Allow SetAttr and Allocate for deleted files

It's safe to call SetAttr and Allocate on fsgofer because the
file path is not used to open the file, if needed.

Fixes #3654

PiperOrigin-RevId: 407149393

3 files changed, 135 insertions, 0 deletions

diff --git a/test/syscalls/BUILD b/test/syscalls/BUILD
index f748d685a..7952fd969 100644
--- a/test/syscalls/BUILD
+++ b/test/syscalls/BUILD
@@ -1053,3 +1053,7 @@ syscall_test(
 syscall_test(
     test = "//test/syscalls/linux:verity_mount_test",
 )
+
+syscall_test(
+    test = "//test/syscalls/linux:deleted_test",
+)
diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 6217ff4dc..020c4673a 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -4432,3 +4432,18 @@ cc_binary(
         "@com_google_absl//absl/container:flat_hash_set",
     ],
 )
+
+cc_binary(
+    name = "deleted_test",
+    testonly = 1,
+    srcs = ["deleted.cc"],
+    linkstatic = 1,
+    deps = [
+        "//test/util:file_descriptor",
+        "//test/util:fs_util",
+        gtest,
+        "//test/util:temp_path",
+        "//test/util:test_main",
+        "//test/util:test_util",
+    ],
+)
diff --git a/test/syscalls/linux/deleted.cc b/test/syscalls/linux/deleted.cc
new file mode 100644
index 000000000..695ceafd3
--- /dev/null
+++ b/test/syscalls/linux/deleted.cc
@@ -0,0 +1,116 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <errno.h>
+#include <fcntl.h>
+#include <time.h>
+#include <unistd.h>
+
+#include <string>
+
+#include "gmock/gmock.h"
+#include "gtest/gtest.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/fs_util.h"
+#include "test/util/temp_path.h"
+#include "test/util/test_util.h"
+
+constexpr mode_t mode = 1;
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+PosixErrorOr<FileDescriptor> createdDeleted() {
+  auto path = NewTempAbsPath();
+  PosixErrorOr<FileDescriptor> fd = Open(path, O_RDWR | O_CREAT, mode);
+  if (!fd.ok()) {
+    return fd.error();
+  }
+
+  auto err = Unlink(path);
+  if (!err.ok()) {
+    return err;
+  }
+  return fd;
+}
+
+TEST(DeletedTest, Utime) {
+  auto fd = ASSERT_NO_ERRNO_AND_VALUE(createdDeleted());
+
+  const struct timespec times[2] = {{10, 0}, {20, 0}};
+  EXPECT_THAT(futimens(fd.get(), times), SyscallSucceeds());
+
+  struct stat stat;
+  ASSERT_THAT(fstat(fd.get(), &stat), SyscallSucceeds());
+  EXPECT_EQ(10, stat.st_atime);
+  EXPECT_EQ(20, stat.st_mtime);
+}
+
+TEST(DeletedTest, Chmod) {
+  auto fd = ASSERT_NO_ERRNO_AND_VALUE(createdDeleted());
+
+  ASSERT_THAT(fchmod(fd.get(), mode + 1), SyscallSucceeds());
+
+  struct stat stat;
+  ASSERT_THAT(fstat(fd.get(), &stat), SyscallSucceeds());
+  EXPECT_EQ(mode + 1, stat.st_mode & ~S_IFMT);
+}
+
+TEST(DeletedTest, Truncate) {
+  auto fd = ASSERT_NO_ERRNO_AND_VALUE(createdDeleted());
+  const std::string data = "foobar";
+  ASSERT_THAT(write(fd.get(), data.c_str(), data.size()), SyscallSucceeds());
+
+  ASSERT_THAT(ftruncate(fd.get(), 0), SyscallSucceeds());
+
+  struct stat stat;
+  ASSERT_THAT(fstat(fd.get(), &stat), SyscallSucceeds());
+  ASSERT_EQ(stat.st_size, 0);
+}
+
+TEST(DeletedTest, Fallocate) {
+  auto fd = ASSERT_NO_ERRNO_AND_VALUE(createdDeleted());
+
+  ASSERT_THAT(fallocate(fd.get(), 0, 0, 123), SyscallSucceeds());
+
+  struct stat stat;
+  ASSERT_THAT(fstat(fd.get(), &stat), SyscallSucceeds());
+  EXPECT_EQ(123, stat.st_size);
+}
+
+// Tests that a file can be created with the same path as a deleted file that
+// still have an open FD to it.
+TEST(DeletedTest, Replace) {
+  auto path = NewTempAbsPath();
+  auto fd = ASSERT_NO_ERRNO_AND_VALUE(Open(path, O_RDWR | O_CREAT, mode));
+  ASSERT_NO_ERRNO(Unlink(path));
+
+  auto other =
+      ASSERT_NO_ERRNO_AND_VALUE(Open(path, O_RDWR | O_CREAT | O_EXCL, mode));
+
+  auto stat = ASSERT_NO_ERRNO_AND_VALUE(Fstat(fd.get()));
+  auto stat_other = ASSERT_NO_ERRNO_AND_VALUE(Fstat(other.get()));
+  ASSERT_NE(stat.st_ino, stat_other.st_ino);
+
+  // Check that the path points to the new file.
+  stat = ASSERT_NO_ERRNO_AND_VALUE(Stat(path));
+  ASSERT_EQ(stat.st_ino, stat_other.st_ino);
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor