160 lines
3.6 KiB
C
160 lines
3.6 KiB
C
/*
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dropin.c -- a set of drop-in replacements for libc functions
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Copyright (C) 2000-2003 Ivo Timmermans <ivo@o2w.nl>,
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2000-2003 Guus Sliepen <guus@sliepen.eu.org>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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$Id: dropin.c,v 1.1.2.14 2003/07/12 17:48:38 guus Exp $
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*/
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#include "config.h"
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <xalloc.h>
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#include <system.h>
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#include <errno.h>
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#ifndef HAVE_DAEMON
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/*
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Replacement for the daemon() function.
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The daemon() function is for programs wishing to detach themselves
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from the controlling terminal and run in the background as system
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daemons.
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Unless the argument nochdir is non-zero, daemon() changes the
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current working directory to the root (``/'').
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Unless the argument noclose is non-zero, daemon() will redirect
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standard input, standard output and standard error to /dev/null.
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*/
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int daemon(int nochdir, int noclose)
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{
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pid_t pid;
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int fd;
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pid = fork();
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/* Check if forking failed */
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if(pid < 0) {
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perror("fork");
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exit(-1);
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}
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/* If we are the parent, terminate */
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if(pid)
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exit(0);
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/* Detach by becoming the new process group leader */
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if(setsid() < 0) {
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perror("setsid");
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return -1;
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}
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/* Change working directory to the root (to avoid keeping mount
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points busy) */
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if(!nochdir) {
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chdir("/");
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}
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/* Redirect stdin/out/err to /dev/null */
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if(!noclose) {
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fd = open("/dev/null", O_RDWR);
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if(fd < 0) {
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perror("opening /dev/null");
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return -1;
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} else {
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dup2(fd, 0);
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dup2(fd, 1);
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dup2(fd, 2);
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}
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}
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return 0;
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}
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#endif
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#ifndef HAVE_GET_CURRENT_DIR_NAME
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/*
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Replacement for the GNU get_current_dir_name function:
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get_current_dir_name will malloc(3) an array big enough to hold the
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current directory name. If the environment variable PWD is set, and
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its value is correct, then that value will be returned.
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*/
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char *get_current_dir_name(void)
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{
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size_t size;
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char *buf;
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char *r;
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/* Start with 100 bytes. If this turns out to be insufficient to
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contain the working directory, double the size. */
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size = 100;
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buf = xmalloc(size);
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errno = 0; /* Success */
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r = getcwd(buf, size);
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/* getcwd returns NULL and sets errno to ERANGE if the bufferspace
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is insufficient to contain the entire working directory. */
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while(r == NULL && errno == ERANGE) {
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free(buf);
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size <<= 1; /* double the size */
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buf = xmalloc(size);
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r = getcwd(buf, size);
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}
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return buf;
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}
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#endif
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#ifndef HAVE_ASPRINTF
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int asprintf(char **buf, const char *fmt, ...)
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{
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int status;
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va_list ap;
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int len;
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len = 4096;
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*buf = xmalloc(len);
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va_start(ap, fmt);
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status = vsnprintf(*buf, len, fmt, ap);
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va_end(ap);
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if(status >= 0)
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*buf = xrealloc(*buf, status);
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if(status > len - 1) {
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len = status;
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va_start(ap, fmt);
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status = vsnprintf(*buf, len, fmt, ap);
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va_end(ap);
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}
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return status;
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}
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#endif
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