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1 | #include "builtin.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 four lines are guaranteed to be at least 83 bytes: | |
12 | * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the | |
13 | * shortest possible type-line, "tag .\n" at 6 bytes is the shortest | |
14 | * single-character-tag line, and "tagger . <> 0 +0000\n" at 20 bytes is | |
15 | * the shortest possible tagger-line. | |
16 | */ | |
17 | ||
18 | /* | |
19 | * We refuse to tag something we can't verify. Just because. | |
20 | */ | |
21 | static int verify_object(const unsigned char *sha1, const char *expected_type) | |
22 | { | |
23 | int ret = -1; | |
24 | enum object_type type; | |
25 | unsigned long size; | |
26 | void *buffer = read_sha1_file(sha1, &type, &size); | |
27 | const unsigned char *repl = lookup_replace_object(sha1); | |
28 | ||
29 | if (buffer) { | |
30 | if (type == type_from_string(expected_type)) | |
31 | ret = check_sha1_signature(repl, buffer, size, expected_type); | |
32 | free(buffer); | |
33 | } | |
34 | return ret; | |
35 | } | |
36 | ||
37 | static int verify_tag(char *buffer, unsigned long size) | |
38 | { | |
39 | int typelen; | |
40 | char type[20]; | |
41 | unsigned char sha1[20]; | |
42 | const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb; | |
43 | size_t len; | |
44 | ||
45 | if (size < 84) | |
46 | return error("wanna fool me ? you obviously got the size wrong !"); | |
47 | ||
48 | buffer[size] = 0; | |
49 | ||
50 | /* Verify object line */ | |
51 | object = buffer; | |
52 | if (memcmp(object, "object ", 7)) | |
53 | return error("char%d: does not start with \"object \"", 0); | |
54 | ||
55 | if (get_sha1_hex(object + 7, sha1)) | |
56 | return error("char%d: could not get SHA1 hash", 7); | |
57 | ||
58 | /* Verify type line */ | |
59 | type_line = object + 48; | |
60 | if (memcmp(type_line - 1, "\ntype ", 6)) | |
61 | return error("char%d: could not find \"\\ntype \"", 47); | |
62 | ||
63 | /* Verify tag-line */ | |
64 | tag_line = strchr(type_line, '\n'); | |
65 | if (!tag_line) | |
66 | return error("char%"PRIuMAX": could not find next \"\\n\"", | |
67 | (uintmax_t) (type_line - buffer)); | |
68 | tag_line++; | |
69 | if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n') | |
70 | return error("char%"PRIuMAX": no \"tag \" found", | |
71 | (uintmax_t) (tag_line - buffer)); | |
72 | ||
73 | /* Get the actual type */ | |
74 | typelen = tag_line - type_line - strlen("type \n"); | |
75 | if (typelen >= sizeof(type)) | |
76 | return error("char%"PRIuMAX": type too long", | |
77 | (uintmax_t) (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 (verify_object(sha1, type)) | |
84 | return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1)); | |
85 | ||
86 | /* Verify the tag-name: we don't allow control characters or spaces in it */ | |
87 | tag_line += 4; | |
88 | for (;;) { | |
89 | unsigned char c = *tag_line++; | |
90 | if (c == '\n') | |
91 | break; | |
92 | if (c > ' ') | |
93 | continue; | |
94 | return error("char%"PRIuMAX": could not verify tag name", | |
95 | (uintmax_t) (tag_line - buffer)); | |
96 | } | |
97 | ||
98 | /* Verify the tagger line */ | |
99 | tagger_line = tag_line; | |
100 | ||
101 | if (memcmp(tagger_line, "tagger ", 7)) | |
102 | return error("char%"PRIuMAX": could not find \"tagger \"", | |
103 | (uintmax_t) (tagger_line - buffer)); | |
104 | ||
105 | /* | |
106 | * Check for correct form for name and email | |
107 | * i.e. " <" followed by "> " on _this_ line | |
108 | * No angle brackets within the name or email address fields. | |
109 | * No spaces within the email address field. | |
110 | */ | |
111 | tagger_line += 7; | |
112 | if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) || | |
113 | strpbrk(tagger_line, "<>\n") != lb+1 || | |
114 | strpbrk(lb+2, "><\n ") != rb) | |
115 | return error("char%"PRIuMAX": malformed tagger field", | |
116 | (uintmax_t) (tagger_line - buffer)); | |
117 | ||
118 | /* Check for author name, at least one character, space is acceptable */ | |
119 | if (lb == tagger_line) | |
120 | return error("char%"PRIuMAX": missing tagger name", | |
121 | (uintmax_t) (tagger_line - buffer)); | |
122 | ||
123 | /* timestamp, 1 or more digits followed by space */ | |
124 | tagger_line = rb + 2; | |
125 | if (!(len = strspn(tagger_line, "0123456789"))) | |
126 | return error("char%"PRIuMAX": missing tag timestamp", | |
127 | (uintmax_t) (tagger_line - buffer)); | |
128 | tagger_line += len; | |
129 | if (*tagger_line != ' ') | |
130 | return error("char%"PRIuMAX": malformed tag timestamp", | |
131 | (uintmax_t) (tagger_line - buffer)); | |
132 | tagger_line++; | |
133 | ||
134 | /* timezone, 5 digits [+-]hhmm, max. 1400 */ | |
135 | if (!((tagger_line[0] == '+' || tagger_line[0] == '-') && | |
136 | strspn(tagger_line+1, "0123456789") == 4 && | |
137 | tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400)) | |
138 | return error("char%"PRIuMAX": malformed tag timezone", | |
139 | (uintmax_t) (tagger_line - buffer)); | |
140 | tagger_line += 6; | |
141 | ||
142 | /* Verify the blank line separating the header from the body */ | |
143 | if (*tagger_line != '\n') | |
144 | return error("char%"PRIuMAX": trailing garbage in tag header", | |
145 | (uintmax_t) (tagger_line - buffer)); | |
146 | ||
147 | /* The actual stuff afterwards we don't care about.. */ | |
148 | return 0; | |
149 | } | |
150 | ||
151 | int cmd_mktag(int argc, const char **argv, const char *prefix) | |
152 | { | |
153 | struct strbuf buf = STRBUF_INIT; | |
154 | unsigned char result_sha1[20]; | |
155 | ||
156 | if (argc != 1) | |
157 | usage("git mktag < signaturefile"); | |
158 | ||
159 | if (strbuf_read(&buf, 0, 4096) < 0) { | |
160 | die_errno("could not read from stdin"); | |
161 | } | |
162 | ||
163 | /* Verify it for some basic sanity: it needs to start with | |
164 | "object <sha1>\ntype\ntagger " */ | |
165 | if (verify_tag(buf.buf, buf.len) < 0) | |
166 | die("invalid tag signature file"); | |
167 | ||
168 | if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0) | |
169 | die("unable to write tag file"); | |
170 | ||
171 | strbuf_release(&buf); | |
172 | printf("%s\n", sha1_to_hex(result_sha1)); | |
173 | return 0; | |
174 | } |