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
  49        if (size < 84)
  50                return error("wanna fool me ? you obviously got the size wrong !");
  51
  52        buffer[size] = 0;
  53
  54        /* Verify object line */
  55        object = buffer;
  56        if (memcmp(object, "object ", 7))
  57                return error("char%d: does not start with \"object \"", 0);
  58
  59        if (get_sha1_hex(object + 7, sha1))
  60                return error("char%d: could not get SHA1 hash", 7);
  61
  62        /* Verify type line */
  63        type_line = object + 48;
  64        if (memcmp(type_line - 1, "\ntype ", 6))
  65                return error("char%d: could not find \"\\ntype \"", 47);
  66
  67        /* Verify tag-line */
  68        tag_line = strchr(type_line, '\n');
  69        if (!tag_line)
  70                return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer);
  71        tag_line++;
  72        if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  73                return error("char" PD_FMT ": no \"tag \" found", 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" PD_FMT ": type too long", 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(sha1, type))
  85                return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
  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" PD_FMT ": could not verify tag name", tag_line - buffer);
  96        }
  97
  98        /* Verify the tagger line */
  99        tagger_line = tag_line;
 100
 101        if (memcmp(tagger_line, "tagger ", 7) || (tagger_line[7] == '\n'))
 102                return error("char" PD_FMT ": could not find \"tagger \"",
 103                        tagger_line - buffer);
 104
 105        /*
 106         * Check for correct form for name and email
 107         * i.e. " <" followed by "> " on _this_ line
 108         */
 109        tagger_line += 7;
 110        if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 111                strchr(tagger_line, '\n') < rb)
 112                return error("char" PD_FMT ": malformed tagger",
 113                        tagger_line - buffer);
 114
 115        /* Check for author name, at least one character, space is acceptable */
 116        if (lb == tagger_line)
 117                return error("char" PD_FMT ": missing tagger name",
 118                        tagger_line - buffer);
 119
 120        /* timestamp */
 121        tagger_line = rb + 2;
 122        if (*tagger_line == ' ')
 123                return error("char" PD_FMT ": malformed tag timestamp",
 124                        tagger_line - buffer);
 125        for (;;) {
 126                unsigned char c = *tagger_line++;
 127                if (c == ' ')
 128                        break;
 129                if (isdigit(c))
 130                        continue;
 131                return error("char" PD_FMT ": malformed tag timestamp",
 132                        tagger_line - buffer);
 133        }
 134
 135        /* timezone, 5 digits [+-]hhmm, max. 1400 */
 136        if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 137              isdigit(tagger_line[1]) && isdigit(tagger_line[2]) &&
 138              isdigit(tagger_line[3]) && isdigit(tagger_line[4]) &&
 139              tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
 140                return error("char" PD_FMT ": malformed tag timezone",
 141                        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" PD_FMT ": trailing garbage in tag header",
 147                        tagger_line - buffer);
 148
 149        /* The actual stuff afterwards we don't care about.. */
 150        return 0;
 151}
 152
 153#undef PD_FMT
 154
 155int main(int argc, char **argv)
 156{
 157        struct strbuf buf;
 158        unsigned char result_sha1[20];
 159
 160        if (argc != 1)
 161                usage("git-mktag < signaturefile");
 162
 163        setup_git_directory();
 164
 165        strbuf_init(&buf, 0);
 166        if (strbuf_read(&buf, 0, 4096) < 0) {
 167                die("could not read from stdin");
 168        }
 169
 170        /* Verify it for some basic sanity: it needs to start with
 171           "object <sha1>\ntype\ntagger " */
 172        if (verify_tag(buf.buf, buf.len) < 0)
 173                die("invalid tag signature file");
 174
 175        if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
 176                die("unable to write tag file");
 177
 178        strbuf_release(&buf);
 179        printf("%s\n", sha1_to_hex(result_sha1));
 180        return 0;
 181}