
			PROTOBUF_C_UNPACK_ERROR("error parsing tag/wiretype at offset %u",
						(unsigned) (at - data));
			goto error_cleanup_during_scan;
		}
		/*
		 * \todo Consider optimizing for field[1].id == tag, if field[1]
		 * exists!
		 */
		if (last_field == NULL || last_field->id != tag) {
			/* lookup field */
			int field_index =
			    int_range_lookup(desc->n_field_ranges,
					     desc->field_ranges,
					     tag);
			if (field_index < 0) {
				field = NULL;
				n_unknown++;
			} else {
				field = desc->fields + field_index;
				last_field = field;
				last_field_index = field_index;
			}
		} else {
			field = last_field;
		}

		if (field != NULL && field->label == PROTOBUF_C_LABEL_REQUIRED)
			REQUIRED_FIELD_BITMAP_SET(last_field_index);

		at += used;
		rem -= used;
		tmp.tag = tag;
		tmp.wire_type = wire_type;
		tmp.field = field;
		tmp.data = at;
		tmp.length_prefix_len = 0;

		switch (wire_type) {
		case PROTOBUF_C_WIRE_TYPE_VARINT: {
			unsigned max_len = rem < 10 ? rem : 10;
			unsigned i;

			for (i = 0; i < max_len; i++)
				if ((at[i] & 0x80) == 0)
					break;
			if (i == max_len) {
				PROTOBUF_C_UNPACK_ERROR("unterminated varint at offset %u",
							(unsigned) (at - data));
				goto error_cleanup_during_scan;
			}
			tmp.len = i + 1;
			break;
		}
		case PROTOBUF_C_WIRE_TYPE_64BIT:
			if (rem < 8) {
				PROTOBUF_C_UNPACK_ERROR("too short after 64bit wiretype at offset %u",
							(unsigned) (at - data));
				goto error_cleanup_during_scan;
			}
			tmp.len = 8;
			break;
		case PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED: {
			size_t pref_len;

			tmp.len = scan_length_prefixed_data(rem, at, &pref_len);
			if (tmp.len == 0) {
				/* NOTE: scan_length_prefixed_data calls UNPACK_ERROR */
				goto error_cleanup_during_scan;
			}
			tmp.length_prefix_len = pref_len;
			break;
		}
		case PROTOBUF_C_WIRE_TYPE_32BIT:
			if (rem < 4) {
				PROTOBUF_C_UNPACK_ERROR("too short after 32bit wiretype at offset %u",
					      (unsigned) (at - data));
				goto error_cleanup_during_scan;
			}
			tmp.len = 4;
			break;
		default:
			PROTOBUF_C_UNPACK_ERROR("unsupported tag %u at offset %u",
						wire_type, (unsigned) (at - data));
			goto error_cleanup_during_scan;
		}

		if (in_slab_index == (1UL <<
			(which_slab + FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2)))
		{
			size_t size;

			in_slab_index = 0;
			if (which_slab == MAX_SCANNED_MEMBER_SLAB) {
				PROTOBUF_C_UNPACK_ERROR("too many fields");
				goto error_cleanup_during_scan;
			}
			which_slab++;
			size = sizeof(ScannedMember)
				<< (which_slab + FIRST_SCANNED_MEMBER_SLAB_SIZE_LOG2);
			scanned_member_slabs[which_slab] = do_alloc(allocator, size);
			if (scanned_member_slabs[which_slab] == NULL)
				goto error_cleanup_during_scan;
		}
		scanned_member_slabs[which_slab][in_slab_index++] = tmp;

		if (field != NULL && field->label == PROTOBUF_C_LABEL_REPEATED) {
			size_t *n = STRUCT_MEMBER_PTR(size_t, rv,
						      field->quantifier_offset);
			if (wire_type == PROTOBUF_C_WIRE_TYPE_LENGTH_PREFIXED &&
			    (0 != (field->flags & PROTOBUF_C_FIELD_FLAG_PACKED) ||
			     is_packable_type(field->type)))
			{
				size_t count;
				if (!count_packed_elements(field->type,
							   tmp.len -
							   tmp.length_prefix_len,
							   tmp.data +
							   tmp.length_prefix_len,
							   &count))
				{
					PROTOBUF_C_UNPACK_ERROR("counting packed elements");
					goto error_cleanup_during_scan;
				}
				*n += count;
			} else {
				*n += 1;
			}
		}

		at += tmp.len;
		rem -= tmp.len;
	}

	/* allocate space for repeated fields, also check that all required fields have been set */
	for (f = 0; f < desc->n_fields; f++) {
		const ProtobufCFieldDescriptor *field = desc->fields + f;
		if (field == NULL) {
			continue;
		}
		if (field->label == PROTOBUF_C_LABEL_REPEATED) {
			size_t siz =
			    sizeof_elt_in_repeated_array(field->type);
			size_t *n_ptr =
			    STRUCT_MEMBER_PTR(size_t, rv,
					      field->quantifier_offset);
			if (*n_ptr != 0) {
				unsigned n = *n_ptr;
				void *a;
				*n_ptr = 0;
				assert(rv->descriptor != NULL);
#define CLEAR_REMAINING_N_PTRS()                                              \
              for(f++;f < desc->n_fields; f++)                                \
                {                                                             \
                  field = desc->fields + f;                                   \
                  if (field->label == PROTOBUF_C_LABEL_REPEATED)              \
                    STRUCT_MEMBER (size_t, rv, field->quantifier_offset) = 0; \
                }
				a = do_alloc(allocator, siz * n);
				if (!a) {
					CLEAR_REMAINING_N_PTRS();
					goto error_cleanup;
				}
				STRUCT_MEMBER(void *, rv, field->offset) = a;
			}
		} else if (field->label == PROTOBUF_C_LABEL_REQUIRED) {
			if (field->default_value == NULL &&
			    !REQUIRED_FIELD_BITMAP_IS_SET(f))
			{
				CLEAR_REMAINING_N_PTRS();
				PROTOBUF_C_UNPACK_ERROR("message '%s': missing required field '%s'",
							desc->name, field->name);
				goto error_cleanup;
			}
		}
	}
#undef CLEAR_REMAINING_N_PTRS

	/* allocate space for unknown fields */
	if (n_unknown) {
		rv->unknown_fields = do_alloc(allocator,
					      n_unknown * sizeof(ProtobufCMessageUnknownField));
		if (rv->unknown_fields == NULL)
			goto error_cleanup;
	} else {
		rv->unknown_fields = NULL;
	}

	/* do real parsing */
	for (i_slab = 0; i_slab <= which_slab; i_slab++) {
		unsigned max = (i_slab == which_slab) ?
			in_slab_index : (1UL << (i_slab + 4));
		ScannedMember *slab = scanned_member_slabs[i_slab];

		for (j = 0; j < max; j++) {
			if (!parse_member(slab + j, rv, allocator)) {
				PROTOBUF_C_UNPACK_ERROR("error parsing member %s of %s",
							slab->field ? slab->field->name : "*unknown-field*",
					desc->name);
				goto error_cleanup;
			}
		}
	}

	/* cleanup */
	for (j = 1; j <= which_slab; j++)
		do_free(allocator, scanned_member_slabs[j]);
	if (required_fields_bitmap_alloced)
		do_free(allocator, required_fields_bitmap);
	return rv;

error_cleanup:
	protobuf_c_message_free_unpacked(rv, allocator);
	for (j = 1; j <= which_slab; j++)
		do_free(allocator, scanned_member_slabs[j]);
	if (required_fields_bitmap_alloced)
		do_free(allocator, required_fields_bitmap);
	return NULL;

error_cleanup_during_scan:
	do_free(allocator, rv);
	for (j = 1; j <= which_slab; j++)
		do_free(allocator, scanned_member_slabs[j]);
	if (required_fields_bitmap_alloced)
		do_free(allocator, required_fields_bitmap);
	return NULL;
}

void
protobuf_c_message_free_unpacked(ProtobufCMessage *message,
				 ProtobufCAllocator *allocator)
{
	const ProtobufCMessageDescriptor *desc;
	unsigned f;

	if (message == NULL)
		return;

	desc = message->descriptor;

	ASSERT_IS_MESSAGE(message);

	if (allocator == NULL)
		allocator = &protobuf_c__allocator;
	message->descriptor = NULL;
	for (f = 0; f < desc->n_fields; f++) {
		if (0 != (desc->fields[f].flags & PROTOBUF_C_FIELD_FLAG_ONEOF) &&
		    desc->fields[f].id !=
		    STRUCT_MEMBER(uint32_t, message, desc->fields[f].quantifier_offset))
		{
			/* This is not the selected oneof, skip it */
			continue;
		}

		if (desc->fields[f].label == PROTOBUF_C_LABEL_REPEATED) {
			size_t n = STRUCT_MEMBER(size_t,
						 message,
						 desc->fields[f].quantifier_offset);
			void *arr = STRUCT_MEMBER(void *,
						  message,
						  desc->fields[f].offset);

			if (arr != NULL) {
				if (desc->fields[f].type == PROTOBUF_C_TYPE_STRING) {
					unsigned i;
					for (i = 0; i < n; i++)
						do_free(allocator, ((char **) arr)[i]);
				} else if (desc->fields[f].type == PROTOBUF_C_TYPE_BYTES) {
					unsigned i;
					for (i = 0; i < n; i++)
						do_free(allocator, ((ProtobufCBinaryData *) arr)[i].data);
				} else if (desc->fields[f].type == PROTOBUF_C_TYPE_MESSAGE) {
					unsigned i;
					for (i = 0; i < n; i++)
						protobuf_c_message_free_unpacked(
							((ProtobufCMessage **) arr)[i],
							allocator
						);
				}
				do_free(allocator, arr);
			}
		} else if (desc->fields[f].type == PROTOBUF_C_TYPE_STRING) {
			char *str = STRUCT_MEMBER(char *, message,
						  desc->fields[f].offset);

			if (str && str != desc->fields[f].default_value)
				do_free(allocator, str);
		} else if (desc->fields[f].type == PROTOBUF_C_TYPE_BYTES) {
			void *data = STRUCT_MEMBER(ProtobufCBinaryData, message,
						   desc->fields[f].offset).data;
			const ProtobufCBinaryData *default_bd;

			default_bd = desc->fields[f].default_value;
			if (data != NULL &&
			    (default_bd == NULL ||
			     default_bd->data != data))
			{
				do_free(allocator, data);
			}
		} else if (desc->fields[f].type == PROTOBUF_C_TYPE_MESSAGE) {
			ProtobufCMessage *sm;

			sm = STRUCT_MEMBER(ProtobufCMessage *, message,
					   desc->fields[f].offset);
			if (sm && sm != desc->fields[f].default_value)
				protobuf_c_message_free_unpacked(sm, allocator);
		}
	}

	for (f = 0; f < message->n_unknown_fields; f++)
		do_free(allocator, message->unknown_fields[f].data);
	if (message->unknown_fields != NULL)
		do_free(allocator, message->unknown_fields);

	do_free(allocator, message);
}

void
protobuf_c_message_init(const ProtobufCMessageDescriptor * descriptor,
			void *message)
{
	descriptor->message_init((ProtobufCMessage *) (message));
}

protobuf_c_boolean
protobuf_c_message_check(const ProtobufCMessage *message)
{
	unsigned i;

	if (!message ||
	    !message->descriptor ||
	    message->descriptor->magic != PROTOBUF_C__MESSAGE_DESCRIPTOR_MAGIC)
	{
		return FALSE;
	}

	for (i = 0; i < message->descriptor->n_fields; i++) {
		const ProtobufCFieldDescriptor *f = message->descriptor->fields + i;
		ProtobufCType type = f->type;
		ProtobufCLabel label = f->label;
		void *field = STRUCT_MEMBER_P (message, f->offset);

		if (f->flags & PROTOBUF_C_FIELD_FLAG_ONEOF) {
			const uint32_t *oneof_case = STRUCT_MEMBER_P (message, f->quantifier_offset);
			if (f->id != *oneof_case) {
				continue; //Do not check if it is an unpopulated oneof member.
			}
		}

		if (label == PROTOBUF_C_LABEL_REPEATED) {
			size_t *quantity = STRUCT_MEMBER_P (message, f->quantifier_offset);

			if (*quantity > 0 && *(void **) field == NULL) {
				return FALSE;
			}

			if (type == PROTOBUF_C_TYPE_MESSAGE) {
				ProtobufCMessage **submessage = *(ProtobufCMessage ***) field;
				unsigned j;
				for (j = 0; j < *quantity; j++) {
					if (!protobuf_c_message_check(submessage[j]))
						return FALSE;
				}
			} else if (type == PROTOBUF_C_TYPE_STRING) {
				char **string = *(char ***) field;
				unsigned j;
				for (j = 0; j < *quantity; j++) {
					if (!string[j])
						return FALSE;
				}
			} else if (type == PROTOBUF_C_TYPE_BYTES) {
				ProtobufCBinaryData *bd = *(ProtobufCBinaryData **) field;
				unsigned j;
				for (j = 0; j < *quantity; j++) {
					if (bd[j].len > 0 && bd[j].data == NULL)
						return FALSE;
				}
			}

		} else { /* PROTOBUF_C_LABEL_REQUIRED or PROTOBUF_C_LABEL_OPTIONAL */

			if (type == PROTOBUF_C_TYPE_MESSAGE) {
				ProtobufCMessage *submessage = *(ProtobufCMessage **) field;
				if (label == PROTOBUF_C_LABEL_REQUIRED || submessage != NULL) {
					if (!protobuf_c_message_check(submessage))
						return FALSE;
				}
			} else if (type == PROTOBUF_C_TYPE_STRING) {
				char *string = *(char **) field;
				if (label == PROTOBUF_C_LABEL_REQUIRED && string == NULL)
					return FALSE;
			} else if (type == PROTOBUF_C_TYPE_BYTES) {
				protobuf_c_boolean *has = STRUCT_MEMBER_P (message, f->quantifier_offset);
				ProtobufCBinaryData *bd = field;
				if (label == PROTOBUF_C_LABEL_REQUIRED || *has == TRUE) {
					if (bd->len > 0 && bd->data == NULL)
						return FALSE;
				}
			}
		}
	}

	return TRUE;
}

/* === services === */

typedef void (*GenericHandler) (void *service,
				const ProtobufCMessage *input,
				ProtobufCClosure closure,
				void *closure_data);
void
protobuf_c_service_invoke_internal(ProtobufCService *service,
				   unsigned method_index,
				   const ProtobufCMessage *input,
				   ProtobufCClosure closure,
				   void *closure_data)
{
	GenericHandler *handlers;
	GenericHandler handler;

	/*
	 * Verify that method_index is within range. If this fails, you are
	 * likely invoking a newly added method on an old service. (Although
	 * other memory corruption bugs can cause this assertion too.)
	 */
	assert(method_index < service->descriptor->n_methods);

	/*
	 * Get the array of virtual methods (which are enumerated by the
	 * generated code).
	 */
	handlers = (GenericHandler *) (service + 1);

	/*
	 * Get our method and invoke it.
	 * \todo Seems like handler == NULL is a situation that needs handling.
	 */
	handler = handlers[method_index];
	(*handler)(service, input, closure, closure_data);
}

void
protobuf_c_service_generated_init(ProtobufCService *service,
				  const ProtobufCServiceDescriptor *descriptor,
				  ProtobufCServiceDestroy destroy)
{
	ASSERT_IS_SERVICE_DESCRIPTOR(descriptor);
	service->descriptor = descriptor;
	service->destroy = destroy;
	service->invoke = protobuf_c_service_invoke_internal;
	memset(&service[1], 0, descriptor->n_methods * sizeof(GenericHandler));
}

void protobuf_c_service_destroy(ProtobufCService *service)
{
	service->destroy(service);
}

/* --- querying the descriptors --- */

const ProtobufCEnumValue *
protobuf_c_enum_descriptor_get_value_by_name(const ProtobufCEnumDescriptor *desc,
					     const char *name)
{
	unsigned start = 0;
	unsigned count;

	if (desc == NULL || desc->values_by_name == NULL)
		return NULL;

	count = desc->n_value_names;

	while (count > 1) {
		unsigned mid = start + count / 2;
		int rv = strcmp(desc->values_by_name[mid].name, name);
		if (rv == 0)
			return desc->values + desc->values_by_name[mid].index;
		else if (rv < 0) {
			count = start + count - (mid + 1);
			start = mid + 1;
		} else
			count = mid - start;
	}
	if (count == 0)
		return NULL;
	if (strcmp(desc->values_by_name[start].name, name) == 0)
		return desc->values + desc->values_by_name[start].index;
	return NULL;
}

const ProtobufCEnumValue *
protobuf_c_enum_descriptor_get_value(const ProtobufCEnumDescriptor *desc,
				     int value)
{
	int rv = int_range_lookup(desc->n_value_ranges, desc->value_ranges, value);
	if (rv < 0)
		return NULL;
	return desc->values + rv;
}

const ProtobufCFieldDescriptor *
protobuf_c_message_descriptor_get_field_by_name(const ProtobufCMessageDescriptor *desc,
						const char *name)
{
	unsigned start = 0;
	unsigned count;
	const ProtobufCFieldDescriptor *field;

	if (desc == NULL || desc->fields_sorted_by_name == NULL)
		return NULL;

	count = desc->n_fields;

	while (count > 1) {
		unsigned mid = start + count / 2;
		int rv;
		field = desc->fields + desc->fields_sorted_by_name[mid];
		rv = strcmp(field->name, name);
		if (rv == 0)
			return field;
		else if (rv < 0) {
			count = start + count - (mid + 1);
			start = mid + 1;
		} else
			count = mid - start;
	}
	if (count == 0)
		return NULL;
	field = desc->fields + desc->fields_sorted_by_name[start];
	if (strcmp(field->name, name) == 0)
		return field;
	return NULL;
}

const ProtobufCFieldDescriptor *
protobuf_c_message_descriptor_get_field(const ProtobufCMessageDescriptor *desc,
					unsigned value)
{
	int rv = int_range_lookup(desc->n_field_ranges,desc->field_ranges, value);
	if (rv < 0)
		return NULL;
	return desc->fields + rv;
}

const ProtobufCMethodDescriptor *
protobuf_c_service_descriptor_get_method_by_name(const ProtobufCServiceDescriptor *desc,
						 const char *name)
{
	unsigned start = 0;
	unsigned count;

	if (desc == NULL || desc->method_indices_by_name == NULL)
		return NULL;

	count = desc->n_methods;

	while (count > 1) {
		unsigned mid = start + count / 2;
		unsigned mid_index = desc->method_indices_by_name[mid];
		const char *mid_name = desc->methods[mid_index].name;
		int rv = strcmp(mid_name, name);

		if (rv == 0)
			return desc->methods + desc->method_indices_by_name[mid];
		if (rv < 0) {
			count = start + count - (mid + 1);
			start = mid + 1;
		} else {
			count = mid - start;
		}
	}
	if (count == 0)
		return NULL;
	if (strcmp(desc->methods[desc->method_indices_by_name[start]].name, name) == 0)
		return desc->methods + desc->method_indices_by_name[start];
	return NULL;
}
