Work around AddressSanitizer bug with vfork

Problem reported by Jim Meyering in:
http://lists.gnu.org/archive/html/emacs-devel/2017-05/msg00246.html
* src/conf_post.h (vfork) [ADDRESS_SANITIZER]: Define to fork.
Unfortunately with the AddressSanitizer in Fedora 25 x86-64, the
vforked child messes up the parent’s shadow memory.  This is too
bad, as we’d rather have AddressSanitizer catch memory-access bugs
related to vfork.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/conf_post.h b/src/conf_post.h
index 4fc0428df5a..1462bd16c75 100644
--- a/src/conf_post.h
+++ b/src/conf_post.h
@@ -302,6 +302,12 @@ extern int emacs_setenv_TZ (char const *);
 # define ATTRIBUTE_NO_SANITIZE_ADDRESS
 #endif
 
+/* gcc -fsanitize=address does not work with vfork in Fedora 25 x86-64.
+   For now, assume that this problem occurs on all platforms.  */
+#if ADDRESS_SANITIZER && !defined vfork
+# define vfork fork
+#endif
+
 /* Some versions of GNU/Linux define noinline in their headers.  */
 #ifdef noinline
 #undef noinline