filesystem.py revision f05b935882198ccf7d81675736e3aeb089c5113a 
1# Copyright (C) 2010 Google Inc. All rights reserved.
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28
29"""Wrapper object for the file system / source tree."""
30
31from __future__ import with_statement
32
33import codecs
34import errno
35import exceptions
36import os
37import shutil
38import tempfile
39import time
40
41class FileSystem(object):
42    """FileSystem interface for webkitpy.
43
44    Unless otherwise noted, all paths are allowed to be either absolute
45    or relative."""
46
47    def exists(self, path):
48        """Return whether the path exists in the filesystem."""
49        return os.path.exists(path)
50
51    def isfile(self, path):
52        """Return whether the path refers to a file."""
53        return os.path.isfile(path)
54
55    def isdir(self, path):
56        """Return whether the path refers to a directory."""
57        return os.path.isdir(path)
58
59    def join(self, *comps):
60        """Return the path formed by joining the components."""
61        return os.path.join(*comps)
62
63    def listdir(self, path):
64        """Return the contents of the directory pointed to by path."""
65        return os.listdir(path)
66
67    def mkdtemp(self, **kwargs):
68        """Create and return a uniquely named directory.
69
70        This is like tempfile.mkdtemp, but if used in a with statement
71        the directory will self-delete at the end of the block (if the
72        directory is empty; non-empty directories raise errors). The
73        directory can be safely deleted inside the block as well, if so
74        desired."""
75        class TemporaryDirectory(object):
76            def __init__(self, **kwargs):
77                self._kwargs = kwargs
78                self._directory_path = None
79
80            def __enter__(self):
81                self._directory_path = tempfile.mkdtemp(**self._kwargs)
82                return self._directory_path
83
84            def __exit__(self, type, value, traceback):
85                # Only self-delete if necessary.
86
87                # FIXME: Should we delete non-empty directories?
88                if os.path.exists(self._directory_path):
89                    os.rmdir(self._directory_path)
90
91        return TemporaryDirectory(**kwargs)
92
93    def maybe_make_directory(self, *path):
94        """Create the specified directory if it doesn't already exist."""
95        try:
96            os.makedirs(os.path.join(*path))
97        except OSError, e:
98            if e.errno != errno.EEXIST:
99                raise
100
101    class _WindowsError(exceptions.OSError):
102        """Fake exception for Linux and Mac."""
103        pass
104
105    def remove(self, path, osremove=os.remove):
106        """On Windows, if a process was recently killed and it held on to a
107        file, the OS will hold on to the file for a short while.  This makes
108        attempts to delete the file fail.  To work around that, this method
109        will retry for a few seconds until Windows is done with the file."""
110        try:
111            exceptions.WindowsError
112        except AttributeError:
113            exceptions.WindowsError = FileSystem._WindowsError
114
115        retry_timeout_sec = 3.0
116        sleep_interval = 0.1
117        while True:
118            try:
119                osremove(path)
120                return True
121            except exceptions.WindowsError, e:
122                time.sleep(sleep_interval)
123                retry_timeout_sec -= sleep_interval
124                if retry_timeout_sec < 0:
125                    raise e
126
127    def read_binary_file(self, path):
128        """Return the contents of the file at the given path as a byte string."""
129        with file(path, 'rb') as f:
130            return f.read()
131
132    def read_text_file(self, path):
133        """Return the contents of the file at the given path as a Unicode string.
134
135        The file is read assuming it is a UTF-8 encoded file with no BOM."""
136        with codecs.open(path, 'r', 'utf8') as f:
137            return f.read()
138
139    def write_binary_file(self, path, contents):
140        """Write the contents to the file at the given location."""
141        with file(path, 'wb') as f:
142            f.write(contents)
143
144    def write_text_file(self, path, contents):
145        """Write the contents to the file at the given location.
146
147        The file is written encoded as UTF-8 with no BOM."""
148        with codecs.open(path, 'w', 'utf8') as f:
149            f.write(contents)
150
151    def copyfile(self, source, destination):
152        """Copies the contents of the file at the given path to the destination
153        path."""
154        shutil.copyfile(source, destination)
155