Always do locking when accessing streams (bug 15142, bug 14697)
diff mbox series

Message ID mvmzhfzgp9u.fsf@suse.de
State New
Headers show
Series
  • Always do locking when accessing streams (bug 15142, bug 14697)
Related show

Commit Message

Andreas Schwab Dec. 11, 2019, 9:55 a.m. UTC
Now that abort no longer calls fflush there is no reason to avoid locking
the stdio streams anywhere.  This fixes a conformance issue and potential
heap corruption during exit.  The test nptl/tst-stdio1 is removed as that
was expecting the problematic behaviour.
---
 libio/genops.c    | 43 +++++++++---------------------------
 libio/libioP.h    |  1 -
 nptl/Makefile     |  2 +-
 nptl/tst-stdio1.c | 56 -----------------------------------------------
 4 files changed, 11 insertions(+), 91 deletions(-)
 delete mode 100644 nptl/tst-stdio1.c

Patch
diff mbox series

diff --git a/libio/genops.c b/libio/genops.c
index f871e7751b..9afe81bd00 100644
--- a/libio/genops.c
+++ b/libio/genops.c
@@ -682,7 +682,7 @@  _IO_adjust_column (unsigned start, const char *line, int count)
 libc_hidden_def (_IO_adjust_column)
 
 int
-_IO_flush_all_lockp (int do_lock)
+_IO_flush_all (void)
 {
   int result = 0;
   FILE *fp;
@@ -695,8 +695,7 @@  _IO_flush_all_lockp (int do_lock)
   for (fp = (FILE *) _IO_list_all; fp != NULL; fp = fp->_chain)
     {
       run_fp = fp;
-      if (do_lock)
-	_IO_flockfile (fp);
+      _IO_flockfile (fp);
 
       if (((fp->_mode <= 0 && fp->_IO_write_ptr > fp->_IO_write_base)
 	   || (_IO_vtable_offset (fp) == 0
@@ -706,8 +705,7 @@  _IO_flush_all_lockp (int do_lock)
 	  && _IO_OVERFLOW (fp, EOF) == EOF)
 	result = EOF;
 
-      if (do_lock)
-	_IO_funlockfile (fp);
+      _IO_funlockfile (fp);
       run_fp = NULL;
     }
 
@@ -718,14 +716,6 @@  _IO_flush_all_lockp (int do_lock)
 
   return result;
 }
-
-
-int
-_IO_flush_all (void)
-{
-  /* We want locking.  */
-  return _IO_flush_all_lockp (1);
-}
 libc_hidden_def (_IO_flush_all)
 
 void
@@ -791,6 +781,9 @@  _IO_unbuffer_all (void)
     {
       int legacy = 0;
 
+      run_fp = fp;
+      _IO_flockfile (fp);
+
 #if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_1)
       if (__glibc_unlikely (_IO_vtable_offset (fp) != 0))
 	legacy = 1;
@@ -800,18 +793,6 @@  _IO_unbuffer_all (void)
 	  /* Iff stream is un-orientated, it wasn't used. */
 	  && (legacy || fp->_mode != 0))
 	{
-#ifdef _IO_MTSAFE_IO
-	  int cnt;
-#define MAXTRIES 2
-	  for (cnt = 0; cnt < MAXTRIES; ++cnt)
-	    if (fp->_lock == NULL || _IO_lock_trylock (*fp->_lock) == 0)
-	      break;
-	    else
-	      /* Give the other thread time to finish up its use of the
-		 stream.  */
-	      __sched_yield ();
-#endif
-
 	  if (! legacy && ! dealloc_buffers && !(fp->_flags & _IO_USER_BUF))
 	    {
 	      fp->_flags |= _IO_USER_BUF;
@@ -825,17 +806,15 @@  _IO_unbuffer_all (void)
 
 	  if (! legacy && fp->_mode > 0)
 	    _IO_wsetb (fp, NULL, NULL, 0);
-
-#ifdef _IO_MTSAFE_IO
-	  if (cnt < MAXTRIES && fp->_lock != NULL)
-	    _IO_lock_unlock (*fp->_lock);
-#endif
 	}
 
       /* Make sure that never again the wide char functions can be
 	 used.  */
       if (! legacy)
 	fp->_mode = -1;
+
+      _IO_funlockfile (fp);
+      run_fp = NULL;
     }
 
 #ifdef _IO_MTSAFE_IO
@@ -861,9 +840,7 @@  libc_freeres_fn (buffer_free)
 int
 _IO_cleanup (void)
 {
-  /* We do *not* want locking.  Some threads might use streams but
-     that is their problem, we flush them underneath them.  */
-  int result = _IO_flush_all_lockp (0);
+  int result = _IO_flush_all ();
 
   /* We currently don't have a reliable mechanism for making sure that
      C++ static destructors are executed in the correct order.
diff --git a/libio/libioP.h b/libio/libioP.h
index 3787605cfb..2187b8edbe 100644
--- a/libio/libioP.h
+++ b/libio/libioP.h
@@ -487,7 +487,6 @@  extern int _IO_new_do_write (FILE *, const char *, size_t);
 extern int _IO_old_do_write (FILE *, const char *, size_t);
 extern int _IO_wdo_write (FILE *, const wchar_t *, size_t);
 libc_hidden_proto (_IO_wdo_write)
-extern int _IO_flush_all_lockp (int);
 extern int _IO_flush_all (void);
 libc_hidden_proto (_IO_flush_all)
 extern int _IO_cleanup (void);
diff --git a/nptl/Makefile b/nptl/Makefile
index fffd9462ff..74e0de0ce2 100644
--- a/nptl/Makefile
+++ b/nptl/Makefile
@@ -297,7 +297,7 @@  tests = tst-attr1 tst-attr2 tst-attr3 tst-default-attr \
 	tst-signal6 \
 	tst-exec1 tst-exec2 tst-exec3 tst-exec4 tst-exec5 \
 	tst-exit1 tst-exit2 tst-exit3 \
-	tst-stdio1 tst-stdio2 \
+	tst-stdio2 \
 	tst-stack1 tst-stack2 tst-stack3 tst-stack4 tst-pthread-getattr \
 	tst-pthread-attr-affinity tst-pthread-mutexattr \
 	tst-unload \
diff --git a/nptl/tst-stdio1.c b/nptl/tst-stdio1.c
deleted file mode 100644
index aec2f658d4..0000000000
--- a/nptl/tst-stdio1.c
+++ /dev/null
@@ -1,56 +0,0 @@ 
-/* Copyright (C) 2002-2019 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
-
-   The GNU C Library is free software; you can redistribute it and/or
-   modify it under the terms of the GNU Lesser General Public
-   License as published by the Free Software Foundation; either
-   version 2.1 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
-   Lesser General Public License for more details.
-
-   You should have received a copy of the GNU Lesser General Public
-   License along with the GNU C Library; if not, see
-   <https://www.gnu.org/licenses/>.  */
-
-#include <pthread.h>
-#include <signal.h>
-#include <stdio.h>
-#include <unistd.h>
-
-static int do_test (void);
-
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
-
-static void *tf (void *a)
-{
-  flockfile (stdout);
-  /* This call should never return.  */
-  return a;
-}
-
-
-int
-do_test (void)
-{
-  pthread_t th;
-
-  flockfile (stdout);
-
-  if (pthread_create (&th, NULL, tf, NULL) != 0)
-    {
-      write_message ("create failed\n");
-      _exit (1);
-    }
-
-  delayed_exit (1);
-  xpthread_join (th);
-
-  puts ("join returned");
-
-  return 1;
-}