271 lines
8.4 KiB
C
271 lines
8.4 KiB
C
/* SPDX-License-Identifier: LGPL-2.1+ */
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#include <errno.h>
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#include <signal.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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#include <stdlib.h>
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#include <string.h>
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#include <sys/prctl.h>
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#include <unistd.h>
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#include "copy.h"
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#include "fd-util.h"
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#include "fileio.h"
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#include "io-util.h"
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#include "locale-util.h"
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#include "log.h"
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#include "macro.h"
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#include "pager.h"
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#include "process-util.h"
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#include "signal-util.h"
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#include "string-util.h"
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#include "strv.h"
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#include "terminal-util.h"
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static pid_t pager_pid = 0;
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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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_noreturn_ static void pager_fallback(void) {
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int r;
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r = copy_bytes(STDIN_FILENO, STDOUT_FILENO, (uint64_t) -1, 0);
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if (r < 0) {
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log_error_errno(r, "Internal pager failed: %m");
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_exit(EXIT_FAILURE);
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}
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_exit(EXIT_SUCCESS);
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}
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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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return log_debug_errno(errno, "Failed to create FILE object: %m");
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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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return r;
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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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int pager_open(PagerFlags flags) {
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_cleanup_close_pair_ int fd[2] = { -1, -1 }, exe_name_pipe[2] = { -1, -1 };
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_cleanup_strv_free_ char **pager_args = NULL;
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const char *pager, *less_opts;
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int r;
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if (flags & PAGER_DISABLE)
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return 0;
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if (pager_pid > 0)
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return 1;
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if (terminal_is_dumb())
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return 0;
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if (!is_main_thread())
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return -EPERM;
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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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if (pager) {
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pager_args = strv_split(pager, WHITESPACE);
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if (!pager_args)
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return -ENOMEM;
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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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/* 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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(void) columns();
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(void) lines();
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if (pipe2(fd, O_CLOEXEC) < 0)
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return log_error_errno(errno, "Failed to create pager pipe: %m");
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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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r = safe_fork("(pager)", FORK_RESET_SIGNALS|FORK_DEATHSIG|FORK_LOG, &pager_pid);
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if (r < 0)
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return r;
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if (r == 0) {
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const char *less_charset, *exe;
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/* In the child start the pager */
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(void) dup2(fd[0], STDIN_FILENO);
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safe_close_pair(fd);
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if (setenv("LESS", less_opts, 1) < 0)
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_exit(EXIT_FAILURE);
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/* Initialize a good charset for less. This is
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* particularly important if we output UTF-8
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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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if (less_charset &&
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setenv("LESSCHARSET", less_charset, 1) < 0)
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_exit(EXIT_FAILURE);
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if (pager_args) {
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if (loop_write(exe_name_pipe[1], pager_args[0], strlen(pager_args[0]) + 1, false) < 0)
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_exit(EXIT_FAILURE);
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execvp(pager_args[0], pager_args);
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}
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/* Debian's alternatives command for pagers is
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* called 'pager'. Note that we do not call
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* sensible-pagers here, since that is just a
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* shell script that implements a logic that
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* is similar to this one anyway, but is
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* Debian-specific. */
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FOREACH_STRING(exe, "pager", "less", "more") {
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if (loop_write(exe_name_pipe[1], exe, strlen(exe) + 1, false) < 0)
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_exit(EXIT_FAILURE);
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execlp(exe, exe, NULL);
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}
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if (loop_write(exe_name_pipe[1], "(built-in)", strlen("(built-in") + 1, false) < 0)
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_exit(EXIT_FAILURE);
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pager_fallback();
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/* not reached */
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}
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/* Return in the parent */
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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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return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
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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);
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return log_error_errno(errno, "Failed to duplicate pager pipe: %m");
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}
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stderr_redirected = true;
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exe_name_pipe[1] = safe_close(exe_name_pipe[1]);
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r = no_quit_on_interrupt(TAKE_FD(exe_name_pipe[0]), less_opts);
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if (r < 0)
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return r;
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if (r > 0)
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(void) ignore_signals(SIGINT, -1);
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return 1;
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}
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void pager_close(void) {
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if (pager_pid <= 0)
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return;
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/* Inform pager that we are done */
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(void) fflush(stdout);
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if (stdout_redirected)
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if (stored_stdout < 0 || dup2(stored_stdout, STDOUT_FILENO) < 0)
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(void) close(STDOUT_FILENO);
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stored_stdout = safe_close(stored_stdout);
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(void) fflush(stderr);
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if (stderr_redirected)
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if (stored_stderr < 0 || dup2(stored_stderr, STDERR_FILENO) < 0)
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(void) close(STDERR_FILENO);
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stored_stderr = safe_close(stored_stderr);
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stdout_redirected = stderr_redirected = false;
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(void) kill(pager_pid, SIGCONT);
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(void) wait_for_terminate(pager_pid, NULL);
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pager_pid = 0;
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}
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bool pager_have(void) {
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return pager_pid > 0;
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}
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int show_man_page(const char *desc, bool null_stdio) {
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const char *args[4] = { "man", NULL, NULL, NULL };
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char *e = NULL;
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pid_t pid;
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size_t k;
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int r;
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k = strlen(desc);
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if (desc[k-1] == ')')
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e = strrchr(desc, '(');
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if (e) {
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char *page = NULL, *section = NULL;
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page = strndupa(desc, e - desc);
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section = strndupa(e + 1, desc + k - e - 2);
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args[1] = section;
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args[2] = page;
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} else
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args[1] = desc;
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r = safe_fork("(man)", FORK_RESET_SIGNALS|FORK_DEATHSIG|(null_stdio ? FORK_NULL_STDIO : 0)|FORK_LOG, &pid);
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if (r < 0)
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return r;
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if (r == 0) {
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/* Child */
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execvp(args[0], (char**) args);
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log_error_errno(errno, "Failed to execute man: %m");
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_exit(EXIT_FAILURE);
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}
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return wait_for_terminate_and_check(NULL, pid, 0);
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}
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