From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 6 Apr 2016 18:39:11 +0000 (-0700)
Subject: Merge branch 'jv/merge-nothing-into-void'
X-Git-Tag: v2.9.0-rc0~148
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/aad627e3c0e7dcf5a59da80cb424e8a4093b0324?hp=-c

Merge branch 'jv/merge-nothing-into-void'

"git merge FETCH_HEAD" dereferenced NULL pointer when merging
nothing into an unborn history (which is arguably unusual usage,
which perhaps was the reason why nobody noticed it).

* jv/merge-nothing-into-void:
merge: fix NULL pointer dereference when merging nothing into void
---

aad627e3c0e7dcf5a59da80cb424e8a4093b0324
diff --combined builtin/merge.c
index c8154aaf6a,bf2f2614fb..30b7bd54fa
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@@ -1187,7 -1187,6 +1187,7 @@@ int cmd_merge(int argc, const char **ar
  	else
  		head_commit = lookup_commit_or_die(head_sha1, "HEAD");
  
 +	init_diff_ui_defaults();
  	git_config(git_merge_config, NULL);
  
  	if (branch_mergeoptions)
@@@ -1258,12 -1257,12 +1258,12 @@@
  			builtin_merge_options);
  
  	if (!head_commit) {
- 		struct commit *remote_head;
  		/*
  		 * If the merged head is a valid one there is no reason
  		 * to forbid "git merge" into a branch yet to be born.
  		 * We do the same for "git pull".
  		 */
+ 		unsigned char *remote_head_sha1;
  		if (squash)
  			die(_("Squash commit into empty head not supported yet"));
  		if (fast_forward == FF_NO)
@@@ -1271,13 -1270,13 +1271,13 @@@
  			    "an empty head"));
  		remoteheads = collect_parents(head_commit, &head_subsumed,
  					      argc, argv, NULL);
- 		remote_head = remoteheads->item;
- 		if (!remote_head)
+ 		if (!remoteheads)
  			die(_("%s - not something we can merge"), argv[0]);
  		if (remoteheads->next)
  			die(_("Can merge only exactly one commit into empty head"));
- 		read_empty(remote_head->object.oid.hash, 0);
- 		update_ref("initial pull", "HEAD", remote_head->object.oid.hash,
+ 		remote_head_sha1 = remoteheads->item->object.oid.hash;
+ 		read_empty(remote_head_sha1, 0);
+ 		update_ref("initial pull", "HEAD", remote_head_sha1,
  			   NULL, 0, UPDATE_REFS_DIE_ON_ERR);
  		goto done;
  	}
diff --combined t/t7600-merge.sh
index dc9f142f53,9d7952f42c..85248a14b6
--- a/t/t7600-merge.sh
+++ b/t/t7600-merge.sh
@@@ -33,11 -33,9 +33,11 @@@ printf '%s\n' 1 2 3 4 5 6 7 8 9 >fil
  printf '%s\n' '1 X' 2 3 4 5 6 7 8 9 >file.1
  printf '%s\n' 1 2 3 4 '5 X' 6 7 8 9 >file.5
  printf '%s\n' 1 2 3 4 5 6 7 8 '9 X' >file.9
 +printf '%s\n' 1 2 3 4 5 6 7 8 '9 Y' >file.9y
  printf '%s\n' '1 X' 2 3 4 5 6 7 8 9 >result.1
  printf '%s\n' '1 X' 2 3 4 '5 X' 6 7 8 9 >result.1-5
  printf '%s\n' '1 X' 2 3 4 '5 X' 6 7 8 '9 X' >result.1-5-9
 +printf '%s\n' 1 2 3 4 5 6 7 8 '9 Z' >result.9z
  >empty
  
  create_merge_msgs () {
@@@ -130,12 -128,6 +130,12 @@@ test_expect_success 'setup' 
  	git tag c2 &&
  	c2=$(git rev-parse HEAD) &&
  	git reset --hard "$c0" &&
 +	cp file.9y file &&
 +	git add file &&
 +	test_tick &&
 +	git commit -m "commit 7" &&
 +	git tag c7 &&
 +	git reset --hard "$c0" &&
  	cp file.9 file &&
  	git add file &&
  	test_tick &&
@@@ -226,26 -218,6 +226,26 @@@ test_expect_success 'merge c1 with c2' 
  	verify_parents $c1 $c2
  '
  
 +test_expect_success 'merge --squash c3 with c7' '
 +	git reset --hard c3 &&
 +	test_must_fail git merge --squash c7 &&
 +	cat result.9z >file &&
 +	git commit --no-edit -a &&
 +
 +	{
 +		cat <<-EOF
 +		Squashed commit of the following:
 +
 +		$(git show -s c7)
 +
 +		# Conflicts:
 +		#	file
 +		EOF
 +	} >expect &&
 +	git cat-file commit HEAD | sed -e '1,/^$/d' >actual &&
 +	test_cmp expect actual
 +'
 +
  test_debug 'git log --graph --decorate --oneline --all'
  
  test_expect_success 'merge c1 with c2 and c3' '
@@@ -753,4 -725,14 +753,14 @@@ test_expect_success 'merge detects mod-
  	test_must_fail git merge -s resolve master
  '
  
+ test_expect_success 'merge nothing into void' '
+ 	git init void &&
+ 	(
+ 		cd void &&
+ 		git remote add up .. &&
+ 		git fetch up &&
+ 		test_must_fail git merge FETCH_HEAD
+ 	)
+ '
+ 
  test_done