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, false);
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 setenv("LESS", less_opts, 1);
109 /* Initialize a good charset for less. This is
110 * particularly important if we output UTF-8
112 less_charset = getenv("SYSTEMD_LESSCHARSET");
113 if (!less_charset && is_locale_utf8())
114 less_charset = "utf-8";
116 setenv("LESSCHARSET", less_charset, 1);
118 /* Make sure the pager goes away when the parent dies */
119 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
122 /* Check whether our parent died before we were able
123 * to set the death signal */
124 if (getppid() != parent_pid)
128 execlp(pager, pager, NULL);
129 execl("/bin/sh", "sh", "-c", pager, NULL);
132 /* Debian's alternatives command for pagers is
133 * called 'pager'. Note that we do not call
134 * sensible-pagers here, since that is just a
135 * shell script that implements a logic that
136 * is similar to this one anyway, but is
137 * Debian-specific. */
138 execlp("pager", "pager", NULL);
140 execlp("less", "less", NULL);
141 execlp("more", "more", NULL);
147 /* Return in the parent */
148 if (dup2(fd[1], STDOUT_FILENO) < 0)
149 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
150 if (dup2(fd[1], STDERR_FILENO) < 0)
151 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
156 void pager_close(void) {
161 /* Inform pager that we are done */
163 stdout = safe_fclose(stdout);
164 stderr = safe_fclose(stderr);
170 (void) kill(pager_pid, SIGCONT);
171 (void) wait_for_terminate(pager_pid, NULL);
175 bool pager_have(void) {
176 return pager_pid > 0;
179 #if 0 /// UNNEEDED by elogind
180 int show_man_page(const char *desc, bool null_stdio) {
181 const char *args[4] = { "man", NULL, NULL, NULL };
190 if (desc[k-1] == ')')
191 e = strrchr(desc, '(');
194 char *page = NULL, *section = NULL;
196 page = strndupa(desc, e - desc);
197 section = strndupa(e + 1, desc + k - e - 2);
206 return log_error_errno(errno, "Failed to fork: %m");
211 (void) reset_all_signal_handlers();
212 (void) reset_signal_mask();
215 r = make_null_stdio();
217 log_error_errno(r, "Failed to kill stdio: %m");
222 execvp(args[0], (char**) args);
223 log_error_errno(errno, "Failed to execute man: %m");
227 r = wait_for_terminate(pid, &status);
231 log_debug("Exit code %i status %i", status.si_code, status.si_status);
232 return status.si_status;