Check for and work around buggy fflush(NULL).

Some really old platforms (eg SunOS4) segfault on fflush(NULL) so check
for and work around.  With klausz at haus-gisela.de.

1 files changed, 10 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 70e72be77..d2fb4469c 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2059,6 +2059,16 @@ AC_CHECK_FUNCS([realpath], [
         )
 ])
 
+AC_MSG_CHECKING([for working fflush(NULL)])
+AC_RUN_IFELSE(
+        [AC_LANG_PROGRAM([[#include <stdio.h>]], [[fflush(NULL); exit(0);]])],
+        AC_MSG_RESULT([yes]),
+        [AC_MSG_RESULT([no])
+         AC_DEFINE([FFLUSH_NULL_BUG], [1],
+            [define if fflush(NULL) does not work])],
+        AC_MSG_WARN([cross compiling: assuming working])
+)
+
 dnl    Checks for time functions
 AC_CHECK_FUNCS([gettimeofday time])
 dnl    Checks for utmp functions