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(repl, buffer, size, expected_type);
  34                 free(buffer);
  35         }
  36         return ret;
  37 }
  38
  39 static int verify_tag(char *buffer, unsigned long size)
  40 {
  41         int typelen;
  42         char type[20];
  43         struct object_id oid;
  44         const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb, *p;
  45         size_t len;
  46
  47         if (size < 84)
  48                 return error("wanna fool me ? you obviously got the size wrong !");
  49
  50         buffer[size] = 0;
  51
  52         /* Verify object line */
  53         object = buffer;
  54         if (memcmp(object, "object ", 7))
  55                 return error("char%d: does not start with \"object \"", 0);
  56
  57         if (parse_oid_hex(object + 7, &oid, &p))
  58                 return error("char%d: could not get SHA1 hash", 7);
  59
  60         /* Verify type line */
  61         type_line = p + 1;
  62         if (memcmp(type_line - 1, "\ntype ", 6))
  63                 return error("char%d: could not find \"\\ntype \"", 47);
  64
  65         /* Verify tag-line */
  66         tag_line = strchr(type_line, '\n');
  67         if (!tag_line)
  68                 return error("char%"PRIuMAX": could not find next \"\\n\"",
  69                                 (uintmax_t) (type_line - buffer));
  70         tag_line++;
  71         if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  72                 return error("char%"PRIuMAX": no \"tag \" found",
  73                                 (uintmax_t) (tag_line - buffer));
  74
  75         /* Get the actual type */
  76         typelen = tag_line - type_line - strlen("type \n");
  77         if (typelen >= sizeof(type))
  78                 return error("char%"PRIuMAX": type too long",
  79                                 (uintmax_t) (type_line+5 - buffer));
  80
  81         memcpy(type, type_line+5, typelen);
  82         type[typelen] = 0;
  83
  84         /* Verify that the object matches */
  85         if (verify_object(&oid, type))
  86                 return error("char%d: could not verify object %s", 7, oid_to_hex(&oid));
  87
  88         /* Verify the tag-name: we don't allow control characters or spaces in it */
  89         tag_line += 4;
  90         for (;;) {
  91                 unsigned char c = *tag_line++;
  92                 if (c == '\n')
  93                         break;
  94                 if (c > ' ')
  95                         continue;
  96                 return error("char%"PRIuMAX": could not verify tag name",
  97                                 (uintmax_t) (tag_line - buffer));
  98         }
  99
 100         /* Verify the tagger line */
 101         tagger_line = tag_line;
 102
 103         if (memcmp(tagger_line, "tagger ", 7))
 104                 return error("char%"PRIuMAX": could not find \"tagger \"",
 105                         (uintmax_t) (tagger_line - buffer));
 106
 107         /*
 108          * Check for correct form for name and email
 109          * i.e. " <" followed by "> " on _this_ line
 110          * No angle brackets within the name or email address fields.
 111          * No spaces within the email address field.
 112          */
 113         tagger_line += 7;
 114         if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 115                 strpbrk(tagger_line, "<>\n") != lb+1 ||
 116                 strpbrk(lb+2, "><\n ") != rb)
 117                 return error("char%"PRIuMAX": malformed tagger field",
 118                         (uintmax_t) (tagger_line - buffer));
 119
 120         /* Check for author name, at least one character, space is acceptable */
 121         if (lb == tagger_line)
 122                 return error("char%"PRIuMAX": missing tagger name",
 123                         (uintmax_t) (tagger_line - buffer));
 124
 125         /* timestamp, 1 or more digits followed by space */
 126         tagger_line = rb + 2;
 127         if (!(len = strspn(tagger_line, "0123456789")))
 128                 return error("char%"PRIuMAX": missing tag timestamp",
 129                         (uintmax_t) (tagger_line - buffer));
 130         tagger_line += len;
 131         if (*tagger_line != ' ')
 132                 return error("char%"PRIuMAX": malformed tag timestamp",
 133                         (uintmax_t) (tagger_line - buffer));
 134         tagger_line++;
 135
 136         /* timezone, 5 digits [+-]hhmm, max. 1400 */
 137         if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 138               strspn(tagger_line+1, "0123456789") == 4 &&
 139               tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
 140                 return error("char%"PRIuMAX": malformed tag timezone",
 141                         (uintmax_t) (tagger_line - buffer));
 142         tagger_line += 6;
 143
 144         /* Verify the blank line separating the header from the body */
 145         if (*tagger_line != '\n')
 146                 return error("char%"PRIuMAX": trailing garbage in tag header",
 147                         (uintmax_t) (tagger_line - buffer));
 148
 149         /* The actual stuff afterwards we don't care about.. */
 150         return 0;
 151 }
 152
 153 int cmd_mktag(int argc, const char **argv, const char *prefix)
 154 {
 155         struct strbuf buf = STRBUF_INIT;
 156         struct object_id result;
 157
 158         if (argc != 1)
 159                 usage("git mktag");
 160
 161         if (strbuf_read(&buf, 0, 4096) < 0) {
 162                 die_errno("could not read from stdin");
 163         }
 164
 165         /* Verify it for some basic sanity: it needs to start with
 166            "object <sha1>\ntype\ntagger " */
 167         if (verify_tag(buf.buf, buf.len) < 0)
 168                 die("invalid tag signature file");
 169
 170         if (write_object_file(buf.buf, buf.len, tag_type, &result) < 0)
 171                 die("unable to write tag file");
 172
 173         strbuf_release(&buf);
 174         printf("%s\n", oid_to_hex(&result));
 175         return 0;
 176 }