Merge branch 'mk/maint-parse-careful'

* mk/maint-parse-careful:
  receive-pack: use strict mode for unpacking objects
  index-pack: introduce checking mode
  unpack-objects: prevent writing of inconsistent objects
  unpack-object: cache for non written objects
  add common fsck error printing function
  builtin-fsck: move common object checking code to fsck.c
  builtin-fsck: reports missing parent commits
  Remove unused object-ref code
  builtin-fsck: move away from object-refs to fsck_walk
  add generic, type aware object chain walker

Conflicts:

	Makefile
	builtin-fsck.c

Documentation/config.txt

@@ -939,6 +939,12 @@ imap::
 	The configuration variables in the 'imap' section are described
 	in linkgit:git-imap-send[1].
 
+receive.fsckObjects::
+	If it is set to true, git-receive-pack will check all received
+	objects. It will abort in the case of a malformed object or a
+	broken link. The result of an abort are only dangling objects.
+	The default value is true.
+
 receive.unpackLimit::
 	If the number of objects received in a push is below this
 	limit then the objects will be unpacked into loose object

Documentation/git-index-pack.txt

@@ -75,6 +75,9 @@ OPTIONS
 	to force the version for the generated pack index, and to force
 	64-bit index entries on objects located above the given offset.
 
+--strict::
+	Die, if the pack contains broken objects or links.
+
 
 Note
 ----

Documentation/git-unpack-objects.txt

@@ -40,6 +40,9 @@ OPTIONS
 	and make the best effort to recover as many objects as
 	possible.
 
+--strict::
+	Don't write objects with broken content or links.
+
 
 Author
 ------

Makefile

@@ -304,7 +304,7 @@ LIB_H = \
 	run-command.h strbuf.h tag.h tree.h git-compat-util.h revision.h \
 	tree-walk.h log-tree.h dir.h path-list.h unpack-trees.h builtin.h \
 	utf8.h reflog-walk.h patch-ids.h attr.h decorate.h progress.h \
-	mailmap.h remote.h parse-options.h transport.h diffcore.h hash.h
+	mailmap.h remote.h parse-options.h transport.h diffcore.h hash.h fsck.h
 
 DIFF_OBJS = \
 	diff.o diff-lib.o diffcore-break.o diffcore-order.o \
@@ -319,7 +319,7 @@ LIB_OBJS = \
 	patch-ids.o \
 	object.o pack-check.o pack-write.o patch-delta.o path.o pkt-line.o \
 	sideband.o reachable.o reflog-walk.o \
-	quote.o read-cache.o refs.o run-command.o dir.o object-refs.o \
+	quote.o read-cache.o refs.o run-command.o dir.o \
 	server-info.o setup.o sha1_file.o sha1_name.o strbuf.o \
 	tag.o tree.o usage.o config.o environment.o ctype.o copy.o \
 	revision.o pager.o tree-walk.o xdiff-interface.o \
@@ -328,7 +328,7 @@ LIB_OBJS = \
 	color.o wt-status.o archive-zip.o archive-tar.o shallow.o utf8.o \
 	convert.o attr.o decorate.o progress.o mailmap.o symlinks.o remote.o \
 	transport.o bundle.o walker.o parse-options.o ws.o archive.o branch.o \
-	alias.o
+	alias.o fsck.o
 
 BUILTIN_OBJS = \
 	builtin-add.o \

builtin-fetch-pack.c

@@ -386,7 +386,6 @@ static int everything_local(struct ref **refs, int nr_match, char **match)
 	int retval;
 	unsigned long cutoff = 0;
 
-	track_object_refs = 0;
 	save_commit_buffer = 0;
 
 	for (ref = *refs; ref; ref = ref->next) {