2 This file is part of systemd.
4 Copyright 2010 Lennart Poettering
6 systemd is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as published by
8 the Free Software Foundation; either version 2.1 of the License, or
9 (at your option) any later version.
11 systemd is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 Lesser General Public License for more details.
16 You should have received a copy of the GNU Lesser General Public License
17 along with systemd; If not, see <http://www.gnu.org/licenses/>.
27 #include <sys/prctl.h>
32 #include "locale-util.h"
36 #include "process-util.h"
37 #include "signal-util.h"
38 #include "string-util.h"
40 #include "terminal-util.h"
42 static pid_t pager_pid = 0;
44 noreturn static void pager_fallback(void) {
47 r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, 0);
49 log_error_errno(r, "Internal pager failed: %m");
56 int pager_open(bool no_pager, bool jump_to_end) {
57 _cleanup_close_pair_ int fd[2] = { -1, -1 };
67 if (terminal_is_dumb())
70 pager = getenv("SYSTEMD_PAGER");
72 pager = getenv("PAGER");
74 /* If the pager is explicitly turned off, honour it */
75 if (pager && STR_IN_SET(pager, "", "cat"))
78 /* Determine and cache number of columns before we spawn the
79 * pager so that we get the value from the actual tty */
83 return log_error_errno(errno, "Failed to create pager pipe: %m");
85 parent_pid = getpid();
89 return log_error_errno(errno, "Failed to fork pager: %m");
91 /* In the child start the pager */
93 const char* less_opts, *less_charset;
95 (void) reset_all_signal_handlers();
96 (void) reset_signal_mask();
98 (void) dup2(fd[0], STDIN_FILENO);
101 /* Initialize a good set of less options */
102 less_opts = getenv("SYSTEMD_LESS");
104 less_opts = "FRSXMK";
106 less_opts = strjoina(less_opts, " +G");
107 if (setenv("LESS", less_opts, 1) < 0)
110 /* Initialize a good charset for less. This is
111 * particularly important if we output UTF-8
113 less_charset = getenv("SYSTEMD_LESSCHARSET");
114 if (!less_charset && is_locale_utf8())
115 less_charset = "utf-8";
117 setenv("LESSCHARSET", less_charset, 1) < 0)
120 /* Make sure the pager goes away when the parent dies */
121 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
124 /* Check whether our parent died before we were able
125 * to set the death signal */
126 if (getppid() != parent_pid)
130 execlp(pager, pager, NULL);
131 execl("/bin/sh", "sh", "-c", pager, NULL);
134 /* Debian's alternatives command for pagers is
135 * called 'pager'. Note that we do not call
136 * sensible-pagers here, since that is just a
137 * shell script that implements a logic that
138 * is similar to this one anyway, but is
139 * Debian-specific. */
140 execlp("pager", "pager", NULL);
142 execlp("less", "less", NULL);
143 execlp("more", "more", NULL);
149 /* Return in the parent */
150 if (dup2(fd[1], STDOUT_FILENO) < 0)
151 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
152 if (dup2(fd[1], STDERR_FILENO) < 0)
153 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
158 void pager_close(void) {
163 /* Inform pager that we are done */
165 (void) kill(pager_pid, SIGCONT);
166 (void) wait_for_terminate(pager_pid, NULL);
170 bool pager_have(void) {
171 return pager_pid > 0;
174 #if 0 /// UNNEEDED by elogind
175 int show_man_page(const char *desc, bool null_stdio) {
176 const char *args[4] = { "man", NULL, NULL, NULL };
185 if (desc[k-1] == ')')
186 e = strrchr(desc, '(');
189 char *page = NULL, *section = NULL;
191 page = strndupa(desc, e - desc);
192 section = strndupa(e + 1, desc + k - e - 2);
201 return log_error_errno(errno, "Failed to fork: %m");
206 (void) reset_all_signal_handlers();
207 (void) reset_signal_mask();
210 r = make_null_stdio();
212 log_error_errno(r, "Failed to kill stdio: %m");
217 execvp(args[0], (char**) args);
218 log_error_errno(errno, "Failed to execute man: %m");
222 r = wait_for_terminate(pid, &status);
226 log_debug("Exit code %i status %i", status.si_code, status.si_status);
227 return status.si_status;