/* this is a cleaned-up version of
 * http://adamlamers.com/?p=5
 */

#include <stdio.h>
#include <malloc.h>
#include <errno.h>

#include "checksum.h"

void
sha256_hash_string (unsigned char hash[SHA256_DIGEST_LENGTH], char outputBuffer[65])
{
	int i = 0;
	for (i = 0; i < SHA256_DIGEST_LENGTH; i++)
	{
		sprintf(outputBuffer + (i * 2), "%02x", hash[i]);
	}
	outputBuffer[64] = 0;
}

void
sha256 (char *string, char outputBuffer[65])
{
	int i;
	unsigned char hash[SHA256_DIGEST_LENGTH];
	SHA256_CTX sha256;

	SHA256_Init (&sha256);
	SHA256_Update (&sha256, string, strlen(string));
	SHA256_Final (hash, &sha256);

	for (i = 0; i < SHA256_DIGEST_LENGTH; i++)
	{
		sprintf (outputBuffer + (i * 2), "%02x", hash[i]);
	}
	outputBuffer[64] = 0;
}

int
sha256_file (char *path, char outputBuffer[65])
{
	int bytesRead;
	unsigned char *buffer;
	unsigned char hash[SHA256_DIGEST_LENGTH];
	SHA256_CTX sha256;

	FILE *file = fopen (path, "rb");
	if (!file)
	{
		return -534;
	}

	SHA256_Init (&sha256);
	buffer = malloc (BUFSIZE);
	bytesRead = 0;

	if (!buffer)
	{
		return ENOMEM;
	}

	while ((bytesRead = fread (buffer, 1, BUFSIZE, file)))
	{
		SHA256_Update (&sha256, buffer, bytesRead);
    }

    SHA256_Final (hash, &sha256);
    sha256_hash_string (hash, outputBuffer);

	fclose (file);
    free (buffer);
    return 0;
}