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/* ============================================================================
* << File: call_script.c >>
* -------------------------
* Authors: Emiliano Castagnari (aka Torian) <ecastag@fi.uba.ar>
* Diego Essaya <dessaya@fi.uba.ar>
* Date: 14/01/04
*
* Description:
* Functions for calling script(1) as a child process and take its
* output using a pipe.
* ============================================================================
* ============================================================================
*
* ChangeLog: View Changelog
*
* ============================================================================
* Copyright (C) 2003, 2004 Diego Essaya, Emiliano Castagnari
*
* This file is part of gems.
*
* gems 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 of the License, or
* (at your option) any later version.
*
* gems 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 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.
* ============================================================================
*/
#include <unistd.h> /* fork(), pipe() */
#include <signal.h> /* kill() */
#include <sys/wait.h> /* wait() */
#include <string.h> /* strcat() */
#include <stdlib.h> /* exit() */
#include <errno.h> /* error values - variable errno */
#include "defaults.h"
#include "version_server.h"
#include "log.h"
#include "call_script.h"
#ifndef DEV_FD_DIR
#define DEV_FD_DIR "/dev/fd/"
#endif
/* PID of script. If zero, it means that script is not running. */
static pid_t script_pid = 0;
/* start_script()
*
* Runs script(1) as a child process and returns in *input_fd the file
* descriptor from which script's output data can be read.
*/
status_t start_script(char *script_bin, int *input_fd)
{
/* Steps:
* - Create a pipe
* - fork()
* * Child -> exec(script -fq /dev/fd/nn)
* where nn is pipefd[1].
* * Father -> read data from pipefd[0]
*
* FIXME: This function supposes the existence of the /dev/fd/ directory.
* Is this portable?...
*/
int pipefd[2];
char fname[20] = DEV_FD_DIR;
char num_str[5];
/* We'll pass 3 arguments to script, so we need a 4 element array of
* strings, the last one being NULL */
char *script_argv[] = {NULL, SCRIPT_OPTIONS, NULL, NULL};
script_argv[0] = script_bin;
g_log(LOG_RUNSCRIPT, script_bin);
/* Create the pipe: */
if (pipe(pipefd) == -1)
{
perror(APPNAME);
return EXIT_FAIL;
}
switch ((script_pid = fork()))
{
case -1:
perror(APPNAME);
return EXIT_FAIL;
case 0: /* CHILD - run script */
/* Close the side of the pipe that is not used: */
close(pipefd[0]);
/* Get the name of the /dev/fd/xx file associated with the pipe */
sprintf(num_str, "%d", pipefd[1]);
strcat(fname, num_str);
script_argv[2] = fname;
/* Execute script: */
execv(script_argv[0], script_argv);
perror(APPNAME);
exit(-1);
}
/* FATHER */
/* Close the side of the pipe that is not used: */
close(pipefd[1]);
*input_fd = pipefd[0];
return CONTINUE;
}
/* kill_script()
*
* If script is running, this function sends the SIGTERM signal to it, and
* wait()s.
*/
void kill_script()
{
if (script_pid > 0)
{
if (kill(script_pid, SIGTERM) == -1)
{
if (errno != ESRCH) perror(APPNAME);
}
else if (wait(NULL) == -1)
perror(APPNAME);
script_pid = 0;
g_log(LOG_ENDSCRIPT);
}
}
/* vim: set ts=4 sw=4: */
|
