Add lax parsing for commit and tag objectsrb/object-parse-flexibility

This changes the behavior of object parsing for commits and tags
so that even when bad data is found inside the object, we will
continue to try to parse as much of the object as we can.  The
existing functions (`git_object_lookup` for example) will still
delete the partially parsed object before returning an error, but
this also adds a new function `git_object_lookup_lax` that will
still return the error, but will also return the object with the
partial data (if we got far enough along in the parsing process to
even create the base object).

1 files changed, 31 insertions, 9 deletions

diff --git a/src/signature.c b/src/signature.c
index 2545b7519..f6d50c8ba 100644
--- a/src/signature.c
+++ b/src/signature.c
@@ -11,7 +11,7 @@
 #include "git2/common.h"
 #include "posix.h"
 
-void git_signature_free(git_signature *sig)
+void git_signature__clear(git_signature *sig)
 {
 	if (sig == NULL)
 		return;
@@ -20,6 +20,11 @@ void git_signature_free(git_signature *sig)
 	sig->name = NULL;
 	git__free(sig->email);
 	sig->email = NULL;
+}
+
+void git_signature_free(git_signature *sig)
+{
+	git_signature__clear(sig);
 	git__free(sig);
 }
 
@@ -176,22 +181,39 @@ int git_signature__parse(git_signature *sig, const char **buffer_out,
 	}
 
 	email_start = git__memrchr(buffer, '<', buffer_end - buffer);
-	email_end = git__memrchr(buffer, '>', buffer_end - buffer);
+	if (!email_start) {
+		/* just stop now with everything as name */
+		sig->name = extract_trimmed(buffer, buffer_end - buffer);
+		sig->email = git__strdup("");
+		*buffer_out = buffer_end + 1;
+		return signature_error("missing e-mail");
+	}
 
-	if (!email_start || !email_end || email_end <= email_start)
+	sig->name = extract_trimmed(buffer, email_start - buffer);
+	email_start += 1;
+
+	email_end = git__memrchr(email_start, '>', buffer_end - email_start);
+	if (!email_end) {
+		sig->email = extract_trimmed(email_start, buffer_end - email_start);
 		return signature_error("malformed e-mail");
+	}
 
-	email_start += 1;
-	sig->name = extract_trimmed(buffer, email_start - buffer - 1);
 	sig->email = extract_trimmed(email_start, email_end - email_start);
 
 	/* Do we even have a time at the end of the signature? */
-	if (email_end + 2 < buffer_end) {
+	if (email_end != NULL && email_end + 2 < buffer_end) {
 		const char *time_start = email_end + 2;
 		const char *time_end;
 
-		if (git__strtol64(&sig->when.time, time_start, &time_end, 10) < 0)
-			return signature_error("invalid Unix timestamp");
+		if (git__strtol64(&sig->when.time, time_start, &time_end, 10) < 0) {
+			/* set timestamp to max value */
+			sig->when.time = (uint64_t)-1L;
+
+			/* skip over invalid timestamp data */
+			time_end = time_start;
+			while (git__isspace(*time_end)) ++time_end;
+			while (*time_end && !git__isspace(*time_end)) ++time_end;
+		}
 
 		/* do we have a timezone? */
 		if (time_end + 1 < buffer_end) {
@@ -202,7 +224,7 @@ int git_signature__parse(git_signature *sig, const char **buffer_out,
 
 			if ((tz_start[0] != '-' && tz_start[0] != '+') ||
 				git__strtol32(&offset, tz_start + 1, &tz_end, 10) < 0) {
-				//malformed timezone, just assume it's zero
+				/* malformed timezone, just assume it's zero */
 				offset = 0;
 			}