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(const unsigned char *sha1, const char *expected_type)
  23{
  24        int ret = -1;
  25        enum object_type type;
  26        unsigned long size;
  27        const unsigned char *repl;
  28        void *buffer = read_sha1_file_repl(sha1, &type, &size, &repl);
  29
  30        if (buffer) {
  31                if (type == type_from_string(expected_type))
  32                        ret = check_sha1_signature(repl, buffer, size, expected_type);
  33                free(buffer);
  34        }
  35        return ret;
  36}
  37
  38#ifdef NO_C99_FORMAT
  39#define PD_FMT "%d"
  40#else
  41#define PD_FMT "%td"
  42#endif
  43
  44static int verify_tag(char *buffer, unsigned long size)
  45{
  46        int typelen;
  47        char type[20];
  48        unsigned char sha1[20];
  49        const char *object, *type_line, *tag_line, *tagger_line, *lb, *rb;
  50        size_t len;
  51
  52        if (size < 84)
  53                return error("wanna fool me ? you obviously got the size wrong !");
  54
  55        buffer[size] = 0;
  56
  57        /* Verify object line */
  58        object = buffer;
  59        if (memcmp(object, "object ", 7))
  60                return error("char%d: does not start with \"object \"", 0);
  61
  62        if (get_sha1_hex(object + 7, sha1))
  63                return error("char%d: could not get SHA1 hash", 7);
  64
  65        /* Verify type line */
  66        type_line = object + 48;
  67        if (memcmp(type_line - 1, "\ntype ", 6))
  68                return error("char%d: could not find \"\\ntype \"", 47);
  69
  70        /* Verify tag-line */
  71        tag_line = strchr(type_line, '\n');
  72        if (!tag_line)
  73                return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer);
  74        tag_line++;
  75        if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n')
  76                return error("char" PD_FMT ": no \"tag \" found", tag_line - buffer);
  77
  78        /* Get the actual type */
  79        typelen = tag_line - type_line - strlen("type \n");
  80        if (typelen >= sizeof(type))
  81                return error("char" PD_FMT ": type too long", type_line+5 - buffer);
  82
  83        memcpy(type, type_line+5, typelen);
  84        type[typelen] = 0;
  85
  86        /* Verify that the object matches */
  87        if (verify_object(sha1, type))
  88                return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1));
  89
  90        /* Verify the tag-name: we don't allow control characters or spaces in it */
  91        tag_line += 4;
  92        for (;;) {
  93                unsigned char c = *tag_line++;
  94                if (c == '\n')
  95                        break;
  96                if (c > ' ')
  97                        continue;
  98                return error("char" PD_FMT ": could not verify tag name", tag_line - buffer);
  99        }
 100
 101        /* Verify the tagger line */
 102        tagger_line = tag_line;
 103
 104        if (memcmp(tagger_line, "tagger ", 7))
 105                return error("char" PD_FMT ": could not find \"tagger \"",
 106                        tagger_line - buffer);
 107
 108        /*
 109         * Check for correct form for name and email
 110         * i.e. " <" followed by "> " on _this_ line
 111         * No angle brackets within the name or email address fields.
 112         * No spaces within the email address field.
 113         */
 114        tagger_line += 7;
 115        if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) ||
 116                strpbrk(tagger_line, "<>\n") != lb+1 ||
 117                strpbrk(lb+2, "><\n ") != rb)
 118                return error("char" PD_FMT ": malformed tagger field",
 119                        tagger_line - buffer);
 120
 121        /* Check for author name, at least one character, space is acceptable */
 122        if (lb == tagger_line)
 123                return error("char" PD_FMT ": missing tagger name",
 124                        tagger_line - buffer);
 125
 126        /* timestamp, 1 or more digits followed by space */
 127        tagger_line = rb + 2;
 128        if (!(len = strspn(tagger_line, "0123456789")))
 129                return error("char" PD_FMT ": missing tag timestamp",
 130                        tagger_line - buffer);
 131        tagger_line += len;
 132        if (*tagger_line != ' ')
 133                return error("char" PD_FMT ": malformed tag timestamp",
 134                        tagger_line - buffer);
 135        tagger_line++;
 136
 137        /* timezone, 5 digits [+-]hhmm, max. 1400 */
 138        if (!((tagger_line[0] == '+' || tagger_line[0] == '-') &&
 139              strspn(tagger_line+1, "0123456789") == 4 &&
 140              tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400))
 141                return error("char" PD_FMT ": malformed tag timezone",
 142                        tagger_line - buffer);
 143        tagger_line += 6;
 144
 145        /* Verify the blank line separating the header from the body */
 146        if (*tagger_line != '\n')
 147                return error("char" PD_FMT ": trailing garbage in tag header",
 148                        tagger_line - buffer);
 149
 150        /* The actual stuff afterwards we don't care about.. */
 151        return 0;
 152}
 153
 154#undef PD_FMT
 155
 156int main(int argc, char **argv)
 157{
 158        struct strbuf buf = STRBUF_INIT;
 159        unsigned char result_sha1[20];
 160
 161        if (argc != 1)
 162                usage("git mktag < signaturefile");
 163
 164        git_extract_argv0_path(argv[0]);
 165
 166        setup_git_directory();
 167
 168        if (strbuf_read(&buf, 0, 4096) < 0) {
 169                die_errno("could not read from stdin");
 170        }
 171
 172        /* Verify it for some basic sanity: it needs to start with
 173           "object <sha1>\ntype\ntagger " */
 174        if (verify_tag(buf.buf, buf.len) < 0)
 175                die("invalid tag signature file");
 176
 177        if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0)
 178                die("unable to write tag file");
 179
 180        strbuf_release(&buf);
 181        printf("%s\n", sha1_to_hex(result_sha1));
 182        return 0;
 183}