2000-03-27 Roland McGrath <roland@baalperazim.frob.com>

	Locking support for stdio streams with glibc-2.2 libio.  EXPERIMENTAL!
	* lockfile.c: New file.
	* libthreads.map: New file.
	* Makefile (SRCS): Add lockfile.c.
	[$(VERSIONING) = yes] ($(libname).so.$(hurd-version)): Depend
	on $(srcdir)/$(libname).map to get version script into the link.

3 files changed, 130 insertions, 2 deletions

diff --git a/libthreads/Makefile b/libthreads/Makefile
index 5b2bc62a..ee862366 100644
--- a/libthreads/Makefile
+++ b/libthreads/Makefile
@@ -1,5 +1,5 @@
 #
-#   Copyright (C) 1994, 1995, 1996, 1997 Free Software Foundation, Inc.
+#   Copyright (C) 1994,95,96,97,2000 Free Software Foundation, Inc.
 #
 #   This program is free software; you can redistribute it and/or
 #   modify it under the terms of the GNU General Public License as
@@ -21,7 +21,7 @@ makemode := library
 # In GNU mig_support.c, sync.c and machine/lock.s are omitted; that work is
 # all done in libc.
 SRCS := call.c cprocs.c cthread_data.c cthreads.c stack.c \
-	cancel-cond.c rwlock.c
+	cancel-cond.c rwlock.c lockfile.c
 I386SRCS := i386/csw.S i386/thread.c
 
 # In GNU machine/cthreads.h is omitted; that work is done in libc headers.
@@ -50,3 +50,11 @@ lndist-i386-files: $(top_srcdir)/hurd-snap/$(dir)/i386
 
 $(top_srcdir)/hurd-snap/$(dir)/i386:
 	mkdir $@
+
+ifeq ($(VERSIONING),yes)
+
+# Adding this dependency gets it included in the command line,
+# where ld will read it as a linker script.
+$(libname).so.$(hurd-version): $(srcdir)/$(libname).map
+
+endif
diff --git a/libthreads/libthreads.map b/libthreads/libthreads.map
new file mode 100644
index 00000000..28c85017
--- /dev/null
+++ b/libthreads/libthreads.map
@@ -0,0 +1,19 @@
+/* This is the version script file used for building libthreads.so. -*- C -*-
+   It is in the form of a linker script, to be including as an input
+   file in the link command, rather than with --version-script.  */
+
+  /* We only define these symbols when built against a libio-using libc,
+     which we presume will be 2.2 that is expecting our lockfile.c hooks.
+     For now, the rest of the library's symbols remain unversioned.  */
+
+VERSION
+{
+  GLIBC_2.2
+    {
+    global:
+      _IO_flockfile; _IO_funlockfile; _IO_ftrylockfile;
+      flockfile; funlockfile; ftrylockfile;
+    local:
+      _cthreads_flockfile; _cthreads_funlockfile; _cthreads_ftrylockfile;
+    };
+};
diff --git a/libthreads/lockfile.c b/libthreads/lockfile.c
new file mode 100644
index 00000000..b0b019de
--- /dev/null
+++ b/libthreads/lockfile.c
@@ -0,0 +1,101 @@
+/* lockfile - Handle locking and unlocking of stream.  Hurd cthreads version.
+   Copyright (C) 2000 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Library General Public License as
+   published by the Free Software Foundation; either version 2 of the
+   License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Library General Public License for more details.
+
+   You should have received a copy of the GNU Library General Public
+   License along with the GNU C Library; see the file COPYING.LIB.  If not,
+   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
+
+#include <cthreads.h>		/* Must come before <stdio.h>! */
+
+#define _IO_MTSAFE_IO
+#include <stdio.h>
+
+#include <assert.h>
+
+
+#ifdef _STDIO_USES_IOSTREAM
+
+#undef _IO_flockfile
+#undef _IO_funlockfile
+#undef _IO_ftrylockfile
+
+void
+_cthreads_flockfile (_IO_FILE *fp)
+{
+  cthread_t self = cthread_self ();
+
+  if (fp->_lock->owner == self)
+    {
+      assert (fp->_lock->count != 0);
+      ++fp->_lock->count;
+    }
+  else
+    {
+      __mutex_lock (&fp->_lock->mutex);
+      assert (fp->_lock->owner == 0);
+      fp->_lock->owner = self;
+      assert (fp->_lock->count == 0);
+      fp->_lock->count = 1;
+    }
+}
+
+void
+_cthreads_funlockfile (_IO_FILE *fp)
+{
+  if (--fp->_lock->count == 0)
+    {
+      assert (fp->_lock->owner == cthread_self ());
+      fp->_lock->owner = 0;
+      __mutex_unlock (&fp->_lock->mutex);
+    }
+}
+
+int
+_cthreads_ftrylockfile (_IO_FILE *fp)
+{
+  cthread_t self = cthread_self ();
+
+  if (fp->_lock->owner == self)
+    {
+      assert (fp->_lock->count != 0);
+      ++fp->_lock->count;
+    }
+  else if (__mutex_try_lock (&fp->_lock->mutex))
+    {
+      assert (fp->_lock->owner == 0);
+      fp->_lock->owner = self;
+      assert (fp->_lock->count == 0);
+      fp->_lock->count = 1;
+    }
+  else
+    return 0;			/* No lock for us.  */
+
+  /* We got the lock. */
+  return 1;
+}
+
+#define strong_alias(src, dst)	asm (".globl " #dst "; " #dst " = " #src)
+#define weak_alias(src, dst)	asm (".weak " #dst  "; " #dst " = " #src)
+
+weak_alias (_cthreads_flockfile, _IO_flockfile);
+weak_alias (_cthreads_funlockfile, _IO_funlockfile);
+weak_alias (_cthreads_ftrylockfile, _IO_ftrylockfile);
+
+weak_alias (_cthreads_flockfile, flockfile);
+weak_alias (_cthreads_funlockfile, funlockfile);
+weak_alias (_cthreads_ftrylockfile, ftrylockfile);
+
+
+#endif /* _STDIO_USES_IOSTREAM */