object-file.c: use "enum" return type for unpack_loose_header()

In a preceding commit we changed and documented unpack_loose_header()
from its previous behavior of returning any negative value or zero, to
only -1 or 0.

Let's add an "enum unpack_loose_header_result" type and use it for
these return values, and have the compiler assert that we're
exhaustively covering all of them.

Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 21 insertions, 13 deletions

diff --git a/object-file.c b/object-file.c
index 59b38aac2b..ade5f33f3c 100644
--- a/object-file.c
+++ b/object-file.c
@@ -1210,10 +1210,12 @@ void *map_loose_object(struct repository *r,
 	return map_loose_object_1(r, NULL, oid, size);
 }
 
-int unpack_loose_header(git_zstream *stream,
-			unsigned char *map, unsigned long mapsize,
-			void *buffer, unsigned long bufsiz,
-			struct strbuf *header)
+enum unpack_loose_header_result unpack_loose_header(git_zstream *stream,
+						    unsigned char *map,
+						    unsigned long mapsize,
+						    void *buffer,
+						    unsigned long bufsiz,
+						    struct strbuf *header)
 {
 	int status;
 
@@ -1229,13 +1231,13 @@ int unpack_loose_header(git_zstream *stream,
 	status = git_inflate(stream, 0);
 	obj_read_lock();
 	if (status < Z_OK)
-		return -1;
+		return ULHR_BAD;
 
 	/*
 	 * Check if entire header is unpacked in the first iteration.
 	 */
 	if (memchr(buffer, '\0', stream->next_out - (unsigned char *)buffer))
-		return 0;
+		return ULHR_OK;
 
 	/*
 	 * We have a header longer than MAX_HEADER_LEN. The "header"
@@ -1243,7 +1245,7 @@ int unpack_loose_header(git_zstream *stream,
 	 * --allow-unknown-type".
 	 */
 	if (!header)
-		return -1;
+		return ULHR_BAD;
 
 	/*
 	 * buffer[0..bufsiz] was not large enough.  Copy the partial
@@ -1264,7 +1266,7 @@ int unpack_loose_header(git_zstream *stream,
 		stream->next_out = buffer;
 		stream->avail_out = bufsiz;
 	} while (status != Z_STREAM_END);
-	return -1;
+	return ULHR_BAD;
 }
 
 static void *unpack_loose_rest(git_zstream *stream,
@@ -1429,13 +1431,19 @@ static int loose_object_info(struct repository *r,
 	if (oi->disk_sizep)
 		*oi->disk_sizep = mapsize;
 
-	if (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
-				allow_unknown ? &hdrbuf : NULL) < 0)
+	switch (unpack_loose_header(&stream, map, mapsize, hdr, sizeof(hdr),
+				    allow_unknown ? &hdrbuf : NULL)) {
+	case ULHR_OK:
+		break;
+	case ULHR_BAD:
 		status = error(_("unable to unpack %s header"),
 			       oid_to_hex(oid));
-	if (status < 0)
-		; /* Do nothing */
-	else if (hdrbuf.len) {
+		break;
+	}
+
+	if (status < 0) {
+		/* Do nothing */
+	} else if (hdrbuf.len) {
 		if ((status = parse_loose_header(hdrbuf.buf, oi, flags)) < 0)
 			status = error(_("unable to parse %s header with --allow-unknown-type"),
 				       oid_to_hex(oid));