diff options
Diffstat (limited to 'mktag.c')
| -rw-r--r-- | mktag.c | 147 |
1 files changed, 147 insertions, 0 deletions
@@ -0,0 +1,147 @@ +#include "cache.h" +#include "tag.h" + +/* + * A signature file has a very simple fixed format: four lines + * of "object <sha1>" + "type <typename>" + "tag <tagname>" + + * "tagger <committer>", followed by a blank line, a free-form tag + * message and a signature block that git itself doesn't care about, + * but that can be verified with gpg or similar. + * + * The first three lines are guaranteed to be at least 63 bytes: + * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the + * shortest possible type-line, and "tag .\n" at 6 bytes is the + * shortest single-character-tag line. + * + * We also artificially limit the size of the full object to 8kB. + * Just because I'm a lazy bastard, and if you can't fit a signature + * in that size, you're doing something wrong. + */ + +/* Some random size */ +#define MAXSIZE (8192) + +/* + * We refuse to tag something we can't verify. Just because. + */ +static int verify_object(unsigned char *sha1, const char *expected_type) +{ + int ret = -1; + char type[100]; + unsigned long size; + void *buffer = read_sha1_file(sha1, type, &size); + + if (buffer) { + if (!strcmp(type, expected_type)) + ret = check_sha1_signature(sha1, buffer, size, type); + free(buffer); + } + return ret; +} + +#ifdef NO_C99_FORMAT +#define PD_FMT "%d" +#else +#define PD_FMT "%td" +#endif + +static int verify_tag(char *buffer, unsigned long size) +{ + int typelen; + char type[20]; + unsigned char sha1[20]; + const char *object, *type_line, *tag_line, *tagger_line; + + if (size < 64) + return error("wanna fool me ? you obviously got the size wrong !"); + + buffer[size] = 0; + + /* Verify object line */ + object = buffer; + if (memcmp(object, "object ", 7)) + return error("char%d: does not start with \"object \"", 0); + + if (get_sha1_hex(object + 7, sha1)) + return error("char%d: could not get SHA1 hash", 7); + + /* Verify type line */ + type_line = object + 48; + if (memcmp(type_line - 1, "\ntype ", 6)) + return error("char%d: could not find \"\\ntype \"", 47); + + /* Verify tag-line */ + tag_line = strchr(type_line, '\n'); + if (!tag_line) + return error("char" PD_FMT ": could not find next \"\\n\"", type_line - buffer); + tag_line++; + if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n') + return error("char" PD_FMT ": no \"tag \" found", tag_line - buffer); + + /* Get the actual type */ + typelen = tag_line - type_line - strlen("type \n"); + if (typelen >= sizeof(type)) + return error("char" PD_FMT ": type too long", type_line+5 - buffer); + + memcpy(type, type_line+5, typelen); + type[typelen] = 0; + + /* Verify that the object matches */ + if (verify_object(sha1, type)) + return error("char%d: could not verify object %s", 7, sha1_to_hex(sha1)); + + /* Verify the tag-name: we don't allow control characters or spaces in it */ + tag_line += 4; + for (;;) { + unsigned char c = *tag_line++; + if (c == '\n') + break; + if (c > ' ') + continue; + return error("char" PD_FMT ": could not verify tag name", tag_line - buffer); + } + + /* Verify the tagger line */ + tagger_line = tag_line; + + if (memcmp(tagger_line, "tagger", 6) || (tagger_line[6] == '\n')) + return error("char" PD_FMT ": could not find \"tagger\"", tagger_line - buffer); + + /* TODO: check for committer info + blank line? */ + /* Also, the minimum length is probably + "tagger .", or 63+8=71 */ + + /* The actual stuff afterwards we don't care about.. */ + return 0; +} + +#undef PD_FMT + +int main(int argc, char **argv) +{ + unsigned long size = 4096; + char *buffer = xmalloc(size); + unsigned char result_sha1[20]; + + if (argc != 1) + usage("git-mktag < signaturefile"); + + setup_git_directory(); + + if (read_pipe(0, &buffer, &size)) { + free(buffer); + die("could not read from stdin"); + } + + /* Verify it for some basic sanity: it needs to start with + "object <sha1>\ntype\ntagger " */ + if (verify_tag(buffer, size) < 0) + die("invalid tag signature file"); + + if (write_sha1_file(buffer, size, tag_type, result_sha1) < 0) + die("unable to write tag file"); + + free(buffer); + + printf("%s\n", sha1_to_hex(result_sha1)); + return 0; +} |