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[COMMITTED PATCH] Demangler fuzzer


Ian Lance Taylor wrote:
> On Tue, Aug 12, 2014 at 10:11 AM, Gary Benson <gbenson@redhat.com> wrote:
> > Ian Lance Taylor wrote:
> > > I think that by default the program should stop.  That will make
> > > it possible to eventually run as part of "make check".  Give it
> > > some number of iterations that stops it in a second or so.  You
> > > can still have it run forever by using -m -1.
> >
> > On my machine it usually fails in 3-5 seconds, so a 1 second run
> > seems a little too short.  How does 10 seconds sound?
> 
> OK, we can start with that, I suppose.

I have committed the patch inlined below.  By default it tries
7.5 million symbols, which takes roughly 10 seconds on my box.
A good seed for testing is 1407772345 which manages 30,123,441
symbols before crashing (about 45 seconds).

Cheers,
Gary

--
2014-08-13  Gary Benson  <gbenson@redhat.com>

	* testsuite/demangler-fuzzer.c: New file.
	* testsuite/Makefile.in (fuzz-demangler): New rule.
	(demangler-fuzzer): Likewise.
	(mostlyclean): Clean up demangler fuzzer.

Index: libiberty/testsuite/Makefile.in
===================================================================
--- libiberty/testsuite/Makefile.in	(revision 213911)
+++ libiberty/testsuite/Makefile.in	(revision 213912)
@@ -59,6 +59,10 @@
 check-expandargv: test-expandargv
 	./test-expandargv
 
+# Run the demangler fuzzer
+fuzz-demangler: demangler-fuzzer
+	./demangler-fuzzer
+
 TEST_COMPILE = $(CC) @DEFS@ $(LIBCFLAGS) -I.. -I$(INCDIR) $(HDEFINES)
 test-demangle: $(srcdir)/test-demangle.c ../libiberty.a
 	$(TEST_COMPILE) -o test-demangle \
@@ -72,6 +76,10 @@
 	$(TEST_COMPILE) -DHAVE_CONFIG_H -I.. -o test-expandargv \
 		$(srcdir)/test-expandargv.c ../libiberty.a
 
+demangler-fuzzer: $(srcdir)/demangler-fuzzer.c ../libiberty.a
+	$(TEST_COMPILE) -o demangler-fuzzer \
+		$(srcdir)/demangler-fuzzer.c ../libiberty.a
+
 # Standard (either GNU or Cygnus) rules we don't use.
 html install-html info install-info clean-info dvi pdf install-pdf \
 install etags tags installcheck:
@@ -81,6 +89,7 @@
 	rm -f test-demangle
 	rm -f test-pexecute
 	rm -f test-expandargv
+	rm -f demangler-fuzzer
 	rm -f core
 clean: mostlyclean
 distclean: clean
Index: libiberty/testsuite/demangler-fuzzer.c
===================================================================
--- libiberty/testsuite/demangler-fuzzer.c	(revision 0)
+++ libiberty/testsuite/demangler-fuzzer.c	(revision 213912)
@@ -0,0 +1,108 @@
+/* Demangler fuzzer.
+
+   Copyright (C) 2014 Free Software Foundation, Inc.
+
+   This file is part of GNU libiberty.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <time.h>
+#include "demangle.h"
+
+#define MAXLEN 253
+#define ALPMIN 33
+#define ALPMAX 127
+
+static char *program_name;
+
+#define DEFAULT_MAXCOUNT 7500000
+
+static void
+print_usage (FILE *fp, int exit_value)
+{
+  fprintf (fp, "Usage: %s [OPTION]...\n", program_name);
+  fprintf (fp, "Options:\n");
+  fprintf (fp, "  -h           Display this message.\n");
+  fprintf (fp, "  -s SEED      Select the random seed to be used.\n");
+  fprintf (fp, "               The default is to base one on the");
+  fprintf (fp, " current time.\n");
+  fprintf (fp, "  -m MAXCOUNT  Exit after MAXCOUNT symbols.\n");
+  fprintf (fp, "               The default is %d.", DEFAULT_MAXCOUNT);
+  fprintf (fp, " Set to `-1' for no limit.\n");
+
+  exit (exit_value);
+}
+
+int
+main (int argc, char *argv[])
+{
+  char symbol[2 + MAXLEN + 1] = "_Z";
+  int seed = -1, seed_set = 0;
+  int count = 0, maxcount = DEFAULT_MAXCOUNT;
+  int optchr;
+
+  program_name = argv[0];
+
+  do
+    {
+      optchr = getopt (argc, argv, "hs:m:t:");
+      switch (optchr)
+	{
+	case '?':  /* Unrecognized option.  */
+	  print_usage (stderr, 1);
+	  break;
+
+	case 'h':
+	  print_usage (stdout, 0);
+	  break;
+
+	case 's':
+	  seed = atoi (optarg);
+	  seed_set = 1;
+	  break;
+
+	case 'm':
+	  maxcount = atoi (optarg);
+	  break;
+	}
+    }
+  while (optchr != -1);
+
+  if (!seed_set)
+    seed = time (NULL);
+  srand (seed);
+  printf ("%s: seed = %d\n", program_name, seed);
+
+  while (maxcount < 0 || count < maxcount)
+    {
+      char *buffer = symbol + 2;
+      int length, i;
+
+      length = rand () % MAXLEN;
+      for (i = 0; i < length; i++)
+	*buffer++ = (rand () % (ALPMAX - ALPMIN)) + ALPMIN;
+
+      *buffer++ = '\0';
+
+      cplus_demangle (symbol, DMGL_AUTO | DMGL_ANSI | DMGL_PARAMS);
+
+      count++;
+    }
+
+  printf ("%s: successfully demangled %d symbols\n", program_name, count);
+  exit (0);
+}


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