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1 | #include "cache.h" | |
2 | #include "tag.h" | |
3 | ||
4 | /* | |
5 | * A signature file has a very simple fixed format: four lines | |
6 | * of "object <sha1>" + "type <typename>" + "tag <tagname>" + | |
7 | * "tagger <committer>", followed by a blank line, a free-form tag | |
8 | * message and a signature block that git itself doesn't care about, | |
9 | * but that can be verified with gpg or similar. | |
10 | * | |
11 | * The first three lines are guaranteed to be at least 63 bytes: | |
12 | * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the | |
13 | * shortest possible type-line, and "tag .\n" at 6 bytes is the | |
14 | * shortest single-character-tag line. | |
15 | * | |
16 | * We also artificially limit the size of the full object to 8kB. | |
17 | * Just because I'm a lazy bastard, and if you can't fit a signature | |
18 | * in that size, you're doing something wrong. | |
19 | */ | |
20 | ||
21 | /* Some random size */ | |
22 | #define MAXSIZE (8192) | |
23 | ||
24 | /* | |
25 | * We refuse to tag something we can't verify. Just because. | |
26 | */ | |
27 | static int verify_object(unsigned char *sha1, const char *expected_type) | |
28 | { | |
29 | int ret = -1; | |
30 | enum object_type type; | |
31 | unsigned long size; | |
32 | void *buffer = read_sha1_file(sha1, &type, &size); | |
33 | ||
34 | if (buffer) { | |
35 | if (type == type_from_string(expected_type)) | |
36 | ret = check_sha1_signature(sha1, buffer, size, expected_type); | |
37 | free(buffer); | |
38 | } | |
39 | return ret; | |
40 | } | |
41 | ||
42 | #ifdef NO_C99_FORMAT | |
43 | #define PD_FMT "%d" | |
44 | #else | |
45 | #define PD_FMT "%td" | |
46 | #endif | |
47 | ||
48 | static int verify_tag(char *buffer, unsigned long size) | |
49 | { | |
50 | int typelen; | |
51 | char type[20]; | |
52 | unsigned char sha1[20]; | |
53 | const char *object, *type_line, *tag_line, *tagger_line; | |
54 | ||
55 | if (size < 64) | |
56 | return error("wanna fool me ? you obviously got the size wrong !"); | |
57 | ||
58 | buffer[size] = 0; | |
59 | ||
60 | /* Verify object line */ | |
61 | object = buffer; | |
62 | if (memcmp(object, "object ", 7)) | |
63 | return error("char%d: does not start with \"object \"", 0); | |
64 | ||
65 | if (get_sha1_hex(object + 7, sha1)) | |
66 | return error("char%d: could not get SHA1 hash", 7); | |
67 | ||
68 | /* Verify type line */ | |
69 | type_line = object + 48; | |
70 | if (memcmp(type_line - 1, "\ntype ", 6)) | |
71 | return error("char%d: could not find \"\\ntype \"", 47); | |
72 | ||
73 | /* Verify tag-line */ | |
74 | tag_line = strchr(type_line, '\n'); | |
75 | if (!tag_line) | |
76 | return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer); | |
77 | tag_line++; | |
78 | if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n') | |
79 | return error("char" PD_FMT ": no \"tag \" found", tag_line - buffer); | |
80 | ||
81 | /* Get the actual type */ | |
82 | typelen = tag_line - type_line - strlen("type \n"); | |
83 | if (typelen >= sizeof(type)) | |
84 | return error("char" PD_FMT ": type too long", type_line+5 - buffer); | |
85 | ||
86 | memcpy(type, type_line+5, typelen); | |
87 | type[typelen] = 0; | |
88 | ||
89 | /* Verify that the object matches */ | |
90 | if (verify_object(sha1, type)) | |
91 | return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1)); | |
92 | ||
93 | /* Verify the tag-name: we don't allow control characters or spaces in it */ | |
94 | tag_line += 4; | |
95 | for (;;) { | |
96 | unsigned char c = *tag_line++; | |
97 | if (c == '\n') | |
98 | break; | |
99 | if (c > ' ') | |
100 | continue; | |
101 | return error("char" PD_FMT ": could not verify tag name", tag_line - buffer); | |
102 | } | |
103 | ||
104 | /* Verify the tagger line */ | |
105 | tagger_line = tag_line; | |
106 | ||
107 | if (memcmp(tagger_line, "tagger", 6) || (tagger_line[6] == '\n')) | |
108 | return error("char" PD_FMT ": could not find \"tagger\"", tagger_line - buffer); | |
109 | ||
110 | /* TODO: check for committer info + blank line? */ | |
111 | /* Also, the minimum length is probably + "tagger .", or 63+8=71 */ | |
112 | ||
113 | /* The actual stuff afterwards we don't care about.. */ | |
114 | return 0; | |
115 | } | |
116 | ||
117 | #undef PD_FMT | |
118 | ||
119 | int main(int argc, char **argv) | |
120 | { | |
121 | unsigned long size = 4096; | |
122 | char *buffer = xmalloc(size); | |
123 | unsigned char result_sha1[20]; | |
124 | ||
125 | if (argc != 1) | |
126 | usage("git-mktag < signaturefile"); | |
127 | ||
128 | setup_git_directory(); | |
129 | ||
130 | if (read_pipe(0, &buffer, &size)) { | |
131 | free(buffer); | |
132 | die("could not read from stdin"); | |
133 | } | |
134 | ||
135 | /* Verify it for some basic sanity: it needs to start with | |
136 | "object <sha1>\ntype\ntagger " */ | |
137 | if (verify_tag(buffer, size) < 0) | |
138 | die("invalid tag signature file"); | |
139 | ||
140 | if (write_sha1_file(buffer, size, tag_type, result_sha1) < 0) | |
141 | die("unable to write tag file"); | |
142 | ||
143 | free(buffer); | |
144 | ||
145 | printf("%s\n", sha1_to_hex(result_sha1)); | |
146 | return 0; | |
147 | } |