2020-11-09 05:23:58 +01:00
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/* SPDX-License-Identifier: LGPL-2.1-or-later */
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2011-07-07 02:34:35 +02:00
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2015-12-03 21:13:37 +01:00
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#include <errno.h>
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#include <stddef.h>
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#include <stdint.h>
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#include <stdio.h>
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2011-07-07 02:34:35 +02:00
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#include <stdlib.h>
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#include <sys/prctl.h>
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2015-10-24 22:58:24 +02:00
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#include <unistd.h>
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2011-07-07 02:34:35 +02:00
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2020-10-07 11:15:05 +02:00
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#include "sd-login.h"
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2015-10-24 22:58:24 +02:00
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#include "copy.h"
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2020-08-31 19:37:13 +02:00
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#include "env-util.h"
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2015-10-25 13:14:12 +01:00
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#include "fd-util.h"
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2018-11-11 19:04:00 +01:00
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#include "fileio.h"
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#include "io-util.h"
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2015-10-26 23:01:30 +01:00
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#include "locale-util.h"
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2015-12-03 21:13:37 +01:00
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#include "log.h"
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2011-07-07 02:34:35 +02:00
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#include "macro.h"
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2015-10-25 13:14:12 +01:00
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#include "pager.h"
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2015-10-24 22:58:24 +02:00
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#include "process-util.h"
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2018-11-26 16:06:26 +01:00
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#include "rlimit-util.h"
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2015-05-31 23:55:55 +02:00
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#include "signal-util.h"
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2015-10-24 22:58:24 +02:00
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#include "string-util.h"
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2016-10-11 17:46:59 +02:00
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#include "strv.h"
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2015-10-24 22:58:24 +02:00
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#include "terminal-util.h"
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2019-03-27 11:32:41 +01:00
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#include "util.h"
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2011-07-07 02:34:35 +02:00
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static pid_t pager_pid = 0;
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2017-12-29 18:14:37 +01:00
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static int stored_stdout = -1;
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static int stored_stderr = -1;
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static bool stdout_redirected = false;
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static bool stderr_redirected = false;
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2018-03-15 06:23:46 +01:00
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_noreturn_ static void pager_fallback(void) {
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2015-08-28 00:11:49 +02:00
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int r;
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2013-11-07 21:06:44 +01:00
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2017-02-13 19:00:22 +01:00
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r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, 0);
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2015-08-28 00:11:49 +02:00
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if (r < 0) {
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log_error_errno(r, "Internal pager failed: %m");
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2011-09-26 23:02:56 +02:00
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_exit(EXIT_FAILURE);
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}
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2013-11-07 21:06:44 +01:00
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2011-09-26 23:02:56 +02:00
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_exit(EXIT_SUCCESS);
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}
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2018-11-11 19:04:00 +01:00
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static int no_quit_on_interrupt(int exe_name_fd, const char *less_opts) {
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_cleanup_fclose_ FILE *file = NULL;
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_cleanup_free_ char *line = NULL;
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int r;
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assert(exe_name_fd >= 0);
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assert(less_opts);
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/* This takes ownership of exe_name_fd */
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file = fdopen(exe_name_fd, "r");
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if (!file) {
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safe_close(exe_name_fd);
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2018-11-29 14:27:01 +01:00
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return log_error_errno(errno, "Failed to create FILE object: %m");
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2018-11-11 19:04:00 +01:00
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}
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/* Find the last line */
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for (;;) {
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_cleanup_free_ char *t = NULL;
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r = read_line(file, LONG_LINE_MAX, &t);
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if (r < 0)
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2018-11-29 14:27:01 +01:00
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return log_error_errno(r, "Failed to read from socket: %m");
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2018-11-11 19:04:00 +01:00
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if (r == 0)
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break;
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free_and_replace(line, t);
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}
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/* We only treat "less" specially.
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* Return true whenever option K is *not* set. */
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r = streq_ptr(line, "less") && !strchr(less_opts, 'K');
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log_debug("Pager executable is \"%s\", options \"%s\", quit_on_interrupt: %s",
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strnull(line), less_opts, yes_no(!r));
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return r;
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}
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2018-11-11 12:56:29 +01:00
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int pager_open(PagerFlags flags) {
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2018-11-11 19:04:00 +01:00
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_cleanup_close_pair_ int fd[2] = { -1, -1 }, exe_name_pipe[2] = { -1, -1 };
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2018-06-28 11:21:39 +02:00
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_cleanup_strv_free_ char **pager_args = NULL;
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2018-11-11 19:04:00 +01:00
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const char *pager, *less_opts;
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2017-12-22 13:08:14 +01:00
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int r;
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2011-07-07 02:34:35 +02:00
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2018-11-11 12:56:29 +01:00
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if (flags & PAGER_DISABLE)
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2016-02-19 19:25:13 +01:00
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return 0;
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2011-07-07 02:34:35 +02:00
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if (pager_pid > 0)
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2012-10-18 23:34:37 +02:00
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return 1;
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2011-07-07 02:34:35 +02:00
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2016-05-30 18:23:54 +02:00
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if (terminal_is_dumb())
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2012-10-18 23:34:37 +02:00
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return 0;
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2011-07-25 04:58:02 +02:00
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2017-12-29 18:13:38 +01:00
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if (!is_main_thread())
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2018-11-29 14:27:01 +01:00
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return log_error_errno(SYNTHETIC_ERRNO(EPERM), "Pager invoked from wrong thread.");
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2017-12-29 18:13:38 +01:00
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2015-09-29 13:59:32 +02:00
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pager = getenv("SYSTEMD_PAGER");
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if (!pager)
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pager = getenv("PAGER");
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2018-06-28 11:21:39 +02:00
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if (pager) {
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pager_args = strv_split(pager, WHITESPACE);
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if (!pager_args)
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2018-11-29 14:27:01 +01:00
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return log_oom();
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2018-06-28 11:21:39 +02:00
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/* If the pager is explicitly turned off, honour it */
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if (strv_isempty(pager_args) || strv_equal(pager_args, STRV_MAKE("cat")))
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return 0;
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}
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2015-09-29 13:59:32 +02:00
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2017-11-10 21:10:17 +01:00
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/* Determine and cache number of columns/lines before we spawn the pager so that we get the value from the
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* actual tty */
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2015-09-29 13:59:32 +02:00
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(void) columns();
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2017-11-10 21:10:17 +01:00
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(void) lines();
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2011-07-07 02:34:35 +02:00
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2017-09-13 10:35:28 +02:00
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if (pipe2(fd, O_CLOEXEC) < 0)
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2014-11-28 19:57:32 +01:00
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return log_error_errno(errno, "Failed to create pager pipe: %m");
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2011-07-07 02:34:35 +02:00
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2018-11-11 19:04:00 +01:00
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/* This is a pipe to feed the name of the executed pager binary into the parent */
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if (pipe2(exe_name_pipe, O_CLOEXEC) < 0)
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return log_error_errno(errno, "Failed to create exe_name pipe: %m");
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/* Initialize a good set of less options */
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less_opts = getenv("SYSTEMD_LESS");
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if (!less_opts)
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less_opts = "FRSXMK";
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if (flags & PAGER_JUMP_TO_END)
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less_opts = strjoina(less_opts, " +G");
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2020-06-09 08:59:33 +02:00
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/* We set SIGINT as PR_DEATHSIG signal here, to match the "K" parameter we set in $LESS, which enables SIGINT behaviour. */
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r = safe_fork("(pager)", FORK_RESET_SIGNALS|FORK_DEATHSIG_SIGINT|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pager_pid);
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2017-12-22 13:08:14 +01:00
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if (r < 0)
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2017-12-27 21:49:19 +01:00
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return r;
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2017-12-22 13:08:14 +01:00
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if (r == 0) {
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2018-11-11 19:04:00 +01:00
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const char *less_charset, *exe;
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2011-07-07 02:34:35 +02:00
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2017-12-22 13:08:14 +01:00
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/* In the child start the pager */
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2015-05-31 23:55:55 +02:00
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2018-11-29 14:27:01 +01:00
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if (dup2(fd[0], STDIN_FILENO) < 0) {
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log_error_errno(errno, "Failed to duplicate file descriptor to STDIN: %m");
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_exit(EXIT_FAILURE);
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}
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2014-03-24 03:22:44 +01:00
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safe_close_pair(fd);
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2011-07-07 02:34:35 +02:00
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2018-11-29 14:27:01 +01:00
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if (setenv("LESS", less_opts, 1) < 0) {
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log_error_errno(errno, "Failed to set environment variable LESS: %m");
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2017-02-19 19:52:18 +01:00
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_exit(EXIT_FAILURE);
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2018-11-29 14:27:01 +01:00
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}
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2011-07-07 02:34:35 +02:00
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2020-08-31 19:37:13 +02:00
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/* Initialize a good charset for less. This is particularly important if we output UTF-8
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2015-08-28 18:17:14 +02:00
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* characters. */
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less_charset = getenv("SYSTEMD_LESSCHARSET");
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if (!less_charset && is_locale_utf8())
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less_charset = "utf-8";
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2017-02-19 19:52:18 +01:00
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if (less_charset &&
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2018-11-29 14:27:01 +01:00
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setenv("LESSCHARSET", less_charset, 1) < 0) {
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log_error_errno(errno, "Failed to set environment variable LESSCHARSET: %m");
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2017-02-19 19:52:18 +01:00
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_exit(EXIT_FAILURE);
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2018-11-29 14:27:01 +01:00
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}
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2015-08-28 18:17:14 +02:00
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2020-08-31 19:37:13 +02:00
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/* People might invoke us from sudo, don't needlessly allow less to be a way to shell out
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2020-10-07 11:15:05 +02:00
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* privileged stuff. If the user set $SYSTEMD_PAGERSECURE, trust their configuration of the
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* pager. If they didn't, use secure mode when under euid is changed. If $SYSTEMD_PAGERSECURE
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* wasn't explicitly set, and we autodetect the need for secure mode, only use the pager we
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* know to be good. */
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2020-10-15 10:54:48 +02:00
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int use_secure_mode = getenv_bool_secure("SYSTEMD_PAGERSECURE");
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2020-10-07 11:15:05 +02:00
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bool trust_pager = use_secure_mode >= 0;
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if (use_secure_mode == -ENXIO) {
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uid_t uid;
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r = sd_pid_get_owner_uid(0, &uid);
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2020-08-31 19:37:13 +02:00
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if (r < 0)
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2020-10-07 11:15:05 +02:00
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log_debug_errno(r, "sd_pid_get_owner_uid() failed, enabling pager secure mode: %m");
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2020-08-31 19:37:13 +02:00
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2020-10-07 11:15:05 +02:00
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use_secure_mode = r < 0 || uid != geteuid();
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} else if (use_secure_mode < 0) {
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log_warning_errno(use_secure_mode, "Unable to parse $SYSTEMD_PAGERSECURE, assuming true: %m");
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use_secure_mode = true;
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2020-08-31 19:37:13 +02:00
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}
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2020-10-07 11:15:05 +02:00
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/* We generally always set variables used by less, even if we end up using a different pager.
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* They shouldn't hurt in any case, and ideally other pagers would look at them too. */
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2020-11-10 12:25:55 +01:00
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r = set_unset_env("LESSSECURE", use_secure_mode ? "1" : NULL, true);
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2020-10-07 11:15:05 +02:00
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if (r < 0) {
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2020-11-10 12:25:55 +01:00
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log_error_errno(r, "Failed to adjust environment variable LESSSECURE: %m");
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2020-10-07 11:15:05 +02:00
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_exit(EXIT_FAILURE);
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}
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if (trust_pager && pager_args) { /* The pager config might be set globally, and we cannot
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* know if the user adjusted it to be appropriate for the
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* secure mode. Thus, start the pager specified through
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* envvars only when $SYSTEMD_PAGERSECURE was explicitly set
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* as well. */
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2018-11-29 14:27:01 +01:00
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r = loop_write(exe_name_pipe[1], pager_args[0], strlen(pager_args[0]) + 1, false);
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if (r < 0) {
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log_error_errno(r, "Failed to write pager name to socket: %m");
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2018-11-11 19:04:00 +01:00
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_exit(EXIT_FAILURE);
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2018-11-29 14:27:01 +01:00
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}
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2018-11-11 19:04:00 +01:00
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2018-06-28 11:21:39 +02:00
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execvp(pager_args[0], pager_args);
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2018-11-29 14:27:01 +01:00
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log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno,
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2019-01-23 17:00:09 +01:00
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"Failed to execute '%s', using fallback pagers: %m", pager_args[0]);
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2018-11-11 19:04:00 +01:00
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}
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2011-07-07 02:34:35 +02:00
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2020-10-07 11:15:05 +02:00
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/* Debian's alternatives command for pagers is called 'pager'. Note that we do not call
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* sensible-pagers here, since that is just a shell script that implements a logic that is
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* similar to this one anyway, but is Debian-specific. */
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2018-11-11 19:04:00 +01:00
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FOREACH_STRING(exe, "pager", "less", "more") {
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2020-10-07 11:15:05 +02:00
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/* Only less implements secure mode right now. */
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if (use_secure_mode && !streq(exe, "less"))
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continue;
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2018-11-29 14:27:01 +01:00
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r = loop_write(exe_name_pipe[1], exe, strlen(exe) + 1, false);
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if (r < 0) {
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log_error_errno(r, "Failed to write pager name to socket: %m");
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2018-11-11 19:04:00 +01:00
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_exit(EXIT_FAILURE);
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2018-11-29 14:27:01 +01:00
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}
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2018-11-11 19:04:00 +01:00
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execlp(exe, exe, NULL);
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2018-11-29 14:27:01 +01:00
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log_full_errno(errno == ENOENT ? LOG_DEBUG : LOG_WARNING, errno,
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2019-01-23 17:00:09 +01:00
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"Failed to execute '%s', using next fallback pager: %m", exe);
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2018-11-11 19:04:00 +01:00
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}
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2011-07-07 02:34:35 +02:00
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2020-10-07 11:15:05 +02:00
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/* Our builtin is also very secure. */
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2019-05-29 21:17:42 +02:00
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r = loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in)") + 1, false);
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2018-11-29 14:27:01 +01:00
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if (r < 0) {
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log_error_errno(r, "Failed to write pager name to socket: %m");
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2018-11-11 19:04:00 +01:00
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_exit(EXIT_FAILURE);
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2018-11-29 14:27:01 +01:00
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}
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2019-05-29 21:17:42 +02:00
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/* Close pipe to signal the parent to start sending data */
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safe_close_pair(exe_name_pipe);
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2011-09-26 23:02:56 +02:00
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pager_fallback();
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/* not reached */
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2011-07-07 02:34:35 +02:00
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}
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/* Return in the parent */
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2017-04-24 18:30:50 +02:00
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stored_stdout = fcntl(STDOUT_FILENO, F_DUPFD_CLOEXEC, 3);
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if (dup2(fd[1], STDOUT_FILENO) < 0) {
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stored_stdout = safe_close(stored_stdout);
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2014-11-28 19:57:32 +01:00
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return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
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2017-04-24 18:30:50 +02:00
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}
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stdout_redirected = true;
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stored_stderr = fcntl(STDERR_FILENO, F_DUPFD_CLOEXEC, 3);
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if (dup2(fd[1], STDERR_FILENO) < 0) {
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stored_stderr = safe_close(stored_stderr);
|
2015-08-28 00:13:34 +02:00
|
|
|
return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
|
2017-04-24 18:30:50 +02:00
|
|
|
}
|
|
|
|
stderr_redirected = true;
|
2011-07-07 02:34:35 +02:00
|
|
|
|
2018-11-11 19:04:00 +01:00
|
|
|
exe_name_pipe[1] = safe_close(exe_name_pipe[1]);
|
|
|
|
|
|
|
|
r = no_quit_on_interrupt(TAKE_FD(exe_name_pipe[0]), less_opts);
|
|
|
|
if (r < 0)
|
|
|
|
return r;
|
|
|
|
if (r > 0)
|
|
|
|
(void) ignore_signals(SIGINT, -1);
|
|
|
|
|
2012-10-18 23:34:37 +02:00
|
|
|
return 1;
|
2011-07-07 02:34:35 +02:00
|
|
|
}
|
|
|
|
|
|
|
|
void pager_close(void) {
|
|
|
|
|
|
|
|
if (pager_pid <= 0)
|
|
|
|
return;
|
|
|
|
|
|
|
|
/* Inform pager that we are done */
|
2017-04-24 18:30:50 +02:00
|
|
|
(void) fflush(stdout);
|
2017-04-27 02:08:52 +02:00
|
|
|
if (stdout_redirected)
|
|
|
|
if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0)
|
|
|
|
(void) close(STDOUT_FILENO);
|
2017-04-24 18:30:50 +02:00
|
|
|
stored_stdout = safe_close(stored_stdout);
|
|
|
|
(void) fflush(stderr);
|
2017-04-27 02:08:52 +02:00
|
|
|
if (stderr_redirected)
|
|
|
|
if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0)
|
|
|
|
(void) close(STDERR_FILENO);
|
2017-04-24 18:30:50 +02:00
|
|
|
stored_stderr = safe_close(stored_stderr);
|
|
|
|
stdout_redirected = stderr_redirected = false;
|
2015-08-28 00:13:34 +02:00
|
|
|
|
2015-09-09 15:20:10 +02:00
|
|
|
(void) kill(pager_pid, SIGCONT);
|
2014-11-09 15:51:04 +01:00
|
|
|
(void) wait_for_terminate(pager_pid, NULL);
|
2011-07-07 02:34:35 +02:00
|
|
|
pager_pid = 0;
|
|
|
|
}
|
2012-10-18 23:34:37 +02:00
|
|
|
|
|
|
|
bool pager_have(void) {
|
|
|
|
return pager_pid > 0;
|
|
|
|
}
|
2014-07-21 00:23:53 +02:00
|
|
|
|
|
|
|
int show_man_page(const char *desc, bool null_stdio) {
|
|
|
|
const char *args[4] = { "man", NULL, NULL, NULL };
|
|
|
|
char *e = NULL;
|
|
|
|
pid_t pid;
|
|
|
|
size_t k;
|
|
|
|
int r;
|
|
|
|
|
|
|
|
k = strlen(desc);
|
|
|
|
|
|
|
|
if (desc[k-1] == ')')
|
|
|
|
e = strrchr(desc, '(');
|
|
|
|
|
|
|
|
if (e) {
|
|
|
|
char *page = NULL, *section = NULL;
|
|
|
|
|
|
|
|
page = strndupa(desc, e - desc);
|
|
|
|
section = strndupa(e + 1, desc + k - e - 2);
|
|
|
|
|
|
|
|
args[1] = section;
|
|
|
|
args[2] = page;
|
|
|
|
} else
|
|
|
|
args[1] = desc;
|
|
|
|
|
2018-11-26 16:11:45 +01:00
|
|
|
r = safe_fork("(man)", FORK_RESET_SIGNALS|FORK_DEATHSIG|(null_stdio ? FORK_NULL_STDIO : 0)|FORK_RLIMIT_NOFILE_SAFE|FORK_LOG, &pid);
|
2017-12-22 13:08:14 +01:00
|
|
|
if (r < 0)
|
2017-12-27 21:49:19 +01:00
|
|
|
return r;
|
2017-12-22 13:08:14 +01:00
|
|
|
if (r == 0) {
|
2014-07-21 00:23:53 +02:00
|
|
|
/* Child */
|
|
|
|
execvp(args[0], (char**) args);
|
2014-11-28 19:29:59 +01:00
|
|
|
log_error_errno(errno, "Failed to execute man: %m");
|
2014-07-21 00:23:53 +02:00
|
|
|
_exit(EXIT_FAILURE);
|
|
|
|
}
|
|
|
|
|
2017-12-29 18:07:00 +01:00
|
|
|
return wait_for_terminate_and_check(NULL, pid, 0);
|
2014-07-21 00:23:53 +02:00
|
|
|
}
|