Created
September 25, 2013 14:51
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w3 sha256 stuff
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| #include <stdio.h> | |
| #include <stdint.h> | |
| #include <sys/stat.h> | |
| #include <unistd.h> | |
| #include <fcntl.h> | |
| #include <string.h> | |
| #include <openssl/evp.h> | |
| #define DIGEST_SIZE 32 | |
| #define BLOCK_SIZE 1024 | |
| int main(int argc, char **argv) | |
| { | |
| struct stat filestat; | |
| int32_t blocks, lblock; | |
| uint64_t fsize; | |
| int fd; | |
| unsigned char ldigest[DIGEST_SIZE]; | |
| unsigned char msg[BLOCK_SIZE + DIGEST_SIZE]; | |
| unsigned int md_len, i, j; | |
| if (argc != 2) { | |
| fprintf(stderr, "Usage: %s <file>\n", argv[0]); | |
| return 1; | |
| } | |
| if (stat(argv[1], &filestat) != 0) { | |
| fprintf(stderr, "Failed to stat file '%s'\n", argv[1]); | |
| return 1; | |
| } | |
| fsize = filestat.st_size; | |
| blocks = fsize / BLOCK_SIZE; | |
| lblock = fsize - (blocks++ * BLOCK_SIZE); | |
| printf("File '%s' has size %d\n", argv[1], fsize); | |
| printf("%d blocks to hash, last block is %d bytes\n", blocks, lblock); | |
| fd = open(argv[1], O_RDONLY); | |
| if (fd == -1) { | |
| fprintf(stderr, "Failed to open file '%s'\n", argv[1]); | |
| } | |
| i = 0; | |
| for (i = 0; i < blocks; i++) { | |
| uint32_t offset = fsize - lblock - (i * BLOCK_SIZE); | |
| uint32_t bsize = i == 0 ? lblock : BLOCK_SIZE; | |
| printf("[%d] Digesting block %d (%d/%d)... ", i, blocks, offset, bsize); | |
| if (lseek(fd, offset, SEEK_SET) == -1) { | |
| printf("Failed to seek file\n"); | |
| return 1; | |
| }; | |
| read(fd, msg, bsize); | |
| if (i != 0) { | |
| memcpy(msg + bsize, ldigest, DIGEST_SIZE); | |
| bsize += DIGEST_SIZE; | |
| } | |
| EVP_Digest(msg, bsize, ldigest, &md_len, EVP_sha256(), NULL); | |
| for(j = 0; j < md_len; j++) | |
| printf("%02x", ldigest[j]); | |
| printf("\n"); | |
| } | |
| close(fd); | |
| return 0; | |
| } |
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