/* mdXhl.c * ----------------------------------------------------------------------------
 * "THE BEER-WARE LICENSE" (Revision 42):
 * <phk@FreeBSD.org> wrote this file.  As long as you retain this notice you
 * can do whatever you want with this stuff. If we meet some day, and you think
 * this stuff is worth it, you can buy me a beer in return.   Poul-Henning Kamp
 * ----------------------------------------------------------------------------
 * libjpeg-turbo Modifications:
 * Copyright (C) 2016, D. R. Commander.
 * Modifications are under the same license as the original code (see above)
 * ----------------------------------------------------------------------------
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#ifdef _WIN32
#include <io.h>
#define close _close
#define fstat _fstat
#define lseek _lseek
#define read _read
#define stat _stat
#else

#include <unistd.h>

#endif

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

#define LENGTH 16

#include "./md5.h"

char *
MD5End(MD5_CTX *ctx, char *buf) {
	int i;
	unsigned char digest[LENGTH];
	static const char hex[] = "0123456789abcdef";

	if (!buf)
		buf = malloc(2 * LENGTH + 1);
	if (!buf)
		return 0;
	MD5Final(digest, ctx);
	for (i = 0; i < LENGTH; i++) {
		buf[i + i] = hex[digest[i] >> 4];
		buf[i + i + 1] = hex[digest[i] & 0x0f];
	}
	buf[i + i] = '\0';
	return buf;
}

char *
MD5File(const char *filename, char *buf) {
	return (MD5FileChunk(filename, buf, 0, 0));
}

char *
MD5FileChunk(const char *filename, char *buf, off_t ofs, off_t len) {
	unsigned char buffer[BUFSIZ];
	MD5_CTX ctx;
	struct stat stbuf;
	int f, i, e;
	off_t n;

	MD5Init(&ctx);
#if _WIN32
	f = _open(filename, O_RDONLY|O_BINARY);
#else
	f = open(filename, O_RDONLY);
#endif
	if (f < 0)
		return 0;
	if (fstat(f, &stbuf) < 0)
		return 0;
	if (ofs > stbuf.st_size)
		ofs = stbuf.st_size;
	if ((len == 0) || (len > stbuf.st_size - ofs))
		len = stbuf.st_size - ofs;
	if (lseek(f, ofs, SEEK_SET) < 0)
		return 0;
	n = len;
	i = 0;
	while (n > 0) {
		if (n > sizeof(buffer))
			i = read(f, buffer, sizeof(buffer));
		else
			i = read(f, buffer, n);
		if (i < 0)
			break;
		MD5Update(&ctx, buffer, i);
		n -= i;
	}
	e = errno;
	close(f);
	errno = e;
	if (i < 0)
		return 0;
	return (MD5End(&ctx, buf));
}

char *
MD5Data(const void *data, unsigned int len, char *buf) {
	MD5_CTX ctx;

	MD5Init(&ctx);
	MD5Update(&ctx, data, len);
	return (MD5End(&ctx, buf));
}
