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, (uint64_t) -1, false);
43 log_error_errno(r, "Internal pager failed: %m");
50 int pager_open(bool jump_to_end) {
51 _cleanup_close_pair_ int fd[2] = { -1, -1 };
61 pager = getenv("SYSTEMD_PAGER");
63 pager = getenv("PAGER");
65 /* If the pager is explicitly turned off, honour it */
66 if (pager && (pager[0] == 0 || streq(pager, "cat")))
69 /* Determine and cache number of columns before we spawn the
70 * pager so that we get the value from the actual tty */
74 return log_error_errno(errno, "Failed to create pager pipe: %m");
76 parent_pid = getpid();
80 return log_error_errno(errno, "Failed to fork pager: %m");
82 /* In the child start the pager */
84 const char* less_opts, *less_charset;
86 (void) reset_all_signal_handlers();
87 (void) reset_signal_mask();
89 (void) dup2(fd[0], STDIN_FILENO);
92 /* Initialize a good set of less options */
93 less_opts = getenv("SYSTEMD_LESS");
97 less_opts = strjoina(less_opts, " +G");
98 setenv("LESS", less_opts, 1);
100 /* Initialize a good charset for less. This is
101 * particularly important if we output UTF-8
103 less_charset = getenv("SYSTEMD_LESSCHARSET");
104 if (!less_charset && is_locale_utf8())
105 less_charset = "utf-8";
107 setenv("LESSCHARSET", less_charset, 1);
109 /* Make sure the pager goes away when the parent dies */
110 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
113 /* Check whether our parent died before we were able
114 * to set the death signal */
115 if (getppid() != parent_pid)
119 execlp(pager, pager, NULL);
120 execl("/bin/sh", "sh", "-c", pager, NULL);
123 /* Debian's alternatives command for pagers is
124 * called 'pager'. Note that we do not call
125 * sensible-pagers here, since that is just a
126 * shell script that implements a logic that
127 * is similar to this one anyway, but is
128 * Debian-specific. */
129 execlp("pager", "pager", NULL);
131 execlp("less", "less", NULL);
132 execlp("more", "more", NULL);
138 /* Return in the parent */
139 if (dup2(fd[1], STDOUT_FILENO) < 0)
140 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
141 if (dup2(fd[1], STDERR_FILENO) < 0)
142 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
147 void pager_close(void) {
152 /* Inform pager that we are done */
153 #if defined(__GLIBC__)
154 stdout = safe_fclose(stdout);
155 stderr = safe_fclose(stderr);
157 (void) safe_fclose(stdout);
158 (void) safe_fclose(stderr);
159 #endif // in musl-libc these are const
161 (void) kill(pager_pid, SIGCONT);
162 (void) wait_for_terminate(pager_pid, NULL);
166 bool pager_have(void) {
167 return pager_pid > 0;
170 /// UNNEEDED by elogind
172 int show_man_page(const char *desc, bool null_stdio) {
173 const char *args[4] = { "man", NULL, NULL, NULL };
182 if (desc[k-1] == ')')
183 e = strrchr(desc, '(');
186 char *page = NULL, *section = NULL;
188 page = strndupa(desc, e - desc);
189 section = strndupa(e + 1, desc + k - e - 2);
198 return log_error_errno(errno, "Failed to fork: %m");
203 (void) reset_all_signal_handlers();
204 (void) reset_signal_mask();
207 r = make_null_stdio();
209 log_error_errno(r, "Failed to kill stdio: %m");
214 execvp(args[0], (char**) args);
215 log_error_errno(errno, "Failed to execute man: %m");
219 r = wait_for_terminate(pid, &status);
223 log_debug("Exit code %i status %i", status.si_code, status.si_status);
224 return status.si_status;