Implement FUSE_SYMLINK

Fixes #3452

3 files changed, 106 insertions, 0 deletions

diff --git a/test/fuse/BUILD b/test/fuse/BUILD
index ff2948eb3..2f91fe2c7 100644
--- a/test/fuse/BUILD
+++ b/test/fuse/BUILD
@@ -21,3 +21,8 @@ syscall_test(
     fuse = "True",
     test = "//test/fuse/linux:mknod_test",
 )
+
+syscall_test(
+    fuse = "True",
+    test = "//test/fuse/linux:symlink_test",
+)
diff --git a/test/fuse/linux/BUILD b/test/fuse/linux/BUILD
index c0f917606..df42857f6 100644
--- a/test/fuse/linux/BUILD
+++ b/test/fuse/linux/BUILD
@@ -58,6 +58,19 @@ cc_binary(
     ],
 )
 
+cc_binary(
+    name = "symlink_test",
+    testonly = 1,
+    srcs = ["symlink_test.cc"],
+    deps = [
+        gtest,
+        ":fuse_base",
+        "//test/util:fuse_util",
+        "//test/util:test_main",
+        "//test/util:test_util",
+    ],
+)
+
 cc_library(
     name = "fuse_base",
     testonly = 1,
diff --git a/test/fuse/linux/symlink_test.cc b/test/fuse/linux/symlink_test.cc
new file mode 100644
index 000000000..2c3a52987
--- /dev/null
+++ b/test/fuse/linux/symlink_test.cc
@@ -0,0 +1,88 @@
+// Copyright 2020 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 <linux/fuse.h>
+#include <sys/stat.h>
+#include <sys/statfs.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "test/fuse/linux/fuse_base.h"
+#include "test/util/fuse_util.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+class SymlinkTest : public FuseTest {
+ protected:
+  const std::string target_file_ = "target_file_";
+  const std::string symlink_ = "symlink_";
+  const mode_t perms_ = S_IRWXU | S_IRWXG | S_IRWXO;
+};
+
+TEST_F(SymlinkTest, CreateSymLink) {
+  const std::string symlink_path =
+      JoinPath(mount_point_.path().c_str(), symlink_);
+
+  struct fuse_out_header out_header = {
+      .len = sizeof(struct fuse_out_header) + sizeof(struct fuse_entry_out),
+  };
+  struct fuse_entry_out out_payload = DefaultEntryOut(S_IFLNK | perms_, 5);
+  auto iov_out = FuseGenerateIovecs(out_header, out_payload);
+  SetServerResponse(FUSE_SYMLINK, iov_out);
+  ASSERT_THAT(symlink(target_file_.c_str(), symlink_path.c_str()),
+              SyscallSucceeds());
+
+  struct fuse_in_header in_header;
+  std::vector<char> actual_target_file(target_file_.length() + 1);
+  std::vector<char> actual_symlink(symlink_.length() + 1);
+  auto iov_in =
+      FuseGenerateIovecs(in_header, actual_symlink, actual_target_file);
+  GetServerActualRequest(iov_in);
+
+  EXPECT_EQ(in_header.len,
+            sizeof(in_header) + symlink_.length() + target_file_.length() + 2);
+  EXPECT_EQ(in_header.opcode, FUSE_SYMLINK);
+  EXPECT_EQ(std::string(actual_target_file.data()), target_file_);
+  EXPECT_EQ(std::string(actual_symlink.data()), symlink_);
+}
+
+TEST_F(SymlinkTest, FileTypeError) {
+  const std::string symlink_path =
+      JoinPath(mount_point_.path().c_str(), symlink_);
+
+  struct fuse_out_header out_header = {
+      .len = sizeof(struct fuse_out_header) + sizeof(struct fuse_entry_out),
+  };
+  struct fuse_entry_out out_payload = DefaultEntryOut(S_IFREG | perms_, 5);
+  auto iov_out = FuseGenerateIovecs(out_header, out_payload);
+  SetServerResponse(FUSE_SYMLINK, iov_out);
+  ASSERT_THAT(symlink(target_file_.c_str(), symlink_path.c_str()),
+              SyscallFailsWithErrno(EIO));
+  SkipServerActualRequest();
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor