test

.gitignore

@@ -1,2 +1,6 @@
 /cache/
 /mnt/
+/test_cache
+/test_mnt
+/test_source
+/test_actual_result

fs.py

@@ -1,10 +1,12 @@
 #!/usr/bin/env python
 
-import os, sys, shutil, pathlib
+import os, sys, errno, shutil, pathlib
 from fuse import FUSE, FuseOSError, Operations
 from collections import namedtuple
 
 Translator = namedtuple('Translator', ['mode', 'output_filename', 'command'])
+# todo: rename 'path' to 'get'
+Entity = namedtuple('Entity', ['path', 'is_translator', 'peek', 'source', 'size'])
 
 class FilterFS(Operations):
     def __init__(self, source, cache):
@@ -23,23 +25,6 @@ class FilterFS(Operations):
             output_filename = components[1], # TODO: forbid ../ attacks
             command = '/'.join(components[2:])
         )
-    def _peek(self, why, path):
-        print('peek', path)
-        p = os.path.join(self.source, path.lstrip('/'))
-        if os.path.islink(p):
-            rl = os.readlink(p)
-            if rl.startswith('/!/'):
-                get = os.path.join(self.cache, 'get', path.lstrip('/'))
-                peek = os.path.join(self.cache, 'peek', path.lstrip('/'))
-                if os.path.exists(get):
-                    p = get
-                else:
-                    translator = self._parse(rl)
-                    p = peek
-                    self._mkparents(p)
-                    pathlib.Path(p).touch()
-                    os.chmod(p, translator.mode)
-        return p
 
     def _get(self, why, path):
         print('get', why, path)
@@ -62,6 +47,28 @@ class FilterFS(Operations):
                 p = cached_output
         return p
     
+    def _get_source(self, why, path):
+        print("_get_source", why, path)
+        return os.path.join(self.source, path.lstrip('/'))
+    
+    def _get_entity(self, why, path):
+        print("_get_entity", why, path)
+        p = os.path.join(self.source, path.lstrip('/'))
+        if os.path.islink(p):
+            rl = os.readlink(p)
+            if rl.startswith('/!/'):
+                get = os.path.join(self.cache, 'get', path.lstrip('/'))
+                peek = os.path.join(self.cache, 'peek', path.lstrip('/'))
+                if os.path.exists(get):
+                    return Entity(path = get, is_translator = True, peek = peek, source = p, size = None)
+                else:
+                    translator = self._parse(rl)
+                    self._mkparents(peek)
+                    pathlib.Path(peek).touch()
+                    os.chmod(peek, translator.mode)
+                    return Entity(path = peek, is_translator = True, peek = peek, source = p, size = 9999999999999999)
+        return Entity(path = p, is_translator = False, peek = p, source = p, size = None)
+
     # directory
     def readdir(self, path, fh):
         yield '.'
@@ -70,29 +77,118 @@ class FilterFS(Operations):
         if os.path.isdir(orig):
             for d in os.listdir(orig):
                 yield d
+    def mkdir(self, path, mode):
+        pass
+    def rmdir(self, path):
+        pass
 
-    # directory, file etc.
+    # directory, file etc
     def getattr(self, path, file_handle = None):
-        st = os.lstat(self._peek("getattr", path))
+        entity = self._get_entity("getattr", path)
+        attr = os.lstat(entity.path)
+        print(entity.path)
         return {
-            'st_mode': st.st_mode, # 0o100775 file, 0o40775 dir
+            'st_mode': attr.st_mode, # 0o100775 file, 0o40775 dir
             #'st_ino': 42,
             #'st_dev': 123,
-            'st_nlink': st.st_nlink,
+            'st_nlink': attr.st_nlink,
-            'st_uid': st.st_uid,
+            'st_uid': attr.st_uid,
-            'st_gid': st.st_gid,
+            'st_gid': attr.st_gid,
-            'st_size': 999999999999999, #st.st_size, # TODO: max file size
+            'st_size': attr.st_size if entity.size is None else entity.size,
-            'st_atime': st.st_atime,
+            'st_atime': attr.st_atime,
-            'st_mtime': st.st_mtime,
+            'st_mtime': attr.st_mtime,
-            'st_ctime': st.st_ctime,
+            'st_ctime': attr.st_ctime,
         }
 
+    def access(self, path, mode):
+        entity = self._get_entity("access", path)
+        if not os.access(entity.path, mode):
+            raise FuseOSError(errno.EACCES)
+    
+    def chmod(self, path, mode):
+        return os.chmod(self._get_entity('chmod', path).peek, mode)
+    def chown(self, path, uid, gid):
+        return os.chown(self._get_source('chown', path), uid, gid)
+    def rename(self, old_path, new_path):
+        old_entity = self._get_entity('rename old', old_path)
+        new_entity = self._get_entity('rename new', new_path)
+        if os.path.exists(new_entity.source):
+            raise FuseOSError(errno.EACCES)
+        else:
+            if entity.is_translator:
+                # TODO: preserve the cache for moved file?
+                os.unlink(old_entity.path)
+                os.unlink(old_entity.peek)
+                return os.rename(old_entity.source, new_entity.source)
+            else:
+                return os.unlink(entity.path, mode)
+    def utimens(self, path, times=None):
+        # TODO: the "peek" should have an utime in addition to a chmod
+        return os.utime(self._get_entity('utimens', path).peek, times)
+    def unlink(self, path):
+        entity = self._get_entity('unlink', path)
+        if entity.is_translator:
+            os.unlink(entity.path)
+            os.unlink(entity.peek)
+            return os.unlink(entity.source)
+        else:
+            return os.unlink(entity.path, mode)
+    def link(self, original_path, clone_path):
+        print('link', original_path, clone_path, 'TODO')
+        pass
+
+    # other:
+    def mknod(self, path, mode, dev):
+        return os.mknod(self._get_entity(path).source, mode, dev)
+
+    # filesystem
+    def statfs(self, path):
+        pass
+    
+    # symlinks
+    #def readlink(self, path):
+    #    pass
+    def symlink(self, destination, symlink_path):
+        pass
+    
     # file
     def open(self, path, flags):
-        return os.open(self._get("open", path), flags)
+        g = self._get("open", path)
+        print('open:', g)
+        return os.open(g, flags)
     def read(self, path, length, offset, file_handle):
         os.lseek(file_handle, offset, os.SEEK_SET)
         return os.read(file_handle, length)
+    def _assert_is_writable(self, why, path):
+        # TODO: might be a bit slow for many repeated writes, but guarantees that
+        # if a translator is created in src and a file handle was already obtained
+        # for its output, no further writes can mix things up?
+        # TODO: write a test for the above test case
+        entity = self._get_entity("_assert_is_writable for " + why, path)
+        if entity.is_translator:
+            raise FuseOSError(errno.EACCES)
+        else:
+            return entity
+    def write(self, path, buffer, offset, file_handle):
+        self._assert_is_writable("write", path)
+        os.lseek(file_handle, offset, os.SEEK_SET)
+        return os.write(file_handle, buffer)
+    def create(self, path, mode, file = None):
+        entity = self._assert_is_writable("write", path)
+        return os.open(entity.path, os.O_CREAT | os.O_WRONLY, mode)
+    def truncate(self, path, length, file_handle = None):
+        entity = self._assert_is_writable("truncate", path)
+        with open(entity.path, 'r+') as f:
+            f.truncate(length)
+    def flush(self, path, file_handle):
+        #self._assert_is_writable("flush", path)
+        return os.fsync(file_handle)
+    def release(self, path, file_handle):
+        print('release', path)
+        return os.close(file_handle)
+    def fsync(self, path, fdatasync, file_handle):
+        self._assert_is_writable("fsync",path)
+        return self.flush(path, file_handle)
 
 def main(source, cache, mountpoint):
     FUSE(FilterFS(source, cache), mountpoint, nothreads=True, foreground=True)

test.sh

@@ -0,0 +1,12 @@
+#!/usr/bin/env bash
+
+set -euET -o pipefail
+
+rm test_cache test_source test_actual_result -fr
+mkdir -p test_cache test_mnt
+cp -ai source test_source
+./fs.py test_source test_cache test_mnt
+touch test_mnt/touched
+echo 42 > test_mnt/written
+cp -ai test_mnt test_actual_result
+diff -r test_actual_result test_expected_result

test_expected_result/*.ogg

@@ -0,0 +1,7 @@
+output(filename) {
+  return filename + '.mp3'
+}
+
+contents(filename) {
+  ... create an mp3 from the ogg
+}

test_expected_result/some_dir/aaa

@@ -0,0 +1 @@
+Hello World!

test_expected_result/some_dir/bbb

@@ -0,0 +1 @@
+HELLO WORLD!