Andrew's git - gitweb.git/blob

   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 */
  21static 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        const unsigned char *repl;
  27        void *buffer = read_sha1_file_repl(sha1, &type, &size, &repl);
  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
  37static 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
 151int 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}