[PATCH] Update git-tag-script to create the .git/refs/tags if it does not already...
[git/git.git] / mktag.c
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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 */
25static int verify_object(unsigned char *sha1, const char *expected_type)
26{
27 int ret = -1;
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28 char type[100];
29 unsigned long size;
30 void *buffer = read_sha1_file(sha1, type, &size);
ec4465ad 31
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32 if (buffer) {
33 if (!strcmp(type, expected_type))
34 ret = check_sha1_signature(sha1, buffer, size, type);
35 free(buffer);
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36 }
37 return ret;
38}
39
40static int verify_tag(char *buffer, unsigned long size)
41{
42 int typelen;
43 char type[20];
44 unsigned char sha1[20];
45 const char *object, *type_line, *tag_line;
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
95 /* The actual stuff afterwards we don't care about.. */
96 return 0;
97}
98
99int main(int argc, char **argv)
100{
101 unsigned long size;
102 char buffer[MAXSIZE];
103 unsigned char result_sha1[20];
104
105 if (argc != 1)
106 usage("cat <signaturefile> | git-mktag");
107
108 // Read the signature
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109 size = 0;
110 for (;;) {
111 int ret = read(0, buffer + size, MAXSIZE - size);
112 if (!ret)
113 break;
114 if (ret < 0) {
115 if (errno == EAGAIN)
116 continue;
117 break;
118 }
119 size += ret;
120 }
ec4465ad 121
40469ee9 122 // Verify it for some basic sanity: it needs to start with "object <sha1>\ntype "
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123 if (verify_tag(buffer, size) < 0)
124 die("invalid tag signature file");
125
126 if (write_sha1_file(buffer, size, "tag", result_sha1) < 0)
127 die("unable to write tag file");
128 printf("%s\n", sha1_to_hex(result_sha1));
129 return 0;
130}