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"
39 #include "terminal-util.h"
41 static pid_t pager_pid = 0;
43 noreturn static void pager_fallback(void) {
46 r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, false);
48 log_error_errno(r, "Internal pager failed: %m");
55 int pager_open(bool jump_to_end) {
56 _cleanup_close_pair_ int fd[2] = { -1, -1 };
66 pager = getenv("SYSTEMD_PAGER");
68 pager = getenv("PAGER");
70 /* If the pager is explicitly turned off, honour it */
71 if (pager && (pager[0] == 0 || streq(pager, "cat")))
74 /* Determine and cache number of columns before we spawn the
75 * pager so that we get the value from the actual tty */
79 return log_error_errno(errno, "Failed to create pager pipe: %m");
81 parent_pid = getpid();
85 return log_error_errno(errno, "Failed to fork pager: %m");
87 /* In the child start the pager */
89 const char* less_opts, *less_charset;
91 (void) reset_all_signal_handlers();
92 (void) reset_signal_mask();
94 (void) dup2(fd[0], STDIN_FILENO);
97 /* Initialize a good set of less options */
98 less_opts = getenv("SYSTEMD_LESS");
100 less_opts = "FRSXMK";
102 less_opts = strjoina(less_opts, " +G");
103 setenv("LESS", less_opts, 1);
105 /* Initialize a good charset for less. This is
106 * particularly important if we output UTF-8
108 less_charset = getenv("SYSTEMD_LESSCHARSET");
109 if (!less_charset && is_locale_utf8())
110 less_charset = "utf-8";
112 setenv("LESSCHARSET", less_charset, 1);
114 /* Make sure the pager goes away when the parent dies */
115 if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
118 /* Check whether our parent died before we were able
119 * to set the death signal */
120 if (getppid() != parent_pid)
124 execlp(pager, pager, NULL);
125 execl("/bin/sh", "sh", "-c", pager, NULL);
128 /* Debian's alternatives command for pagers is
129 * called 'pager'. Note that we do not call
130 * sensible-pagers here, since that is just a
131 * shell script that implements a logic that
132 * is similar to this one anyway, but is
133 * Debian-specific. */
134 execlp("pager", "pager", NULL);
136 execlp("less", "less", NULL);
137 execlp("more", "more", NULL);
143 /* Return in the parent */
144 if (dup2(fd[1], STDOUT_FILENO) < 0)
145 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
146 if (dup2(fd[1], STDERR_FILENO) < 0)
147 return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
152 void pager_close(void) {
157 /* Inform pager that we are done */
158 #if defined(__GLIBC__)
159 stdout = safe_fclose(stdout);
160 stderr = safe_fclose(stderr);
162 (void) safe_fclose(stdout);
163 (void) safe_fclose(stderr);
164 #endif // in musl-libc these are const
166 (void) kill(pager_pid, SIGCONT);
167 (void) wait_for_terminate(pager_pid, NULL);
171 bool pager_have(void) {
172 return pager_pid > 0;
175 #if 0 /// UNNEEDED by elogind
176 int show_man_page(const char *desc, bool null_stdio) {
177 const char *args[4] = { "man", NULL, NULL, NULL };
186 if (desc[k-1] == ')')
187 e = strrchr(desc, '(');
190 char *page = NULL, *section = NULL;
192 page = strndupa(desc, e - desc);
193 section = strndupa(e + 1, desc + k - e - 2);
202 return log_error_errno(errno, "Failed to fork: %m");
207 (void) reset_all_signal_handlers();
208 (void) reset_signal_mask();
211 r = make_null_stdio();
213 log_error_errno(r, "Failed to kill stdio: %m");
218 execvp(args[0], (char**) args);
219 log_error_errno(errno, "Failed to execute man: %m");
223 r = wait_for_terminate(pid, &status);
227 log_debug("Exit code %i status %i", status.si_code, status.si_status);
228 return status.si_status;