Use FileWrapper instead of StringIO for bug 2112 fix.

src/calibre/__init__.py

@@ -246,6 +246,23 @@ class CurrentDir(object):
         os.chdir(self.cwd)
 
 
+class FileWrapper(object):
+    '''
+    Used primarily with pyPdf to ensure the stream is properly closed.
+    '''
+
+    def __init__(self, stream):
+        for x in ('read', 'seek', 'tell'):
+            setattr(self, x, getattr(stream, x))
+
+    def __exit__(self, *args):
+        for x in ('read', 'seek', 'tell'):
+            setattr(self, x, None)
+
+    def __enter__(self):
+        return self
+
+
 def detect_ncpus():
     """Detects the number of effective CPUs in the system"""
     try:

src/calibre/ebooks/metadata/pdf.py

@@ -4,8 +4,9 @@ __license__   = 'GPL v3'
 __copyright__ = '2008, Kovid Goyal <kovid at kovidgoyal.net>'
 '''Read meta information from PDF files'''
 
-import sys, os, StringIO
+import sys, os, cStringIO
 
+from calibre import FileWrapper
 from calibre.ebooks.metadata import MetaInformation, authors_to_string
 from calibre.ptempfile import TemporaryDirectory
 from pyPdf import PdfFileReader, PdfFileWriter
@@ -21,7 +22,6 @@ def get_metadata(stream, extract_cover=True):
     """ Return metadata as a L{MetaInfo} object """
     mi = MetaInformation(_('Unknown'), [_('Unknown')])
     stream.seek(0)
-    stream = StringIO.StringIO(stream.read())
 
     if extract_cover and _imagemagick_loaded:
         try:
@@ -33,6 +33,7 @@ def get_metadata(stream, extract_cover=True):
             traceback.print_exc()
 
     try:
+        with FileWrapper(stream) as stream:
             info = PdfFileReader(stream).getDocumentInfo()
             if info.title:
                 mi.title = info.title
@@ -52,17 +53,17 @@ def get_metadata(stream, extract_cover=True):
 
 def set_metadata(stream, mi):
     stream.seek(0)
-    # Use a StringIO object for the pdf because we will want to over
+    # Use a cStringIO object for the pdf because we will want to over
     # write it later and if we are working on the stream directly it
     # could cause some issues.
-    raw = StringIO.StringIO(stream.read())
+    raw = cStringIO.StringIO(stream.read())
     orig_pdf = PdfFileReader(raw)
     title = mi.title if mi.title else orig_pdf.documentInfo.title
     author = authors_to_string(mi.authors) if mi.authors else orig_pdf.documentInfo.author
     out_pdf = PdfFileWriter(title=title, author=author)
     for page in orig_pdf.pages:
         out_pdf.addPage(page)
-    out_str = StringIO.StringIO()
+    out_str = cStringIO.StringIO()
     out_pdf.write(out_str)
     stream.seek(0)
     stream.truncate()
@@ -72,12 +73,11 @@ def set_metadata(stream, mi):
 
 def get_cover(stream):
     stream.seek(0)
-    if not isinstance(stream, StringIO.StringIO):
-        stream = StringIO.StringIO(stream.read())
     
-    data = StringIO.StringIO()
+    data = cStringIO.StringIO()
 
     try:
+        with FileWrapper(stream) as stream:
             pdf = PdfFileReader(stream)
             output = PdfFileWriter()