[PATCH] jobserver: detect properly O_NONBLOCK

["Martin Liška" <mliska@suse.cz>]

That handles systems that don't have O_NONBLOCK, in that case
WPA streaming is not using jobserver if --jobserver-auth uses 'fifo'.

Patch can bootstrap on x86_64-linux-gnu and survives regression tests.
Tested with mingw cross compiler as well.

Ready to be installed?
Thanks,
Martin

gcc/ChangeLog:

	* configure.ac: Detect O_NONBLOCK flag for open.
	* config.in: Regenerate.
	* configure: Regenerate.
	* opts-common.cc (jobserver_info::connect): Set is_connected
	  properly based on O_NONBLOCK.
	* opts-jobserver.h (struct jobserver_info): Add is_connected
	  member variable.

gcc/lto/ChangeLog:

	* lto.cc (wait_for_child): Ask if we are connected to jobserver.
	(stream_out_partitions): Likewise.
---
 gcc/config.in        |  6 ++++++
 gcc/configure        | 39 +++++++++++++++++++++++++++++++++++++--
 gcc/configure.ac     | 11 +++++++++++
 gcc/lto/lto.cc       | 12 ++++++------
 gcc/opts-common.cc   | 11 ++++++++++-
 gcc/opts-jobserver.h |  2 ++
 6 files changed, 72 insertions(+), 9 deletions(-)

diff --git a/gcc/config.in b/gcc/config.in
index 413b2bd36cb..abab9bf5024 100644
--- a/gcc/config.in
+++ b/gcc/config.in
@@ -2148,6 +2148,12 @@
 #endif
 
 
+/* Define if O_NONBLOCK supported by fcntl. */
+#ifndef USED_FOR_TARGET
+#undef HOST_HAS_O_NONBLOCK
+#endif
+
+
 /* Define which stat syscall is able to handle 64bit indodes. */
 #ifndef USED_FOR_TARGET
 #undef HOST_STAT_FOR_64BIT_INODES
diff --git a/gcc/configure b/gcc/configure
index da7a45066b5..8b416c1a142 100755
--- a/gcc/configure
+++ b/gcc/configure
@@ -12460,6 +12460,41 @@ $as_echo "#define HOST_HAS_O_CLOEXEC 1" >>confdefs.h
 
 fi
 
+# Check if O_NONBLOCK is defined by fcntl
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for O_NONBLOCK" >&5
+$as_echo_n "checking for O_NONBLOCK... " >&6; }
+if ${ac_cv_o_nonblock+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <fcntl.h>
+int
+main ()
+{
+
+return open ("/dev/null", O_RDONLY | O_NONBLOCK);
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+  ac_cv_o_nonblock=yes
+else
+  ac_cv_o_nonblock=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_o_nonblock" >&5
+$as_echo "$ac_cv_o_nonblock" >&6; }
+if test $ac_cv_o_nonblock = yes; then
+
+$as_echo "#define HOST_HAS_O_NONBLOCK 1" >>confdefs.h
+
+fi
+
 # C++ Modules would like some networking features to provide the mapping
 # server.  You can still use modules without them though.
 # The following network-related checks could probably do with some
@@ -19678,7 +19713,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 19681 "configure"
+#line 19716 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -19784,7 +19819,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 19787 "configure"
+#line 19822 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
diff --git a/gcc/configure.ac b/gcc/configure.ac
index f70b6c24fda..4ebdad38b9b 100644
--- a/gcc/configure.ac
+++ b/gcc/configure.ac
@@ -1707,6 +1707,17 @@ if test $ac_cv_o_cloexec = yes; then
   [Define if O_CLOEXEC supported by fcntl.])
 fi
 
+# Check if O_NONBLOCK is defined by fcntl
+AC_CACHE_CHECK(for O_NONBLOCK, ac_cv_o_nonblock, [
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
+#include <fcntl.h>]], [[
+return open ("/dev/null", O_RDONLY | O_NONBLOCK);]])],
+[ac_cv_o_nonblock=yes],[ac_cv_o_nonblock=no])])
+if test $ac_cv_o_nonblock = yes; then
+  AC_DEFINE(HOST_HAS_O_NONBLOCK, 1,
+  [Define if O_NONBLOCK supported by fcntl.])
+fi
+
 # C++ Modules would like some networking features to provide the mapping
 # server.  You can still use modules without them though.
 # The following network-related checks could probably do with some
diff --git a/gcc/lto/lto.cc b/gcc/lto/lto.cc
index c82307f4f7e..3a9147b01b5 100644
--- a/gcc/lto/lto.cc
+++ b/gcc/lto/lto.cc
@@ -213,11 +213,11 @@ wait_for_child ()
     }
   while (!WIFEXITED (status) && !WIFSIGNALED (status));
 
-    --nruns;
+  --nruns;
 
-    /* Return token to the jobserver if active.  */
-    if (jinfo != NULL && jinfo->is_active)
-      jinfo->return_token ();
+  /* Return token to the jobserver if active.  */
+  if (jinfo != NULL && jinfo->is_connected)
+    jinfo->return_token ();
 }
 #endif
 
@@ -254,7 +254,7 @@ stream_out_partitions (char *temp_filename, int blen, int min, int max,
      streaming process.  */
   if (!last)
     {
-      if (jinfo != NULL && jinfo->is_active)
+      if (jinfo != NULL && jinfo->is_connected)
 	while (true)
 	  {
 	    if (jinfo->get_token ())
@@ -291,7 +291,7 @@ stream_out_partitions (char *temp_filename, int blen, int min, int max,
       while (nruns > 0)
 	wait_for_child ();
 
-      if (jinfo != NULL && jinfo->is_active)
+      if (jinfo != NULL && jinfo->is_connected)
 	jinfo->disconnect ();
     }
   asm_nodes_output = true;
diff --git a/gcc/opts-common.cc b/gcc/opts-common.cc
index 4dec9f94447..bff2be02d38 100644
--- a/gcc/opts-common.cc
+++ b/gcc/opts-common.cc
@@ -2064,7 +2064,16 @@ void
 jobserver_info::connect ()
 {
   if (!pipe_path.empty ())
-    pipefd = open (pipe_path.c_str (), O_RDWR | O_NONBLOCK);
+    {
+#if HOST_HAS_O_NONBLOCK
+      pipefd = open (pipe_path.c_str (), O_RDWR | O_NONBLOCK);
+      is_connected = true;
+#else
+      is_connected = false;
+#endif
+    }
+  else
+    is_connected = true;
 }
 
 void
diff --git a/gcc/opts-jobserver.h b/gcc/opts-jobserver.h
index 76c1d9b2882..284b2417837 100644
--- a/gcc/opts-jobserver.h
+++ b/gcc/opts-jobserver.h
@@ -55,6 +55,8 @@ struct jobserver_info
   int pipefd = -1;
   /* Return true if jobserver is active.  */
   bool is_active = false;
+  /* Return true if communication with jobserver is working.  */
+  bool is_connected = false;
 };
 
 #endif /* GCC_JOBSERVER_H */
-- 
2.37.1