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 static int stored_stdout = -1;
57 static int stored_stderr = -1;
58 static bool stdout_redirected = false;
59 static bool stderr_redirected = false;
61 int pager_open(bool no_pager, bool jump_to_end) {
62 _cleanup_close_pair_ int fd[2] = { -1, -1 };
72 if (terminal_is_dumb())
75 pager = getenv("SYSTEMD_PAGER");
77 pager = getenv("PAGER");
79 /* If the pager is explicitly turned off, honour it */
80 if (pager && STR_IN_SET(pager, "", "cat"))
83 /* Determine and cache number of columns before we spawn the
84 * pager so that we get the value from the actual tty */
88 return log_error_errno(errno, "Failed to create pager pipe: %m");
90 parent_pid = getpid();
94 return log_error_errno(errno, "Failed to fork pager: %m");
96 /* In the child start the pager */
98 const char* less_opts, *less_charset;
100 (void) reset_all_signal_handlers();
101 (void) reset_signal_mask();
103 (void) dup2(fd[0], STDIN_FILENO);
106 /* Initialize a good set of less options */
107 less_opts = getenv("SYSTEMD_LESS");
109 less_opts = "FRSXMK";
111 less_opts = strjoina(less_opts, " +G");
112 if (setenv("LESS", less_opts, 1) < 0)
115 /* Initialize a good charset for less. This is
116 * particularly important if we output UTF-8
118 less_charset = getenv("SYSTEMD_LESSCHARSET");
119 if (!less_charset && is_locale_utf8())
120 less_charset = "utf-8";
122 setenv("LESSCHARSET", less_charset, 1) < 0)
125 /* Make sure the pager goes away when the parent dies */
126 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
129 /* Check whether our parent died before we were able
130 * to set the death signal */
131 if (getppid() != parent_pid)
135 execlp(pager, pager, NULL);
136 execl("/bin/sh", "sh", "-c", pager, NULL);
139 /* Debian's alternatives command for pagers is
140 * called 'pager'. Note that we do not call
141 * sensible-pagers here, since that is just a
142 * shell script that implements a logic that
143 * is similar to this one anyway, but is
144 * Debian-specific. */
145 execlp("pager", "pager", NULL);
147 execlp("less", "less", NULL);
148 execlp("more", "more", NULL);
154 /* Return in the parent */
155 stored_stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 3);
156 if (dup2(fd[1], STDOUT_FILENO) < 0) {
157 stored_stdout = safe_close(stored_stdout);
158 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
160 stdout_redirected = true;
162 stored_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
163 if (dup2(fd[1], STDERR_FILENO) < 0) {
164 stored_stderr = safe_close(stored_stderr);
165 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
167 stderr_redirected = true;
172 void pager_close(void) {
177 /* Inform pager that we are done */
178 (void) fflush(stdout);
179 if (stdout_redirected)
180 if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0)
181 (void) close(STDOUT_FILENO);
182 stored_stdout = safe_close(stored_stdout);
183 (void) fflush(stderr);
184 if (stderr_redirected)
185 if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0)
186 (void) close(STDERR_FILENO);
187 stored_stderr = safe_close(stored_stderr);
188 stdout_redirected = stderr_redirected = false;
190 (void) kill(pager_pid, SIGCONT);
191 (void) wait_for_terminate(pager_pid, NULL);
195 bool pager_have(void) {
196 return pager_pid > 0;
199 #if 0 /// UNNEEDED by elogind
200 int show_man_page(const char *desc, bool null_stdio) {
201 const char *args[4] = { "man", NULL, NULL, NULL };
210 if (desc[k-1] == ')')
211 e = strrchr(desc, '(');
214 char *page = NULL, *section = NULL;
216 page = strndupa(desc, e - desc);
217 section = strndupa(e + 1, desc + k - e - 2);
226 return log_error_errno(errno, "Failed to fork: %m");
231 (void) reset_all_signal_handlers();
232 (void) reset_signal_mask();
235 r = make_null_stdio();
237 log_error_errno(r, "Failed to kill stdio: %m");
242 execvp(args[0], (char**) args);
243 log_error_errno(errno, "Failed to execute man: %m");
247 r = wait_for_terminate(pid, &status);
251 log_debug("Exit code %i status %i", status.si_code, status.si_status);
252 return status.si_status;