glibc/posix/spawn_faction_addopen.c
Adhemerval Zanella db8cbc6a7a posix: Use posix_spawn for wordexp
This patch replaces the fork+exec by posix_spawn on wordexp, which
allows a better scability on Linux and simplifies the thread
cancellation handling.

The only change which can not be implemented with posix_spawn the
/dev/null check to certify it is indeed the expected device.  I am
not sure how effetive this check is since /dev/null tampering means
something very wrong with the system and this is the least of the
issues.  My view is the tests is really out of the place and the
hardening provided is minimum.

If the idea is still to provide such check, I think a possibilty
would be to open /dev/null, check it, add a dup2 file action, and
close the file descriptor.

Checked on powerpc64le-linux-gnu and x86_64-linux-gnu.

	* include/spawn.h (__posix_spawn_file_actions_addopen): New
	prototype.
	* posix/spawn_faction_addopen.c (posix_spawn_file_actions_addopen):
	Add internal alias.
	* posix/wordexp.c (create_environment, free_environment): New
	functions.
	(exec_comm_child, exec_comm): Use posix_spawn instead of fork+exec.
	* posix/wordexp-test.c: Use libsupport.
2019-10-09 17:48:41 -03:00

65 lines
2.0 KiB
C

/* Copyright (C) 2000-2019 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 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 <errno.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include "spawn_int.h"
/* Add an action to FILE-ACTIONS which tells the implementation to call
`open' for the given file during the `spawn' call. */
int
__posix_spawn_file_actions_addopen (posix_spawn_file_actions_t *file_actions,
int fd, const char *path, int oflag,
mode_t mode)
{
struct __spawn_action *rec;
if (!__spawn_valid_fd (fd))
return EBADF;
char *path_copy = __strdup (path);
if (path_copy == NULL)
return ENOMEM;
/* Allocate more memory if needed. */
if (file_actions->__used == file_actions->__allocated
&& __posix_spawn_file_actions_realloc (file_actions) != 0)
{
/* This can only mean we ran out of memory. */
free (path_copy);
return ENOMEM;
}
/* Add the new value. */
rec = &file_actions->__actions[file_actions->__used];
rec->tag = spawn_do_open;
rec->action.open_action.fd = fd;
rec->action.open_action.path = path_copy;
rec->action.open_action.oflag = oflag;
rec->action.open_action.mode = mode;
/* Account for the new entry. */
++file_actions->__used;
return 0;
}
weak_alias (__posix_spawn_file_actions_addopen,
posix_spawn_file_actions_addopen)