| #include "cache.h" |
| |
| /* |
| * A signature file has a very simple fixed format: three lines |
| * of "object <sha1>" + "type <typename>" + "tag <tagname>", |
| * followed by some free-form signature that git itself doesn't |
| * care about, but that can be verified with gpg or similar. |
| * |
| * The first three lines are guaranteed to be at least 63 bytes: |
| * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the |
| * shortest possible type-line, and "tag .\n" at 6 bytes is the |
| * shortest single-character-tag line. |
| * |
| * We also artificially limit the size of the full object to 8kB. |
| * Just because I'm a lazy bastard, and if you can't fit a signature |
| * in that size, you're doing something wrong. |
| */ |
| |
| // Some random size |
| #define MAXSIZE (8192) |
| |
| /* |
| * We refuse to tag something we can't verify. Just because. |
| */ |
| static int verify_object(unsigned char *sha1, const char *expected_type) |
| { |
| int ret = -1; |
| char type[100]; |
| unsigned long size; |
| void *buffer = read_sha1_file(sha1, type, &size); |
| |
| if (buffer) { |
| if (!strcmp(type, expected_type)) |
| ret = check_sha1_signature(sha1, buffer, size, type); |
| free(buffer); |
| } |
| return ret; |
| } |
| |
| static int verify_tag(char *buffer, unsigned long size) |
| { |
| int typelen; |
| char type[20]; |
| unsigned char sha1[20]; |
| const char *object, *type_line, *tag_line, *tagger_line; |
| |
| if (size < 64 || size > MAXSIZE-1) |
| return -1; |
| buffer[size] = 0; |
| |
| /* Verify object line */ |
| object = buffer; |
| if (memcmp(object, "object ", 7)) |
| return -1; |
| if (get_sha1_hex(object + 7, sha1)) |
| return -1; |
| |
| /* Verify type line */ |
| type_line = object + 48; |
| if (memcmp(type_line - 1, "\ntype ", 6)) |
| return -1; |
| |
| /* Verify tag-line */ |
| tag_line = strchr(type_line, '\n'); |
| if (!tag_line) |
| return -1; |
| tag_line++; |
| if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n') |
| return -1; |
| |
| /* Get the actual type */ |
| typelen = tag_line - type_line - strlen("type \n"); |
| if (typelen >= sizeof(type)) |
| return -1; |
| memcpy(type, type_line+5, typelen); |
| type[typelen] = 0; |
| |
| /* Verify that the object matches */ |
| if (get_sha1_hex(object + 7, sha1)) |
| return -1; |
| if (verify_object(sha1, type)) |
| return -1; |
| |
| /* Verify the tag-name: we don't allow control characters or spaces in it */ |
| tag_line += 4; |
| for (;;) { |
| unsigned char c = *tag_line++; |
| if (c == '\n') |
| break; |
| if (c > ' ') |
| continue; |
| return -1; |
| } |
| |
| /* Verify the tagger line */ |
| tagger_line = tag_line; |
| |
| if (memcmp(tagger_line, "tagger", 6) || (tagger_line[6] == '\n')) |
| return -1; |
| |
| /* The actual stuff afterwards we don't care about.. */ |
| return 0; |
| } |
| |
| int main(int argc, char **argv) |
| { |
| unsigned long size; |
| char buffer[MAXSIZE]; |
| unsigned char result_sha1[20]; |
| |
| if (argc != 1) |
| usage("cat <signaturefile> | git-mktag"); |
| |
| // Read the signature |
| size = 0; |
| for (;;) { |
| int ret = read(0, buffer + size, MAXSIZE - size); |
| if (!ret) |
| break; |
| if (ret < 0) { |
| if (errno == EAGAIN) |
| continue; |
| break; |
| } |
| size += ret; |
| } |
| |
| // Verify it for some basic sanity: it needs to start with "object <sha1>\ntype\ntagger " |
| if (verify_tag(buffer, size) < 0) |
| die("invalid tag signature file"); |
| |
| if (write_sha1_file(buffer, size, "tag", result_sha1) < 0) |
| die("unable to write tag file"); |
| printf("%s\n", sha1_to_hex(result_sha1)); |
| return 0; |
| } |