| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 1 | #include "cache.h" |
| 2 | |
| 3 | /* |
| 4 | * A signature file has a very simple fixed format: three lines |
| 5 | * of "object <sha1>" + "type <typename>" + "tag <tagname>", |
| 6 | * followed by some free-form signature that git itself doesn't |
| 7 | * care about, but that can be verified with gpg or similar. |
| 8 | * |
| 9 | * The first three lines are guaranteed to be at least 63 bytes: |
| 10 | * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the |
| 11 | * shortest possible type-line, and "tag .\n" at 6 bytes is the |
| 12 | * shortest single-character-tag line. |
| 13 | * |
| 14 | * We also artificially limit the size of the full object to 8kB. |
| 15 | * Just because I'm a lazy bastard, and if you can't fit a signature |
| 16 | * in that size, you're doing something wrong. |
| 17 | */ |
| 18 | |
| 19 | // Some random size |
| 20 | #define MAXSIZE (8192) |
| 21 | |
| 22 | /* |
| 23 | * We refuse to tag something we can't verify. Just because. |
| 24 | */ |
| 25 | static int verify_object(unsigned char *sha1, const char *expected_type) |
| 26 | { |
| 27 | int ret = -1; |
| Nicolas Pitre | 91d7b8a | 2005-05-20 20:57:28 | [diff] [blame] | 28 | char type[100]; |
| 29 | unsigned long size; |
| 30 | void *buffer = read_sha1_file(sha1, type, &size); |
| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 31 | |
| Nicolas Pitre | 91d7b8a | 2005-05-20 20:57:28 | [diff] [blame] | 32 | if (buffer) { |
| 33 | if (!strcmp(type, expected_type)) |
| 34 | ret = check_sha1_signature(sha1, buffer, size, type); |
| 35 | free(buffer); |
| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 36 | } |
| 37 | return ret; |
| 38 | } |
| 39 | |
| 40 | static int verify_tag(char *buffer, unsigned long size) |
| 41 | { |
| 42 | int typelen; |
| 43 | char type[20]; |
| 44 | unsigned char sha1[20]; |
| Eric W. Biederman | c818566 | 2005-07-15 01:02:10 | [diff] [blame] | 45 | const char *object, *type_line, *tag_line, *tagger_line; |
| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 46 | |
| 47 | if (size < 64 || size > MAXSIZE-1) |
| 48 | return -1; |
| 49 | buffer[size] = 0; |
| 50 | |
| 51 | /* Verify object line */ |
| 52 | object = buffer; |
| 53 | if (memcmp(object, "object ", 7)) |
| 54 | return -1; |
| 55 | if (get_sha1_hex(object + 7, sha1)) |
| 56 | return -1; |
| 57 | |
| 58 | /* Verify type line */ |
| 59 | type_line = object + 48; |
| 60 | if (memcmp(type_line - 1, "\ntype ", 6)) |
| 61 | return -1; |
| 62 | |
| 63 | /* Verify tag-line */ |
| 64 | tag_line = strchr(type_line, '\n'); |
| 65 | if (!tag_line) |
| 66 | return -1; |
| 67 | tag_line++; |
| 68 | if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n') |
| 69 | return -1; |
| 70 | |
| 71 | /* Get the actual type */ |
| 72 | typelen = tag_line - type_line - strlen("type \n"); |
| 73 | if (typelen >= sizeof(type)) |
| 74 | return -1; |
| 75 | memcpy(type, type_line+5, typelen); |
| 76 | type[typelen] = 0; |
| 77 | |
| 78 | /* Verify that the object matches */ |
| 79 | if (get_sha1_hex(object + 7, sha1)) |
| 80 | return -1; |
| 81 | if (verify_object(sha1, type)) |
| 82 | return -1; |
| 83 | |
| 84 | /* Verify the tag-name: we don't allow control characters or spaces in it */ |
| 85 | tag_line += 4; |
| 86 | for (;;) { |
| 87 | unsigned char c = *tag_line++; |
| 88 | if (c == '\n') |
| 89 | break; |
| 90 | if (c > ' ') |
| 91 | continue; |
| 92 | return -1; |
| 93 | } |
| 94 | |
| Eric W. Biederman | c818566 | 2005-07-15 01:02:10 | [diff] [blame] | 95 | /* Verify the tagger line */ |
| 96 | tagger_line = tag_line; |
| 97 | |
| 98 | if (memcmp(tagger_line, "tagger", 6) || (tagger_line[6] == '\n')) |
| 99 | return -1; |
| 100 | |
| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 101 | /* The actual stuff afterwards we don't care about.. */ |
| 102 | return 0; |
| 103 | } |
| 104 | |
| 105 | int main(int argc, char **argv) |
| 106 | { |
| 107 | unsigned long size; |
| 108 | char buffer[MAXSIZE]; |
| 109 | unsigned char result_sha1[20]; |
| 110 | |
| 111 | if (argc != 1) |
| 112 | usage("cat <signaturefile> | git-mktag"); |
| 113 | |
| 114 | // Read the signature |
| Linus Torvalds | b97e3df | 2005-05-29 19:06:32 | [diff] [blame] | 115 | size = 0; |
| 116 | for (;;) { |
| 117 | int ret = read(0, buffer + size, MAXSIZE - size); |
| 118 | if (!ret) |
| 119 | break; |
| 120 | if (ret < 0) { |
| 121 | if (errno == EAGAIN) |
| 122 | continue; |
| 123 | break; |
| 124 | } |
| 125 | size += ret; |
| 126 | } |
| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 127 | |
| Eric W. Biederman | c818566 | 2005-07-15 01:02:10 | [diff] [blame] | 128 | // Verify it for some basic sanity: it needs to start with "object <sha1>\ntype\ntagger " |
| Linus Torvalds | ec4465a | 2005-04-25 19:07:44 | [diff] [blame] | 129 | if (verify_tag(buffer, size) < 0) |
| 130 | die("invalid tag signature file"); |
| 131 | |
| 132 | if (write_sha1_file(buffer, size, "tag", result_sha1) < 0) |
| 133 | die("unable to write tag file"); |
| 134 | printf("%s\n", sha1_to_hex(result_sha1)); |
| 135 | return 0; |
| 136 | } |
