[vfs2][gofer] Return appropriate errors when opening and creating files.

Fixes php test ext/standard/tests/file/touch_variation5.phpt on vfs2.
Updates #3516

Also spotted a bug with O_EXCL, where we did not return EEXIST when we tried
to open the root of the filesystem with O_EXCL | O_CREAT.

Added some more tests for open() corner cases.

PiperOrigin-RevId: 326346863

1 files changed, 32 insertions, 0 deletions

diff --git a/test/syscalls/linux/open.cc b/test/syscalls/linux/open.cc
index bf350946b..c7147c20b 100644
--- a/test/syscalls/linux/open.cc
+++ b/test/syscalls/linux/open.cc
@@ -95,6 +95,38 @@ TEST_F(OpenTest, OTruncAndReadOnlyFile) {
       Open(dirpath.c_str(), O_TRUNC | O_RDONLY, 0666));
 }
 
+TEST_F(OpenTest, OCreateDirectory) {
+  SKIP_IF(IsRunningWithVFS1());
+  auto dirpath = GetAbsoluteTestTmpdir();
+
+  // Normal case: existing directory.
+  ASSERT_THAT(open(dirpath.c_str(), O_RDWR | O_CREAT, 0666),
+              SyscallFailsWithErrno(EISDIR));
+  // Trailing separator on existing directory.
+  ASSERT_THAT(open(dirpath.append("/").c_str(), O_RDWR | O_CREAT, 0666),
+              SyscallFailsWithErrno(EISDIR));
+  // Trailing separator on non-existing directory.
+  ASSERT_THAT(open(JoinPath(dirpath, "non-existent").append("/").c_str(),
+                   O_RDWR | O_CREAT, 0666),
+              SyscallFailsWithErrno(EISDIR));
+  // "." special case.
+  ASSERT_THAT(open(JoinPath(dirpath, ".").c_str(), O_RDWR | O_CREAT, 0666),
+              SyscallFailsWithErrno(EISDIR));
+}
+
+TEST_F(OpenTest, MustCreateExisting) {
+  auto dirPath = GetAbsoluteTestTmpdir();
+
+  // Existing directory.
+  ASSERT_THAT(open(dirPath.c_str(), O_RDWR | O_CREAT | O_EXCL, 0666),
+              SyscallFailsWithErrno(EEXIST));
+
+  // Existing file.
+  auto newFile = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFileIn(dirPath));
+  ASSERT_THAT(open(newFile.path().c_str(), O_RDWR | O_CREAT | O_EXCL, 0666),
+              SyscallFailsWithErrno(EEXIST));
+}
+
 TEST_F(OpenTest, ReadOnly) {
   char buf;
   const FileDescriptor ro_file =