GLib.file_test
Description: Reference for GLib.file_test

### Function

# GLibfile_test

#### Declaration [src]

    gboolean
    g_file_test (
      const gchar* filename,
      GFileTest test
    )

#### Description [src]

Returns `TRUE` if any of the tests in the bitfield `test` are `TRUE`. For example, `(G_FILE_TEST_EXISTS | G_FILE_TEST_IS_DIR)` will return `TRUE` if the file exists; the check whether it’s a directory doesn’t matter since the existence test is `TRUE`. With the current set of available tests, there’s no point passing in more than one test at a time.

Apart from `G_FILE_TEST_IS_SYMLINK` all tests follow symbolic links, so for a symbolic link to a regular file `g_file_test()` will return `TRUE` for both `G_FILE_TEST_IS_SYMLINK` and `G_FILE_TEST_IS_REGULAR`.

Note, that for a dangling symbolic link `g_file_test()` will return `TRUE` for `G_FILE_TEST_IS_SYMLINK` and `FALSE` for all other flags.

You should never use `g_file_test()` to test whether it is safe to perform an operation, because there is always the possibility of the condition changing before you actually perform the operation, see TOCTOU.

For example, you might think you could use `G_FILE_TEST_IS_SYMLINK` to know whether it is safe to write to a file without being tricked into writing into a different location. It doesn’t work!

     // DON'T DO THIS
     if (!g_file_test (filename, G_FILE_TEST_IS_SYMLINK))
       {
         fd = g_open (filename, O_WRONLY);
         // write to fd
       }

     // DO THIS INSTEAD
     fd = g_open (filename, O_WRONLY | O_NOFOLLOW | O_CLOEXEC);
     if (fd == -1)
       {
         // check error
         if (errno == ELOOP)
           // file is a symlink and can be ignored
         else
           // handle errors as before
       }
     else
       {
         // write to fd
       }

Another thing to note is that `G_FILE_TEST_EXISTS` and `G_FILE_TEST_IS_EXECUTABLE` are implemented using the `access()` system call. This usually doesn’t matter, but if your program is setuid or setgid it means that these tests will give you the answer for the real user ID and group ID, rather than the effective user ID and group ID.

On Windows, there are no symlinks, so testing for `G_FILE_TEST_IS_SYMLINK` will always return `FALSE`. Testing for `G_FILE_TEST_IS_EXECUTABLE` will just check that the file exists and its name indicates that it is executable, checking for well-known extensions and those listed in the `PATHEXT` environment variable.

#### Parameters

`filename`

  Type: `const gchar*`

  A filename to test in the GLib file name encoding.

  The data is owned by the caller of the function.
  The value is a platform-native string, using the preferred OS encoding on Unix and UTF-8 on Windows.

`test`

  Type: `GFileTest`

  Bitfield of `GFileTest` flags.

#### Return value

Type: `gboolean`

Whether a test was `TRUE`.