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-rw-r--r--builtin/mktag.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/builtin/mktag.c b/builtin/mktag.c
new file mode 100644
index 0000000..640ab64
--- /dev/null
+++ b/builtin/mktag.c
@@ -0,0 +1,174 @@
+#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;
+}