builtin/mktag.c

   1 #include "builtin.h"
   2 #include "tag.h"
   3 #include "replace-object.h"
   4
   5 /*
   6  * A signature file has a very simple fixed format: four lines
   7  * of "object <sha1>" + "type <typename>" + "tag <tagname>" +
   8  * "tagger <committer>", followed by a blank line, a free-form tag
   9  * message and a signature block that git itself doesn't care about,
  10  * but that can be verified with gpg or similar.
  11  *
  12  * The first four lines are guaranteed to be at least 83 bytes:
  13  * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the
  14  * shortest possible type-line, "tag .\n" at 6 bytes is the shortest
  15  * single-character-tag line, and "tagger . <> 0 +0000\n" at 20 bytes is
  16  * the shortest possible tagger-line.
  17  */
  18
  19 /*
  20  * We refuse to tag something we can't verify. Just because.
  21  */
  22 static int verify_object(const struct object_id *oid, const char *expected_type)
  23 {
  24         int ret = -1;
  25         enum object_type type;
  26         unsigned long size;
  27         void *buffer = read_object_file(oid, &type, &size);
  28         const struct object_id *repl = lookup_replace_object(the_repository, oid);
  29
  30         if (buffer) {
  31                 if (type == type_from_string(expected_type))
  32                         ret = check_object_signature(repl, buffer, size, expected_type);
  33                 free(buffer);
  34         }
  35         return ret;
  36 }
  37
  38 static int verify_tag(char *buffer, unsigned long size)
  39 {
  40         int typelen;
  41         char type[20];
  42         struct object_id oid;
  43         const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb, *p;
  44         size_t len;
  45
  46         if (size < 84)
  47                 return error("wanna fool me ? you obviously got the size wrong !");
  48
  49         buffer[size] = 0;
  50
  51         /* Verify object line */
  52         object = buffer;
  53         if (memcmp(object, "object ", 7))
  54                 return error("char%d: does not start with \"object \"", 0);
  55
  56         if (parse_oid_hex(object + 7, &oid, &p))
  57                 return error("char%d: could not get SHA1 hash", 7);
  58
  59         /* Verify type line */
  60         type_line = p + 1;
  61         if (memcmp(type_line - 1, "\ntype ", 6))
  62                 return error("char%d: could not find \"\\ntype \"", 47);
  63
  64         /* Verify tag-line */
  65         tag_line = strchr(type_line, '\n');
  66         if (!tag_line)
  67                 return error("char%"PRIuMAX": could not find next \"\\n\"",
  68                                 (uintmax_t) (type_line - buffer));
  69         tag_line++;
  70         if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  71                 return error("char%"PRIuMAX": no \"tag \" found",
  72                                 (uintmax_t) (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%"PRIuMAX": type too long",
  78                                 (uintmax_t) (type_line+5 - buffer));
  79
  80         memcpy(type, type_line+5, typelen);
  81         type[typelen] = 0;
  82
  83         /* Verify that the object matches */
  84         if (verify_object(&oid, type))
  85                 return error("char%d: could not verify object %s", 7, oid_to_hex(&oid));
  86
  87         /* Verify the tag-name: we don't allow control characters or spaces in it */
  88         tag_line += 4;
  89         for (;;) {
  90                 unsigned char c = *tag_line++;
  91                 if (c == '\n')
  92                         break;
  93                 if (c > ' ')
  94                         continue;
  95                 return error("char%"PRIuMAX": could not verify tag name",
  96                                 (uintmax_t) (tag_line - buffer));
  97         }
  98
  99         /* Verify the tagger line */
 100         tagger_line = tag_line;
 101
 102         if (memcmp(tagger_line, "tagger ", 7))
 103                 return error("char%"PRIuMAX": could not find \"tagger \"",
 104                         (uintmax_t) (tagger_line - buffer));
 105
 106         /*
 107          * Check for correct form for name and email
 108          * i.e. " <" followed by "> " on _this_ line
 109          * No angle brackets within the name or email address fields.
 110          * No spaces within the email address field.
 111          */
 112         tagger_line += 7;
 113         if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 114                 strpbrk(tagger_line, "<>\n") != lb+1 ||
 115                 strpbrk(lb+2, "><\n ") != rb)
 116                 return error("char%"PRIuMAX": malformed tagger field",
 117                         (uintmax_t) (tagger_line - buffer));
 118
 119         /* Check for author name, at least one character, space is acceptable */
 120         if (lb == tagger_line)
 121                 return error("char%"PRIuMAX": missing tagger name",
 122                         (uintmax_t) (tagger_line - buffer));
 123
 124         /* timestamp, 1 or more digits followed by space */
 125         tagger_line = rb + 2;
 126         if (!(len = strspn(tagger_line, "0123456789")))
 127                 return error("char%"PRIuMAX": missing tag timestamp",
 128                         (uintmax_t) (tagger_line - buffer));
 129         tagger_line += len;
 130         if (*tagger_line != ' ')
 131                 return error("char%"PRIuMAX": malformed tag timestamp",
 132                         (uintmax_t) (tagger_line - buffer));
 133         tagger_line++;
 134
 135         /* timezone, 5 digits [+-]hhmm, max. 1400 */
 136         if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 137               strspn(tagger_line+1, "0123456789") == 4 &&
 138               tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
 139                 return error("char%"PRIuMAX": malformed tag timezone",
 140                         (uintmax_t) (tagger_line - buffer));
 141         tagger_line += 6;
 142
 143         /* Verify the blank line separating the header from the body */
 144         if (*tagger_line != '\n')
 145                 return error("char%"PRIuMAX": trailing garbage in tag header",
 146                         (uintmax_t) (tagger_line - buffer));
 147
 148         /* The actual stuff afterwards we don't care about.. */
 149         return 0;
 150 }
 151
 152 int cmd_mktag(int argc, const char **argv, const char *prefix)
 153 {
 154         struct strbuf buf = STRBUF_INIT;
 155         struct object_id result;
 156
 157         if (argc != 1)
 158                 usage("git mktag");
 159
 160         if (strbuf_read(&buf, 0, 4096) < 0) {
 161                 die_errno("could not read from stdin");
 162         }
 163
 164         /* Verify it for some basic sanity: it needs to start with
 165            "object <sha1>\ntype\ntagger " */
 166         if (verify_tag(buf.buf, buf.len) < 0)
 167                 die("invalid tag signature file");
 168
 169         if (write_object_file(buf.buf, buf.len, tag_type, &result) < 0)
 170                 die("unable to write tag file");
 171
 172         strbuf_release(&buf);
 173         printf("%s\n", oid_to_hex(&result));
 174         return 0;
 175 }