Andrew's git - gitweb.git/blob

   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 */
  23static 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
  39static 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
 153int 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}