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480 lines
12 KiB
C
480 lines
12 KiB
C
/*
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* atrun.c - run jobs queued by at; run with root privileges.
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* Copyright (C) 1993, 1994 Thomas Koenig
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. The name of the author(s) may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR(S) ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR(S) BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/* System Headers */
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#include <sys/fcntl.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <ctype.h>
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#include <dirent.h>
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#include <errno.h>
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#include <pwd.h>
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#include <grp.h>
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#include <signal.h>
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#include <stddef.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <unistd.h>
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#include <syslog.h>
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#ifdef __FreeBSD__
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#include <paths.h>
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#else
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#include <getopt.h>
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#endif
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/* Local headers */
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#include "gloadavg.h"
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#define MAIN
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#include "privs.h"
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/* Macros */
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#ifndef ATJOB_DIR
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#define ATJOB_DIR "/usr/spool/atjobs/"
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#endif
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#ifndef ATSPOOL_DIR
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#define ATSPOOL_DIR "/usr/spool/atspool/"
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#endif
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#ifndef LOADAVG_MX
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#define LOADAVG_MX 1.5
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#endif
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/* File scope variables */
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static char *namep;
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static char rcsid[] = "$Id: atrun.c,v 1.5 1995/08/21 12:34:17 ache Exp $";
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static debug = 0;
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void perr(const char *a);
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/* Local functions */
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static int
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write_string(int fd, const char* a)
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{
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return write(fd, a, strlen(a));
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}
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#undef DEBUG_FORK
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#ifdef DEBUG_FORK
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static pid_t
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myfork()
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{
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pid_t res;
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res = fork();
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if (res == 0)
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kill(getpid(),SIGSTOP);
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return res;
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}
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#define fork myfork
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#endif
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static void
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run_file(const char *filename, uid_t uid, gid_t gid)
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{
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/* Run a file by by spawning off a process which redirects I/O,
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* spawns a subshell, then waits for it to complete and sends
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* mail to the user.
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*/
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pid_t pid;
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int fd_out, fd_in;
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int queue;
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char mailbuf[9];
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char *mailname = NULL;
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FILE *stream;
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int send_mail = 0;
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struct stat buf, lbuf;
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off_t size;
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struct passwd *pentry;
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int fflags;
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long nuid;
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long ngid;
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PRIV_START
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if (chmod(filename, S_IRUSR) != 0)
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{
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perr("Cannot change file permissions");
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}
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PRIV_END
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pid = fork();
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if (pid == -1)
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perr("Cannot fork");
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else if (pid != 0)
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return;
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/* Let's see who we mail to. Hopefully, we can read it from
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* the command file; if not, send it to the owner, or, failing that,
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* to root.
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*/
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pentry = getpwuid(uid);
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if (pentry == NULL)
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{
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syslog(LOG_ERR,"Userid %lu not found - aborting job %s",
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(unsigned long) uid, filename);
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exit(EXIT_FAILURE);
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}
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PRIV_START
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stream=fopen(filename, "r");
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PRIV_END
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#ifdef __FreeBSD__
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if (pentry->pw_expire && time(NULL) >= pentry->pw_expire)
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{
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syslog(LOG_ERR, "Userid %lu is expired - aborting job %s",
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(unsigned long) uid, filename);
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exit(EXIT_FAILURE);
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}
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#endif
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if (stream == NULL)
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perr("Cannot open input file");
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if ((fd_in = dup(fileno(stream))) <0)
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perr("Error duplicating input file descriptor");
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if (fstat(fd_in, &buf) == -1)
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perr("Error in fstat of input file descriptor");
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if (lstat(filename, &lbuf) == -1)
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perr("Error in fstat of input file");
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if (S_ISLNK(lbuf.st_mode)) {
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syslog(LOG_ERR,"Symbolic link encountered in job %s - aborting",
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filename);
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exit(EXIT_FAILURE);
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}
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if ((lbuf.st_dev != buf.st_dev) || (lbuf.st_ino != buf.st_ino) ||
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(lbuf.st_uid != buf.st_uid) || (lbuf.st_gid != buf.st_gid) ||
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(lbuf.st_size!=buf.st_size)) {
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syslog(LOG_ERR,"Somebody changed files from under us for job %s - "
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"aborting",filename);
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exit(EXIT_FAILURE);
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}
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if (buf.st_nlink > 1) {
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syslog(LOG_ERR,"Someboy is trying to run a linked script for job %s",
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filename);
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exit(EXIT_FAILURE);
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}
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if ((fflags = fcntl(fd_in, F_GETFD)) <0)
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perr("Error in fcntl");
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fcntl(fd_in, F_SETFD, fflags & ~FD_CLOEXEC);
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if (fscanf(stream, "#!/bin/sh\n# atrun uid=%ld gid=%ld\n# mail %8s %d",
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&nuid, &ngid, mailbuf, &send_mail) != 4)
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{
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syslog(LOG_ERR,"File %s is in wrong format - aborting",
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filename);
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exit(EXIT_FAILURE);
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}
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if (mailbuf[0] == '-') {
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syslog(LOG_ERR,"illegal mail name %s in %s",mailbuf,filename);
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exit(EXIT_FAILURE);
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}
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mailname = mailbuf;
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if (nuid != uid) {
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syslog(LOG_ERR,"Job %s - userid %d does not match file uid %d",
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filename, nuid, uid);
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exit(EXIT_FAILURE);
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}
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if (ngid != gid) {
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syslog(LOG_ERR,"Job %s - groupid %d does not match file gid %d",
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filename, ngid, gid);
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exit(EXIT_FAILURE);
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}
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fclose(stream);
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if (chdir(ATSPOOL_DIR) < 0)
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perr("Cannot chdir to " ATSPOOL_DIR);
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/* Create a file to hold the output of the job we are about to run.
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* Write the mail header.
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*/
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if((fd_out=open(filename,
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O_WRONLY | O_CREAT | O_EXCL, S_IWUSR | S_IRUSR)) < 0)
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perr("Cannot create output file");
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write_string(fd_out, "Subject: Output from your job ");
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write_string(fd_out, filename);
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write_string(fd_out, "\n\n");
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fstat(fd_out, &buf);
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size = buf.st_size;
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close(STDIN_FILENO);
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close(STDOUT_FILENO);
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close(STDERR_FILENO);
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pid = fork();
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if (pid < 0)
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perr("Error in fork");
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else if (pid == 0)
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{
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char *nul = NULL;
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char **nenvp = &nul;
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/* Set up things for the child; we want standard input from the input file,
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* and standard output and error sent to our output file.
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*/
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if (lseek(fd_in, (off_t) 0, SEEK_SET) < 0)
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perr("Error in lseek");
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if (dup(fd_in) != STDIN_FILENO)
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perr("Error in I/O redirection");
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if (dup(fd_out) != STDOUT_FILENO)
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perr("Error in I/O redirection");
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if (dup(fd_out) != STDERR_FILENO)
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perr("Error in I/O redirection");
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close(fd_in);
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close(fd_out);
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if (chdir(ATJOB_DIR) < 0)
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perr("Cannot chdir to " ATJOB_DIR);
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queue = *filename;
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PRIV_START
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nice(tolower(queue) - 'a');
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if (chdir(pentry->pw_dir))
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chdir("/");
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if (initgroups(pentry->pw_name,pentry->pw_gid))
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perr("Cannot delete saved userids");
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if (setgid(gid) < 0)
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perr("Cannot change group");
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if (setuid(uid) < 0)
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perr("Cannot set user id");
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if(execle("/bin/sh","sh",(char *) NULL, nenvp) != 0)
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perr("Exec failed for /bin/sh");
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PRIV_END
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}
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/* We're the parent. Let's wait.
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*/
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close(fd_in);
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close(fd_out);
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waitpid(pid, (int *) NULL, 0);
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/* Send mail. Unlink the output file first, so it is deleted after
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* the run.
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*/
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stat(filename, &buf);
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if (open(filename, O_RDONLY) != STDIN_FILENO)
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perr("Open of jobfile failed");
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unlink(filename);
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if ((buf.st_size != size) || send_mail)
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{
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PRIV_START
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if (chdir(pentry->pw_dir))
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chdir("/");
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if (initgroups(pentry->pw_name,pentry->pw_gid))
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perr("Cannot delete saved userids");
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if (setgid(gid) < 0)
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perr("Cannot change group");
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if (setuid(uid) < 0)
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perr("Cannot set user id");
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#ifdef __FreeBSD__
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execl(_PATH_SENDMAIL, "sendmail", "-F", "Atrun Service",
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"-odi", "-oem",
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mailname, (char *) NULL);
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#else
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execl(MAIL_CMD, MAIL_CMD, mailname, (char *) NULL);
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#endif
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perr("Exec failed for mail command");
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PRIV_END
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}
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exit(EXIT_SUCCESS);
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}
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/* Global functions */
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/* Needed in gloadavg.c */
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void
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perr(const char *a)
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{
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if (debug)
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{
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perror(a);
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}
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else
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syslog(LOG_ERR, "%s: %m", a);
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exit(EXIT_FAILURE);
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}
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int
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main(int argc, char *argv[])
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{
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/* Browse through ATJOB_DIR, checking all the jobfiles wether they should
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* be executed and or deleted. The queue is coded into the first byte of
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* the job filename, the date (in minutes since Eon) as a hex number in the
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* following eight bytes, followed by a dot and a serial number. A file
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* which has not been executed yet is denoted by its execute - bit set.
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* For those files which are to be executed, run_file() is called, which forks
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* off a child which takes care of I/O redirection, forks off another child
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* for execution and yet another one, optionally, for sending mail.
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* Files which already have run are removed during the next invocation.
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*/
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DIR *spool;
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struct dirent *dirent;
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struct stat buf;
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unsigned long ctm;
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unsigned long jobno;
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char queue;
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time_t now, run_time;
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char batch_name[] = "Z2345678901234";
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uid_t batch_uid;
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gid_t batch_gid;
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int c;
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int run_batch;
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double load_avg = LOADAVG_MX;
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/* We don't need root privileges all the time; running under uid and gid daemon
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* is fine.
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*/
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RELINQUISH_PRIVS_ROOT(DAEMON_UID, DAEMON_GID)
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openlog("atrun", LOG_PID, LOG_CRON);
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opterr = 0;
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errno = 0;
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while((c=getopt(argc, argv, "dl:"))!= EOF)
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{
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switch (c)
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{
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case 'l':
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if (sscanf(optarg, "%lf", &load_avg) != 1)
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perr("garbled option -l");
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if (load_avg <= 0.)
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load_avg = LOADAVG_MX;
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break;
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case 'd':
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debug ++;
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break;
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case '?':
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perr("unknown option");
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break;
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default:
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perr("idiotic option - aborted");
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break;
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}
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}
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namep = argv[0];
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if (chdir(ATJOB_DIR) != 0)
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perr("Cannot change to " ATJOB_DIR);
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/* Main loop. Open spool directory for reading and look over all the
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* files in there. If the filename indicates that the job should be run
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* and the x bit is set, fork off a child which sets its user and group
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* id to that of the files and exec a /bin/sh which executes the shell
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* script. Unlink older files if they should no longer be run. For
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* deletion, their r bit has to be turned on.
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*
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* Also, pick the oldest batch job to run, at most one per invocation of
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* atrun.
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*/
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if ((spool = opendir(".")) == NULL)
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perr("Cannot read " ATJOB_DIR);
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now = time(NULL);
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run_batch = 0;
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batch_uid = (uid_t) -1;
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batch_gid = (gid_t) -1;
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while ((dirent = readdir(spool)) != NULL) {
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if (stat(dirent->d_name,&buf) != 0)
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perr("Cannot stat in " ATJOB_DIR);
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/* We don't want directories
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*/
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if (!S_ISREG(buf.st_mode))
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continue;
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if (sscanf(dirent->d_name,"%c%5lx%8lx",&queue,&jobno,&ctm) != 3)
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continue;
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run_time = (time_t) ctm*60;
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if ((S_IXUSR & buf.st_mode) && (run_time <=now)) {
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if (isupper(queue) && (strcmp(batch_name,dirent->d_name) > 0)) {
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run_batch = 1;
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strncpy(batch_name, dirent->d_name, sizeof(batch_name));
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batch_uid = buf.st_uid;
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batch_gid = buf.st_gid;
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}
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/* The file is executable and old enough
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*/
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if (islower(queue))
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run_file(dirent->d_name, buf.st_uid, buf.st_gid);
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}
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/* Delete older files
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*/
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if ((run_time < now) && !(S_IXUSR & buf.st_mode) && (S_IRUSR & buf.st_mode))
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unlink(dirent->d_name);
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}
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/* run the single batch file, if any
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*/
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if (run_batch && (gloadavg() < load_avg))
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run_file(batch_name, batch_uid, batch_gid);
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closelog();
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exit(EXIT_SUCCESS);
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}
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