From af6c15a730507dcfdf87d902aec6ada9f7fa89ba Mon Sep 17 00:00:00 2001
From: Steve Slaven <bpk@hoopajoo.net>
Date: Tue, 28 Jul 2009 07:55:57 -0700
Subject: Modify ftruncate to allow growing or shrinking to a size other than 0


diff --git a/fusearchive.py b/fusearchive.py
index f8cce35..00a156d 100755
--- a/fusearchive.py
+++ b/fusearchive.py
@@ -380,7 +380,7 @@ class FuseArchive(Fuse):
     def truncate(self, path, len):
         # Truncate using the ftruncate on the file
         dmsg( 2, "Using FuseArchiveFile to truncate " + path + " to " + str(len) )
-        f = self.FuseArchiveFile( path, os.O_APPEND, 0 )
+        f = self.FuseArchiveFile( path, os.O_WRONLY | os.O_APPEND, 0 )
         f.ftruncate(len)
         f.release( 0 )
 
@@ -730,6 +730,7 @@ class FuseArchive(Fuse):
                 } )
 
 
+
             return 1
 
 
@@ -760,11 +761,69 @@ class FuseArchive(Fuse):
             stats.overstat( self.size )
             return stats
 
-        def ftruncate(self, len):
-            if len > 0:
-                print "WARNING: ftruncate is broken for non-zero len!!!"
+        def ftruncate(self, length):
+            if not self.wr:
+                return errno.IOError
+
+            curr_chunks = len( self.chunks )
+            need_chunks = ( length / self.chunk_size )
+            extra_bytes = length % self.chunk_size
+            dmsg( 3, "Ftruncate - " + str(length) )
+            dmsg( 3, " - curr_chunks: " + str( curr_chunks ) )
+            dmsg( 3, " - need_chunks: " + str( need_chunks ) )
+            dmsg( 3, " - extra_bytes: " + str( extra_bytes ) )
+
+            if extra_bytes:
+                dmsg( 3, "Need an extra chunk" )
+                need_chunks += 1
+
+            self._load_chunk( 0 )
+
+            pdb.set_trace()
+            if need_chunks == 0:
+                dmsg( 3, "Creating 0 chunk file" )
+                self.chunks = []
+            elif need_chunks > curr_chunks:
+                dmsg( 3, "Need to pad out file" )
+
+                # Just write out null bytes to the length requested
+                self.flush()
+                tmp_size = self.size
+                while tmp_size < length:
+                    to_write = 4096
+                    if tmp_size + to_write > length:
+                        to_write = length - tmp_size
+
+                    dmsg( 3, "Writing " + str( to_write ) + " bytes to extend file to " + str( length ) )
+                    self.write( "\0" * to_write, tmp_size + 1 )
+                    tmp_size += to_write
+
+            else:
+                dmsg( 3, "Truncating chunks" )
+                while True:
+                    dmsg( 3, "Need chunks: " + str( need_chunks ) + " curr: " + str( curr_chunks ) )
+                    if need_chunks == curr_chunks:
+                        break
+
+                    dmsg( 3, "Deleting chunk " + str( self.chunk_index ) )
+                    self.chunks.pop()
+                    curr_chunks = len( self.chunks )
+
+            # Now make sure this chunk is the right size, first load the
+            # last chunk
+            if len( self.chunks ):
+                self._load_chunk( len( self.chunks ) - 1 )
+                dmsg( 3, "Loaded final chunk, len: " + str( len( self.chunk ) ) )
+
+            # Now truncate or extend this item
+            if len( self.chunk ) < extra_bytes:
+                remaining = extra_bytes - len(self.chunk)
+                dmsg( 3, "Extending final chunk " + str( remaining ) + " bytes" )
+                self.chunk += "\0" * remaining
+            else:
+                dmsg( 3, "Truncating final chunk to " + str( extra_bytes ) )
+                self.chunk = self.chunk[ :extra_bytes ]
 
-            self.chunks = []
             self.modified = True
             self._load_chunk( 0 )
             self._fflush()
-- 
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