1 files changed, 45 insertions, 0 deletions
diff --git a/test/syscalls/linux/open.cc b/test/syscalls/linux/open.cc
index 267ae19f6..670c0284b 100644
--- a/test/syscalls/linux/open.cc
+++ b/test/syscalls/linux/open.cc
@@ -186,6 +186,28 @@ TEST_F(OpenTest, OpenNoFollowStillFollowsLinksInPath) {
       ASSERT_NO_ERRNO_AND_VALUE(Open(path_via_symlink, O_RDONLY | O_NOFOLLOW));
 }
 
+// Test that open(2) can follow symlinks that point back to the same tree.
+// Test sets up files as follows:
+//   root/child/symlink => redirects to ../..
+//   root/child/target => regular file
+//
+// open("root/child/symlink/root/child/file")
+TEST_F(OpenTest, SymlinkRecurse) {
+  auto root =
+      ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDirIn(GetAbsoluteTestTmpdir()));
+  auto child = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateDirIn(root.path()));
+  auto symlink = ASSERT_NO_ERRNO_AND_VALUE(
+      TempPath::CreateSymlinkTo(child.path(), "../.."));
+  auto target = ASSERT_NO_ERRNO_AND_VALUE(
+      TempPath::CreateFileWith(child.path(), "abc", 0644));
+  auto path_via_symlink =
+      JoinPath(symlink.path(), Basename(root.path()), Basename(child.path()),
+               Basename(target.path()));
+  const auto contents =
+      ASSERT_NO_ERRNO_AND_VALUE(GetContents(path_via_symlink));
+  ASSERT_EQ(contents, "abc");
+}
+
 TEST_F(OpenTest, Fault) {
   char* totally_not_null = nullptr;
   ASSERT_THAT(open(totally_not_null, O_RDONLY), SyscallFailsWithErrno(EFAULT));
@@ -394,6 +416,29 @@ TEST_F(OpenTest, CanTruncateWriteOnlyNoReadPermission_NoRandomSave) {
   EXPECT_EQ(stat.st_size, 0);
 }
 
+TEST_F(OpenTest, CanTruncateWithStrangePermissions) {
+  ASSERT_NO_ERRNO(SetCapability(CAP_DAC_OVERRIDE, false));
+  ASSERT_NO_ERRNO(SetCapability(CAP_DAC_READ_SEARCH, false));
+  const DisableSave ds;  // Permissions are dropped.
+  std::string path = NewTempAbsPath();
+  int fd;
+  // Create a file without user permissions.
+  EXPECT_THAT(  // SAVE_BELOW
+      fd = open(path.c_str(), O_CREAT | O_TRUNC | O_WRONLY, 055),
+      SyscallSucceeds());
+  EXPECT_THAT(close(fd), SyscallSucceeds());
+
+  // Cannot open file because we are owner and have no permissions set.
+  EXPECT_THAT(open(path.c_str(), O_RDONLY), SyscallFailsWithErrno(EACCES));
+
+  // We *can* chmod the file, because we are the owner.
+  EXPECT_THAT(chmod(path.c_str(), 0755), SyscallSucceeds());
+
+  // Now we can open the file again.
+  EXPECT_THAT(fd = open(path.c_str(), O_RDWR), SyscallSucceeds());
+  EXPECT_THAT(close(fd), SyscallSucceeds());
+}
+
 }  // namespace
 
 }  // namespace testing