builtin/mktag.c

   1 #include "builtin.h"
   2 #include "tag.h"
   3 #include "replace-object.h"
   4 #include "object-store.h"
   5
   6 /*
   7  * A signature file has a very simple fixed format: four lines
   8  * of "object <sha1>" + "type <typename>" + "tag <tagname>" +
   9  * "tagger <committer>", followed by a blank line, a free-form tag
  10  * message and a signature block that git itself doesn't care about,
  11  * but that can be verified with gpg or similar.
  12  *
  13  * The first four lines are guaranteed to be at least 83 bytes:
  14  * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the
  15  * shortest possible type-line, "tag .\n" at 6 bytes is the shortest
  16  * single-character-tag line, and "tagger . <> 0 +0000\n" at 20 bytes is
  17  * the shortest possible tagger-line.
  18  */
  19
  20 /*
  21  * We refuse to tag something we can't verify. Just because.
  22  */
  23 static int verify_object(const struct object_id *oid, const char *expected_type)
  24 {
  25         int ret = -1;
  26         enum object_type type;
  27         unsigned long size;
  28         void *buffer = read_object_file(oid, &type, &size);
  29         const struct object_id *repl = lookup_replace_object(the_repository, oid);
  30
  31         if (buffer) {
  32                 if (type == type_from_string(expected_type)) {
  33                         ret = check_object_signature(the_repository, repl,
  34                                                      buffer, size,
  35                                                      expected_type);
  36                 }
  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         struct object_id oid;
  47         const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb, *p;
  48         size_t len;
  49
  50         if (size < 84)
  51                 return error("wanna fool me ? you obviously got the size wrong !");
  52
  53         buffer[size] = 0;
  54
  55         /* Verify object line */
  56         object = buffer;
  57         if (memcmp(object, "object ", 7))
  58                 return error("char%d: does not start with \"object \"", 0);
  59
  60         if (parse_oid_hex(object + 7, &oid, &p))
  61                 return error("char%d: could not get SHA1 hash", 7);
  62
  63         /* Verify type line */
  64         type_line = p + 1;
  65         if (memcmp(type_line - 1, "\ntype ", 6))
  66                 return error("char%d: could not find \"\\ntype \"", 47);
  67
  68         /* Verify tag-line */
  69         tag_line = strchr(type_line, '\n');
  70         if (!tag_line)
  71                 return error("char%"PRIuMAX": could not find next \"\\n\"",
  72                                 (uintmax_t) (type_line - buffer));
  73         tag_line++;
  74         if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  75                 return error("char%"PRIuMAX": no \"tag \" found",
  76                                 (uintmax_t) (tag_line - buffer));
  77
  78         /* Get the actual type */
  79         typelen = tag_line - type_line - strlen("type \n");
  80         if (typelen >= sizeof(type))
  81                 return error("char%"PRIuMAX": type too long",
  82                                 (uintmax_t) (type_line+5 - buffer));
  83
  84         memcpy(type, type_line+5, typelen);
  85         type[typelen] = 0;
  86
  87         /* Verify that the object matches */
  88         if (verify_object(&oid, type))
  89                 return error("char%d: could not verify object %s", 7, oid_to_hex(&oid));
  90
  91         /* Verify the tag-name: we don't allow control characters or spaces in it */
  92         tag_line += 4;
  93         for (;;) {
  94                 unsigned char c = *tag_line++;
  95                 if (c == '\n')
  96                         break;
  97                 if (c > ' ')
  98                         continue;
  99                 return error("char%"PRIuMAX": could not verify tag name",
 100                                 (uintmax_t) (tag_line - buffer));
 101         }
 102
 103         /* Verify the tagger line */
 104         tagger_line = tag_line;
 105
 106         if (memcmp(tagger_line, "tagger ", 7))
 107                 return error("char%"PRIuMAX": could not find \"tagger \"",
 108                         (uintmax_t) (tagger_line - buffer));
 109
 110         /*
 111          * Check for correct form for name and email
 112          * i.e. " <" followed by "> " on _this_ line
 113          * No angle brackets within the name or email address fields.
 114          * No spaces within the email address field.
 115          */
 116         tagger_line += 7;
 117         if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 118                 strpbrk(tagger_line, "<>\n") != lb+1 ||
 119                 strpbrk(lb+2, "><\n ") != rb)
 120                 return error("char%"PRIuMAX": malformed tagger field",
 121                         (uintmax_t) (tagger_line - buffer));
 122
 123         /* Check for author name, at least one character, space is acceptable */
 124         if (lb == tagger_line)
 125                 return error("char%"PRIuMAX": missing tagger name",
 126                         (uintmax_t) (tagger_line - buffer));
 127
 128         /* timestamp, 1 or more digits followed by space */
 129         tagger_line = rb + 2;
 130         if (!(len = strspn(tagger_line, "0123456789")))
 131                 return error("char%"PRIuMAX": missing tag timestamp",
 132                         (uintmax_t) (tagger_line - buffer));
 133         tagger_line += len;
 134         if (*tagger_line != ' ')
 135                 return error("char%"PRIuMAX": malformed tag timestamp",
 136                         (uintmax_t) (tagger_line - buffer));
 137         tagger_line++;
 138
 139         /* timezone, 5 digits [+-]hhmm, max. 1400 */
 140         if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 141               strspn(tagger_line+1, "0123456789") == 4 &&
 142               tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
 143                 return error("char%"PRIuMAX": malformed tag timezone",
 144                         (uintmax_t) (tagger_line - buffer));
 145         tagger_line += 6;
 146
 147         /* Verify the blank line separating the header from the body */
 148         if (*tagger_line != '\n')
 149                 return error("char%"PRIuMAX": trailing garbage in tag header",
 150                         (uintmax_t) (tagger_line - buffer));
 151
 152         /* The actual stuff afterwards we don't care about.. */
 153         return 0;
 154 }
 155
 156 int cmd_mktag(int argc, const char **argv, const char *prefix)
 157 {
 158         struct strbuf buf = STRBUF_INIT;
 159         struct object_id result;
 160
 161         if (argc != 1)
 162                 usage("git mktag");
 163
 164         if (strbuf_read(&buf, 0, 4096) < 0) {
 165                 die_errno("could not read from stdin");
 166         }
 167
 168         /* Verify it for some basic sanity: it needs to start with
 169            "object <sha1>\ntype\ntagger " */
 170         if (verify_tag(buf.buf, buf.len) < 0)
 171                 die("invalid tag signature file");
 172
 173         if (write_object_file(buf.buf, buf.len, tag_type, &result) < 0)
 174                 die("unable to write tag file");
 175
 176         strbuf_release(&buf);
 177         printf("%s\n", oid_to_hex(&result));
 178         return 0;
 179 }