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/>.
25 #include <sys/prctl.h>
30 #include "locale-util.h"
33 #include "process-util.h"
34 #include "signal-util.h"
35 #include "string-util.h"
36 #include "terminal-util.h"
39 static pid_t pager_pid = 0;
41 noreturn static void pager_fallback(void) {
44 r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, false);
46 log_error_errno(r, "Internal pager failed: %m");
53 int pager_open(bool jump_to_end) {
54 _cleanup_close_pair_ int fd[2] = { -1, -1 };
64 pager = getenv("SYSTEMD_PAGER");
66 pager = getenv("PAGER");
68 /* If the pager is explicitly turned off, honour it */
69 if (pager && (pager[0] == 0 || streq(pager, "cat")))
72 /* Determine and cache number of columns before we spawn the
73 * pager so that we get the value from the actual tty */
77 return log_error_errno(errno, "Failed to create pager pipe: %m");
79 parent_pid = getpid();
83 return log_error_errno(errno, "Failed to fork pager: %m");
85 /* In the child start the pager */
87 const char* less_opts, *less_charset;
89 (void) reset_all_signal_handlers();
90 (void) reset_signal_mask();
92 (void) dup2(fd[0], STDIN_FILENO);
95 /* Initialize a good set of less options */
96 less_opts = getenv("SYSTEMD_LESS");
100 less_opts = strjoina(less_opts, " +G");
101 setenv("LESS", less_opts, 1);
103 /* Initialize a good charset for less. This is
104 * particularly important if we output UTF-8
106 less_charset = getenv("SYSTEMD_LESSCHARSET");
107 if (!less_charset && is_locale_utf8())
108 less_charset = "utf-8";
110 setenv("LESSCHARSET", less_charset, 1);
112 /* Make sure the pager goes away when the parent dies */
113 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
116 /* Check whether our parent died before we were able
117 * to set the death signal */
118 if (getppid() != parent_pid)
122 execlp(pager, pager, NULL);
123 execl("/bin/sh", "sh", "-c", pager, NULL);
126 /* Debian's alternatives command for pagers is
127 * called 'pager'. Note that we do not call
128 * sensible-pagers here, since that is just a
129 * shell script that implements a logic that
130 * is similar to this one anyway, but is
131 * Debian-specific. */
132 execlp("pager", "pager", NULL);
134 execlp("less", "less", NULL);
135 execlp("more", "more", NULL);
141 /* Return in the parent */
142 if (dup2(fd[1], STDOUT_FILENO) < 0)
143 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
144 if (dup2(fd[1], STDERR_FILENO) < 0)
145 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
150 void pager_close(void) {
155 /* Inform pager that we are done */
156 #if defined(__GLIBC__)
157 stdout = safe_fclose(stdout);
158 stderr = safe_fclose(stderr);
160 (void) safe_fclose(stdout);
161 (void) safe_fclose(stderr);
162 #endif // in musl-libc these are const
164 (void) kill(pager_pid, SIGCONT);
165 (void) wait_for_terminate(pager_pid, NULL);
169 bool pager_have(void) {
170 return pager_pid > 0;
173 /// 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;