[PATCH] Clear LD_PRELOAD when forking external symbolizer.

[Sergey Matveev]

Hi kcc, glider, samsonov,

http://llvm-reviews.chandlerc.com/D704

Files:
  lib/sanitizer_common/sanitizer_symbolizer_linux.cc

Index: lib/sanitizer_common/sanitizer_symbolizer_linux.cc
===================================================================
--- lib/sanitizer_common/sanitizer_symbolizer_linux.cc
+++ lib/sanitizer_common/sanitizer_symbolizer_linux.cc
@@ -36,6 +36,23 @@
 
 static const int kSymbolizerStartupTimeMillis = 10;
 
+void UnsetEnvVar(const char name[]) {
+  uptr name_length = internal_strlen(name);
+  uptr i;
+  int var_index = -1;
+  for (i = 0; environ[i]; i++) {
+    if (internal_strlen(environ[i]) >= name_length + 1 &&
+        internal_strncmp(environ[i], name, name_length) == 0 &&
+        environ[i][name_length] == '=')
+      var_index = i;
+  }
+  if (var_index < 0)
+    return;
+  // environ[i - 1] is the last nonzero entry.
+  environ[var_index] = environ[i - 1];
+  environ[i - 1] = 0;
+}
+
 bool StartSymbolizerSubprocess(const char *path_to_symbolizer,
                                int *input_fd, int *output_fd) {
   if (!FileExists(path_to_symbolizer)) {
@@ -100,6 +117,7 @@
     internal_close(infd[1]);
     for (int fd = getdtablesize(); fd > 2; fd--)
       internal_close(fd);
+    UnsetEnvVar("LD_PRELOAD");
     execl(path_to_symbolizer, path_to_symbolizer, (char*)0);
     internal__exit(1);
   }
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