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[Bug-gnulib] addition: execute.h, execute.c, w32spawn.h
From: |
Bruno Haible |
Subject: |
[Bug-gnulib] addition: execute.h, execute.c, w32spawn.h |
Date: |
Mon, 20 Oct 2003 13:18:49 +0200 |
User-agent: |
KMail/1.5 |
Hi,
After wait-process, here is the proposed module for executing subprocesses
in a synchronous way. It's a single function, which - unlike system() -
doesn't require an intermediate /bin/sh. A minimal amount of redirection
is possible: Either of stdin, stdout, stderr of the child process can
be redirected to /dev/null.
The file w32-spawn.h is required for msvc and mingw builds on Windows.
Subprocesses with which the parent communicates via pipes will be covered
by a different, but very similar, module.
Comments?
Bruno
================================== execute.h ==================================
/* Creation of autonomous subprocesses.
Copyright (C) 2001-2003 Free Software Foundation, Inc.
Written by Bruno Haible <address@hidden>, 2001.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#ifndef _EXECUTE_H
#define _EXECUTE_H
#include <stdbool.h>
/* Execute a command, optionally redirecting any of the three standard file
descriptors to /dev/null. Return its exit code.
If it didn't terminate correctly, exit if exit_on_error is true, otherwise
return 127.
If slave_process is true, the child process will be terminated when its
creator receives a catchable fatal signal.
It is recommended that no signal is blocked or ignored while execute()
is called. See pipe.h for the reason. */
extern int execute (const char *progname,
const char *prog_path, char **prog_argv,
bool null_stdin, bool null_stdout, bool null_stderr,
bool slave_process, bool exit_on_error);
#endif /* _EXECUTE_H */
================================== execute.c ==================================
/* Creation of autonomous subprocesses.
Copyright (C) 2001-2003 Free Software Foundation, Inc.
Written by Bruno Haible <address@hidden>, 2001.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
/* Specification. */
#include "execute.h"
#include <errno.h>
#include <fcntl.h>
#include <stdbool.h>
#include <stdlib.h>
#include <signal.h>
#ifdef HAVE_UNISTD_H
# include <unistd.h>
#endif
#include "error.h"
#include "exit.h"
#include "fatal-signal.h"
#include "wait-process.h"
#include "gettext.h"
#define _(str) gettext (str)
#if defined _MSC_VER || defined __MINGW32__
/* Native Woe32 API. */
# include <process.h>
# include "w32spawn.h"
#else
/* Unix API. */
# ifdef HAVE_POSIX_SPAWN
# include <spawn.h>
# else
# ifdef HAVE_VFORK_H
# include <vfork.h>
# endif
# endif
#endif
#ifndef STDIN_FILENO
# define STDIN_FILENO 0
#endif
#ifndef STDOUT_FILENO
# define STDOUT_FILENO 1
#endif
#ifndef STDERR_FILENO
# define STDERR_FILENO 2
#endif
#ifdef EINTR
/* EINTR handling for close(), open().
These functions can return -1/EINTR even though we don't have any
signal handlers set up, namely when we get interrupted via SIGSTOP. */
static inline int
nonintr_close (int fd)
{
int retval;
do
retval = close (fd);
while (retval < 0 && errno == EINTR);
return retval;
}
#define close nonintr_close
static inline int
nonintr_open (const char *pathname, int oflag, mode_t mode)
{
int retval;
do
retval = open (pathname, oflag, mode);
while (retval < 0 && errno == EINTR);
return retval;
}
#undef open /* avoid warning on VMS */
#define open nonintr_open
#endif
/* Execute a command, optionally redirecting any of the three standard file
descriptors to /dev/null. Return its exit code.
If it didn't terminate correctly, exit if exit_on_error is true, otherwise
return 127.
If slave_process is true, the child process will be terminated when its
creator receives a catchable fatal signal. */
int
execute (const char *progname,
const char *prog_path, char **prog_argv,
bool null_stdin, bool null_stdout, bool null_stderr,
bool slave_process, bool exit_on_error)
{
#if defined _MSC_VER || defined __MINGW32__
/* Native Woe32 API. */
int orig_stdin;
int orig_stdout;
int orig_stderr;
int exitcode;
int nullinfd;
int nulloutfd;
prog_argv = prepare_spawn (prog_argv);
/* Save standard file handles of parent process. */
if (null_stdin)
orig_stdin = dup_noinherit (STDIN_FILENO);
if (null_stdout)
orig_stdout = dup_noinherit (STDOUT_FILENO);
if (null_stderr)
orig_stderr = dup_noinherit (STDERR_FILENO);
exitcode = -1;
/* Create standard file handles of child process. */
nullinfd = -1;
nulloutfd = -1;
if ((!null_stdin
|| ((nullinfd = open ("NUL", O_RDONLY, 0)) >= 0
&& (nullinfd == STDIN_FILENO
|| (dup2 (nullinfd, STDIN_FILENO) >= 0
&& close (nullinfd) >= 0))))
&& (!(null_stdout || null_stderr)
|| ((nulloutfd = open ("NUL", O_RDWR, 0)) >= 0
&& (!null_stdout
|| nulloutfd == STDOUT_FILENO
|| dup2 (nulloutfd, STDOUT_FILENO) >= 0)
&& (!null_stderr
|| nulloutfd == STDERR_FILENO
|| dup2 (nulloutfd, STDERR_FILENO) >= 0)
&& ((null_stdout && nulloutfd == STDOUT_FILENO)
|| (null_stderr && nulloutfd == STDERR_FILENO)
|| close (nulloutfd) >= 0))))
exitcode = spawnvp (P_WAIT, prog_path, prog_argv);
if (nulloutfd >= 0)
close (nulloutfd);
if (nullinfd >= 0)
close (nullinfd);
/* Restore standard file handles of parent process. */
if (null_stderr)
dup2 (orig_stderr, STDERR_FILENO), close (orig_stderr);
if (null_stdout)
dup2 (orig_stdout, STDOUT_FILENO), close (orig_stdout);
if (null_stdin)
dup2 (orig_stdin, STDIN_FILENO), close (orig_stdin);
if (exitcode == -1)
{
if (exit_on_error || !null_stderr)
error (exit_on_error ? EXIT_FAILURE : 0, errno,
_("%s subprocess failed"), progname);
return 127;
}
return exitcode;
#else
/* Unix API. */
/* Note about 127: Some errors during posix_spawnp() cause the function
posix_spawnp() to return an error code; some other errors cause the
subprocess to exit with return code 127. It is implementation
dependent which error is reported which way. We treat both cases as
equivalent. */
#if HAVE_POSIX_SPAWN
sigset_t blocked_signals;
posix_spawn_file_actions_t actions;
bool actions_allocated;
posix_spawnattr_t attrs;
bool attrs_allocated;
int err;
pid_t child;
#else
int child;
#endif
#if HAVE_POSIX_SPAWN
if (slave_process)
{
sigprocmask (SIG_SETMASK, NULL, &blocked_signals);
block_fatal_signals ();
}
actions_allocated = false;
attrs_allocated = false;
if ((err = posix_spawn_file_actions_init (&actions)) != 0
|| (actions_allocated = true,
(null_stdin
&& (err = posix_spawn_file_actions_addopen (&actions,
STDIN_FILENO,
"/dev/null", O_RDONLY,
0))
!= 0)
|| (null_stdout
&& (err = posix_spawn_file_actions_addopen (&actions,
STDOUT_FILENO,
"/dev/null", O_RDWR,
0))
!= 0)
|| (null_stderr
&& (err = posix_spawn_file_actions_addopen (&actions,
STDERR_FILENO,
"/dev/null", O_RDWR,
0))
!= 0)
|| (slave_process
&& ((err = posix_spawnattr_init (&attrs)) != 0
|| (attrs_allocated = true,
(err = posix_spawnattr_setsigmask (&attrs,
&blocked_signals))
!= 0
|| (err = posix_spawnattr_setflags (&attrs,
POSIX_SPAWN_SETSIGMASK))
!= 0)))
|| (err = posix_spawnp (&child, prog_path, &actions,
attrs_allocated ? &attrs : NULL, prog_argv,
environ))
!= 0))
{
if (actions_allocated)
posix_spawn_file_actions_destroy (&actions);
if (attrs_allocated)
posix_spawnattr_destroy (&attrs);
if (slave_process)
unblock_fatal_signals ();
if (exit_on_error || !null_stderr)
error (exit_on_error ? EXIT_FAILURE : 0, err,
_("%s subprocess failed"), progname);
return 127;
}
posix_spawn_file_actions_destroy (&actions);
if (attrs_allocated)
posix_spawnattr_destroy (&attrs);
#else
if (slave_process)
block_fatal_signals ();
/* Use vfork() instead of fork() for efficiency. */
if ((child = vfork ()) == 0)
{
/* Child process code. */
int nullinfd;
int nulloutfd;
if ((!null_stdin
|| ((nullinfd = open ("/dev/null", O_RDONLY, 0)) >= 0
&& (nullinfd == STDIN_FILENO
|| (dup2 (nullinfd, STDIN_FILENO) >= 0
&& close (nullinfd) >= 0))))
&& (!(null_stdout || null_stderr)
|| ((nulloutfd = open ("/dev/null", O_RDWR, 0)) >= 0
&& (!null_stdout
|| nulloutfd == STDOUT_FILENO
|| dup2 (nulloutfd, STDOUT_FILENO) >= 0)
&& (!null_stderr
|| nulloutfd == STDERR_FILENO
|| dup2 (nulloutfd, STDERR_FILENO) >= 0)
&& ((null_stdout && nulloutfd == STDOUT_FILENO)
|| (null_stderr && nulloutfd == STDERR_FILENO)
|| close (nulloutfd) >= 0)))
&& (!slave_process || (unblock_fatal_signals (), true)))
execvp (prog_path, prog_argv);
_exit (127);
}
if (child == -1)
{
if (slave_process)
unblock_fatal_signals ();
if (exit_on_error || !null_stderr)
error (exit_on_error ? EXIT_FAILURE : 0, errno,
_("%s subprocess failed"), progname);
return 127;
}
#endif
if (slave_process)
{
register_slave_subprocess (child);
unblock_fatal_signals ();
}
return wait_subprocess (child, progname, null_stderr,
slave_process, exit_on_error);
#endif
}
================================== w32spawn.h =================================
/* Auxiliary functions for the creation of subprocesses. Native Woe32 API.
Copyright (C) 2003 Free Software Foundation, Inc.
Written by Bruno Haible <address@hidden>, 2003.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software Foundation,
Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
/* Get declarations of the Win32 API functions. */
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
/* Get _get_osfhandle() and _open_osfhandle(). */
#include <io.h>
#include <stdbool.h>
#include <errno.h>
#include "strpbrk.h"
#include "xalloc.h"
/* Duplicates a file handle, making the copy uninheritable. */
static int
dup_noinherit (int fd)
{
HANDLE curr_process = GetCurrentProcess ();
HANDLE old_handle = (HANDLE) _get_osfhandle (fd);
HANDLE new_handle;
int nfd;
if (!DuplicateHandle (curr_process, /* SourceProcessHandle */
old_handle, /* SourceHandle */
curr_process, /* TargetProcessHandle */
(PHANDLE) &new_handle, /* TargetHandle */
(DWORD) 0, /* DesiredAccess */
FALSE, /* InheritHandle */
DUPLICATE_SAME_ACCESS)) /* Options */
error (EXIT_FAILURE, 0, _("DuplicateHandle failed with error code 0x%08x"),
GetLastError ());
nfd = _open_osfhandle ((long) new_handle, O_BINARY);
if (nfd < 0)
error (EXIT_FAILURE, errno, _("_open_osfhandle failed"));
return nfd;
}
/* Prepares an argument vector before calling spawn().
Note that spawn() does not by itself call the command interpreter
(getenv ("COMSPEC") != NULL ? getenv ("COMSPEC") :
({ OSVERSIONINFO v; v.dwOSVersionInfoSize = sizeof(OSVERSIONINFO);
GetVersionEx(&v);
v.dwPlatformId == VER_PLATFORM_WIN32_NT;
}) ? "cmd.exe" : "command.com").
Instead it simply concatenates the arguments, separated by ' ', and calls
CreateProcess(). We must quote the arguments since Win32 CreateProcess()
interprets characters like ' ', '\t', '\\', '"' (but not '<' and '>') in a
special way:
- Space and tab are interpreted as delimiters. They are not treated as
delimiters if they are surrounded by double quotes: "...".
- Unescaped double quotes are removed from the input. Their only effect is
that within double quotes, space and tab are treated like normal
characters.
- Backslashes not followed by double quotes are not special.
- But 2*n+1 backslashes followed by a double quote become
n backslashes followed by a double quote (n >= 0):
\" -> "
\\\" -> \"
\\\\\" -> \\"
*/
#define SHELL_SPECIAL_CHARS "\"\\
\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"
#define SHELL_SPACE_CHARS "
\001\002\003\004\005\006\007\010\011\012\013\014\015\016\017\020\021\022\023\024\025\026\027\030\031\032\033\034\035\036\037"
static char **
prepare_spawn (char **argv)
{
size_t argc;
char **new_argv;
size_t i;
/* Count number of arguments. */
for (argc = 0; argv[argc] != NULL; argc++)
;
/* Allocate new argument vector. */
new_argv = (char **) xmalloc ((argc + 1) * sizeof (char *));
/* Put quoted arguments into the new argument vector. */
for (i = 0; i < argc; i++)
{
const char *string = argv[i];
if (string[0] == '\0')
new_argv[i] = xstrdup ("\"\"");
else if (strpbrk (string, SHELL_SPECIAL_CHARS) != NULL)
{
bool quote_around = (strpbrk (string, SHELL_SPACE_CHARS) != NULL);
size_t length;
unsigned int backslashes;
const char *s;
char *quoted_string;
char *p;
length = 0;
backslashes = 0;
if (quote_around)
length++;
for (s = string; *s != '\0'; s++)
{
char c = *s;
if (c == '"')
length += backslashes + 1;
length++;
if (c == '\\')
backslashes++;
else
backslashes = 0;
}
if (quote_around)
length += backslashes + 1;
quoted_string = (char *) xmalloc (length + 1);
p = quoted_string;
backslashes = 0;
if (quote_around)
*p++ = '"';
for (s = string; *s != '\0'; s++)
{
char c = *s;
if (c == '"')
{
unsigned int j;
for (j = backslashes + 1; j > 0; j--)
*p++ = '\\';
}
*p++ = c;
if (c == '\\')
backslashes++;
else
backslashes = 0;
}
if (quote_around)
{
unsigned int j;
for (j = backslashes; j > 0; j--)
*p++ = '\\';
*p++ = '"';
}
*p = '\0';
new_argv[i] = quoted_string;
}
else
new_argv[i] = (char *) string;
}
new_argv[argc] = NULL;
return new_argv;
}
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