From: Philippe Waroquiers <philippe.waroquiers@skynet.be>
Date: Wed, 19 Apr 2017 20:15:50 +0000 (+0000)
Subject: Have a cleaner way to remove the massif preload from LD_PRELOAD.
X-Git-Tag: svn/VALGRIND_3_13_0~128
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0282832312e2de76b2f3a5d3f22bf34749d5979a;p=thirdparty%2Fvalgrind.git

Have a cleaner way to remove the massif preload from LD_PRELOAD.

The previous code was removing the massif preload (when --pages-as-heap=yes)
by replacing the entry with spaces.
This is not very clear, and I suspect this gives problems with the
android linker, which seems to use such a space entry as a real entry
to load (and then fails to start the application).

This patch really removes the entry, by shifting the characters.

Tested on amd64/debian.



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@16306
---

diff --git a/massif/ms_main.c b/massif/ms_main.c
index cda4635265..2d5091aa02 100644
--- a/massif/ms_main.c
+++ b/massif/ms_main.c
@@ -1947,8 +1947,6 @@ static void ms_post_clo_init(void)
 {
    Int i;
    HChar* LD_PRELOAD_val;
-   HChar* s;
-   HChar* s2;
 
    /* We will record execontext up to clo_depth + overestimate and
       we will store this as ec => we need to increase the backtrace size
@@ -1969,35 +1967,42 @@ static void ms_post_clo_init(void)
 
    // If --pages-as-heap=yes we don't want malloc replacement to occur.  So we
    // disable vgpreload_massif-$PLATFORM.so by removing it from LD_PRELOAD (or
-   // platform-equivalent).  We replace it entirely with spaces because then
-   // the linker doesn't complain (it does complain if we just change the name
-   // to a bogus file).  This is a bit of a hack, but LD_PRELOAD is setup well
-   // before tool initialisation, so this seems the best way to do it.
+   // platform-equivalent). This is a bit of a hack, but LD_PRELOAD is setup
+   // well before tool initialisation, so this seems the best way to do it.
    if (clo_pages_as_heap) {
+      HChar* s1;
+      HChar* s2;
+
       clo_heap_admin = 0;     // No heap admin on pages.
 
       LD_PRELOAD_val = VG_(getenv)( VG_(LD_PRELOAD_var_name) );
       tl_assert(LD_PRELOAD_val);
 
+      VERB(2, "clo_pages_as_heap orig LD_PRELOAD '%s'\n", LD_PRELOAD_val);
+
       // Make sure the vgpreload_core-$PLATFORM entry is there, for sanity.
-      s2 = VG_(strstr)(LD_PRELOAD_val, "vgpreload_core");
-      tl_assert(s2);
+      s1 = VG_(strstr)(LD_PRELOAD_val, "vgpreload_core");
+      tl_assert(s1);
 
       // Now find the vgpreload_massif-$PLATFORM entry.
-      s2 = VG_(strstr)(LD_PRELOAD_val, "vgpreload_massif");
-      tl_assert(s2);
+      s1 = VG_(strstr)(LD_PRELOAD_val, "vgpreload_massif");
+      tl_assert(s1);
+      s2 = s1;
 
-      // Blank out everything to the previous ':', which must be there because
+      // Position s1 on the previous ':', which must be there because
       // of the preceding vgpreload_core-$PLATFORM entry.
-      for (s = s2; *s != ':'; s--) {
-         *s = ' ';
-      }
+      for (; *s1 != ':'; s1--)
+         ;
 
-      // Blank out everything to the end of the entry, which will be '\0' if
-      // LD_PRELOAD was empty before Valgrind started, or ':' otherwise.
-      for (s = s2; *s != ':' && *s != '\0'; s++) {
-         *s = ' ';
-      }
+      // Position s2 on the next ':' or \0
+      for (; *s2 != ':' && *s2 != '\0'; s2++)
+         ;
+
+      // Move all characters from s2 to s1
+      while ((*s1++ = *s2++))
+         ;
+
+      VERB(2, "clo_pages_as_heap cleaned LD_PRELOAD '%s'\n", LD_PRELOAD_val);
    }
 
    // Print alloc-fns and ignore-fns, if necessary.