Fix struct dirent d_type macro test

[sjshuck]

Fixes #347. Credit to Andrew Gunnerson (@chenxiaolong).

Test program:

module Main (main) where

import Control.Exception                (bracket)
import Data.Function                    (fix)
import Foreign.C.String                 (peekCString)
import System.Posix.Directory
import System.Posix.Directory.Internals
import Text.Printf                      (printf)

printDirEnt :: DirEnt -> IO ()
printDirEnt dirEnt = do
    dName <- dirEntName dirEnt >>= peekCString
    dType <- dirEntType dirEnt
    printf "%-20s%s\n" dName (show dType)

main :: IO ()
main = bracket (openDirStream "/home/steve/foo") closeDirStream $ \dirStream ->
    fix $ \go -> readDirStreamWith printDirEnt dirStream >>= mapM_ (\_ -> go)

Output for unix-2.8.7.0:

.                   DirType 0
..                  DirType 0
a regular file.txt  DirType 0
a directory.d       DirType 0
a symlink           DirType 0

Output with this change:

.                   DirType 4
..                  DirType 4
a regular file.txt  DirType 8
a directory.d       DirType 4
a symlink           DirType 10

[Bodigrim]

@sjshuck could you add a test please?

[sjshuck]

I'm a little stuck on how to skip the test if d_type isn't defined or if the filesystem doesn't set non-zero values for it. Open to suggestions.

Do all test containers have a cc installed on them?

[Bodigrim]

Do all test containers have a cc installed on them?

I think so, these are generic CI machines, not bare minimum containers.

Is #ifdef HAVE_STRUCT_DIRENT_D_TYPE inaccessible in the test suite?

[sjshuck]

Is #ifdef HAVE_STRUCT_DIRENT_D_TYPE inaccessible in the test suite?

I'm not sure TBH. I don't know how standard of a macro that is, how much it has to do with GNU, Linux, ... I did the test another way, compiling optimistically with d_type, and if the compilation fails, I'm assuming it's because that isn't defined, and the Haskell test is skipped. I could scrape stderr and find mention of "d_type" in it to be extra sure, I suppose.

[sjshuck]

Temporarily changed back to the incorrect #ifdef HAVE_DIRENT_D_TYPE and the test on my Linux machine fails with

DirEnt of /proc/self has DirType 0; expected DirType 10!

[Bodigrim]

Awesome!

[sjshuck]

Anything else needed of me?