Bug #337465 - Make ebuild-ipc use an array in order to force a

single atomic read of a whole pickle.

diff --git a/bin/ebuild-ipc.py b/bin/ebuild-ipc.py
index 61677c8f1d2be864f21e0b83844c9a6e0e914947..28352b56d6022dd1a8321b5d04dfb88121934784 100755 (executable)
--- a/bin/ebuild-ipc.py
+++ b/bin/ebuild-ipc.py
@@ -5,6 +5,7 @@
 # This is a helper which ebuild processes can use
 # to communicate with portage's main python process.
 
+import array
 import logging
 import os
 import pickle
@@ -36,6 +37,7 @@ class EbuildIpc(object):
        # Timeout for each individual communication attempt (we retry
        # as long as the daemon process appears to be alive).
        _COMMUNICATE_RETRY_TIMEOUT_SECONDS = 15
+       _BUFSIZE = 4096
 
        def __init__(self):
                self.fifo_dir = os.environ['PORTAGE_BUILDDIR']
@@ -138,11 +140,22 @@ class EbuildIpc(object):
                # File streams are in unbuffered mode since we do atomic
                # read and write of whole pickles.
                input_file = open(self.ipc_out_fifo, 'rb', 0)
-               data = input_file.read()
+
+               # For maximum portability, us an array in order to force
+               # a single atomic read of a whole pickle (bug #337465).
+               buf = array.array('B')
+
+               try:
+                       buf.fromfile(input_file, self._BUFSIZE)
+               except (EOFError, IOError) as e:
+                       if not buf:
+                               portage.util.writemsg_level(
+                                       "ebuild-ipc: %s\n" % (e,),
+                                       level=logging.ERROR, noiselevel=-1)
 
                retval = 2
 
-               if not data:
+               if not buf:
 
                        portage.util.writemsg_level(
                                "ebuild-ipc: %s\n" % \
@@ -152,7 +165,7 @@ class EbuildIpc(object):
                else:
 
                        try:
-                               reply = pickle.loads(data)
+                               reply = pickle.loads(buf.tostring())
                        except SystemExit:
                                raise
                        except Exception as e: