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