matplotlib · pelson · Apr 16, 2013 · Mar 6, 2013 · Mar 6, 2013 · Mar 6, 2013
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -213,16 +213,28 @@ def _is_writable_dir(p):
     p is a string pointing to a putative writable dir -- return True p
     is such a string, else False
     """
-    try: p + ''  # test is string like
-    except TypeError: return False
+    try:
+        p + ''  # test is string like
+    except TypeError:
+        return False
+
+    # Test whether the operating system thinks it's a writable directory.
+    # Note that this check is necessary on Google App Engine, because the
+    # subsequent check will succeed even though p may not be writable.
+    if not os.access(p, os.W_OK) or not os.path.isdir(p):
+        return False
+
+    # Also test that it is actually possible to write to a file here.
     try:
         t = tempfile.TemporaryFile(dir=p)
         try:
             t.write(ascii('1'))
         finally:
             t.close()
-    except OSError: return False
-    else: return True
+    except OSError:
+        return False
+
+    return True
 
 class Verbose:
     """
@@ -475,38 +487,42 @@ def checkdep_usetex(s):
 
 def _get_home():
     """Find user's home directory if possible.
-    Otherwise raise error.
+    Otherwise, returns None.
 
-    :see:  http://mail.python.org/pipermail/python-list/2005-February/263921.html
+    :see:  http://mail.python.org/pipermail/python-list/2005-February/325395.html
     """
-    path=''
     try:
-        path=os.path.expanduser("~")
-    except:
+        path = os.path.expanduser("~")
+    except ImportError:
+        # This happens on Google App Engine (pwd module is not present).
         pass
-    if not os.path.isdir(path):
-        for evar in ('HOME', 'USERPROFILE', 'TMP'):
-            try:
-                path = os.environ[evar]
-                if os.path.isdir(path):
-                    break
-            except: pass
-    if path:
-        return path
     else:
-        raise RuntimeError('please define environment variable $HOME')
+        if os.path.isdir(path):
+            return path
+    for evar in ('HOME', 'USERPROFILE', 'TMP'):
+        path = os.environ.get(evar)
+        if path is not None and os.path.isdir(path):
+            return path
+    return None
 
 
 def _create_tmp_config_dir():
     """
     If the config directory can not be created, create a temporary
     directory.
+
+    Returns None if a writable temporary directory could not be created.
     """
     import getpass
     import tempfile
 
-    tempdir = os.path.join(
-        tempfile.gettempdir(), 'matplotlib-%s' % getpass.getuser())
+    try:
+        tempdir = tempfile.gettempdir()
+    except NotImplementedError:
+        # Some restricted platforms (such as Google App Engine) do not provide
+        # gettempdir.
+        return None
+    tempdir = os.path.join(tempdir, 'matplotlib-%s' % getpass.getuser())
     os.environ['MPLCONFIGDIR'] = tempdir
 
     return tempdir
@@ -518,35 +534,42 @@ def _get_configdir():
     """
     Return the string representing the configuration directory.
 
-    Default is HOME/.matplotlib.  You can override this with the
-    MPLCONFIGDIR environment variable.  If the default is not
-    writable, and MPLCONFIGDIR is not set, then
-    tempfile.gettempdir() is used to provide a directory in
-    which a matplotlib subdirectory is created as the configuration
-    directory.
+    The directory is chosen as follows:
+
+    1. If the MPLCONFIGDIR environment variable is supplied, choose that. Else,
+       choose the '.matplotlib' subdirectory of the user's home directory (and
+       create it if necessary).
+    2. If the chosen directory exists and is writable, use that as the
+       configuration directory.
+    3. If possible, create a temporary directory, and use it as the
+       configuration directory.
+    4. A writable directory could not be found or created; return None.
     """
 
     configdir = os.environ.get('MPLCONFIGDIR')
     if configdir is not None:
         if not os.path.exists(configdir):
-            os.makedirs(configdir)
+            mkdirs(configdir)
         if not _is_writable_dir(configdir):
             return _create_tmp_config_dir()
         return configdir
 
     h = get_home()
-    p = os.path.join(get_home(), '.matplotlib')
+    if h is not None:
+        p = os.path.join(h, '.matplotlib')
 
-    if os.path.exists(p):
-        if not _is_writable_dir(p):
-            return _create_tmp_config_dir()
-    else:
-        if not _is_writable_dir(h):
-            return _create_tmp_config_dir()
-        from matplotlib.cbook import mkdirs
-        mkdirs(p)
+        if os.path.exists(p):
+            if not _is_writable_dir(p):
+                return _create_tmp_config_dir()
+        else:
+            if not _is_writable_dir(h):
+                return _create_tmp_config_dir()
+            from matplotlib.cbook import mkdirs
+            mkdirs(p)
 
-    return p
+        return p
+
+    return _create_tmp_config_dir()
 get_configdir = verbose.wrap('CONFIGDIR=%s', _get_configdir, always=False)
 
 
@@ -636,27 +659,39 @@ def matplotlib_fname():
 
     """
 
-    oldname = os.path.join( os.getcwd(), '.matplotlibrc')
+    oldname = os.path.join(os.getcwd(), '.matplotlibrc')
     if os.path.exists(oldname):
-        print("""\
-WARNING: Old rc filename ".matplotlibrc" found in working dir
-  and and renamed to new default rc file name "matplotlibrc"
-  (no leading"dot"). """, file=sys.stderr)
-        shutil.move('.matplotlibrc', 'matplotlibrc')
+        try:
+            shutil.move('.matplotlibrc', 'matplotlibrc')
+        except IOError as e:
+            warnings.warn('File could not be renamed: %s' % e)
+        else:
+            warnings.warn("""\
+Old rc filename ".matplotlibrc" found in working dir and and renamed to new
+    default rc file name "matplotlibrc" (no leading ".").""")
 
     home = get_home()
-    oldname = os.path.join( home, '.matplotlibrc')
-    if os.path.exists(oldname):
-        configdir = get_configdir()
-        newname = os.path.join(configdir, 'matplotlibrc')
-        print("""\
-WARNING: Old rc filename "%s" found and renamed to
-  new default rc file name "%s"."""%(oldname, newname), file=sys.stderr)
-
-        shutil.move(oldname, newname)
-
+    configdir = get_configdir()
+    if home:
+        oldname = os.path.join(home, '.matplotlibrc')
+        if os.path.exists(oldname):
+            if configdir is not None:
+                newname = os.path.join(configdir, 'matplotlibrc')
+
+                try:
+                    shutil.move(oldname, newname)
+                except IOError as e:
+                    warnings.warn('File could not be renamed: %s' % e)
+                else:
+                    warnings.warn("""\
+Old rc filename "%s" found and renamed to new default rc file name "%s"."""
+                              % (oldname, newname))
+            else:
+                warnings.warn("""\
+Could not rename old rc file "%s": a suitable configuration directory could not
+    be found.""" % oldname)
 
-    fname = os.path.join( os.getcwd(), 'matplotlibrc')
+    fname = os.path.join(os.getcwd(), 'matplotlibrc')
     if os.path.exists(fname): return fname
 
     if 'MATPLOTLIBRC' in os.environ:
@@ -666,9 +701,10 @@ def matplotlib_fname():
             if os.path.exists(fname):
                 return fname
 
-    fname = os.path.join(get_configdir(), 'matplotlibrc')
-    if os.path.exists(fname): return fname
-
+    if configdir is not None:
+        fname = os.path.join(configdir, 'matplotlibrc')
+        if os.path.exists(fname):
+            return fname
 
     path =  get_data_path() # guaranteed to exist or raise
     fname = os.path.join(path, 'matplotlibrc')

diff --git a/lib/matplotlib/finance.py b/lib/matplotlib/finance.py
@@ -28,7 +28,13 @@
 
 
 configdir = get_configdir()
-cachedir = os.path.join(configdir, 'finance.cache')
+# cachedir will be None if there is no writable directory.
+if configdir is not None:
+    cachedir = os.path.join(configdir, 'finance.cache')
+else:
+    # Should only happen in a restricted environment (such as Google App
+    # Engine). Deal with this gracefully by not caching finance data.
+    cachedir = None
 
 
 stock_dt = np.dtype([('date', object),
@@ -178,20 +184,25 @@ def fetch_historical_yahoo(ticker, date1, date2, cachename=None,dividends=False)
                      d2[0], d2[1], d2[2], ticker, g)
 
 
-    if cachename is None:
+    # Cache the finance data if cachename is supplied, or there is a writable
+    # cache directory.
+    if cachename is None and cachedir is not None:
         cachename = os.path.join(cachedir, md5(url).hexdigest())
-    if os.path.exists(cachename):
-        fh = open(cachename)
-        verbose.report('Using cachefile %s for %s'%(cachename, ticker))
+    if cachename is not None:
+        if os.path.exists(cachename):
+            fh = open(cachename)
+            verbose.report('Using cachefile %s for %s'%(cachename, ticker))
+        else:
+            mkdirs(os.path.abspath(os.path.dirname(cachename)))
+            with contextlib.closing(urlopen(url)) as urlfh:
+                with open(cachename, 'wb') as fh:
+                    fh.write(urlfh.read())
+            verbose.report('Saved %s data to cache file %s'%(ticker, cachename))
+            fh = open(cachename, 'r')
+
+        return fh
     else:
-        mkdirs(os.path.abspath(os.path.dirname(cachename)))
-        with contextlib.closing(urlopen(url)) as urlfh:
-            with open(cachename, 'wb') as fh:
-                fh.write(urlfh.read())
-        verbose.report('Saved %s data to cache file %s'%(ticker, cachename))
-        fh = open(cachename, 'r')
-
-    return fh
+        return urlopen(url)
 
 
 def quotes_historical_yahoo(ticker, date1, date2, asobject=False,

diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
@@ -1311,28 +1311,38 @@ def findfont(prop, fontext='ttf'):
         return result
 
 else:
-    if sys.version_info[0] >= 3:
-        _fmcache = os.path.join(get_configdir(), 'fontList.py3k.cache')
+    configdir = get_configdir()
+    if configdir is not None:
+        if sys.version_info[0] >= 3:
+            _fmcache = os.path.join(configdir, 'fontList.py3k.cache')
+        else:
+            _fmcache = os.path.join(configdir, 'fontList.cache')
     else:
-        _fmcache = os.path.join(get_configdir(), 'fontList.cache')
+        # Should only happen in a restricted environment (such as Google App
+        # Engine). Deal with this gracefully by not caching fonts.
+        _fmcache = None
 
     fontManager = None
 
     def _rebuild():
         global fontManager
         fontManager = FontManager()
-        pickle_dump(fontManager, _fmcache)
+        if _fmcache:
+            pickle_dump(fontManager, _fmcache)
         verbose.report("generated new fontManager")
 
-    try:
-        fontManager = pickle_load(_fmcache)
-        if (not hasattr(fontManager, '_version') or
-            fontManager._version != FontManager.__version__):
+    if _fmcache:
+        try:
+            fontManager = pickle_load(_fmcache)
+            if (not hasattr(fontManager, '_version') or
+                fontManager._version != FontManager.__version__):
+                _rebuild()
+            else:
+                fontManager.default_size = None
+                verbose.report("Using fontManager instance from %s" % _fmcache)
+        except:
             _rebuild()
-        else:
-            fontManager.default_size = None
-            verbose.report("Using fontManager instance from %s" % _fmcache)
-    except:
+    else:
         _rebuild()
 
     def findfont(prop, **kw):

diff --git a/lib/matplotlib/testing/compare.py b/lib/matplotlib/testing/compare.py
@@ -99,7 +99,10 @@ def compare_float( expected, actual, relTol = None, absTol = None ):
 # parameters old and new to a list that can be passed to Popen to
 # convert files with that extension to png format.
 def get_cache_dir():
-   cache_dir = os.path.join(_get_configdir(), 'test_cache')
+   configdir = _get_configdir()
+   if configdir is None:
+      raise RuntimeError('Could not find a suitable configuration directory')
+   cache_dir = os.path.join(configdir, 'test_cache')
    if not os.path.exists(cache_dir):
       try:
          os.makedirs(cache_dir)

diff --git a/lib/matplotlib/texmanager.py b/lib/matplotlib/texmanager.py
@@ -41,6 +41,7 @@
 import os
 import shutil
 import sys
+import warnings
 
 from hashlib import md5
 
@@ -94,16 +95,30 @@ class TexManager:
     oldcache = os.path.join(oldpath, '.tex.cache')
 
     configdir = mpl.get_configdir()
-    texcache = os.path.join(configdir, 'tex.cache')
+    if configdir is not None:
+        texcache = os.path.join(configdir, 'tex.cache')
+    else:
+        # Should only happen in a restricted environment (such as Google App
+        # Engine). Deal with this gracefully by not creating a cache directory.
+        texcache = None
 
     if os.path.exists(oldcache):
-        # FIXME raise proper warning
-        print("""\
-WARNING: found a TeX cache dir in the deprecated location "%s".
-  Moving it to the new default location "%s".""" % (oldcache, texcache),
-              file=sys.stderr)
-        shutil.move(oldcache, texcache)
-    mkdirs(texcache)
+        if texcache is not None:
+            try:
+                shutil.move(oldcache, texcache)
+            except IOError as e:
+                warnings.warn('File could not be renamed: %s' % e)
+            else:
+                warnings.warn("""\
+Found a TeX cache dir in the deprecated location "%s".
+    Moving it to the new default location "%s".""" % (oldcache, texcache))
+        else:
+            warnings.warn("""\
+Could not rename old TeX cache dir "%s": a suitable configuration
+    directory could not be found.""" % oldcache)
+
+    if texcache is not None:
+        mkdirs(texcache)
 
     _dvipng_hack_alpha = None
     #_dvipng_hack_alpha = dvipng_hack_alpha()
@@ -145,6 +160,11 @@ class TexManager:
 
     def __init__(self):
 
+        if self.texcache is None:
+            raise RuntimeError(
+                ('Cannot create TexManager, as there is no cache directory '
+                 'available'))
+
         mkdirs(self.texcache)
         ff = rcParams['font.family'].lower()
         if ff in self.font_families: