configure: fix F_SETPIPE_SZ detection

Currently CEPH_HAVE_SETPIPE_SZ is not set even if F_SETPIPE_SZ is
available, because AC_COMPILE_IFELSE test program as written always
fails to compile.  F_SETPIPE_SZ is a macro, so use AC_EGREP_CPP which
works on the preprocessor output instead of trying to compile.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>

diff --git a/configure.ac b/configure.ac
index 5773688b02342d8d9814b7549f924aad9479bbc2..c0c50fac597ee89e9d90362a978ccf496484225f 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -640,11 +640,21 @@ AC_CHECK_FUNC([splice],
        [AC_DEFINE([CEPH_HAVE_SPLICE], [], [splice(2) is supported])],
        [])
 
-AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#include <fcntl.h>
-F_SETPIPE_SZ]])],
-       [AC_DEFINE([CEPH_HAVE_SETPIPE_SZ], [], [F_SETPIPE_SZ is supported])],
-       [AC_MSG_NOTICE(["F_SETPIPE_SZ not found, zero-copy may be less efficent"])])
-
+# F_SETPIPE_SZ in fcntl.h
+AC_MSG_CHECKING([for F_SETPIPE_SZ in fcntl.h])
+AC_EGREP_CPP([yes_have_f_setpipe_sz], [
+  #define _GNU_SOURCE
+  #include <fcntl.h>
+  #ifdef F_SETPIPE_SZ
+  yes_have_f_setpipe_sz
+  #endif
+], [
+  AC_MSG_RESULT([yes])
+  AC_DEFINE([CEPH_HAVE_SETPIPE_SZ], [], [F_SETPIPE_SZ is supported])
+], [
+  AC_MSG_RESULT([no])
+  AC_MSG_NOTICE([F_SETPIPE_SZ not found, zero-copy may be less efficent])
+])
 
 AC_CHECK_FUNCS([posix_fallocate])
 AC_CHECK_HEADERS([sys/prctl.h])