run-command: invalidate lstat cache after a command finished

dscho · matheustavares · dscho · commit 0d58fef58a6f · 2021-02-12T15:47:02.000+01:00
In the previous commit, we intercepted calls to `rmdir()` to invalidate
the lstat cache in the successful case, so that the lstat cache could
not have the idea that a directory exists where there is none.

The same situation can arise, of course, when a separate process is
spawned (most notably, this is the case in `submodule_move_head()`).
Obviously, we cannot know whether a directory was removed in that
process, therefore we must invalidate the lstat cache afterwards.

Note: in contrast to `lstat_cache_aware_rmdir()`, we invalidate the
lstat cache even in case of an error: the process might have removed a
directory and still have failed afterwards.

Co-authored-by: Matheus Tavares &lt;matheus.bernardino@usp.br&gt;
Signed-off-by: Johannes Schindelin &lt;johannes.schindelin@gmx.de&gt;
diff --git a/run-command.c b/run-command.c
@@ -953,6 +953,7 @@ int finish_command(struct child_process *cmd)
 {
 	int ret = wait_or_whine(cmd->pid, cmd->argv[0], 0);
 	child_process_clear(cmd);
+	invalidate_lstat_cache();
 	return ret;
 }
 
@@ -1239,13 +1240,19 @@ int start_async(struct async *async)
 int finish_async(struct async *async)
 {
 #ifdef NO_PTHREADS
-	return wait_or_whine(async->pid, "child process", 0);
+	int ret = wait_or_whine(async->pid, "child process", 0);
+
+	invalidate_lstat_cache();
+
+	return ret;
 #else
 	void *ret = (void *)(intptr_t)(-1);
 
 	if (pthread_join(async->tid, &ret))
 		error("pthread_join failed");
+	invalidate_lstat_cache();
 	return (int)(intptr_t)ret;
+
 #endif
 }
 
diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
@@ -862,4 +862,40 @@ do
 	'
 done
 
+test_expect_success PERL,SYMLINKS,CASE_INSENSITIVE_FS \
+"delayed checkout with submodule collision don't write to the wrong place" '
+	git init collision-with-submodule &&
+	(
+		cd collision-with-submodule &&
+		git config filter.delay.process "\"$TEST_ROOT/rot13-filter.pl\" --always-delay delayed.log clean smudge delay" &&
+		git config filter.delay.required true &&
+
+		# We need Git to treat the submodule "a" and the
+		# leading dir "A" as different paths in the index.
+		git config --local core.ignoreCase false &&
+
+		empty_oid=$(printf "" | git hash-object -w --stdin) &&
+		attr_oid=$(echo "A/B/y filter=delay" | git hash-object -w --stdin) &&
+		cat >objs <<-EOF &&
+		100644 blob $empty_oid	A/B/x
+		100644 blob $empty_oid	A/B/y
+		100644 blob $attr_oid	.gitattributes
+		EOF
+		git update-index --index-info <objs &&
+
+		git init a &&
+		mkdir target-dir &&
+		symlink_oid=$(printf "%s" "$PWD/target-dir" | git -C a hash-object -w --stdin) &&
+		echo "120000 blob $symlink_oid	b" >objs &&
+		git -C a update-index --index-info <objs &&
+		git -C a commit -m sub &&
+		git submodule add ./a &&
+		git commit -m super &&
+
+		git checkout --recurse-submodules . &&
+		grep "IN: smudge A/B/y .* \\[DELAYED\\]" delayed.log &&
+		test_path_is_missing target-dir/y
+	)
+'
+
 test_done
