Write variables to file and read file to variable, easily.

file-buffer.c

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

void *ftob(const char *file, unsigned int *size, ...) {
	FILE *fp;
	unsigned char *buffer;
	long int _size;

	if ((fp = fopen(file, "rb")) == NULL) {
		fprintf(stderr, "ERROR: Could not open '%s'\n", file);
		return NULL;
	}
	
	if (fseek(fp, 0, SEEK_END) != 0) {
		fprintf(stderr, "ERROR: Could not set cursor to end of '%s'.\n", file);
		return NULL;
	}

	if ((_size = ftell(fp)) == -1) {
		fprintf(stderr, "ERROR: Could not get cursor position of '%s'.\n", file);
		return NULL;
	}

	if (fseek(fp, 0, SEEK_SET) != 0) {
		fprintf(stderr, "ERROR: Could not set cursor to end of '%s'.\n", file);
		return NULL;
	}

	if ((buffer = malloc(sizeof(char) * _size + sizeof(char))) == NULL) {
		fprintf(stderr, "ERROR: Could not allocate %li bytes to hold file content.\n", _size);
		fclose(fp);
		return NULL;
	}

	if (fread(buffer, 1, _size, fp) != (unsigned)_size) {
		fprintf(stderr, "ERROR: Could not read %li bytes from file.\n", _size);
		fclose(fp);
		return NULL;
	}
	
	buffer[_size] = 0;
	
	fclose(fp);

	if (size) *size = _size;

	return buffer;
}

#define ftob(...) ftob(__VA_ARGS__, 0)

int btof(const char *file, void *data, unsigned int size) {
	FILE *fp;
	unsigned int amount;
	
	if ((fp = fopen(file, "wb")) == NULL) return -1;
	
	amount = fwrite(data, size, 1, fp);
	
	fclose(fp);
	
	return amount;
}

/*///////////////////////////////////
	
		Testing:
		
///////////////////////////////////*/

int main(void) {
	unsigned int size = -1;
	char *file = ftob("file.txt", &size);

	printf("Size: %i\n", size);
	printf("Content: [%s]\n", file);
	
	return 0;
}