90 lines
1.9 KiB
C++
90 lines
1.9 KiB
C++
#include <iostream>
|
|
#include <openssl/md5.h> /* md5sum */
|
|
#include <sys/stat.h>
|
|
#include <sys/mman.h>
|
|
#include <fcntl.h>
|
|
#include <cstring>
|
|
|
|
|
|
/**
|
|
* Get the size of the file by its file descriptor
|
|
*
|
|
* @param file_descript
|
|
*/
|
|
unsigned long get_size_by_fd(int fd)
|
|
{
|
|
struct stat statbuf;
|
|
if (fstat(fd, &statbuf) < 0)
|
|
{
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
return statbuf.st_size;
|
|
}
|
|
|
|
/**
|
|
* Print the MD5 sum as hex-digits.
|
|
*
|
|
* @param MD5 checksum
|
|
*/
|
|
void print_md5_sum(unsigned char* md5)
|
|
{
|
|
for (unsigned int i = 0; i < MD5_DIGEST_LENGTH; i++)
|
|
{
|
|
printf("%02x", md5[i]);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* Converts MD5 checksum to hex.
|
|
*
|
|
* @param MD5 checksum
|
|
*/
|
|
std::string to_hex(unsigned char* md5)
|
|
{
|
|
static const char digits[] = "0123456789abcdef";
|
|
std::string result;
|
|
|
|
for (unsigned int i = 0; i < MD5_DIGEST_LENGTH; i++)
|
|
{
|
|
result += digits[md5[i] / MD5_DIGEST_LENGTH];
|
|
result += digits[md5[i] % MD5_DIGEST_LENGTH];
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* Computes a MD5 checksum and compares it to its corresponding calibrated checksum.
|
|
*
|
|
* @param File path to compute checksum, corresponding calibrated checksum
|
|
*/
|
|
void md5sum(std::string file_path, unsigned char md5[MD5_DIGEST_LENGTH])
|
|
{
|
|
/*
|
|
* Variable initialisation
|
|
*/
|
|
int file_descript;
|
|
unsigned long file_size;
|
|
unsigned char* file_buffer;
|
|
|
|
/* Checks if the file path can be opened. */
|
|
file_descript = open(file_path.c_str(), O_RDONLY);
|
|
if (file_descript < 0)
|
|
{
|
|
std::cerr << "Unable to open " << file_path << std::endl;
|
|
exit(EXIT_FAILURE);
|
|
}
|
|
|
|
/* Grabs the size of file */
|
|
file_size = get_size_by_fd(file_descript);
|
|
|
|
/* Generates the buffer */
|
|
file_buffer = (unsigned char*) mmap((caddr_t)0, file_size, PROT_READ, MAP_SHARED, file_descript, 0);
|
|
|
|
/* Computes the MD5 checksum to result */
|
|
MD5(file_buffer, file_size, md5);
|
|
|
|
/* Removes fime_buffer and file_size */
|
|
munmap(file_buffer, file_size);
|
|
}
|