[Assorted-commits] SF.net SVN: assorted:[1061] sandbox/trunk/src/nix

[<yan...@us...>]

Revision: 1061
          http://assorted.svn.sourceforge.net/assorted/?rev=1061&view=rev
Author:   yangzhang
Date:     2008-11-06 09:06:41 +0000 (Thu, 06 Nov 2008)

Log Message:
-----------
added demo of LD_PRELOAD

Added Paths:
-----------
    sandbox/trunk/src/nix/preload/
    sandbox/trunk/src/nix/preload/interposer.c
    sandbox/trunk/src/nix/preload/run.bash
    sandbox/trunk/src/nix/preload/test.c
    sandbox/trunk/src/nix/preload/test.cc

Added: sandbox/trunk/src/nix/preload/interposer.c
===================================================================
--- sandbox/trunk/src/nix/preload/interposer.c	                        (rev 0)
+++ sandbox/trunk/src/nix/preload/interposer.c	2008-11-06 09:06:41 UTC (rev 1061)
@@ -0,0 +1,30 @@
+#define _GNU_SOURCE
+#include <stdio.h>
+#include <dlfcn.h>
+
+void *
+malloc(size_t sz)
+{
+  // Find and cache the next malloc (in our example it should be the "real"
+  // malloc).
+  static void * (*func)();
+  if (!func)
+    func = (void *(*)()) dlsym(RTLD_NEXT, "malloc");
+
+  // Do our thang.
+#ifdef VERBOSE
+  printf("malloc(%u) is called\n", sz);
+#endif
+
+  // Call real malloc.
+  void *p = func(sz);
+
+  // Do our thang.
+#ifdef VERBOSE
+  printf("malloc returned %p\n", p);
+#endif
+  if (!p)
+    printf("malloc failed!\n");
+
+  return p;
+}

Added: sandbox/trunk/src/nix/preload/run.bash
===================================================================
--- sandbox/trunk/src/nix/preload/run.bash	                        (rev 0)
+++ sandbox/trunk/src/nix/preload/run.bash	2008-11-06 09:06:41 UTC (rev 1061)
@@ -0,0 +1,9 @@
+#!/usr/bin/env bash
+
+set -o errexit -o nounset
+
+gcc -Wall -o testc  test.c
+g++ -Wall -o testcc test.cc
+gcc -Wall -shared -fPIC -ldl -o interposer.so interposer.c
+LD_PRELOAD=./interposer.so ./testc
+LD_PRELOAD=./interposer.so ./testcc || true


Property changes on: sandbox/trunk/src/nix/preload/run.bash
___________________________________________________________________
Added: svn:executable
   + *

Added: sandbox/trunk/src/nix/preload/test.c
===================================================================
--- sandbox/trunk/src/nix/preload/test.c	                        (rev 0)
+++ sandbox/trunk/src/nix/preload/test.c	2008-11-06 09:06:41 UTC (rev 1061)
@@ -0,0 +1,11 @@
+#include <stdlib.h>
+#include <stdio.h>
+
+int
+main()
+{
+  char *msg = (char*) malloc(16);
+  snprintf(msg, 16, "hello!\n");
+  printf("%s", msg);
+  return 0;
+}

Added: sandbox/trunk/src/nix/preload/test.cc
===================================================================
--- sandbox/trunk/src/nix/preload/test.cc	                        (rev 0)
+++ sandbox/trunk/src/nix/preload/test.cc	2008-11-06 09:06:41 UTC (rev 1061)
@@ -0,0 +1,7 @@
+// Intentionally fail.
+
+int
+main() {
+  operator new(-1);
+  return 0;
+}


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