Update.

* posix/Makefile (tests): Add tst-fork.

ChangeLog

@@ -1,5 +1,7 @@
 2000-05-28  Ulrich Drepper  <drepper@redhat.com>
 
+	* posix/Makefile (tests): Add tst-fork.
+
 	* resolv/inet_pton.c: Loose __P.
 
 2000-05-21  Jakub Jelinek  <jakub@redhat.com>

linuxthreads/ChangeLog

@@ -1,3 +1,23 @@
+2000-05-28  Ulrich Drepper  <drepper@redhat.com>
+
+	* Makefile (tests): Add ex8.
+	* Examples/ex8.c: New file.
+
+2000-05-12  Kaz Kylheku  <kaz@ashi.footprints.net>
+
+	Bugfix: The pthread_atfork mechanism now takes care of its
+	own internal mutex at fork time.
+
+	* ptfork.c (__fork): Revised so that the mutex is held across
+	the fork operation and while the handlers are called, and so that
+	the child resets the mutex.
+	Added calls to new functions __flockallfiles and __funlockallfiles.
+
+	* linuxthreads.texi: Updated pthread_atfork documentation to make
+	it clear that fork and pthread_atfork can't be reentered from
+	atfork handlers, that pthread_atfork and fork are mutually atomic,
+	and that the handlers are inherited by the child process.
+
 2000-05-24  Ulrich Drepper  <drepper@redhat.com>
 
 	* Makefile (libpthread-routines): Add pspinlock.

linuxthreads/Examples/ex8.c

@@ -0,0 +1,101 @@
+/* Tests for fork in multi-threaded environment.
+   Copyright (C) 2000 Free Software Foundation, Inc.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 2000.
+
+   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 <errno.h>
+#include <error.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <unistd.h>
+#include <wait.h>
+
+enum
+{
+  PREPARE_BIT = 1,
+  PARENT_BIT = 2,
+  CHILD_BIT = 4
+};
+
+static int var;
+
+static void
+prepare (void)
+{
+  var |= PREPARE_BIT;
+}
+
+static void
+parent (void)
+{
+  var |= PARENT_BIT;
+}
+
+static void
+child (void)
+{
+  var |= CHILD_BIT;
+}
+
+
+static void *thread (void *arg);
+
+
+int
+main (void)
+{
+  pthread_t th;
+  void *res;
+
+  pthread_atfork (prepare, parent, child);
+
+  if (pthread_create (&th, NULL, thread, NULL) != 0)
+    error (EXIT_FAILURE, 0, "cannot create thread");
+
+  pthread_join (th, &res);
+
+  return (int) res;
+}
+
+
+static void *
+thread (void *arg)
+{
+  int status;
+  pid_t pid;
+
+  pid = fork ();
+  if (pid == 0)
+    {
+      /* We check whether the `prepare' and `child' function ran.  */
+      exit (var != (PREPARE_BIT | CHILD_BIT));
+    }
+  else if (pid == (pid_t) -1)
+    error (EXIT_FAILURE, errno, "cannot fork");
+
+  if (waitpid (pid, &status, 0) != pid)
+    error (EXIT_FAILURE, errno, "wrong child");
+
+  if (WTERMSIG (status) != 0)
+    error (EXIT_FAILURE, 0, "Child terminated incorrectly");
+  status = WEXITSTATUS (status);
+
+  if (status == 0)
+    status = var != (PREPARE_BIT | PARENT_BIT);
+
+  return (void *) status;
+}

linuxthreads/Makefile

@@ -38,7 +38,7 @@ libpthread-routines := attr cancel condvar join manager mutex ptfork \
 		       oldsemaphore events getcpuclockid pspinlock
 
 vpath %.c Examples
-tests = ex1 ex2 ex3 ex4 ex5 ex6 ex7
+tests = ex1 ex2 ex3 ex4 ex5 ex6 ex7 ex8
 
 include ../Rules
 
@@ -67,3 +67,4 @@ $(objpfx)ex4: $(libpthread)
 $(objpfx)ex5: $(libpthread)
 $(objpfx)ex6: $(libpthread)
 $(objpfx)ex7: $(libpthread)
+$(objpfx)ex8: $(libpthread)

linuxthreads/linuxthreads.texi

@@ -1314,6 +1314,20 @@ handlers are called in FIFO order (first added, first called).
 If there is insufficient memory available to register the handlers,
 @code{pthread_atfork} fails and returns @code{ENOMEM}.  Otherwise it
 returns 0.
+
+The functions @code{fork} and @code{pthread_atfork} must not be regarded as
+reentrant from the context of the handlers.  That is to say, if a
+@code{pthread_atfork} handler invoked from within @code{fork} calls
+@code{pthread_atfork} or @code{fork}, the behavior is undefined.
+
+Registering a triplet of handlers is an atomic operation with respect to fork.
+If new handlers are registered at about the same time as a fork occurs, either
+all three handlers will be called, or none of them will be called.
+
+The handlers are inherited by the child process, and there is no 
+way to remove them, short of using @code{exec} to load a new
+pocess image.
+
 @end deftypefun
 
 To understand the purpose of @code{pthread_atfork}, recall that

linuxthreads/ptfork.c

@@ -78,25 +78,29 @@ extern int __libc_fork(void);
 pid_t __fork(void)
 {
   pid_t pid;
-  struct handler_list * prepare, * child, * parent;
 
   pthread_mutex_lock(&pthread_atfork_lock);
-  prepare = pthread_atfork_prepare;
-  child = pthread_atfork_child;
-  parent = pthread_atfork_parent;
-  pthread_mutex_unlock(&pthread_atfork_lock);
-  pthread_call_handlers(prepare);
+
+  pthread_call_handlers(pthread_atfork_prepare);
   __pthread_once_fork_prepare();
+
   pid = __libc_fork();
+
   if (pid == 0) {
     __pthread_reset_main_thread();
+
     __fresetlockfiles();
-    pthread_call_handlers(child);
     __pthread_once_fork_child();
+    pthread_call_handlers(pthread_atfork_child);
+
+    pthread_mutex_init(&pthread_atfork_lock, NULL);
   } else {
-    pthread_call_handlers(parent);
     __pthread_once_fork_parent();
+    pthread_call_handlers(pthread_atfork_parent);
+
+    pthread_mutex_unlock(&pthread_atfork_lock);
   }
+
   return pid;
 }
 

posix/Makefile

@@ -66,7 +66,7 @@ aux		:= init-posix environ
 tests		:= tstgetopt testfnm runtests runptests	     \
 		   tst-preadwrite tst-preadwrite64 test-vfork regexbug1 \
 		   tst-getlogin tst-mmap tst-getaddrinfo tst-truncate \
-		   tst-truncate64
+		   tst-truncate64 tst-fork
 ifeq (yes,$(build-shared))
 test-srcs	:= globtest
 tests           += wordexp-test

posix/tst-fork.c

@@ -0,0 +1,136 @@
+/* Tests for fork.
+   Copyright (C) 2000 Free Software Foundation, Inc.
+   Contributed by Ulrich Drepper <drepper@cygnus.com>, 2000.
+
+   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 <errno.h>
+#include <error.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <wait.h>
+
+
+static const char testdata[] = "This is a test";
+static const char testdata2[] = "And here we go again";
+
+
+int
+main (void)
+{
+  const char *tmpdir = getenv ("TMPDIR");
+  char buf[100];
+  size_t tmpdirlen;
+  char *name;
+  int fd;
+  pid_t pid;
+  off_t off;
+  int status;
+
+  if (tmpdir == NULL || *tmpdir == '\0')
+    tmpdir = "/tmp";
+  tmpdirlen = strlen (tmpdir);
+
+  name = (char *) malloc (tmpdirlen + strlen ("/forkXXXXXX") + 1);
+  if (name == NULL)
+    error (EXIT_FAILURE, errno, "cannot allocate file name");
+
+  mempcpy (mempcpy (name, tmpdir, tmpdirlen),
+	   "/forkXXXXXX", sizeof ("/forkXXXXXX"));
+
+  /* Open our test file.   */
+  fd = mkstemp (name);
+  if (fd == -1)
+     error (EXIT_FAILURE, errno, "cannot open test file `%s'", name);
+
+  /* Make sure it gets removed.  */
+  unlink (name);
+
+  /* Write some data.  */
+  if (write (fd, testdata, strlen (testdata)) != strlen (testdata))
+    error (EXIT_FAILURE, errno, "cannot write test data");
+
+  /* Get the position in the stream.  */
+  off = lseek (fd, 0, SEEK_CUR);
+  if (off == (off_t) -1 || off != strlen (testdata))
+    error (EXIT_FAILURE, errno, "wrong file position");
+
+  /* Now fork of the process.  */
+  pid = fork ();
+  if (pid == 0)
+    {
+      /* This is the child.  First get the position of the descriptor.  */
+      off = lseek (fd, 0, SEEK_CUR);
+      if (off == (off_t) -1 || off != strlen (testdata))
+	error (EXIT_FAILURE, errno, "wrong file position in child");
+
+      /* Reset the position.  */
+      if (lseek (fd, 0, SEEK_SET) != 0)
+	error (EXIT_FAILURE, errno, "cannot reset position in child");
+
+      /* Read the data.  */
+      if (read (fd, buf, sizeof buf) != strlen (testdata))
+	error (EXIT_FAILURE, errno, "cannot read data in child");
+
+      /* Compare the data.  */
+      if (memcmp (buf, testdata, strlen (testdata)) != 0)
+	error (EXIT_FAILURE, 0, "data comparison failed in child");
+
+      /* Reset position again.  */
+      if (lseek (fd, 0, SEEK_SET) != 0)
+	error (EXIT_FAILURE, errno, "cannot reset position again in child");
+
+      /* Write new data.  */
+      if (write (fd, testdata2, strlen (testdata2)) != strlen (testdata2))
+	error (EXIT_FAILURE, errno, "cannot write new data in child");
+
+      /* Close the file.  This must not remove it.  */
+      close (fd);
+
+      _exit (0);
+    }
+  else if (pid < 0)
+    /* Something went wrong.  */
+    error (EXIT_FAILURE, errno, "cannot fork");
+
+  /* Wait for the child.  */
+  if (waitpid (pid, &status, 0) != pid)
+    error (EXIT_FAILURE, 0, "Oops, wrong test program terminated");
+
+  if (WTERMSIG (status) != 0)
+    error (EXIT_FAILURE, 0, "Child terminated incorrectly");
+  status = WEXITSTATUS (status);
+
+  if (status == 0)
+    {
+      /* Test whether the child wrote the right data.  First test the
+	 position.  It must be the same as in the child.  */
+      if (lseek (fd, 0, SEEK_CUR) != strlen (testdata2))
+	error (EXIT_FAILURE, 0, "file position not changed");
+
+      if (lseek (fd, 0, SEEK_SET) != 0)
+	error (EXIT_FAILURE, errno, "cannot reset file position");
+
+      if (read (fd, buf, sizeof buf) != strlen (testdata2))
+	error (EXIT_FAILURE, errno, "cannot read new data");
+
+      if (memcmp (buf, testdata2, strlen (testdata2)) != 0)
+	error (EXIT_FAILURE, 0, "new data not read correctly");
+    }
+
+  return status;
+}