-static void pager_open(void) {
- int fd[2];
- const char *pager;
- pid_t parent_pid;
-
- if (pager_pid > 0)
- return;
-
- if (!on_tty() || arg_no_pager)
- return;
-
- if ((pager = getenv("SYSTEMD_PAGER")) || (pager = getenv("PAGER")))
- if (!*pager || streq(pager, "cat"))
- return;
-
- /* Determine and cache number of columns before we spawn the
- * pager so that we get the value from the actual tty */
- columns();
-
- if (pipe(fd) < 0) {
- log_error("Failed to create pager pipe: %m");
- return;
- }
-
- parent_pid = getpid();
-
- pager_pid = fork();
- if (pager_pid < 0) {
- log_error("Failed to fork pager: %m");
- close_pipe(fd);
- return;
- }
-
- /* In the child start the pager */
- if (pager_pid == 0) {
-
- dup2(fd[0], STDIN_FILENO);
- close_pipe(fd);
-
- setenv("LESS", "FRSX", 0);
-
- /* Make sure the pager goes away when the parent dies */
- if (prctl(PR_SET_PDEATHSIG, SIGTERM) < 0)
- _exit(EXIT_FAILURE);
-
- /* Check whether our parent died before we were able
- * to set the death signal */
- if (getppid() != parent_pid)
- _exit(EXIT_SUCCESS);
-
- if (pager) {
- execlp(pager, pager, NULL);
- execl("/bin/sh", "sh", "-c", pager, NULL);
- } else {
- /* Debian's alternatives command for pagers is
- * called 'pager'. Note that we do not call
- * sensible-pagers here, since that is just a
- * shell script that implements a logic that
- * is similar to this one anyway, but is
- * Debian-specific. */
- execlp("pager", "pager", NULL);
-
- execlp("less", "less", NULL);
- execlp("more", "more", NULL);
- }
-
- log_error("Unable to execute pager: %m");
- _exit(EXIT_FAILURE);
- }
-
- /* Return in the parent */
- if (dup2(fd[1], STDOUT_FILENO) < 0)
- log_error("Failed to duplicate pager pipe: %m");
-
- close_pipe(fd);
-}
-
-static void pager_close(void) {
- siginfo_t dummy;
-
- if (pager_pid <= 0)
- return;
-
- /* Inform pager that we are done */
- fclose(stdout);
- kill(pager_pid, SIGCONT);
- wait_for_terminate(pager_pid, &dummy);
- pager_pid = 0;
-}
-