Andrew's git - gitweb.git/blob

   1#include "cache.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(unsigned char *sha1, const char *expected_type)
  22{
  23        int ret = -1;
  24        enum object_type type;
  25        unsigned long size;
  26        void *buffer = read_sha1_file(sha1, &type, &size);
  27
  28        if (buffer) {
  29                if (type == type_from_string(expected_type))
  30                        ret = check_sha1_signature(sha1, buffer, size, expected_type);
  31                free(buffer);
  32        }
  33        return ret;
  34}
  35
  36#ifdef NO_C99_FORMAT
  37#define PD_FMT "%d"
  38#else
  39#define PD_FMT "%td"
  40#endif
  41
  42static int verify_tag(char *buffer, unsigned long size)
  43{
  44        int typelen;
  45        char type[20];
  46        unsigned char sha1[20];
  47        const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb;
  48        size_t len;
  49
  50        if (size < 84)
  51                return error("wanna fool me ? you obviously got the size wrong !");
  52
  53        buffer[size] = 0;
  54
  55        /* Verify object line */
  56        object = buffer;
  57        if (memcmp(object, "object ", 7))
  58                return error("char%d: does not start with \"object \"", 0);
  59
  60        if (get_sha1_hex(object + 7, sha1))
  61                return error("char%d: could not get SHA1 hash", 7);
  62
  63        /* Verify type line */
  64        type_line = object + 48;
  65        if (memcmp(type_line - 1, "\ntype ", 6))
  66                return error("char%d: could not find \"\\ntype \"", 47);
  67
  68        /* Verify tag-line */
  69        tag_line = strchr(type_line, '\n');
  70        if (!tag_line)
  71                return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer);
  72        tag_line++;
  73        if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  74                return error("char" PD_FMT ": no \"tag \" found", 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" PD_FMT ": type too long", 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(sha1, type))
  86                return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
  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" PD_FMT ": could not verify tag name", 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" PD_FMT ": could not find \"tagger \"",
 104                        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" PD_FMT ": malformed tagger field",
 117                        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" PD_FMT ": missing tagger name",
 122                        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" PD_FMT ": missing tag timestamp",
 128                        tagger_line - buffer);
 129        tagger_line += len;
 130        if (*tagger_line != ' ')
 131                return error("char" PD_FMT ": malformed tag timestamp",
 132                        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" PD_FMT ": malformed tag timezone",
 140                        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" PD_FMT ": trailing garbage in tag header",
 146                        tagger_line - buffer);
 147
 148        /* The actual stuff afterwards we don't care about.. */
 149        return 0;
 150}
 151
 152#undef PD_FMT
 153
 154int main(int argc, char **argv)
 155{
 156        struct strbuf buf;
 157        unsigned char result_sha1[20];
 158
 159        if (argc != 1)
 160                usage("git-mktag < signaturefile");
 161
 162        setup_git_directory();
 163
 164        strbuf_init(&buf, 0);
 165        if (strbuf_read(&buf, 0, 4096) < 0) {
 166                die("could not read from stdin");
 167        }
 168
 169        /* Verify it for some basic sanity: it needs to start with
 170           "object <sha1>\ntype\ntagger " */
 171        if (verify_tag(buf.buf, buf.len) < 0)
 172                die("invalid tag signature file");
 173
 174        if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
 175                die("unable to write tag file");
 176
 177        strbuf_release(&buf);
 178        printf("%s\n", sha1_to_hex(result_sha1));
 179        return 0;
 180}