#include "builtin.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 four lines are guaranteed to be at least 83 bytes: * "object <sha1>\n" is 48 bytes, "type tag\n" at 9 bytes is the * shortest possible type-line, "tag .\n" at 6 bytes is the shortest * single-character-tag line, and "tagger . <> 0 +0000\n" at 20 bytes is * the shortest possible tagger-line. */ /* * We refuse to tag something we can't verify. Just because. */ static int verify_object(const unsigned char *sha1, const char *expected_type) { int ret = -1; enum object_type type; unsigned long size; void *buffer = read_sha1_file(sha1, &type, &size); const unsigned char *repl = lookup_replace_object(sha1); if (buffer) { if (type == type_from_string(expected_type)) ret = check_sha1_signature(repl, buffer, size, expected_type); free(buffer); } return ret; } 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, *lb, *rb; size_t len; if (size < 84) 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%"PRIuMAX": could not find next \"\\n\"", (uintmax_t) (type_line - buffer)); tag_line++; if (memcmp(tag_line, "tag ", 4) || tag_line[4] == '\n') return error("char%"PRIuMAX": no \"tag \" found", (uintmax_t) (tag_line - buffer)); /* Get the actual type */ typelen = tag_line - type_line - strlen("type \n"); if (typelen >= sizeof(type)) return error("char%"PRIuMAX": type too long", (uintmax_t) (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%"PRIuMAX": could not verify tag name", (uintmax_t) (tag_line - buffer)); } /* Verify the tagger line */ tagger_line = tag_line; if (memcmp(tagger_line, "tagger ", 7)) return error("char%"PRIuMAX": could not find \"tagger \"", (uintmax_t) (tagger_line - buffer)); /* * Check for correct form for name and email * i.e. " <" followed by "> " on _this_ line * No angle brackets within the name or email address fields. * No spaces within the email address field. */ tagger_line += 7; if (!(lb = strstr(tagger_line, " <")) || !(rb = strstr(lb+2, "> ")) || strpbrk(tagger_line, "<>\n") != lb+1 || strpbrk(lb+2, "><\n ") != rb) return error("char%"PRIuMAX": malformed tagger field", (uintmax_t) (tagger_line - buffer)); /* Check for author name, at least one character, space is acceptable */ if (lb == tagger_line) return error("char%"PRIuMAX": missing tagger name", (uintmax_t) (tagger_line - buffer)); /* timestamp, 1 or more digits followed by space */ tagger_line = rb + 2; if (!(len = strspn(tagger_line, "0123456789"))) return error("char%"PRIuMAX": missing tag timestamp", (uintmax_t) (tagger_line - buffer)); tagger_line += len; if (*tagger_line != ' ') return error("char%"PRIuMAX": malformed tag timestamp", (uintmax_t) (tagger_line - buffer)); tagger_line++; /* timezone, 5 digits [+-]hhmm, max. 1400 */ if (!((tagger_line[0] == '+' || tagger_line[0] == '-') && strspn(tagger_line+1, "0123456789") == 4 && tagger_line[5] == '\n' && atoi(tagger_line+1) <= 1400)) return error("char%"PRIuMAX": malformed tag timezone", (uintmax_t) (tagger_line - buffer)); tagger_line += 6; /* Verify the blank line separating the header from the body */ if (*tagger_line != '\n') return error("char%"PRIuMAX": trailing garbage in tag header", (uintmax_t) (tagger_line - buffer)); /* The actual stuff afterwards we don't care about.. */ return 0; } int cmd_mktag(int argc, const char **argv, const char *prefix) { struct strbuf buf = STRBUF_INIT; unsigned char result_sha1[20]; if (argc != 1) usage("git mktag < signaturefile"); if (strbuf_read(&buf, 0, 4096) < 0) { die_errno("could not read from stdin"); } /* Verify it for some basic sanity: it needs to start with "object <sha1>\ntype\ntagger " */ if (verify_tag(buf.buf, buf.len) < 0) die("invalid tag signature file"); if (write_sha1_file(buf.buf, buf.len, tag_type, result_sha1) < 0) die("unable to write tag file"); strbuf_release(&buf); printf("%s\n", sha1_to_hex(result_sha1)); return 0; }