144 lines
4.0 KiB
C
144 lines
4.0 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
|
|
|
|
/***
|
|
This file is part of systemd.
|
|
|
|
Copyright 2010 Lennart Poettering
|
|
|
|
systemd is free software; you can redistribute it and/or modify it
|
|
under the terms of the GNU Lesser General Public License as published by
|
|
the Free Software Foundation; either version 2.1 of the License, or
|
|
(at your option) any later version.
|
|
|
|
systemd 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
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with systemd; If not, see <http://www.gnu.org/licenses/>.
|
|
***/
|
|
|
|
#include <sys/types.h>
|
|
#include <fcntl.h>
|
|
#include <stdlib.h>
|
|
#include <unistd.h>
|
|
#include <string.h>
|
|
#include <sys/prctl.h>
|
|
|
|
#include "pager.h"
|
|
#include "util.h"
|
|
#include "macro.h"
|
|
|
|
static pid_t pager_pid = 0;
|
|
|
|
_noreturn_ static void pager_fallback(void) {
|
|
ssize_t n;
|
|
do {
|
|
n = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL, 64*1024, 0);
|
|
} while (n > 0);
|
|
if (n < 0) {
|
|
log_error("Internal pager failed: %m");
|
|
_exit(EXIT_FAILURE);
|
|
}
|
|
_exit(EXIT_SUCCESS);
|
|
}
|
|
|
|
int pager_open(void) {
|
|
int fd[2];
|
|
const char *pager;
|
|
pid_t parent_pid;
|
|
int r;
|
|
|
|
if (pager_pid > 0)
|
|
return 1;
|
|
|
|
if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
|
|
if (!*pager || streq(pager, "cat"))
|
|
return 0;
|
|
|
|
if (!on_tty())
|
|
return 0;
|
|
|
|
/* Determine and cache number of columns before we spawn the
|
|
* pager so that we get the value from the actual tty */
|
|
columns();
|
|
|
|
if (pipe(fd) < 0) {
|
|
log_error("Failed to create pager pipe: %m");
|
|
return -errno;
|
|
}
|
|
|
|
parent_pid = getpid();
|
|
|
|
pager_pid = fork();
|
|
if (pager_pid < 0) {
|
|
r = -errno;
|
|
log_error("Failed to fork pager: %m");
|
|
close_pipe(fd);
|
|
return r;
|
|
}
|
|
|
|
/* In the child start the pager */
|
|
if (pager_pid == 0) {
|
|
|
|
dup2(fd[0], STDIN_FILENO);
|
|
close_pipe(fd);
|
|
|
|
setenv("LESS", "FRSX", 0);
|
|
|
|
/* Make sure the pager goes away when the parent dies */
|
|
if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
|
|
_exit(EXIT_FAILURE);
|
|
|
|
/* Check whether our parent died before we were able
|
|
* to set the death signal */
|
|
if (getppid() != parent_pid)
|
|
_exit(EXIT_SUCCESS);
|
|
|
|
if (pager) {
|
|
execlp(pager, pager, NULL);
|
|
execl("/bin/sh", "sh", "-c", pager, NULL);
|
|
}
|
|
|
|
/* Debian's alternatives command for pagers is
|
|
* called 'pager'. Note that we do not call
|
|
* sensible-pagers here, since that is just a
|
|
* shell script that implements a logic that
|
|
* is similar to this one anyway, but is
|
|
* Debian-specific. */
|
|
execlp("pager", "pager", NULL);
|
|
|
|
execlp("less", "less", NULL);
|
|
execlp("more", "more", NULL);
|
|
|
|
pager_fallback();
|
|
/* not reached */
|
|
}
|
|
|
|
/* Return in the parent */
|
|
if (dup2(fd[1], STDOUT_FILENO) < 0) {
|
|
log_error("Failed to duplicate pager pipe: %m");
|
|
return -errno;
|
|
}
|
|
|
|
close_pipe(fd);
|
|
return 1;
|
|
}
|
|
|
|
void pager_close(void) {
|
|
|
|
if (pager_pid <= 0)
|
|
return;
|
|
|
|
/* Inform pager that we are done */
|
|
fclose(stdout);
|
|
kill(pager_pid, SIGCONT);
|
|
wait_for_terminate(pager_pid, NULL);
|
|
pager_pid = 0;
|
|
}
|
|
|
|
bool pager_have(void) {
|
|
return pager_pid > 0;
|
|
}
|