raise OSError if acl_to_text / acl_from_text returns NULL

Also did a small structural refactors there.

src/borg/platform/darwin.pyx

@@ -130,7 +130,7 @@ def acl_get(path, item, st, numeric_ids=False, fd=None):
             raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
         text = acl_to_text(acl, NULL)
         if text == NULL:
-            return
+            raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
         if numeric_ids:
             item['acl_extended'] = _remove_non_numeric_identifier(text)
         else:
@@ -145,14 +145,14 @@ def acl_set(path, item, numeric_ids=False, fd=None):
     acl_text = item.get('acl_extended')
     if acl_text is not None:
         try:
+            if isinstance(path, str):
+                path = os.fsencode(path)
             if numeric_ids:
                 acl = acl_from_text(acl_text)
             else:
                 acl = acl_from_text(<bytes>_remove_numeric_id_if_possible(acl_text))
             if acl == NULL:
-                return
-            if isinstance(path, str):
-                path = os.fsencode(path)
+                raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
             if fd is not None:
                 if acl_set_fd_np(fd, acl, ACL_TYPE_EXTENDED) == -1:
                     raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))

src/borg/platform/freebsd.pyx

@@ -122,23 +122,21 @@ def setxattr(path, name, value, *, follow_symlinks=False):
 
 
 cdef _get_acl(p, type, item, attribute, flags, fd=None):
-    cdef acl_t acl = NULL
-    cdef char *text = NULL
-    try:
+    cdef acl_t acl
+    cdef char *text
     if fd is not None:
         acl = acl_get_fd_np(fd, type)
     else:
         acl = acl_get_link_np(p, type)
-        if acl is not NULL:
+    if acl == NULL:
+        raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(p))
     text = acl_to_text_np(acl, NULL, flags)
-            if text is not NULL:
+    if text == NULL:
+        acl_free(acl)
+        raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(p))
     item[attribute] = text
-    finally:
     acl_free(text)
     acl_free(acl)
-    else:
-        raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(p))
-
 
 def acl_get(path, item, st, numeric_ids=False, fd=None):
     """Saves ACL Entries
@@ -168,7 +166,8 @@ cdef _set_acl(path, type, item, attribute, numeric_ids=False, fd=None):
         elif numeric_ids and type in (ACL_TYPE_ACCESS, ACL_TYPE_DEFAULT):
             text = posix_acl_use_stored_uid_gid(text)
         acl = acl_from_text(<bytes>text)
-        if acl:
+        if acl == NULL:
+            raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
         try:
             if fd is not None:
                 if acl_set_fd_np(fd, acl, type) == -1:

src/borg/platform/linux.pyx

@@ -261,11 +261,13 @@ def acl_get(path, item, st, numeric_ids=False, fd=None):
                 raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
         if access_acl:
             access_text = acl_to_text(access_acl, NULL)
-            if access_text:
+            if access_text == NULL:
+                raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
             item['acl_access'] = converter(access_text)
         if default_acl:
             default_text = acl_to_text(default_acl, NULL)
-            if default_text:
+            if default_text == NULL:
+                raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
             item['acl_default'] = converter(default_text)
     finally:
         acl_free(access_text)
@@ -292,7 +294,8 @@ def acl_set(path, item, numeric_ids=False, fd=None):
     if access_text is not None:
         try:
             access_acl = acl_from_text(<bytes>converter(access_text))
-            if access_acl is not NULL:
+            if access_acl == NULL:
+                raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
             if fd is not None:
                 if acl_set_fd(fd, access_acl) == -1:
                     raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
@@ -305,7 +308,8 @@ def acl_set(path, item, numeric_ids=False, fd=None):
     if default_text is not None:
         try:
             default_acl = acl_from_text(<bytes>converter(default_text))
-            if default_acl is not NULL:
+            if default_acl == NULL:
+                raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))
             # only directories can get a default ACL. there is no fd-based api to set it.
             if acl_set_file(path, ACL_TYPE_DEFAULT, default_acl) == -1:
                 raise OSError(errno.errno, os.strerror(errno.errno), os.fsdecode(path))