Merge branch 'jk/fully-peeled-packed-ref' into maint-1.8.1

* jk/fully-peeled-packed-ref:
  pack-refs: add fully-peeled trait
  pack-refs: write peeled entry for non-tags
  use parse_object_or_die instead of die("bad object")
  avoid segfaults on parse_object failure

9 files changed, 145 insertions, 27 deletions

diff --git a/builtin/grep.c b/builtin/grep.c
index 0e1b6c860e..e8f0f92cf7 100644
--- a/builtin/grep.c
+++ b/builtin/grep.c
@@ -820,9 +820,7 @@ int cmd_grep(int argc, const char **argv, const char *prefix)
 		unsigned char sha1[20];
 		/* Is it a rev? */
 		if (!get_sha1(arg, sha1)) {
-			struct object *object = parse_object(sha1);
-			if (!object)
-				die(_("bad object %s"), arg);
+			struct object *object = parse_object_or_die(sha1, arg);
 			add_object_array(object, arg, &list);
 			continue;
 		}
diff --git a/builtin/prune.c b/builtin/prune.c
index 8cb8b9186a..85843d4f17 100644
--- a/builtin/prune.c
+++ b/builtin/prune.c
@@ -149,9 +149,7 @@ int cmd_prune(int argc, const char **argv, const char *prefix)
 		const char *name = *argv++;
 
 		if (!get_sha1(name, sha1)) {
-			struct object *object = parse_object(sha1);
-			if (!object)
-				die("bad object: %s", name);
+			struct object *object = parse_object_or_die(sha1, name);
 			add_pending_object(&revs, object, "");
 		}
 		else
diff --git a/bundle.c b/bundle.c
index 6210a6be89..505e07e934 100644
--- a/bundle.c
+++ b/bundle.c
@@ -279,12 +279,12 @@ int create_bundle(struct bundle_header *header, const char *path,
 		if (buf.len > 0 && buf.buf[0] == '-') {
 			write_or_die(bundle_fd, buf.buf, buf.len);
 			if (!get_sha1_hex(buf.buf + 1, sha1)) {
-				struct object *object = parse_object(sha1);
+				struct object *object = parse_object_or_die(sha1, buf.buf);
 				object->flags |= UNINTERESTING;
 				add_pending_object(&revs, object, xstrdup(buf.buf));
 			}
 		} else if (!get_sha1_hex(buf.buf, sha1)) {
-			struct object *object = parse_object(sha1);
+			struct object *object = parse_object_or_die(sha1, buf.buf);
 			object->flags |= SHOWN;
 		}
 	}
@@ -361,7 +361,7 @@ int create_bundle(struct bundle_header *header, const char *path,
 				 * end up triggering "empty bundle"
 				 * error.
 				 */
-				obj = parse_object(sha1);
+				obj = parse_object_or_die(sha1, e->name);
 				obj->flags |= SHOWN;
 				add_pending_object(&revs, obj, e->name);
 			}
diff --git a/object.c b/object.c
index 4af3451bf8..20703f52ed 100644
--- a/object.c
+++ b/object.c
@@ -185,6 +185,16 @@ struct object *parse_object_buffer(const unsigned char *sha1, enum object_type t
 	return obj;
 }
 
+struct object *parse_object_or_die(const unsigned char *sha1,
+				   const char *name)
+{
+	struct object *o = parse_object(sha1);
+	if (o)
+		return o;
+
+	die(_("unable to parse object: %s"), name ? name : sha1_to_hex(sha1));
+}
+
 struct object *parse_object(const unsigned char *sha1)
 {
 	unsigned long size;
diff --git a/object.h b/object.h
index 6a97b6ba1a..97d384b80a 100644
--- a/object.h
+++ b/object.h
@@ -54,9 +54,20 @@ struct object *lookup_object(const unsigned char *sha1);
 
 extern void *create_object(const unsigned char *sha1, int type, void *obj);
 
-/** Returns the object, having parsed it to find out what it is. **/
+/*
+ * Returns the object, having parsed it to find out what it is.
+ *
+ * Returns NULL if the object is missing or corrupt.
+ */
 struct object *parse_object(const unsigned char *sha1);
 
+/*
+ * Like parse_object, but will die() instead of returning NULL. If the
+ * "name" parameter is not NULL, it is included in the error message
+ * (otherwise, the sha1 hex is given).
+ */
+struct object *parse_object_or_die(const unsigned char *sha1, const char *name);
+
 /* Given the result of read_sha1_file(), returns the object after
  * parsing it.  eaten_p indicates if the object has a borrowed copy
  * of buffer and the caller should not free() it.
diff --git a/pack-refs.c b/pack-refs.c
index f09a054228..4461f71a37 100644
--- a/pack-refs.c
+++ b/pack-refs.c
@@ -27,6 +27,7 @@ static int handle_one_ref(const char *path, const unsigned char *sha1,
 			  int flags, void *cb_data)
 {
 	struct pack_refs_cb_data *cb = cb_data;
+	struct object *o;
 	int is_tag_ref;
 
 	/* Do not pack the symbolic refs */
@@ -39,14 +40,13 @@ static int handle_one_ref(const char *path, const unsigned char *sha1,
 		return 0;
 
 	fprintf(cb->refs_file, "%s %s\n", sha1_to_hex(sha1), path);
-	if (is_tag_ref) {
-		struct object *o = parse_object(sha1);
-		if (o->type == OBJ_TAG) {
-			o = deref_tag(o, path, 0);
-			if (o)
-				fprintf(cb->refs_file, "^%s\n",
-					sha1_to_hex(o->sha1));
-		}
+
+	o = parse_object_or_die(sha1, path);
+	if (o->type == OBJ_TAG) {
+		o = deref_tag(o, path, 0);
+		if (o)
+			fprintf(cb->refs_file, "^%s\n",
+				sha1_to_hex(o->sha1));
 	}
 
 	if ((cb->flags & PACK_REFS_PRUNE) && !do_not_prune(flags)) {
@@ -128,7 +128,7 @@ int pack_refs(unsigned int flags)
 		die_errno("unable to create ref-pack file structure");
 
 	/* perhaps other traits later as well */
-	fprintf(cbdata.refs_file, "# pack-refs with: peeled \n");
+	fprintf(cbdata.refs_file, "# pack-refs with: peeled fully-peeled \n");
 
 	for_each_ref(handle_one_ref, &cbdata);
 	if (ferror(cbdata.refs_file))
diff --git a/reachable.c b/reachable.c
index bf7970661f..e7e6a1e342 100644
--- a/reachable.c
+++ b/reachable.c
@@ -152,11 +152,9 @@ static int add_one_reflog_ent(unsigned char *osha1, unsigned char *nsha1,
 
 static int add_one_ref(const char *path, const unsigned char *sha1, int flag, void *cb_data)
 {
-	struct object *object = parse_object(sha1);
+	struct object *object = parse_object_or_die(sha1, path);
 	struct rev_info *revs = (struct rev_info *)cb_data;
 
-	if (!object)
-		die("bad object ref: %s:%s", path, sha1_to_hex(sha1));
 	add_pending_object(revs, object, "");
 
 	return 0;
diff --git a/refs.c b/refs.c
index 541fec2065..6770e962a9 100644
--- a/refs.c
+++ b/refs.c
@@ -804,11 +804,38 @@ static const char *parse_ref_line(char *line, unsigned char *sha1)
 	return line;
 }
 
+/*
+ * Read f, which is a packed-refs file, into dir.
+ *
+ * A comment line of the form "# pack-refs with: " may contain zero or
+ * more traits. We interpret the traits as follows:
+ *
+ *   No traits:
+ *
+ *      Probably no references are peeled. But if the file contains a
+ *      peeled value for a reference, we will use it.
+ *
+ *   peeled:
+ *
+ *      References under "refs/tags/", if they *can* be peeled, *are*
+ *      peeled in this file. References outside of "refs/tags/" are
+ *      probably not peeled even if they could have been, but if we find
+ *      a peeled value for such a reference we will use it.
+ *
+ *   fully-peeled:
+ *
+ *      All references in the file that can be peeled are peeled.
+ *      Inversely (and this is more important), any references in the
+ *      file for which no peeled value is recorded is not peelable. This
+ *      trait should typically be written alongside "peeled" for
+ *      compatibility with older clients, but we do not require it
+ *      (i.e., "peeled" is a no-op if "fully-peeled" is set).
+ */
 static void read_packed_refs(FILE *f, struct ref_dir *dir)
 {
 	struct ref_entry *last = NULL;
 	char refline[PATH_MAX];
-	int flag = REF_ISPACKED;
+	enum { PEELED_NONE, PEELED_TAGS, PEELED_FULLY } peeled = PEELED_NONE;
 
 	while (fgets(refline, sizeof(refline), f)) {
 		unsigned char sha1[20];
@@ -817,15 +844,20 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
 
 		if (!strncmp(refline, header, sizeof(header)-1)) {
 			const char *traits = refline + sizeof(header) - 1;
-			if (strstr(traits, " peeled "))
-				flag |= REF_KNOWS_PEELED;
+			if (strstr(traits, " fully-peeled "))
+				peeled = PEELED_FULLY;
+			else if (strstr(traits, " peeled "))
+				peeled = PEELED_TAGS;
 			/* perhaps other traits later as well */
 			continue;
 		}
 
 		refname = parse_ref_line(refline, sha1);
 		if (refname) {
-			last = create_ref_entry(refname, sha1, flag, 1);
+			last = create_ref_entry(refname, sha1, REF_ISPACKED, 1);
+			if (peeled == PEELED_FULLY ||
+			    (peeled == PEELED_TAGS && !prefixcmp(refname, "refs/tags/")))
+				last->flag |= REF_KNOWS_PEELED;
 			add_ref(dir, last);
 			continue;
 		}
@@ -833,8 +865,15 @@ static void read_packed_refs(FILE *f, struct ref_dir *dir)
 		    refline[0] == '^' &&
 		    strlen(refline) == 42 &&
 		    refline[41] == '\n' &&
-		    !get_sha1_hex(refline + 1, sha1))
+		    !get_sha1_hex(refline + 1, sha1)) {
 			hashcpy(last->u.value.peeled, sha1);
+			/*
+			 * Regardless of what the file header said,
+			 * we definitely know the value of *this*
+			 * reference:
+			 */
+			last->flag |= REF_KNOWS_PEELED;
+		}
 	}
 }
 
diff --git a/t/t3211-peel-ref.sh b/t/t3211-peel-ref.sh
new file mode 100755
index 0000000000..d4d7792eae
--- /dev/null
+++ b/t/t3211-peel-ref.sh
@@ -0,0 +1,64 @@
+#!/bin/sh
+
+test_description='tests for the peel_ref optimization of packed-refs'
+. ./test-lib.sh
+
+test_expect_success 'create annotated tag in refs/tags' '
+	test_commit base &&
+	git tag -m annotated foo
+'
+
+test_expect_success 'create annotated tag outside of refs/tags' '
+	git update-ref refs/outside/foo refs/tags/foo
+'
+
+# This matches show-ref's output
+print_ref() {
+	echo "$(git rev-parse "$1") $1"
+}
+
+test_expect_success 'set up expected show-ref output' '
+	{
+		print_ref "refs/heads/master" &&
+		print_ref "refs/outside/foo" &&
+		print_ref "refs/outside/foo^{}" &&
+		print_ref "refs/tags/base" &&
+		print_ref "refs/tags/foo" &&
+		print_ref "refs/tags/foo^{}"
+	} >expect
+'
+
+test_expect_success 'refs are peeled outside of refs/tags (loose)' '
+	git show-ref -d >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'refs are peeled outside of refs/tags (packed)' '
+	git pack-refs --all &&
+	git show-ref -d >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success 'create old-style pack-refs without fully-peeled' '
+	# Git no longer writes without fully-peeled, so we just write our own
+	# from scratch; we could also munge the existing file to remove the
+	# fully-peeled bits, but that seems even more prone to failure,
+	# especially if the format ever changes again. At least this way we
+	# know we are emulating exactly what an older git would have written.
+	{
+		echo "# pack-refs with: peeled " &&
+		print_ref "refs/heads/master" &&
+		print_ref "refs/outside/foo" &&
+		print_ref "refs/tags/base" &&
+		print_ref "refs/tags/foo" &&
+		echo "^$(git rev-parse "refs/tags/foo^{}")"
+	} >tmp &&
+	mv tmp .git/packed-refs
+'
+
+test_expect_success 'refs are peeled outside of refs/tags (old packed)' '
+	git show-ref -d >actual &&
+	test_cmp expect actual
+'
+
+test_done