Andrew's git - gitweb.git/blob

   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 */
  22static 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
  38static 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
 152int 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}