[PATCH] Prevent people shooting themselves in the foot with MALLOC_CHECK_=

[Jakub Jelinek <jakub@redhat.com>]

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Hi!

If malloc.c didn't try to special case MALLOC_CHECK_= (empty string in
the env var), I'd say why bother, but as it does, it probably doesn't
hurt to handle it gracefully.

ATM apps segfault, because in that case mallopt (M_CHECK_ACTION, something)
is not called, but __malloc_check_init is.  But in that case
malloc_consolidate has not been called and we die later on.

I'm attaching 2 patches, one which handles MALLOC_CHECK_= as if
MALLOC_CHECK_=3 was given (3 stands for DEFAULT_CHECK_ACTION here),
the other ignores MALLOC_CHECK_ var completely if it contains an empty
string.

	Jakub

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2006-04-24  Jakub Jelinek  <jakub@redhat.com>

	* malloc/arena.c (ptmalloc_init): Call mALLOPt with
	DEFAULT_CHECK_ACTION if MALLOC_CHECK_ env var contains an empty
	string.

--- libc/malloc/arena.c	6 Mar 2006 06:18:35 -0000	1.20
+++ libc/malloc/arena.c	24 Apr 2006 08:54:16 -0000
@@ -552,7 +552,7 @@ ptmalloc_init (void)
   s = getenv("MALLOC_CHECK_");
 #endif
   if(s) {
-    if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
+    mALLOPt(M_CHECK_ACTION, s[0] ? (int)(s[0] - '0') : DEFAULT_CHECK_ACTION);
     if (check_action != 0)
       __malloc_check_init();
   }

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2006-04-24  Jakub Jelinek  <jakub@redhat.com>

	* malloc/arena.c (ptmalloc_init): Don't call __malloc_check_init
	if MALLOC_CHECK_ env var contains an empty string.

--- libc/malloc/arena.c	6 Mar 2006 06:18:35 -0000	1.20
+++ libc/malloc/arena.c	24 Apr 2006 08:55:04 -0000
@@ -551,8 +551,8 @@ ptmalloc_init (void)
     }
   s = getenv("MALLOC_CHECK_");
 #endif
-  if(s) {
-    if(s[0]) mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
+  if(s && s[0]) {
+    mALLOPt(M_CHECK_ACTION, (int)(s[0] - '0'));
     if (check_action != 0)
       __malloc_check_init();
   }