convert object type handling from a string to a number
[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 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 }