Tarball conversion

1 files changed, 114 insertions, 0 deletions

diff --git a/bzrlib/atomicfile.py b/bzrlib/atomicfile.py
new file mode 100644
index 0000000..92e1505
--- /dev/null
+++ b/bzrlib/atomicfile.py
@@ -0,0 +1,114 @@
+# Copyright (C) 2005, 2006, 2008, 2009, 2010 Canonical Ltd
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+
+from __future__ import absolute_import
+
+import os
+
+from bzrlib.lazy_import import lazy_import
+lazy_import(globals(), """
+import stat
+import warnings
+
+from bzrlib import (
+    errors,
+    osutils,
+    symbol_versioning,
+    )
+""")
+
+# not forksafe - but we dont fork.
+_pid = os.getpid()
+_hostname = None
+
+
+class AtomicFile(object):
+    """A file that does an atomic-rename to move into place.
+
+    This also causes hardlinks to break when it's written out.
+
+    Open this as for a regular file, then use commit() to move into
+    place or abort() to cancel.
+    """
+
+    __slots__ = ['tmpfilename', 'realfilename', '_fd']
+
+    def __init__(self, filename, mode='wb', new_mode=None):
+        global _hostname
+
+        self._fd = None
+
+        if _hostname is None:
+            _hostname = osutils.get_host_name()
+
+        self.tmpfilename = '%s.%d.%s.%s.tmp' % (filename, _pid, _hostname,
+                                                osutils.rand_chars(10))
+
+        self.realfilename = filename
+
+        flags = os.O_EXCL | os.O_CREAT | os.O_WRONLY | osutils.O_NOINHERIT
+        if mode == 'wb':
+            flags |= osutils.O_BINARY
+        elif mode != 'wt':
+            raise ValueError("invalid AtomicFile mode %r" % mode)
+
+        if new_mode is not None:
+            local_mode = new_mode
+        else:
+            local_mode = 0666
+
+        # Use a low level fd operation to avoid chmodding later.
+        # This may not succeed, but it should help most of the time
+        self._fd = os.open(self.tmpfilename, flags, local_mode)
+
+        if new_mode is not None:
+            # Because of umask issues, we may need to chmod anyway
+            # the common case is that we won't, though.
+            st = os.fstat(self._fd)
+            if stat.S_IMODE(st.st_mode) != new_mode:
+                osutils.chmod_if_possible(self.tmpfilename, new_mode)
+
+    def __repr__(self):
+        return '%s(%r)' % (self.__class__.__name__,
+                           self.realfilename)
+
+    def write(self, data):
+        """Write some data to the file. Like file.write()"""
+        os.write(self._fd, data)
+
+    def _close_tmpfile(self, func_name):
+        """Close the local temp file in preparation for commit or abort"""
+        if self._fd is None:
+            raise errors.AtomicFileAlreadyClosed(path=self.realfilename,
+                                                 function=func_name)
+        fd = self._fd
+        self._fd = None
+        os.close(fd)
+
+    def commit(self):
+        """Close the file and move to final name."""
+        self._close_tmpfile('commit')
+        osutils.rename(self.tmpfilename, self.realfilename)
+
+    def abort(self):
+        """Discard temporary file without committing changes."""
+        self._close_tmpfile('abort')
+        os.remove(self.tmpfilename)
+
+    def close(self):
+        """Discard the file unless already committed."""
+        if self._fd is not None:
+            self.abort()