5430f7f2bc
We finally got the OK from all contributors with non-trivial commits to relicense systemd from GPL2+ to LGPL2.1+. Some udev bits continue to be GPL2+ for now, but we are looking into relicensing them too, to allow free copy/paste of all code within systemd. The bits that used to be MIT continue to be MIT. The big benefit of the relicensing is that closed source code may now link against libsystemd-login.so and friends.
135 lines
3.8 KiB
C
135 lines
3.8 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <sys/types.h>
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#include <fcntl.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <string.h>
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#include <sys/prctl.h>
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#include "pager.h"
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#include "util.h"
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#include "macro.h"
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static pid_t pager_pid = 0;
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_noreturn_ static void pager_fallback(void) {
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ssize_t n;
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do {
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n = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL, 64*1024, 0);
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} while (n > 0);
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if (n < 0) {
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log_error("Internal pager failed: %m");
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_exit(EXIT_FAILURE);
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}
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_exit(EXIT_SUCCESS);
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}
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void pager_open(void) {
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int fd[2];
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const char *pager;
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pid_t parent_pid;
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if (pager_pid > 0)
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return;
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if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
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if (!*pager || streq(pager, "cat"))
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return;
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if (isatty(STDOUT_FILENO) <= 0)
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return;
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/* Determine and cache number of columns before we spawn the
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* pager so that we get the value from the actual tty */
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columns();
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if (pipe(fd) < 0) {
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log_error("Failed to create pager pipe: %m");
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return;
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}
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parent_pid = getpid();
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pager_pid = fork();
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if (pager_pid < 0) {
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log_error("Failed to fork pager: %m");
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close_pipe(fd);
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return;
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}
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/* In the child start the pager */
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if (pager_pid == 0) {
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dup2(fd[0], STDIN_FILENO);
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close_pipe(fd);
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setenv("LESS", "FRSX", 0);
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/* Make sure the pager goes away when the parent dies */
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if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
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_exit(EXIT_FAILURE);
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/* Check whether our parent died before we were able
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* to set the death signal */
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if (getppid() != parent_pid)
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_exit(EXIT_SUCCESS);
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if (pager) {
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execlp(pager, pager, NULL);
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execl("/bin/sh", "sh", "-c", pager, NULL);
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}
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/* Debian's alternatives command for pagers is
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* called 'pager'. Note that we do not call
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* sensible-pagers here, since that is just a
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* shell script that implements a logic that
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* is similar to this one anyway, but is
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* Debian-specific. */
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execlp("pager", "pager", NULL);
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execlp("less", "less", NULL);
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execlp("more", "more", NULL);
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pager_fallback();
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/* not reached */
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}
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/* Return in the parent */
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if (dup2(fd[1], STDOUT_FILENO) < 0)
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log_error("Failed to duplicate pager pipe: %m");
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close_pipe(fd);
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}
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void pager_close(void) {
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if (pager_pid <= 0)
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return;
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/* Inform pager that we are done */
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fclose(stdout);
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kill(pager_pid, SIGCONT);
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wait_for_terminate(pager_pid, NULL);
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pager_pid = 0;
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}
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