[PATCH] Fix PR gcov-profile/54487 (profiledbootstrap intermittent failures) (issue6496113)

[Teresa Johnson]

This fixes PR gcov-profile/54487 where the gcda files were not locked
by the profile-use read, enabling writes by other instrumented compiles
to change the profile in the middle of the profile use read. The GCOV_LOCKED
macro was not set because it was guarded by HOST_HAS_F_SETLKW, which was
never set. The fix is to add a compile test in the configure to set it.

Tested with bootstrap and profiledbootstrap on x86_64-unknown-linux-gnu.
Ok for trunk?

Thanks,
Teresa

2012-09-12  Teresa Johnson  <tejohnson@google.com>

	* configure.ac(HOST_HAS_F_SETLKW): Set based on compile
	test using F_SETLKW with fcntl.
	* configure, config.in: Regenerate.

Index: configure
===================================================================
--- configure	(revision 191225)
+++ configure	(working copy)
@@ -10731,6 +10731,41 @@ $as_echo "#define HAVE_CLOCK_T 1" >>confdefs.h
 
 fi
 
+# Check if F_SETLKW is supported by fcntl.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for F_SETLKW" >&5
+$as_echo_n "checking for F_SETLKW... " >&6; }
+if test "${ac_cv_f_setlkw+set}" = set; then :
+  $as_echo_n "(cached) " >&6
+else
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include "fcntl.h"
+
+int
+main ()
+{
+struct flock fl; fl.l_whence = 0; fl.l_start = 0; fl.l_len = 0; fl.l_pid = 0; return fcntl (1, F_SETLKW, &fl);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_cv_f_setlkw=yes
+else
+  ac_cv_f_setlkw=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_f_setlkw" >&5
+$as_echo "$ac_cv_f_setlkw" >&6; }
+if test $ac_cv_f_setlkw = yes; then
+
+$as_echo "#define HOST_HAS_F_SETLKW 1" >>confdefs.h
+
+fi
+
 # Restore CFLAGS, CXXFLAGS from before the gcc_AC_NEED_DECLARATIONS tests.
 CFLAGS="$saved_CFLAGS"
 CXXFLAGS="$saved_CXXFLAGS"
@@ -17742,7 +17777,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 17745 "configure"
+#line 17780 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -17848,7 +17883,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 17851 "configure"
+#line 17886 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
Index: config.in
===================================================================
--- config.in	(revision 191225)
+++ config.in	(working copy)
@@ -1600,6 +1600,12 @@
 #endif
 
 
+/* Define if F_SETLKW supported by fcntl. */
+#ifndef USED_FOR_TARGET
+#undef HOST_HAS_F_SETLKW
+#endif
+
+
 /* Define as const if the declaration of iconv() needs const. */
 #ifndef USED_FOR_TARGET
 #undef ICONV_CONST
Index: configure.ac
===================================================================
--- configure.ac	(revision 191225)
+++ configure.ac	(working copy)
@@ -1159,6 +1159,16 @@ if test $gcc_cv_type_clock_t = yes; then
   [Define if <time.h> defines clock_t.])
 fi
 
+# Check if F_SETLKW is supported by fcntl.
+AC_CACHE_CHECK(for F_SETLKW, ac_cv_f_setlkw, [
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include "fcntl.h"
+]], [[struct flock fl; fl.l_whence = 0; fl.l_start = 0; fl.l_len = 0; fl.l_pid = 0; return fcntl (1, F_SETLKW, &fl);]])],[ac_cv_f_setlkw=yes],[ac_cv_f_setlkw=no])])
+if test $ac_cv_f_setlkw = yes; then
+  AC_DEFINE(HOST_HAS_F_SETLKW, 1,
+  [Define if F_SETLKW supported by fcntl.])
+fi
+
 # Restore CFLAGS, CXXFLAGS from before the gcc_AC_NEED_DECLARATIONS tests.
 CFLAGS="$saved_CFLAGS"
 CXXFLAGS="$saved_CXXFLAGS"

--
This patch is available for review at http://codereview.appspot.com/6496113