properly open and close processes

[lilass.git] / dsl.py

diff --git a/dsl.py b/dsl.py
index 890ea70e8cdc5b24520ea3cf30fe1b1b0fa56f06..d13d0a0f8dc058c008fe2e12dbc7393624cb242b 100755 (executable)
--- a/dsl.py
+++ b/dsl.py
@@ -78,13 +78,24 @@ def loadConfigFile(file):
        # add some convencience get functions
        return result
 
+# helper function: execute a process, return output as iterator, throw exception if there was an error
+# you *must* iterate to the end if you use this!
+def processOutputGen(*args):
+       p = subprocess.Popen(args, stdout=subprocess.PIPE)
+       for line in p.stdout:
+               yield line
+       p.wait() # wait for process to exit (it closed stdout, so it can't block anymore)
+       if p.returncode != 0:
+               raise Exception("Error executing "+str(args))
+def processOutputIt(*args):
+       return list(processOutputGen(*args)) # list() iterates over the generator
+
 # Run xrandr and return a dict of output names mapped to lists of available resolutions, each being a (width, height) pair.
 # An empty list indicates that the connector is disabled.
 def getXrandrInformation():
-       p = subprocess.Popen(["xrandr", "-q"], stdout=subprocess.PIPE)
        connectors = {} # map of connector names to a list of resolutions
        connector = None # current connector
-       for line in p.stdout:
+       for line in processOutputGen("xrandr", "-q"):
                # screen?
                m = re.search(r'^Screen [0-9]+: ', line)
                if m is not None: # ignore this line
@@ -107,10 +118,6 @@ def getXrandrInformation():
                # not fatal as my xrandr shows strange stuff when a display is enabled, but not connected
                #raise Exception("Unknown line in xrandr output:\n"+line)
                print "Warning: Unknown xrandr line %s" % line
-       # be sure to always proprly finish up with the xrandr
-       p.communicate()
-       # if everything succeededso far, check return code
-       if p.returncode != 0: raise Exception("Querying xrandr for data failed.")
        return connectors
 
 # convert a (width, height) pair into a string accepted by xrandr as argument for --mode