Add which pathfinding for executables

README.md

@@ -41,6 +41,12 @@ Nautilus, the default file manager of GNOME.
 
 Please note that mat2 requires at least Python3.5.
 
+# Requirements setup on macOS (OS X) using [Homebrew](https://brew.sh/)
+
+```bash
+brew install exiftool cairo pygobject3 poppler gdk-pixbuf librsvg ffmpeg
+```
+
 # Running the test suite
 
 ```bash

libmat2/bubblewrap.py

@@ -22,10 +22,9 @@ CalledProcessError = subprocess.CalledProcessError
 
 
 def _get_bwrap_path() -> str:
-    bwrap_path = '/usr/bin/bwrap'
-    if os.path.isfile(bwrap_path):
-        if os.access(bwrap_path, os.X_OK):
-            return bwrap_path
+    which_path = shutil.which('bwrap')
+    if which_path:
+        return which_path
 
     raise RuntimeError("Unable to find bwrap")  # pragma: no cover
 

libmat2/exiftool.py

@@ -2,6 +2,7 @@ import functools
 import json
 import logging
 import os
+import shutil
 import subprocess
 from typing import Dict, Union, Set
 
@@ -71,14 +72,12 @@ class ExiftoolParser(abstract.AbstractParser):
 
 @functools.lru_cache()
 def _get_exiftool_path() -> str:  # pragma: no cover
-    possible_pathes = {
-        '/usr/bin/exiftool',              # debian/fedora
-        '/usr/bin/vendor_perl/exiftool',  # archlinux
-    }
+    which_path = shutil.which('exiftool')
+    if which_path:
+        return which_path
 
-    for possible_path in possible_pathes:
-        if os.path.isfile(possible_path):
-            if os.access(possible_path, os.X_OK):
-                return possible_path
+    # Exiftool on Arch Linux has a weird path
+    if os.access('/usr/bin/vendor_perl/exiftool', os.X_OK):
+        return '/usr/bin/vendor_perl/exiftool'
 
     raise RuntimeError("Unable to find exiftool")

libmat2/video.py

@@ -1,6 +1,6 @@
 import subprocess
 import functools
-import os
+import shutil
 import logging
 
 from typing import Dict, Union
@@ -137,9 +137,8 @@ class MP4Parser(AbstractFFmpegParser):
 
 @functools.lru_cache()
 def _get_ffmpeg_path() -> str:  # pragma: no cover
-    ffmpeg_path = '/usr/bin/ffmpeg'
-    if os.path.isfile(ffmpeg_path):
-        if os.access(ffmpeg_path, os.X_OK):
-            return ffmpeg_path
+    which_path = shutil.which('ffmpeg')
+    if which_path:
+        return which_path
 
     raise RuntimeError("Unable to find ffmpeg")