Plumb VFS2 imported fds into virtual filesystem.

- When setting up the virtual filesystem, mount a host.filesystem to contain
  all files that need to be imported.
- Make read/preadv syscalls to the host in cases where preadv2 may not be
  supported yet (likewise for writing).
- Make save/restore functions in kernel/kernel.go return early if vfs2 is
  enabled.

PiperOrigin-RevId: 300922353

1 files changed, 56 insertions, 4 deletions

diff --git a/test/syscalls/linux/stat.cc b/test/syscalls/linux/stat.cc
index c951ac3b3..513b9cd1c 100644
--- a/test/syscalls/linux/stat.cc
+++ b/test/syscalls/linux/stat.cc
@@ -607,7 +607,7 @@ int statx(int dirfd, const char* pathname, int flags, unsigned int mask,
 }
 
 TEST_F(StatTest, StatxAbsPath) {
-  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, 0) < 0 &&
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
           errno == ENOSYS);
 
   struct kernel_statx stx;
@@ -617,7 +617,7 @@ TEST_F(StatTest, StatxAbsPath) {
 }
 
 TEST_F(StatTest, StatxRelPathDirFD) {
-  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, 0) < 0 &&
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
           errno == ENOSYS);
 
   struct kernel_statx stx;
@@ -631,7 +631,7 @@ TEST_F(StatTest, StatxRelPathDirFD) {
 }
 
 TEST_F(StatTest, StatxRelPathCwd) {
-  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, 0) < 0 &&
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
           errno == ENOSYS);
 
   ASSERT_THAT(chdir(GetAbsoluteTestTmpdir().c_str()), SyscallSucceeds());
@@ -643,7 +643,7 @@ TEST_F(StatTest, StatxRelPathCwd) {
 }
 
 TEST_F(StatTest, StatxEmptyPath) {
-  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, 0) < 0 &&
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
           errno == ENOSYS);
 
   const auto fd = ASSERT_NO_ERRNO_AND_VALUE(Open(test_file_name_, O_RDONLY));
@@ -653,6 +653,58 @@ TEST_F(StatTest, StatxEmptyPath) {
   EXPECT_TRUE(S_ISREG(stx.stx_mode));
 }
 
+TEST_F(StatTest, StatxDoesNotRejectExtraneousMaskBits) {
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
+          errno == ENOSYS);
+
+  struct kernel_statx stx;
+  // Set all mask bits except for STATX__RESERVED.
+  uint mask = 0xffffffff & ~0x80000000;
+  EXPECT_THAT(statx(-1, test_file_name_.c_str(), 0, mask, &stx),
+              SyscallSucceeds());
+  EXPECT_TRUE(S_ISREG(stx.stx_mode));
+}
+
+TEST_F(StatTest, StatxRejectsReservedMaskBit) {
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
+          errno == ENOSYS);
+
+  struct kernel_statx stx;
+  // Set STATX__RESERVED in the mask.
+  EXPECT_THAT(statx(-1, test_file_name_.c_str(), 0, 0x80000000, &stx),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+TEST_F(StatTest, StatxSymlink) {
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
+          errno == ENOSYS);
+
+  std::string parent_dir = "/tmp";
+  TempPath link = ASSERT_NO_ERRNO_AND_VALUE(
+      TempPath::CreateSymlinkTo(parent_dir, test_file_name_));
+  std::string p = link.path();
+
+  struct kernel_statx stx;
+  EXPECT_THAT(statx(AT_FDCWD, p.c_str(), AT_SYMLINK_NOFOLLOW, STATX_ALL, &stx),
+              SyscallSucceeds());
+  EXPECT_TRUE(S_ISLNK(stx.stx_mode));
+  EXPECT_THAT(statx(AT_FDCWD, p.c_str(), 0, STATX_ALL, &stx),
+              SyscallSucceeds());
+  EXPECT_TRUE(S_ISREG(stx.stx_mode));
+}
+
+TEST_F(StatTest, StatxInvalidFlags) {
+  SKIP_IF(!IsRunningOnGvisor() && statx(-1, nullptr, 0, 0, nullptr) < 0 &&
+          errno == ENOSYS);
+
+  struct kernel_statx stx;
+  EXPECT_THAT(statx(AT_FDCWD, test_file_name_.c_str(), 12345, 0, &stx),
+              SyscallFailsWithErrno(EINVAL));
+  EXPECT_THAT(statx(AT_FDCWD, test_file_name_.c_str(),
+                    0x6000 /* AT_STATX_SYNC_TYPE */, 0, &stx),
+              SyscallFailsWithErrno(EINVAL));
+}
+
 }  // namespace
 
 }  // namespace testing