fa4a9e6003b5014fb8e222ad8813ce5954f9a38a
[git/git.git] / mktag.c
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 char type[100];
31 unsigned long size;
32 void *buffer = read_sha1_file(sha1, type, &size);
33
34 if (buffer) {
35 if (!strcmp(type, expected_type))
36 ret = check_sha1_signature(sha1, buffer, size, type);
37 free(buffer);
38 }
39 return ret;
40 }
41
42 static int verify_tag(char *buffer, unsigned long size)
43 {
44 int typelen;
45 char type[20];
46 unsigned char sha1[20];
47 const char *object, *type_line, *tag_line, *tagger_line;
48
49 if (size < 64)
50 return error("wanna fool me ? you obviously got the size wrong !");
51
52 buffer[size] = 0;
53
54 /* Verify object line */
55 object = buffer;
56 if (memcmp(object, "object ", 7))
57 return error("char%d: does not start with \"object \"", 0);
58
59 if (get_sha1_hex(object + 7, sha1))
60 return error("char%d: could not get SHA1 hash", 7);
61
62 /* Verify type line */
63 type_line = object + 48;
64 if (memcmp(type_line - 1, "\ntype ", 6))
65 return error("char%d: could not find \"\\ntype \"", 47);
66
67 /* Verify tag-line */
68 tag_line = strchr(type_line, '\n');
69 if (!tag_line)
70 return error("char%td: could not find next \"\\n\"", type_line - buffer);
71 tag_line++;
72 if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
73 return error("char%td: no \"tag \" found", tag_line - buffer);
74
75 /* Get the actual type */
76 typelen = tag_line - type_line - strlen("type \n");
77 if (typelen >= sizeof(type))
78 return error("char%td: type too long", type_line+5 - buffer);
79
80 memcpy(type, type_line+5, typelen);
81 type[typelen] = 0;
82
83 /* Verify that the object matches */
84 if (verify_object(sha1, type))
85 return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
86
87 /* Verify the tag-name: we don't allow control characters or spaces in it */
88 tag_line += 4;
89 for (;;) {
90 unsigned char c = *tag_line++;
91 if (c == '\n')
92 break;
93 if (c > ' ')
94 continue;
95 return error("char%td: could not verify tag name", tag_line - buffer);
96 }
97
98 /* Verify the tagger line */
99 tagger_line = tag_line;
100
101 if (memcmp(tagger_line, "tagger", 6) || (tagger_line[6] == '\n'))
102 return error("char%td: could not find \"tagger\"", tagger_line - buffer);
103
104 /* TODO: check for committer info + blank line? */
105 /* Also, the minimum length is probably + "tagger .", or 63+8=71 */
106
107 /* The actual stuff afterwards we don't care about.. */
108 return 0;
109 }
110
111 int main(int argc, char **argv)
112 {
113 unsigned long size = 4096;
114 char *buffer = malloc(size);
115 unsigned char result_sha1[20];
116
117 if (argc != 1)
118 usage("cat <signaturefile> | git-mktag");
119
120 setup_git_directory();
121
122 if (read_pipe(0, &buffer, &size)) {
123 free(buffer);
124 die("could not read from stdin");
125 }
126
127 /* Verify it for some basic sanity: it needs to start with
128 "object <sha1>\ntype\ntagger " */
129 if (verify_tag(buffer, size) < 0)
130 die("invalid tag signature file");
131
132 if (write_sha1_file(buffer, size, tag_type, result_sha1) < 0)
133 die("unable to write tag file");
134
135 free(buffer);
136
137 printf("%s\n", sha1_to_hex(result_sha1));
138 return 0;
139 }