Make file descriptors close-on-exec when possible.

This simplifies Emacs a bit, since it no longer needs to worry
about closing file descriptors by hand in some cases.
It also fixes some unlikely races.  Not all such races, as
libraries often open files internally without setting
close-on-exec, but it's an improvement.
* admin/merge-gnulib (GNULIB_MODULES): Add fcntl, pipe2.
(GNULIB_TOOL_FLAGS): Avoid binary-io, close.  Do not avoid fcntl.
* configure.ac (mkostemp): New function to check for.
(PTY_OPEN): Pass O_CLOEXEC to posix_openpt.
* lib/fcntl.c, lib/getdtablesize.c, lib/pipe2.c, m4/fcntl.m4:
* m4/getdtablesize.m4, m4/pipe2.m4: New files, taken from gnulib.
* lib/gnulib.mk, m4/gnulib-comp.m4: Regenerate.
* nt/gnulib.mk: Remove empty gl_GNULIB_ENABLED_verify section;
otherwise, gnulib-tool complains given close-on-exec changes.
* nt/inc/ms-w32.h (pipe): Remove.
* nt/mingw-cfg.site (ac_cv_func_fcntl, gl_cv_func_fcntl_f_dupfd_cloexec)
(gl_cv_func_fcntl_f_dupfd_works, ac_cv_func_pipe2): New vars.
* src/alloc.c (valid_pointer_p) [!WINDOWSNT]:
* src/callproc.c (Fcall_process) [!MSDOS]:
* src/emacs.c (main) [!DOS_NT]:
* src/nsterm.m (ns_term_init):
* src/process.c (create_process):
Use 'pipe2' with O_CLOEXEC instead of 'pipe'.
* src/emacs.c (Fcall_process_region) [HAVE_MKOSTEMP]:
* src/filelock.c (create_lock_file) [HAVE_MKOSTEMP]:
Prefer mkostemp with O_CLOEXEC to mkstemp.
* src/callproc.c (relocate_fd) [!WINDOWSNT]:
* src/emacs.c (main): Use F_DUPFD_CLOEXEC, not plain F_DUPFD.
No need to use fcntl (..., F_SETFD, FD_CLOEXEC), since we're
now using pipe2.
* src/filelock.c (create_lock_file) [! HAVE_MKOSTEMP]:
Make the resulting file descriptor close-on-exec.
* src/lisp.h, src/lread.c, src/process.c (close_load_descs, close_process_descs):
* src/lread.c (load_descriptor_list, load_descriptor_unwind):
Remove; no longer needed.  All uses removed.
* src/process.c (SOCK_CLOEXEC): Define to 0 if not supplied by system.
(close_on_exec, accept4, process_socket) [!SOCK_CLOEXEC]:
New functions.
(socket) [!SOCK_CLOEXEC]: Supply a substitute.
(Fmake_network_process, Fnetwork_interface_list):
(Fnetwork_interface_info, server_accept_connection):
Make newly-created socket close-on-exec.
* src/sysdep.c (emacs_open, emacs_fopen):
Make new-created descriptor close-on-exec.
* src/w32.c (fcntl): Support F_DUPFD_CLOEXEC well enough for Emacs.
* src/w32.c, src/w32.h (pipe2): Rename from 'pipe', with new flags arg.

Fixes: debbugs:14803

4 files changed, 14 insertions, 4 deletions

diff --git a/nt/ChangeLog b/nt/ChangeLog
index 1a0746b3181..a9b4f836644 100644
--- a/nt/ChangeLog
+++ b/nt/ChangeLog
@@ -1,3 +1,12 @@
+2013-07-07  Paul Eggert  <eggert@cs.ucla.edu>
+
+        Make file descriptors close-on-exec when possible (Bug#14803).
+        * gnulib.mk: Remove empty gl_GNULIB_ENABLED_verify section;
+        otherwise, gnulib-tool complains given close-on-exec changes.
+        * inc/ms-w32.h (pipe): Remove.
+        * mingw-cfg.site (ac_cv_func_fcntl, gl_cv_func_fcntl_f_dupfd_cloexec)
+        (gl_cv_func_fcntl_f_dupfd_works, ac_cv_func_pipe2): New vars.
+
 2013-06-25  Juanma Barranquero  <lekktu@gmail.com>
 
         * configure.bat: Add warning to the help text about using the
diff --git a/nt/gnulib.mk b/nt/gnulib.mk
index ac4fc2768d9..df27dcf610c 100644
--- a/nt/gnulib.mk
+++ b/nt/gnulib.mk
@@ -876,9 +876,6 @@ EXTRA_DIST += utimens.h
 
 ## begin gnulib module verify
 
-if gl_GNULIB_ENABLED_verify
-
-endif
 EXTRA_DIST += verify.h
 
 ## end   gnulib module verify
diff --git a/nt/inc/ms-w32.h b/nt/inc/ms-w32.h
index 29c8e383893..3e50c78f145 100644
--- a/nt/inc/ms-w32.h
+++ b/nt/inc/ms-w32.h
@@ -211,7 +211,6 @@ extern struct tm * sys_localtime (const time_t *);
 #define mktemp  sys_mktemp
 #undef open
 #define open    sys_open
-#define pipe    sys_pipe
 #undef read
 #define read    sys_read
 #define rename  sys_rename
diff --git a/nt/mingw-cfg.site b/nt/mingw-cfg.site
index 41e4f23784e..cf55fe04ed8 100644
--- a/nt/mingw-cfg.site
+++ b/nt/mingw-cfg.site
@@ -67,6 +67,10 @@ gl_cv_func_readlink_works=yes
 gl_cv_func_symlink_works=yes
 ac_cv_func_readlinkat=yes
 ac_cv_func_faccessat=yes
+# Implemented in w32.c
+ac_cv_func_fcntl=yes
+gl_cv_func_fcntl_f_dupfd_cloexec=yes
+gl_cv_func_fcntl_f_dupfd_works=yes
 # We don't need fdopendir
 ac_cv_func_fdopendir="not-needed"
 gl_cv_func_fdopendir_works="no-but-not-needed-so-yes"
@@ -95,6 +99,7 @@ ac_cv_func_getloadavg=yes
 # Avoid compiling gnulib mktime
 gl_cv_func_working_mktime=yes
 # Implemented in w32.c
+ac_cv_func_pipe2=yes
 ac_cv_have_decl_unsetenv=yes
 ac_cv_func_unsetenv=yes
 gt_cv_func_unsetenv_ret='int'