1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 #include <sys/types.h>
27 #include <sys/prctl.h>
33 static pid_t pager_pid = 0;
35 _noreturn_ static void pager_fallback(void) {
39 n = splice(STDIN_FILENO, NULL, STDOUT_FILENO, NULL, 64*1024, 0);
43 log_error("Internal pager failed: %m");
50 int pager_open(bool jump_to_end) {
59 if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
60 if (!*pager || streq(pager, "cat"))
66 /* Determine and cache number of columns before we spawn the
67 * pager so that we get the value from the actual tty */
71 log_error("Failed to create pager pipe: %m");
75 parent_pid = getpid();
80 log_error("Failed to fork pager: %m");
85 /* In the child start the pager */
88 dup2(fd[0], STDIN_FILENO);
92 setenv("LESS", "FRSXMK+G", 1);
94 setenv("LESS", "FRSXMK", 1);
96 /* Make sure the pager goes away when the parent dies */
97 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
100 /* Check whether our parent died before we were able
101 * to set the death signal */
102 if (getppid() != parent_pid)
106 execlp(pager, pager, NULL);
107 execl("/bin/sh", "sh", "-c", pager, NULL);
110 /* Debian's alternatives command for pagers is
111 * called 'pager'. Note that we do not call
112 * sensible-pagers here, since that is just a
113 * shell script that implements a logic that
114 * is similar to this one anyway, but is
115 * Debian-specific. */
116 execlp("pager", "pager", NULL);
118 execlp("less", "less", NULL);
119 execlp("more", "more", NULL);
125 /* Return in the parent */
126 if (dup2(fd[1], STDOUT_FILENO) < 0) {
127 log_error("Failed to duplicate pager pipe: %m");
135 void pager_close(void) {
140 /* Inform pager that we are done */
142 kill(pager_pid, SIGCONT);
143 wait_for_terminate(pager_pid, NULL);
147 bool pager_have(void) {
148 return pager_pid > 0;