fsck: git receive-pack: support excluding objects from fsck'ing

The optional new config option `receive.fsck.skipList` specifies the path
to a file listing the names, i.e. SHA-1s, one per line, of objects that
are to be ignored by `git receive-pack` when `receive.fsckObjects = true`.

This is extremely handy in case of legacy repositories where it would
cause more pain to change incorrect objects than to live with them
(e.g. a duplicate 'author' line in an early commit object).

The intended use case is for server administrators to inspect objects
that are reported by `git push` as being too problematic to enter the
repository, and to add the objects' SHA-1 to a (preferably sorted) file
when the objects are legitimate, i.e. when it is determined that those
problematic objects should be allowed to enter the server.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/fsck.c b/fsck.c
index 7a614bb..1523243 100644
--- a/fsck.c
+++ b/fsck.c
@@ -8,6 +8,7 @@
 #include "fsck.h"
 #include "refs.h"
 #include "utf8.h"
+#include "sha1-array.h"
 
 #define FSCK_FATAL -1
 #define FSCK_INFO -2
@@ -127,6 +128,43 @@ static int fsck_msg_type(enum fsck_msg_id msg_id,
 	return msg_type;
 }
 
+static void init_skiplist(struct fsck_options *options, const char *path)
+{
+	static struct sha1_array skiplist = SHA1_ARRAY_INIT;
+	int sorted, fd;
+	char buffer[41];
+	unsigned char sha1[20];
+
+	if (options->skiplist)
+		sorted = options->skiplist->sorted;
+	else {
+		sorted = 1;
+		options->skiplist = &skiplist;
+	}
+
+	fd = open(path, O_RDONLY);
+	if (fd < 0)
+		die("Could not open skip list: %s", path);
+	for (;;) {
+		int result = read_in_full(fd, buffer, sizeof(buffer));
+		if (result < 0)
+			die_errno("Could not read '%s'", path);
+		if (!result)
+			break;
+		if (get_sha1_hex(buffer, sha1) || buffer[40] != '\n')
+			die("Invalid SHA-1: %s", buffer);
+		sha1_array_append(&skiplist, sha1);
+		if (sorted && skiplist.nr > 1 &&
+				hashcmp(skiplist.sha1[skiplist.nr - 2],
+					sha1) > 0)
+			sorted = 0;
+	}
+	close(fd);
+
+	if (sorted)
+		skiplist.sorted = 1;
+}
+
 static int parse_msg_type(const char *str)
 {
 	if (!strcmp(str, "error"))
@@ -191,6 +229,14 @@ void fsck_set_msg_types(struct fsck_options *options, const char *values)
 			buf[equal] = tolower(buf[equal]);
 		buf[equal] = '\0';
 
+		if (!strcmp(buf, "skiplist")) {
+			if (equal == len)
+				die("skiplist requires a path");
+			init_skiplist(options, buf + equal + 1);
+			buf += len + 1;
+			continue;
+		}
+
 		if (equal == len)
 			die("Missing '=': '%s'", buf);
 
@@ -229,6 +275,10 @@ static int report(struct fsck_options *options, struct object *object,
 	if (msg_type == FSCK_IGNORE)
 		return 0;
 
+	if (options->skiplist && object &&
+			sha1_array_lookup(options->skiplist, object->sha1) >= 0)
+		return 0;
+
 	if (msg_type == FSCK_FATAL)
 		msg_type = FSCK_ERROR;
 	else if (msg_type == FSCK_INFO)