Basic non-portable example of serialization in C using void* buffers

serialize.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#define BUFFER_INIT 32

typedef struct SerializedBuffer
{
	void* data;
	size_t index;
	size_t size;
	size_t read;
} SerializedBuffer;

SerializedBuffer* makeBuffer()
{
	SerializedBuffer* buffer = malloc(sizeof(SerializedBuffer));

	buffer->data = malloc(BUFFER_INIT);
	buffer->size = BUFFER_INIT;
	buffer->index = 0;
	buffer->read = 0;

	return buffer;
}

void padBuffer(SerializedBuffer* buffer, size_t bytes)
{
	if ((buffer->index + bytes) > buffer->size)
	{
		buffer->data = realloc(buffer->data, buffer->size * 2);
		buffer->size *= 2;
	}
}

void pack_int(SerializedBuffer *buffer, int x)
{
	padBuffer(buffer, sizeof(int));

	memcpy(((char*)buffer->data) + buffer->index, &x, sizeof(int));
	buffer->index += sizeof(int);
}

void pack_string(SerializedBuffer *buffer, char *text)
{
	size_t len = strlen(text) + 1;

	padBuffer(buffer, sizeof(char) * len);

	memcpy(((char*)buffer->data) + buffer->index, text, sizeof(char) * len);
	buffer->index += sizeof(char) * len;
}

int unpack_int(SerializedBuffer* buffer)
{
	int out;

	memcpy(&out, ((char*)buffer->data) + (buffer->read), sizeof(int));
	buffer->read += sizeof(int);

	return out;
}

char* unpack_string(SerializedBuffer* buffer)
{
	int size = 32;
	char* out = malloc(sizeof(char) * size);
	int i = 0;
	char c;

	while ((c = ((char*)buffer->data)[buffer->read++]) != '\0')
	{
		out[i++] = c;

		if (i > size)
		{
			out = realloc(out, size * 2);
			size *= 2;
		}
	}

	out[i] = '\0';

	out = realloc(out, i + 1);

	return out;
}

typedef struct test
{
	int x;
	char* y;
} test;

SerializedBuffer* pack_test(test* obj)
{
	SerializedBuffer* buffer = makeBuffer();

	pack_int(buffer, obj->x);
	pack_string(buffer, obj->y);

	return buffer;
}

int unpack_test(SerializedBuffer* buffer, test* out)
{
	out->x = unpack_int(buffer);
	out->y = unpack_string(buffer);

	return 1;
}

int main()
{
	test start = {3, "1"};

	SerializedBuffer* buffer = pack_test(&start);

	test out;

	unpack_test(buffer, &out);

	printf("%d\n", buffer->size);

	return 0;
}