142 lines
3.6 KiB
C
142 lines
3.6 KiB
C
/*
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* Copyright (c) 2009, Erik van der Kouwe
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* All rights reserved.
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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 are met:
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*
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
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* EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Functionality implemented according to this specification:
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* http://www.opengroup.org/onlinepubs/000095399/utilities/nohup.html
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*/
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <signal.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#define NOHUP_OUT_FILENAME "nohup.out"
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static void print_usage(const char *argv0)
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{
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printf("Usage: %s command [arg...]\n", argv0);
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}
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static int redirect_tty(void)
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{
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int fd;
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char buffer[PATH_MAX + 1], *home;
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/* redirect stdout to a file if needed */
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if (isatty(STDOUT_FILENO))
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{
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/* first try: current directory */
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fd = open(NOHUP_OUT_FILENAME, O_WRONLY | O_APPEND | O_CREAT, S_IRUSR | S_IWUSR);
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if (fd < 0)
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{
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/* alternative: home directory */
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home = getenv("HOME");
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if (home)
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{
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snprintf(buffer, sizeof(buffer), "%s/%s", home, NOHUP_OUT_FILENAME);
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buffer[sizeof(buffer) - 1] = 0;
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fd = open(buffer, O_WRONLY | O_APPEND | O_CREAT, S_IRUSR | S_IWUSR);
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}
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}
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if (fd < 0)
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{
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perror("cannot create " NOHUP_OUT_FILENAME " and $HOME/" NOHUP_OUT_FILENAME);
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return -1;
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}
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/* move the fd to stdout */
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if (dup2(fd, STDOUT_FILENO) < 0 || close(fd) < 0)
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{
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perror("cannot redirect stdout");
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return -1;
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}
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}
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/* redirect stderr to stdout if needed */
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if (isatty(STDERR_FILENO))
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{
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if (dup2(STDOUT_FILENO, STDERR_FILENO) < 0)
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{
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perror("cannot redirect stderr");
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return -1;
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}
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}
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return 0;
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}
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int main(int argc, char **argv)
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{
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struct sigaction sa;
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/* check parameters */
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if (argc < 2)
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{
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print_usage(argv[0]);
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return 127;
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}
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/* ignore SIGHUP */
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sa.sa_handler = SIG_IGN;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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if (sigaction(SIGHUP, &sa, NULL) < 0)
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{
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perror("cannot ignore SIGHUP");
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return 127;
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}
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/* redirect TTY input and output */
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if (redirect_tty() < 0)
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return 127;
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/* run the command */
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execvp(argv[1], argv + 1);
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perror("cannot execute");
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/* exit code depends on whether the utility was found */
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switch (errno)
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{
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case ELOOP:
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case ENAMETOOLONG:
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case ENOENT:
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case ENOTDIR:
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/* utility not found */
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return 127;
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default:
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/* exec failed for other reason */
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return 126;
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}
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}
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