Changeset 1047 in tailor

Timestamp:

12/26/05 19:19:34 (7 years ago)

Author:

lele@…

Hash name:

20051226181934-7a6fb-92576d41e53da346e2e33e0933849d33e2456026

Message:

Avoid execution of too long command lines
Now the mechanism that executes external commands respects a maximum
size for the command line, eventually executing the external command
multiple times operating on a slice of the original arguments at a
time.

Location:

vcpx

Files:

• shwrap.py (modified) (2 diffs)
• tests/shwrap.py (modified) (1 diff)

vcpx/shwrap.py

@@ -49 +49 @@
     DRY_RUN = False
     """Don't really execute the command."""
+
+    MAX_CMDLINE_LENGTH = 8000
+    """Don't execute commands longer than this number of characters."""
 
     def __init__(self, command=None, cwd=None):
@@ -128 +131 @@
 
     def execute(self, *args, **kwargs):
+        """Execute the command, avoiding too long command line."""
+
+        from cStringIO import StringIO
+
+        if len(args) == 1 and type(args[0]) == type([]):
+            allargs = list(args[0])
+        else:
+            allargs = list(args)
+
+        maxlen = self.MAX_CMDLINE_LENGTH
+        if maxlen is None or len(allargs) < 2:
+            return self._execute(allargs, **kwargs)
+
+        startlen = len(' '.join(self.command))
+        allout = None
+        allerr = None
+        while allargs:
+            thisrun = []
+            clen = startlen
+            pop = allargs.pop
+            append = thisrun.append
+            while allargs and clen<maxlen:
+                thisarg = pop(0)
+                clen += len(thisarg)+1
+                append(thisarg)
+            thisout, thiserr = self._execute(*thisrun, **kwargs)
+            if thisout is not None:
+                if allout is None:
+                    allout = StringIO()
+                allout.write(thisout.read())
+            if thiserr is not None:
+                if allerr is None:
+                    allerr = StringIO()
+                allerr.write(thiserr.read())
+            if self.exit_status:
+                break
+        if allout is not None:
+            allout.seek(0)
+        if allerr is not None:
+            allerr.seek(0)
+        return allout, allerr
+
+    def _execute(self, *args, **kwargs):
         """Execute the command."""
 

vcpx/tests/shwrap.py

@@ -75 +75 @@
         c = ExternalCommand([r'a \" backslashed quote mark\\'])
         self.assertEqual(str(c), r'$ "a \\\" backslashed quote mark\\\\"')
+
+    def testSplittedExecution(self):
+        """Verify the mechanism that avoids too long command lines"""
+
+        args = [str(i) * 20 for i in range(10)]
+        c = ExternalCommand(['echo'])
+        c.MAX_CMDLINE_LENGTH = 30
+        out = c.execute(args, stdout=PIPE)[0]
+        self.assertEqual(out.read(), '\n'.join([args[i]+' '+args[i+1]
+                                                for i in range(0,10,2)])+'\n')
+
+        c = ExternalCommand(['echo'])
+        c.MAX_CMDLINE_LENGTH = None
+        out = c.execute(args, stdout=PIPE)[0]
+        self.assertEqual(out.read(), ' '.join(args)+'\n')