Initial commit

.gitignore

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+/cache/
+/mnt/

fs.py

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+#!/usr/bin/env python
+
+import os, sys, shutil, pathlib
+from fuse import FUSE, FuseOSError, Operations
+
+class FilterFS(Operations):
+    def __init__(self, source, cache):
+        self.source = source
+        self.cache = cache
+    def _original(self, path):
+        print(path)
+        p = os.path.join(self.source, path.lstrip('/'))
+        if os.path.islink(p):
+            rl = os.readlink(p)
+            if rl.startswith('/!/'):
+                cached_output = os.path.join(self.cache, path.lstrip('/'))
+                if not os.path.exists(cached_output):
+                    rl = rl[3:]
+                    d = os.path.dirname(p)
+                    # begin hack
+                    old_cwd = os.getcwd()
+                    os.chdir(d)
+                    os.system(rl)
+                    os.chdir(old_cwd)
+                    pathlib.Path(os.path.dirname(cached_output)).mkdir(parents = True, exist_ok = True)
+                    shutil.move(os.path.join(d, 'out'), cached_output)
+                    # end hack
+                p = cached_output
+        return p
+
+    # directory
+    def readdir(self, path, fh):
+        yield '.'
+        yield '..'
+        if os.path.isdir(self._original(path)):
+            for d in os.listdir(self._original(path)):
+                yield d
+
+    # directory, file etc.
+    def getattr(self, path, file_handle = None):
+        st = os.lstat(self._original(path))
+        return {
+            'st_mode': st.st_mode, # 0o100775 file, 0o40775 dir
+            #'st_ino': 42,
+            #'st_dev': 123,
+            'st_nlink': st.st_nlink,
+            'st_uid': st.st_uid,
+            'st_gid': st.st_gid,
+            'st_size': st.st_size,
+            'st_atime': st.st_atime,
+            'st_mtime': st.st_mtime,
+            'st_ctime': st.st_ctime,
+        }
+    
+    # file
+    def open(self, path, flags):
+        return os.open(self._original(path), flags)
+    def read(self, path, length, offset, file_handle):
+        os.lseek(file_handle, offset, os.SEEK_SET)
+        return os.read(file_handle, length)
+
+def main(source, cache, mountpoint):
+    FUSE(FilterFS(source, cache), mountpoint, nothreads=True, foreground=True)
+
+if __name__ == '__main__':
+    main(sys.argv[1], sys.argv[2], sys.argv[3])

source/*.ogg

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+output(filename) {
+  return filename + '.mp3'
+}
+
+contents(filename) {
+  ... create an mp3 from the ogg
+}

source/foo.mp3

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+/!/lame -vbr -b 240 foo.ogg output.mp3; mv output.mp3 out

source/some_dir/aaa

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+Hello World!

source/some_dir/bbb

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+/!/tr '[:lower:]' '[:upper:'] < aaa > out