refactor reading of configuration files in client.py

This makes it so that an optional file which is unreadable or is rm'ed
at the wrong moment will be ignored instead of raising an exception.
It also bums out a couple of unnecessary lines of code (the explicit
".close()" call).

diff --git a/src/allmydata/client.py b/src/allmydata/client.py
index e15cae28578b1f9e83461085f1bd30a27b5abcf4..5976a7b17a55017effd51b9ed4fd5edce49b572f 100644 (file)
--- a/src/allmydata/client.py
+++ b/src/allmydata/client.py
@@ -44,23 +44,20 @@ class Client(node.Node, Referenceable):
         self.add_service(Uploader())
         self.add_service(Downloader())
         self.add_service(VirtualDrive())
-        WEBPORTFILE = os.path.join(self.basedir, self.WEBPORTFILE)
-        if os.path.exists(WEBPORTFILE):
-            f = open(WEBPORTFILE, "r")
-            webport = f.read().strip() # strports string
-            f.close()
+        try:
+            webport = open(os.path.join(self.basedir, self.WEBPORTFILE),
+                           "r").read().strip() # strports string
+        except EnvironmentError:
+            pass # absent or unreadable webport file
+        else:
             ws = WebishServer(webport)
-            local_access_file = os.path.join(self.basedir,
-                                             self.WEB_ALLOW_LOCAL_ACCESS_FILE)
-            if os.path.exists(local_access_file):
-                ws.allow_local_access(True)
+            ws.allow_local_access(os.path.exists(os.path.join(self.basedir,
+                                  self.WEB_ALLOW_LOCAL_ACCESS_FILE)))
             self.add_service(ws)
 
         INTRODUCER_FURL_FILE = os.path.join(self.basedir,
                                             self.INTRODUCER_FURL_FILE)
-        f = open(INTRODUCER_FURL_FILE, "r")
-        self.introducer_furl = f.read().strip()
-        f.close()
+        self.introducer_furl = open(INTRODUCER_FURL_FILE, "r").read().strip()
 
         hotline_file = os.path.join(self.basedir,
                                     self.SUICIDE_PREVENTION_HOTLINE_FILE)
@@ -72,12 +69,13 @@ class Client(node.Node, Referenceable):
     def init_storage(self):
         storedir = os.path.join(self.basedir, self.STOREDIR)
         sizelimit = None
-        SIZELIMIT_FILE = os.path.join(self.basedir,
-                                      self.SIZELIMIT_FILE)
-        if os.path.exists(SIZELIMIT_FILE):
-            f = open(SIZELIMIT_FILE, "r")
-            data = f.read().strip()
-            f.close()
+
+        try:
+            data = open(os.path.join(self.basedir, self.SIZELIMIT_FILE),
+                        "r").read().strip()
+        except EnvironmentError:
+            pass # absent or unreadable sizelimit file
+        else:
             m = re.match(r"^(\d+)([kKmMgG]?[bB]?)$", data)
             if not m:
                 log.msg("SIZELIMIT_FILE contains unparseable value %s" % data)
@@ -114,16 +112,18 @@ class Client(node.Node, Referenceable):
         self.log("tub_ready")
 
         my_old_name = None
-        MYSELF_FURL_PATH = os.path.join(self.basedir, self.MY_FURL_FILE)
-        if os.path.exists(MYSELF_FURL_PATH):
-            my_old_furl = open(MYSELF_FURL_PATH, "r").read().strip()
+        try:
+            my_old_furl = open(os.path.join(self.basedir, self.MY_FURL_FILE),
+                               "r").read().strip()
+        except EnvironmentError:
+            pass # absent or unreadable myfurl file
+        else:
             sturdy = SturdyRef(my_old_furl)
             my_old_name = sturdy.name
 
         self.my_furl = self.tub.registerReference(self, my_old_name)
-        f = open(MYSELF_FURL_PATH, "w")
-        f.write(self.my_furl + "\n")
-        f.close()
+        open(os.path.join(self.basedir, self.MY_FURL_FILE),
+             "w").write(self.my_furl + "\n")
 
         ic = IntroducerClient(self.tub, self.introducer_furl, self.my_furl)
         self.introducer_client = ic
@@ -136,9 +136,7 @@ class Client(node.Node, Referenceable):
         c.setServiceParent(self)
         control_url = self.tub.registerReference(c)
         control_furl_file = os.path.join(self.basedir, "control.furl")
-        f = open(control_furl_file, "w")
-        f.write(control_url + "\n")
-        f.close()
+        open(control_furl_file, "w").write(control_url + "\n")
         os.chmod(control_furl_file, 0600)