Andrew's git - gitweb.git/blob

   1#include "cache.h"
   2#include "tag.h"
   3#include "exec_cmd.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(unsigned char *sha1, const char *expected_type)
  23{
  24        int ret = -1;
  25        enum object_type type;
  26        unsigned long size;
  27        void *buffer = read_sha1_file(sha1, &type, &size);
  28
  29        if (buffer) {
  30                if (type == type_from_string(expected_type))
  31                        ret = check_sha1_signature(sha1, buffer, size, expected_type);
  32                free(buffer);
  33        }
  34        return ret;
  35}
  36
  37#ifdef NO_C99_FORMAT
  38#define PD_FMT "%d"
  39#else
  40#define PD_FMT "%td"
  41#endif
  42
  43static int verify_tag(char *buffer, unsigned long size)
  44{
  45        int typelen;
  46        char type[20];
  47        unsigned char sha1[20];
  48        const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb;
  49        size_t len;
  50
  51        if (size < 84)
  52                return error("wanna fool me ? you obviously got the size wrong !");
  53
  54        buffer[size] = 0;
  55
  56        /* Verify object line */
  57        object = buffer;
  58        if (memcmp(object, "object ", 7))
  59                return error("char%d: does not start with \"object \"", 0);
  60
  61        if (get_sha1_hex(object + 7, sha1))
  62                return error("char%d: could not get SHA1 hash", 7);
  63
  64        /* Verify type line */
  65        type_line = object + 48;
  66        if (memcmp(type_line - 1, "\ntype ", 6))
  67                return error("char%d: could not find \"\\ntype \"", 47);
  68
  69        /* Verify tag-line */
  70        tag_line = strchr(type_line, '\n');
  71        if (!tag_line)
  72                return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer);
  73        tag_line++;
  74        if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  75                return error("char" PD_FMT ": no \"tag \" found", tag_line - buffer);
  76
  77        /* Get the actual type */
  78        typelen = tag_line - type_line - strlen("type \n");
  79        if (typelen >= sizeof(type))
  80                return error("char" PD_FMT ": type too long", 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(sha1, type))
  87                return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
  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" PD_FMT ": could not verify tag name", 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" PD_FMT ": could not find \"tagger \"",
 105                        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" PD_FMT ": malformed tagger field",
 118                        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" PD_FMT ": missing tagger name",
 123                        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" PD_FMT ": missing tag timestamp",
 129                        tagger_line - buffer);
 130        tagger_line += len;
 131        if (*tagger_line != ' ')
 132                return error("char" PD_FMT ": malformed tag timestamp",
 133                        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" 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 = STRBUF_INIT;
 158        unsigned char result_sha1[20];
 159
 160        if (argc != 1)
 161                usage("git mktag < signaturefile");
 162
 163        git_extract_argv0_path(argv[0]);
 164
 165        setup_git_directory();
 166
 167        if (strbuf_read(&buf, 0, 4096) < 0) {
 168                die("could not read from stdin");
 169        }
 170
 171        /* Verify it for some basic sanity: it needs to start with
 172           "object <sha1>\ntype\ntagger " */
 173        if (verify_tag(buf.buf, buf.len) < 0)
 174                die("invalid tag signature file");
 175
 176        if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
 177                die("unable to write tag file");
 178
 179        strbuf_release(&buf);
 180        printf("%s\n", sha1_to_hex(result_sha1));
 181        return 0;
 182}