Clean up IsDirectory

src/libpsl-native/src/isdirectory.cpp

@@ -7,7 +7,7 @@
 #include "getfileowner.h"
 #include "isdirectory.h"
 
-#include <errno.h>
+#include <assert.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <pwd.h>
@@ -25,20 +25,11 @@
 //! char* is marshaled as an LPStr, which on Linux is UTF-8.
 //! @endparblock
 //!
-//! @exception errno Passes this error via errno to GetLastError:
-//! - ERROR_INVALID_PARAMETER: parameter is not valid
-//!
 //! @retval true if directory, false otherwise
 //!
 bool IsDirectory(const char* path)
 {
-    errno = 0;
-
-    if (!path)
-    {
-        errno = ERROR_INVALID_PARAMETER;
-        return false;
-    }
+    assert(path);
 
     struct stat buf;
     int32_t ret = GetStat(path, &buf);

src/libpsl-native/test/test-isdirectory.cpp

@@ -21,11 +21,5 @@ TEST(IsDirectoryTest, BinLsIsNotDirectory)
 TEST(IsDirectoryTest, ReturnsFalseForFakeDirectory)
 {
     EXPECT_FALSE(IsDirectory("SomeMadeUpFileNameThatDoesNotExist"));
-    EXPECT_EQ(errno, ERROR_FILE_NOT_FOUND);
-}
-
-TEST(IsDirectoryTest, ReturnsFalseForNullInput)
-{
-    EXPECT_FALSE(IsDirectory(NULL));
-    EXPECT_EQ(errno, ERROR_INVALID_PARAMETER);
+    EXPECT_EQ(ENOENT, errno);
 }