mirror of https://github.com/ericonr/purr-c.git
98 lines
2.3 KiB
C
98 lines
2.3 KiB
C
#define _POSIX_C_SOURCE 200112L /* fdopen, nanosleep */
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#include <unistd.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <signal.h>
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#include <spawn.h>
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#include <time.h>
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#include <sys/wait.h>
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#include "pager.h"
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#include "compat.h"
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int launch_pager(struct pager_proc *p)
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{
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int rv = -1;
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int pipes[2];
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// using close-on-exec here is safe, because fds created by dup don't
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// inherit flags
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if (pipe_cloexec(pipes)) {
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perror("pipe_cloexec()");
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return rv;
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}
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char *pager = getenv("PAGER");
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if (pager == NULL || *pager == 0) {
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pager = "less";
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}
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char *const pager_cmd[] = {pager, NULL};
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// only overwrite LESS if it doesn't exist.
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// set less to exit if output fits in terminal.
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setenv("LESS", "-F", 0);
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posix_spawnattr_t spawn;
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if (posix_spawnattr_init(&spawn) < 0) {
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perror("posix_spawnattr_init()");
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goto err_out;
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}
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posix_spawn_file_actions_t actions;
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if (posix_spawn_file_actions_init(&actions) < 0) {
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perror("posix_spawn_file_actions_init()");
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goto spawn_out;
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}
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if (posix_spawn_file_actions_adddup2(&actions, pipes[0], STDIN_FILENO) < 0
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|| posix_spawn_file_actions_addclose(&actions, pipes[1]) < 0) {
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perror("posix_spawn_file_actions_add*()");
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goto actions_out;
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}
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extern char **environ;
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pid_t pid;
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if (posix_spawnp(&pid, pager, &actions, &spawn, pager_cmd, environ) != 0) {
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perror("posix_spawnp()");
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goto actions_out;
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}
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// applying close-on-exec to fd here shouldn't change anything, but it's
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// also cheap, so there's no reason not to do it.
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p->file = fdopen(pipes[1], "we");
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if (p->file == NULL) {
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perror("fdopen()");
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goto actions_out;
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}
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p->pid = pid;
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rv = 0;
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actions_out:
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posix_spawn_file_actions_destroy(&actions);
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spawn_out:
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posix_spawnattr_destroy(&spawn);
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err_out:
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close(pipes[0]);
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if (rv) close(pipes[1]);
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return rv;
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}
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int wait_for_pager(struct pager_proc p, bool should_kill)
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{
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int status = 0;
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fclose(p.file);
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if (should_kill) {
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// quick interval to make redirection noticeable
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struct timespec sleep_time = { .tv_nsec = 200L * 1000L * 1000L };
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nanosleep(&sleep_time, NULL);
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kill(p.pid, SIGTERM);
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}
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waitpid(p.pid, &status, 0);
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return status;
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}
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