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open: support O_CLOEXEC * NEWS, doc/posix-functions/open.texi: * doc/posix-functions/openat.texi: Document this. * lib/fcntl.in.h (O_CLOEXEC): Default to a nonzero value. (GNULIB_defined_O_CLOEXEC): New symbol. * lib/open.c: Include cloexec.h. (open): Support O_CLOEXEC. * lib/openat.c: Include cloexec.h. (rpl_openat): Support O_CLOEXEC. * lib/popen-safer.c: Do not include cloexec.h. (open_noinherit): Remove. (popen_safer): Use O_CLOEXEC instead of set_cloexec_flag. * lib/save-cwd.c: Do not include cloexec.h. (save_cwd): Use O_CLOEXEC instead of set_cloexec_flag. * m4/open-cloexec.m4: New file. * m4/open.m4 (gl_FUNC_OPEN): Require gl_PREPROC_O_CLOEXEC. Replace 'open' if O_CLOEXEC is not present. * m4/openat.m4 (gl_FUNC_OPENAT): Require gl_PREPROC_O_CLOEXEC. Replace 'openat' if O_CLOEXEC is not present. * modules/freopen (Depends-on): Depend on 'open' if replacing freopen. * modules/open (Files): Add m4/open-cloexec.m4. (Depends-on): Depend on cloexec if replacing 'open'. * modules/openat (Files): Add m4/open-cloexec.m4. (Depends-on): Depend on cloexec if replacing openat. * modules/popen-safer (Depends-on): Remove cloexec. * modules/save-cwd (Depends-on): Remove cloexec, and add fd-safer-flag and 'open'.
author Paul Eggert <eggert@cs.ucla.edu>
date Mon, 14 Aug 2017 13:04:46 -0700
parents 733fbf6b39bc
children af227a875ce7
files ChangeLog NEWS doc/posix-functions/open.texi doc/posix-functions/openat.texi lib/fcntl.in.h lib/open.c lib/openat.c lib/popen-safer.c lib/save-cwd.c m4/open-cloexec.m4 m4/open.m4 m4/openat.m4 modules/freopen modules/open modules/openat modules/popen-safer modules/save-cwd
diffstat 17 files changed, 151 insertions(+), 49 deletions(-) [+]
line wrap: on
line diff
--- a/ChangeLog	Sun Aug 13 11:03:40 2017 -0700
+++ b/ChangeLog	Mon Aug 14 13:04:46 2017 -0700
@@ -1,3 +1,34 @@
+2017-08-14  Paul Eggert  <eggert@cs.ucla.edu>
+
+
+	open: support O_CLOEXEC
+	* NEWS, doc/posix-functions/open.texi:
+	* doc/posix-functions/openat.texi: Document this.
+	* lib/fcntl.in.h (O_CLOEXEC): Default to a nonzero value.
+	(GNULIB_defined_O_CLOEXEC): New symbol.
+	* lib/open.c: Include cloexec.h.
+	(open): Support O_CLOEXEC.
+	* lib/openat.c: Include cloexec.h.
+	(rpl_openat): Support O_CLOEXEC.
+	* lib/popen-safer.c: Do not include cloexec.h.
+	(open_noinherit): Remove.
+	(popen_safer): Use O_CLOEXEC instead of set_cloexec_flag.
+	* lib/save-cwd.c: Do not include cloexec.h.
+	(save_cwd): Use O_CLOEXEC instead of set_cloexec_flag.
+	* m4/open-cloexec.m4: New file.
+	* m4/open.m4 (gl_FUNC_OPEN): Require gl_PREPROC_O_CLOEXEC.
+	Replace 'open' if O_CLOEXEC is not present.
+	* m4/openat.m4 (gl_FUNC_OPENAT): Require gl_PREPROC_O_CLOEXEC.
+	Replace 'openat' if O_CLOEXEC is not present.
+	* modules/freopen (Depends-on): Depend on 'open' if replacing freopen.
+	* modules/open (Files): Add m4/open-cloexec.m4.
+	(Depends-on): Depend on cloexec if replacing 'open'.
+	* modules/openat (Files): Add m4/open-cloexec.m4.
+	(Depends-on): Depend on cloexec if replacing openat.
+	* modules/popen-safer (Depends-on): Remove cloexec.
+	* modules/save-cwd (Depends-on): Remove cloexec, and add
+	fd-safer-flag and 'open'.
+
 2017-08-13  Paul Eggert  <eggert@cs.ucla.edu>
 
 	reallocarray: minor fixes
--- a/NEWS	Sun Aug 13 11:03:40 2017 -0700
+++ b/NEWS	Mon Aug 14 13:04:46 2017 -0700
@@ -42,6 +42,10 @@
 
 Date        Modules         Changes
 
+2017-08-14  fcntl-h         This module now defaults O_CLOEXEC to a nonzero
+                            value instead of to 0, as the 'open' and
+                            'openat' modules now emulate O_CLOEXEC.
+
 2017-07-23  strftime        This module is renamed to 'nstrftime'.
 
 2017-05-19  closeout        close_stdout longer closes stderr when addresses
--- a/doc/posix-functions/open.texi	Sun Aug 13 11:03:40 2017 -0700
+++ b/doc/posix-functions/open.texi	Mon Aug 14 13:04:46 2017 -0700
@@ -9,6 +9,9 @@
 Portability problems fixed by the Gnulib module open:
 @itemize
 @item
+Some platforms do not support @code{O_CLOEXEC}:
+Solaris 10, probably many others.
+@item
 On platforms where @code{off_t} is a 32-bit type, @code{open} may not work
 correctly with files larger than 2 GB.  (Cf. @code{AC_SYS_LARGEFILE}.)
 @item
@@ -35,6 +38,9 @@
 Portability problems not fixed by Gnulib:
 @itemize
 @item
+The Gnulib replacement for @code{O_CLOEXEC} is not atomic, and so is
+not safe in the presence of multiple threads or signal handlers.
+@item
 @code{open ("symlink", O_NOFOLLOW ...)} fails with @code{errno} set to
 @code{EMLINK} instead of the POSIX-required @code{ELOOP} on some
 platforms:
--- a/doc/posix-functions/openat.texi	Sun Aug 13 11:03:40 2017 -0700
+++ b/doc/posix-functions/openat.texi	Mon Aug 14 13:04:46 2017 -0700
@@ -14,6 +14,9 @@
 AIX 5.1, HP-UX 11, IRIX 6.5, OSF/1 5.1, Cygwin 1.5.x, mingw, MSVC 14, Interix 3.5, BeOS.
 But the replacement function is not safe to be used in libraries and is not multithread-safe.
 @item
+Some platforms do not support @code{O_CLOEXEC}:
+Solaris 10.
+@item
 On platforms where @code{off_t} is a 32-bit type, @code{open} may not work
 correctly with files larger than 2 GB.  (Cf. @code{AC_SYS_LARGEFILE}.)
 @item
@@ -26,6 +29,9 @@
 Portability problems not fixed by Gnulib:
 @itemize
 @item
+The Gnulib replacement for @code{O_CLOEXEC} is not atomic, and so is
+not safe in the presence of multiple threads or signal handlers.
+@item
 @code{openat (fd, "symlink", O_NOFOLLOW ...)} fails with @code{errno}
 set to @code{EMLINK} instead of the POSIX-required @code{ELOOP} on
 some platforms:
--- a/lib/fcntl.in.h	Sun Aug 13 11:03:40 2017 -0700
+++ b/lib/fcntl.in.h	Mon Aug 14 13:04:46 2017 -0700
@@ -213,7 +213,10 @@
 #endif
 
 #ifndef O_CLOEXEC
-# define O_CLOEXEC 0
+# define O_CLOEXEC 0x40000000 /* Try to not collide with system O_* flags.  */
+# define GNULIB_defined_O_CLOEXEC 1
+#else
+# define GNULIB_defined_O_CLOEXEC 0
 #endif
 
 #ifndef O_DIRECT
--- a/lib/open.c	Sun Aug 13 11:03:40 2017 -0700
+++ b/lib/open.c	Mon Aug 14 13:04:46 2017 -0700
@@ -38,6 +38,8 @@
    this include because of the preliminary #include <fcntl.h> above.  */
 #include "fcntl.h"
 
+#include "cloexec.h"
+
 #include <errno.h>
 #include <stdarg.h>
 #include <string.h>
@@ -52,6 +54,13 @@
 int
 open (const char *filename, int flags, ...)
 {
+  /* 0 = unknown, 1 = yes, -1 = no.  */
+#if GNULIB_defined_O_CLOEXEC
+  int have_cloexec = -1;
+#else
+  static int have_cloexec;
+#endif
+
   mode_t mode;
   int fd;
 
@@ -115,7 +124,25 @@
     }
 #endif
 
-  fd = orig_open (filename, flags, mode);
+  fd = orig_open (filename,
+                  flags & ~(have_cloexec <= 0 ? O_CLOEXEC : 0), mode);
+
+  if (flags & O_CLOEXEC)
+    {
+      if (! have_cloexec)
+        {
+          if (0 <= fd)
+            have_cloexec = 1;
+          else if (errno == EINVAL)
+            {
+              fd = orig_open (filename, flags & ~O_CLOEXEC, mode);
+              have_cloexec = -1;
+            }
+        }
+      if (have_cloexec < 0 && 0 <= fd)
+        set_cloexec_flag (fd, true);
+    }
+
 
 #if REPLACE_FCHDIR
   /* Implementing fchdir and fdopendir requires the ability to open a
--- a/lib/openat.c	Sun Aug 13 11:03:40 2017 -0700
+++ b/lib/openat.c	Mon Aug 14 13:04:46 2017 -0700
@@ -41,6 +41,8 @@
 
 #include "openat.h"
 
+#include "cloexec.h"
+
 #include <stdarg.h>
 #include <stdbool.h>
 #include <stddef.h>
@@ -50,10 +52,18 @@
 
 #if HAVE_OPENAT
 
-/* Like openat, but work around Solaris 9 bugs with trailing slash.  */
+/* Like openat, but support O_CLOEXEC and work around Solaris 9 bugs
+   with trailing slash.  */
 int
 rpl_openat (int dfd, char const *filename, int flags, ...)
 {
+  /* 0 = unknown, 1 = yes, -1 = no.  */
+#if GNULIB_defined_O_CLOEXEC
+  int have_cloexec = -1;
+#else
+  static int have_cloexec;
+#endif
+
   mode_t mode;
   int fd;
 
@@ -103,7 +113,25 @@
     }
 # endif
 
-  fd = orig_openat (dfd, filename, flags, mode);
+  fd = orig_openat (dfd, filename,
+                    flags & ~(have_cloexec <= 0 ? O_CLOEXEC : 0), mode);
+
+  if (flags & O_CLOEXEC)
+    {
+      if (! have_cloexec)
+        {
+          if (0 <= fd)
+            have_cloexec = 1;
+          else if (errno == EINVAL)
+            {
+              fd = orig_openat (dfd, filename, flags & ~O_CLOEXEC, mode);
+              have_cloexec = -1;
+            }
+        }
+      if (have_cloexec < 0 && 0 <= fd)
+        set_cloexec_flag (fd, true);
+    }
+
 
 # if OPEN_TRAILING_SLASH_BUG
   /* If the filename ends in a slash and fd does not refer to a directory,
--- a/lib/popen-safer.c	Sun Aug 13 11:03:40 2017 -0700
+++ b/lib/popen-safer.c	Mon Aug 14 13:04:46 2017 -0700
@@ -25,39 +25,6 @@
 #include <fcntl.h>
 #include <unistd.h>
 
-#include "cloexec.h"
-
-/* Like open (name, flags | O_CLOEXEC), although not necessarily
-   atomic.  FLAGS must not include O_CREAT.  */
-
-static int
-open_noinherit (char const *name, int flags)
-{
-  int fd;
-#if O_CLOEXEC
-  /* 0 = unknown, 1 = yes, -1 = no.  */
-  static int have_cloexec;
-  if (have_cloexec >= 0)
-    {
-      fd = open (name, flags | O_CLOEXEC);
-      if (have_cloexec == 0 && (0 <= fd || errno == EINVAL))
-        have_cloexec = (0 <= fd ? 1 : -1);
-      if (have_cloexec == 1)
-        return fd;
-    }
-#endif
-
-  fd = open (name, flags);
-  if (0 <= fd && set_cloexec_flag (fd, true) != 0)
-    {
-      int saved_errno = errno;
-      close (fd);
-      fd = -1;
-      errno = saved_errno;
-    }
-  return fd;
-}
-
 /* Like popen, but do not return stdin, stdout, or stderr.  */
 
 FILE *
@@ -72,7 +39,7 @@
      call (even though this puts more pressure on open fds), so that
      the original fd created by popen is safe.  */
   FILE *fp;
-  int fd = open_noinherit ("/dev/null", O_RDONLY);
+  int fd = open ("/dev/null", O_RDONLY | O_CLOEXEC);
   if (0 <= fd && fd <= STDERR_FILENO)
     {
       /* Maximum recursion depth is 3.  */
--- a/lib/save-cwd.c	Sun Aug 13 11:03:40 2017 -0700
+++ b/lib/save-cwd.c	Mon Aug 14 13:04:46 2017 -0700
@@ -30,7 +30,6 @@
 
 #include "chdir-long.h"
 #include "unistd--.h"
-#include "cloexec.h"
 
 #if GNULIB_FCNTL_SAFER
 # include "fcntl--.h"
@@ -64,16 +63,15 @@
 {
   cwd->name = NULL;
 
-  cwd->desc = open (".", O_SEARCH);
+  cwd->desc = open (".", O_SEARCH | O_CLOEXEC);
   if (!GNULIB_FCNTL_SAFER)
-    cwd->desc = fd_safer (cwd->desc);
+    cwd->desc = fd_safer_flag (cwd->desc, O_CLOEXEC);
   if (cwd->desc < 0)
     {
       cwd->name = getcwd (NULL, 0);
       return cwd->name ? 0 : -1;
     }
 
-  set_cloexec_flag (cwd->desc, true);
   return 0;
 }
 
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/m4/open-cloexec.m4	Mon Aug 14 13:04:46 2017 -0700
@@ -0,0 +1,21 @@
+# Test whether O_CLOEXEC is defined.
+
+dnl Copyright 2017 Free Software Foundation, Inc.
+dnl This file is free software; the Free Software Foundation
+dnl gives unlimited permission to copy and/or distribute it,
+dnl with or without modifications, as long as this notice is preserved.
+
+AC_DEFUN([gl_PREPROC_O_CLOEXEC],
+[
+  AC_CACHE_CHECK([for O_CLOEXEC],
+    [gl_cv_macro_O_CLOEXEC],
+    [AC_COMPILE_IFELSE(
+       [AC_LANG_PROGRAM([[#include <fcntl.h>
+                          #ifndef O_CLOEXEC
+                            choke me;
+                          #endif
+                        ]],
+                        [[return O_CLOEXEC;]])],
+       [gl_cv_macro_O_CLOEXEC=yes],
+       [gl_cv_macro_O_CLOEXEC=no])])
+])
--- a/m4/open.m4	Sun Aug 13 11:03:40 2017 -0700
+++ b/m4/open.m4	Mon Aug 14 13:04:46 2017 -0700
@@ -1,4 +1,4 @@
-# open.m4 serial 14
+# open.m4 serial 15
 dnl Copyright (C) 2007-2017 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -7,6 +7,7 @@
 AC_DEFUN([gl_FUNC_OPEN],
 [
   AC_REQUIRE([AC_CANONICAL_HOST])
+  AC_REQUIRE([gl_PREPROC_O_CLOEXEC])
   case "$host_os" in
     mingw* | pw*)
       REPLACE_OPEN=1
@@ -15,6 +16,9 @@
       dnl open("foo/") should not create a file when the file name has a
       dnl trailing slash.  FreeBSD only has the problem on symlinks.
       AC_CHECK_FUNCS_ONCE([lstat])
+      if test "$gl_cv_macro_O_CLOEXEC" != yes; then
+        REPLACE_OPEN=1
+      fi
       AC_CACHE_CHECK([whether open recognizes a trailing slash],
         [gl_cv_func_open_slash],
         [# Assume that if we have lstat, we can also check symlinks.
--- a/m4/openat.m4	Sun Aug 13 11:03:40 2017 -0700
+++ b/m4/openat.m4	Mon Aug 14 13:04:46 2017 -0700
@@ -1,4 +1,4 @@
-# serial 45
+# serial 46
 # See if we need to use our replacement for Solaris' openat et al functions.
 
 dnl Copyright (C) 2004-2017 Free Software Foundation, Inc.
@@ -14,10 +14,12 @@
   AC_REQUIRE([gl_USE_SYSTEM_EXTENSIONS])
   AC_CHECK_FUNCS_ONCE([openat])
   AC_REQUIRE([gl_FUNC_LSTAT_FOLLOWS_SLASHED_SYMLINK])
-  case $ac_cv_func_openat+$gl_cv_func_lstat_dereferences_slashed_symlink in
-  yes+*yes)
+  AC_REQUIRE([gl_PREPROC_O_CLOEXEC])
+  case $ac_cv_func_openat+$gl_cv_func_lstat_dereferences_slashed_symlink+$gl_cv_macro_O_CLOEXEC in
+  yes+*yes+yes)
     ;;
   yes+*)
+    # Solaris 10 lacks O_CLOEXEC.
     # Solaris 9 has *at functions, but uniformly mishandles trailing
     # slash in all of them.
     REPLACE_OPENAT=1
--- a/modules/freopen	Sun Aug 13 11:03:40 2017 -0700
+++ b/modules/freopen	Mon Aug 14 13:04:46 2017 -0700
@@ -7,6 +7,7 @@
 
 Depends-on:
 fcntl-h        [test $REPLACE_FREOPEN = 1]
+open           [test $REPLACE_FREOPEN = 1]
 stdio
 largefile
 
--- a/modules/open	Sun Aug 13 11:03:40 2017 -0700
+++ b/modules/open	Mon Aug 14 13:04:46 2017 -0700
@@ -4,11 +4,13 @@
 Files:
 lib/open.c
 m4/open.m4
+m4/open-cloexec.m4
 m4/mode_t.m4
 
 Depends-on:
 fcntl-h
 largefile
+cloexec         [test $REPLACE_OPEN = 1]
 fstat           [test $REPLACE_OPEN = 1]
 stat            [test $REPLACE_OPEN = 1]
 
--- a/modules/openat	Sun Aug 13 11:03:40 2017 -0700
+++ b/modules/openat	Mon Aug 14 13:04:46 2017 -0700
@@ -4,6 +4,7 @@
 Files:
 lib/openat.c
 m4/openat.m4
+m4/open-cloexec.m4
 m4/lstat.m4
 m4/mode_t.m4
 
@@ -14,6 +15,7 @@
 openat-h        [test $HAVE_OPENAT = 0 || test $REPLACE_OPENAT = 1]
 stdbool         [test $HAVE_OPENAT = 0 || test $REPLACE_OPENAT = 1]
 sys_stat        [test $HAVE_OPENAT = 0 || test $REPLACE_OPENAT = 1]
+cloexec         [test $REPLACE_OPENAT = 1]
 fstat           [test $REPLACE_OPENAT = 1]
 at-internal     [test $HAVE_OPENAT = 0]
 dosname         [test $HAVE_OPENAT = 0]
--- a/modules/popen-safer	Sun Aug 13 11:03:40 2017 -0700
+++ b/modules/popen-safer	Mon Aug 14 13:04:46 2017 -0700
@@ -7,7 +7,6 @@
 lib/popen-safer.c
 
 Depends-on:
-cloexec
 open
 popen
 unistd-safer
--- a/modules/save-cwd	Sun Aug 13 11:03:40 2017 -0700
+++ b/modules/save-cwd	Mon Aug 14 13:04:46 2017 -0700
@@ -8,9 +8,10 @@
 
 Depends-on:
 chdir-long
-cloexec
+fchdir
+fd-safer-flag
 getcwd-lgpl
-fchdir
+open
 stdbool
 unistd-safer