add configure option to disable _exit() wrapper

darshan-runtime/configure.ac

@@ -754,6 +754,18 @@ if test "x$enable_darshan_runtime" = xyes ; then
    # look for glibc-specific functions
    AC_CHECK_FUNCS([pwritev preadv pwritev2 preadv2])
 
+   # allow users to opt out of wrapping of _exit as a shutdown hook in
+   # Darshan's non-MPI mode, in case this functionality is problematic
+   AC_ARG_ENABLE([exit-wrapper],
+      [AS_HELP_STRING([--disable-exit-wrapper],
+                      [Disables wrapping of _exit() calls as last ditch shutdown
+                       hook for the Darshan library when used in non-MPI mode.])],
+      [], [enable_exit_wrapper=yes])
+   if test "x$enable_exit_wrapper" = "xyes" ; then
+      AC_DEFINE([__DARSHAN_ENABLE_EXIT_WRAPPER], 1,
+                [Define if the Darshan runtime library should wrap _exit() calls])
+   fi
+
    DARSHAN_VERSION="AC_PACKAGE_VERSION"
    AC_SUBST(LDFLAGS)
    AC_SUBST(__DARSHAN_LOG_PATH)

darshan-runtime/doc/darshan-runtime.txt

@@ -120,6 +120,8 @@ make install
 * `--disable-ld-preload`: disables building of the Darshan LD_PRELOAD library
 * `--enable-group-readable-logs`: sets Darshan log file permissions to allow
   group read access.
+* `--disable-exit-wrapper`: disables wrapping of `_exit()` calls as last ditch
+  shutdown hook for the Darshan library when used in non-MPI mode.
 * `CC=`: specifies the C compiler to use for compilation.
 
 .Configure arguments for controlling which Darshan modules to use:

darshan-runtime/lib/darshan-core-init-finalize.c

@@ -115,7 +115,7 @@ __attribute__((destructor)) void serial_finalize(void)
 }
 #endif
 
-#ifdef DARSHAN_PRELOAD
+#if defined(DARSHAN_PRELOAD) && defined(__DARSHAN_ENABLE_EXIT_WRAPPER)
 void (*__real__exit)(int status) __attribute__ ((noreturn)) = NULL;
 void _exit(int status)
 {