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 struct object_id *oid, const char *expected_type)
  22{
  23        int ret = -1;
  24        enum object_type type;
  25        unsigned long size;
  26        void *buffer = read_sha1_file(oid->hash, &type, &size);
  27        const unsigned char *repl = lookup_replace_object(oid->hash);
  28
  29        if (buffer) {
  30                struct object_id reploid;
  31                hashcpy(reploid.hash, repl);
  32
  33                if (type == type_from_string(expected_type))
  34                        ret = check_object_signature(&reploid, buffer, size, expected_type);
  35                free(buffer);
  36        }
  37        return ret;
  38}
  39
  40static int verify_tag(char *buffer, unsigned long size)
  41{
  42        int typelen;
  43        char type[20];
  44        struct object_id oid;
  45        const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb, *p;
  46        size_t len;
  47
  48        if (size < 84)
  49                return error("wanna fool me ? you obviously got the size wrong !");
  50
  51        buffer[size] = 0;
  52
  53        /* Verify object line */
  54        object = buffer;
  55        if (memcmp(object, "object ", 7))
  56                return error("char%d: does not start with \"object \"", 0);
  57
  58        if (parse_oid_hex(object + 7, &oid, &p))
  59                return error("char%d: could not get SHA1 hash", 7);
  60
  61        /* Verify type line */
  62        type_line = p + 1;
  63        if (memcmp(type_line - 1, "\ntype ", 6))
  64                return error("char%d: could not find \"\\ntype \"", 47);
  65
  66        /* Verify tag-line */
  67        tag_line = strchr(type_line, '\n');
  68        if (!tag_line)
  69                return error("char%"PRIuMAX": could not find next \"\\n\"",
  70                                (uintmax_t) (type_line - buffer));
  71        tag_line++;
  72        if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  73                return error("char%"PRIuMAX": no \"tag \" found",
  74                                (uintmax_t) (tag_line - buffer));
  75
  76        /* Get the actual type */
  77        typelen = tag_line - type_line - strlen("type \n");
  78        if (typelen >= sizeof(type))
  79                return error("char%"PRIuMAX": type too long",
  80                                (uintmax_t) (type_line+5 - buffer));
  81
  82        memcpy(type, type_line+5, typelen);
  83        type[typelen] = 0;
  84
  85        /* Verify that the object matches */
  86        if (verify_object(&oid, type))
  87                return error("char%d: could not verify object %s", 7, oid_to_hex(&oid));
  88
  89        /* Verify the tag-name: we don't allow control characters or spaces in it */
  90        tag_line += 4;
  91        for (;;) {
  92                unsigned char c = *tag_line++;
  93                if (c == '\n')
  94                        break;
  95                if (c > ' ')
  96                        continue;
  97                return error("char%"PRIuMAX": could not verify tag name",
  98                                (uintmax_t) (tag_line - buffer));
  99        }
 100
 101        /* Verify the tagger line */
 102        tagger_line = tag_line;
 103
 104        if (memcmp(tagger_line, "tagger ", 7))
 105                return error("char%"PRIuMAX": could not find \"tagger \"",
 106                        (uintmax_t) (tagger_line - buffer));
 107
 108        /*
 109         * Check for correct form for name and email
 110         * i.e. " <" followed by "> " on _this_ line
 111         * No angle brackets within the name or email address fields.
 112         * No spaces within the email address field.
 113         */
 114        tagger_line += 7;
 115        if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 116                strpbrk(tagger_line, "<>\n") != lb+1 ||
 117                strpbrk(lb+2, "><\n ") != rb)
 118                return error("char%"PRIuMAX": malformed tagger field",
 119                        (uintmax_t) (tagger_line - buffer));
 120
 121        /* Check for author name, at least one character, space is acceptable */
 122        if (lb == tagger_line)
 123                return error("char%"PRIuMAX": missing tagger name",
 124                        (uintmax_t) (tagger_line - buffer));
 125
 126        /* timestamp, 1 or more digits followed by space */
 127        tagger_line = rb + 2;
 128        if (!(len = strspn(tagger_line, "0123456789")))
 129                return error("char%"PRIuMAX": missing tag timestamp",
 130                        (uintmax_t) (tagger_line - buffer));
 131        tagger_line += len;
 132        if (*tagger_line != ' ')
 133                return error("char%"PRIuMAX": malformed tag timestamp",
 134                        (uintmax_t) (tagger_line - buffer));
 135        tagger_line++;
 136
 137        /* timezone, 5 digits [+-]hhmm, max. 1400 */
 138        if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 139              strspn(tagger_line+1, "0123456789") == 4 &&
 140              tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
 141                return error("char%"PRIuMAX": malformed tag timezone",
 142                        (uintmax_t) (tagger_line - buffer));
 143        tagger_line += 6;
 144
 145        /* Verify the blank line separating the header from the body */
 146        if (*tagger_line != '\n')
 147                return error("char%"PRIuMAX": trailing garbage in tag header",
 148                        (uintmax_t) (tagger_line - buffer));
 149
 150        /* The actual stuff afterwards we don't care about.. */
 151        return 0;
 152}
 153
 154int cmd_mktag(int argc, const char **argv, const char *prefix)
 155{
 156        struct strbuf buf = STRBUF_INIT;
 157        struct object_id result;
 158
 159        if (argc != 1)
 160                usage("git mktag");
 161
 162        if (strbuf_read(&buf, 0, 4096) < 0) {
 163                die_errno("could not read from stdin");
 164        }
 165
 166        /* Verify it for some basic sanity: it needs to start with
 167           "object <sha1>\ntype\ntagger " */
 168        if (verify_tag(buf.buf, buf.len) < 0)
 169                die("invalid tag signature file");
 170
 171        if (write_object_file(buf.buf, buf.len, tag_type, &result) < 0)
 172                die("unable to write tag file");
 173
 174        strbuf_release(&buf);
 175        printf("%s\n", oid_to_hex(&result));
 176        return 0;
 177}