[utils] Add posix expanduser implementation and clarify the original source

youtube_dl/utils.py

@@ -204,45 +204,79 @@ def compat_ord(c):
     else: return ord(c)
 
 
-# Environment variables should be decoded with filesystem encoding
-# otherwise this results in issues like #3854 #2918 #3217
 if sys.version_info >= (3, 0):
     compat_getenv = os.getenv
     compat_expanduser = os.path.expanduser
 else:
+    # Environment variables should be decoded with filesystem encoding.
+    # Otherwise it will fail if any non-ASCII characters present (see #3854 #3217 #2918)
+
     def compat_getenv(key, default=None):
         env = os.getenv(key, default)
         if env:
             env = env.decode(get_filesystem_encoding())
         return env
 
-    def compat_expanduser(path):
-        """Expand ~ and ~user constructs.
+    # HACK: The default implementations of os.path.expanduser from cpython do not decode
+    # environment variables with filesystem encoding. We will work around this by
+    # providing adjusted implementations.
+    # The following are os.path.expanduser implementations from cpython 2.7.8 stdlib
+    # for different platforms with correct environment variables decoding.
 
-        If user or $HOME is unknown, do nothing."""
-        if path[:1] != '~':
-            return path
-        i, n = 1, len(path)
-        while i < n and path[i] not in '/\\':
-            i += 1
+    if os.name == 'posix':
+        def compat_expanduser(path):
+            """Expand ~ and ~user constructions.  If user or $HOME is unknown,
+            do nothing."""
+            if not path.startswith('~'):
+                return path
+            i = path.find('/', 1)
+            if i < 0:
+                i = len(path)
+            if i == 1:
+                if 'HOME' not in os.environ:
+                    import pwd
+                    userhome = pwd.getpwuid(os.getuid()).pw_dir
+                else:
+                    userhome = compat_getenv('HOME')
+            else:
+                import pwd
+                try:
+                    pwent = pwd.getpwnam(path[1:i])
+                except KeyError:
+                    return path
+                userhome = pwent.pw_dir
+            userhome = userhome.rstrip('/')
+            return (userhome + path[i:]) or '/'
+    elif os.name == 'nt' or os.name == 'ce':
+        def compat_expanduser(path):
+            """Expand ~ and ~user constructs.
 
-        if 'HOME' in os.environ:
-            userhome = compat_getenv('HOME')
-        elif 'USERPROFILE' in os.environ:
-            userhome = compat_getenv('USERPROFILE')
-        elif not 'HOMEPATH' in os.environ:
-            return path
-        else:
-            try:
-                drive = compat_getenv('HOMEDRIVE')
-            except KeyError:
-                drive = ''
-            userhome = os.path.join(drive, compat_getenv('HOMEPATH'))
+            If user or $HOME is unknown, do nothing."""
+            if path[:1] != '~':
+                return path
+            i, n = 1, len(path)
+            while i < n and path[i] not in '/\\':
+                i = i + 1
 
-        if i != 1:  # ~user
-            userhome = os.path.join(os.path.dirname(userhome), path[1:i])
+            if 'HOME' in os.environ:
+                userhome = compat_getenv('HOME')
+            elif 'USERPROFILE' in os.environ:
+                userhome = compat_getenv('USERPROFILE')
+            elif not 'HOMEPATH' in os.environ:
+                return path
+            else:
+                try:
+                    drive = compat_getenv('HOMEDRIVE')
+                except KeyError:
+                    drive = ''
+                userhome = os.path.join(drive, compat_getenv('HOMEPATH'))
 
-        return userhome + path[i:]
+            if i != 1: #~user
+                userhome = os.path.join(os.path.dirname(userhome), path[1:i])
+
+            return userhome + path[i:]
+    else:
+        compat_expanduser = os.path.expanduser
 
 
 # This is not clearly defined otherwise