Centaur | Reader

Reader (md5.c) https://centaur.pw/software/md5/md5.c [Direct Link]
/* Centaur MD5
 *
 * Version 3.0
 * 4/7/2024
 *
 * Functions for checking MD5 sums of files and strings
 *
 * md5.c
 */

#include <ctype.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <openssl/md5.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/mman.h>

#include "md5.h"

int hashcompare(char hash1[MD5_STRING_LENGTH], char hash2[MD5_STRING_LENGTH])
{
	char _hash1[MD5_STRING_LENGTH];
	char _hash2[MD5_STRING_LENGTH];
	int a;
	for (a = 0; a < MD5_STRING_LENGTH; a++)
	{
		_hash1[a] = tolower(hash1[a]);
	}
	for (a = 0; a < MD5_STRING_LENGTH; a++)
	{
		_hash2[a] = tolower(hash2[a]);
	}
	if (!strcmp(_hash1, _hash2)) return(0); else return(1);
}

int ftype(char file[])
{
	struct stat statbuf;
	int s = stat(file, &statbuf);
	if (s != 0)
	{
		return(_NONE);
	}
	if (S_ISREG (statbuf.st_mode)) 
	{
		return(_FILE);
	} else if (S_ISDIR (statbuf.st_mode)) 
	{
		return(_DIR);
	} else {
		return(_NONE);
	}
}

int valid_md5_file(char fname[])
{
	FILE *fptr;
	char c;
	char test_md5[33];

	if (ftype(fname) == _DIR)
	{
		return(-2);
	}

	fptr = fopen(fname, "r");

	if (!fptr) return(-1);

	c = fgetc(fptr);

	if (!isprint(c) && c != ' ' && c != '\n' && c != '\t')
	{
		fclose(fptr);
		return(0);
	}

	rewind(fptr);

	fscanf(fptr, "%s", test_md5);

	fclose(fptr);

	if (strlen(test_md5) != 32) return(0); else return(1);
}

char * md5string(char string[], int uppercase)
{
	int i;
	unsigned char digest[16];
	static char md5str[33];
	static char md5str_u[33];
	MD5_CTX context;
	MD5_Init(&context);
	MD5_Update(&context, string, strlen(string));
	MD5_Final(digest, &context);

	for (i = 0; i < 16; i++)
	{
	    sprintf(&md5str[i*2], "%02x", (unsigned int)digest[i]);
	}

	if (uppercase)
	{
		for (i = 0; i < strlen(md5str); i++)
		{
			md5str_u[i] = toupper(md5str[i]);
		}
		return(md5str_u);
	}
	else
	{
		return(md5str);
	}
}

unsigned long fdsize(int fd)
{
	struct stat statbuf;
	if (fstat(fd, &statbuf) < 0) return(-1);
	return statbuf.st_size;
}

char * md5file(char fname[], int uppercase)
{
	if (ftype(fname) == _DIR) return("(directory)                     ");

	int i;
	int file_descript;
	unsigned long file_size;
	char* file_buffer;
	static char md5f_retv_u[33];

	file_descript = open(fname, O_RDONLY);
	if (file_descript < 0) return("(file access error)             ");

	file_size = fdsize(file_descript);

	file_buffer = mmap(0, file_size, PROT_READ, MAP_SHARED, file_descript, 0);
	MD5((unsigned char*) file_buffer, file_size, result);
	munmap(file_buffer, file_size); 

	for(i = 0; i < MD5_DIGEST_LENGTH; i++)
	{
		sprintf(&md5f_retv[i*2], "%02x", result[i]);
	}

	if (uppercase)
	{
		for (i = 0; i < strlen(md5f_retv); i++)
		{
			md5f_retv_u[i] = toupper(md5f_retv[i]);
		}
		return(md5f_retv_u);
	}
	return(md5f_retv);
}