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/>.
26 #include <sys/prctl.h>
30 #include "process-util.h"
32 #include "terminal-util.h"
33 #include "signal-util.h"
36 static pid_t pager_pid = 0;
38 noreturn static void pager_fallback(void) {
41 r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (off_t) -1, false);
43 log_error_errno(r, "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 return log_error_errno(errno, "Failed to create pager pipe: %m");
73 parent_pid = getpid();
78 log_error_errno(errno, "Failed to fork pager: %m");
83 /* In the child start the pager */
85 const char* less_opts, *less_charset;
87 (void) reset_all_signal_handlers();
88 (void) reset_signal_mask();
90 dup2(fd[0], STDIN_FILENO);
93 /* Initialize a good set of less options */
94 less_opts = getenv("SYSTEMD_LESS");
98 less_opts = strjoina(less_opts, " +G");
99 setenv("LESS", less_opts, 1);
101 /* Initialize a good charset for less. This is
102 * particularly important if we output UTF-8
104 less_charset = getenv("SYSTEMD_LESSCHARSET");
105 if (!less_charset && is_locale_utf8())
106 less_charset = "utf-8";
108 setenv("LESSCHARSET", less_charset, 1);
110 /* Make sure the pager goes away when the parent dies */
111 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
114 /* Check whether our parent died before we were able
115 * to set the death signal */
116 if (getppid() != parent_pid)
120 execlp(pager, pager, NULL);
121 execl("/bin/sh", "sh", "-c", pager, NULL);
124 /* Debian's alternatives command for pagers is
125 * called 'pager'. Note that we do not call
126 * sensible-pagers here, since that is just a
127 * shell script that implements a logic that
128 * is similar to this one anyway, but is
129 * Debian-specific. */
130 execlp("pager", "pager", NULL);
132 execlp("less", "less", NULL);
133 execlp("more", "more", NULL);
139 /* Return in the parent */
140 if (dup2(fd[1], STDOUT_FILENO) < 0)
141 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
142 if (dup2(fd[1], STDERR_FILENO) < 0)
143 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
149 void pager_close(void) {
154 /* Inform pager that we are done */
156 #if defined(__GLIBC__)
158 #endif // in musl-libc this is a const
161 #if defined(__GLIBC__)
163 #endif // in musl-libc this is a const
165 kill(pager_pid, SIGCONT);
166 (void) wait_for_terminate(pager_pid, NULL);
170 bool pager_have(void) {
171 return pager_pid > 0;
174 /// UNNEEDED by elogind
176 int show_man_page(const char *desc, bool null_stdio) {
177 const char *args[4] = { "man", NULL, NULL, NULL };
186 if (desc[k-1] == ')')
187 e = strrchr(desc, '(');
190 char *page = NULL, *section = NULL;
192 page = strndupa(desc, e - desc);
193 section = strndupa(e + 1, desc + k - e - 2);
202 return log_error_errno(errno, "Failed to fork: %m");
207 (void) reset_all_signal_handlers();
208 (void) reset_signal_mask();
211 r = make_null_stdio();
213 log_error_errno(r, "Failed to kill stdio: %m");
218 execvp(args[0], (char**) args);
219 log_error_errno(errno, "Failed to execute man: %m");
223 r = wait_for_terminate(pid, &status);
227 log_debug("Exit code %i status %i", status.si_code, status.si_status);
228 return status.si_status;