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Use posix_spawn for pager. 

Cleaner and better error reporting than fork/exec.
This commit is contained in:
Érico Rolim 2020-10-06 17:48:19 -03:00
parent 532b17129f
commit f6075da891
1 changed files with 39 additions and 22 deletions
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61
pager.c
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@ -3,6 +3,7 @@
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <spawn.h>
#include <sys/wait.h>
#include "pager.h"
@ -10,8 +11,8 @@
int launch_pager(struct pager_proc *p)
{
int rv = -1;
int pipes[2];
int pipes[2];
if (pipe(pipes) < 0) {
perror("pipe()");
return rv;
@ -26,30 +27,46 @@ int launch_pager(struct pager_proc *p)
// only overwrite LESS if it doesn't exist.
// set less to exit if output fits in terminal.
setenv("LESS", "-F", 0);
p->pid = fork();
if (p->pid < 0) {
perror("fork()");
// protect against accidental usage of the PID
p->pid = 0;
return rv;
posix_spawnattr_t spawn;
if (posix_spawnattr_init(&spawn) < 0) {
perror("posix_spawnattr_init()");
goto err_out;
}
if (p->pid == 0) {
close(pipes[1]);
dup2(pipes[0], STDIN_FILENO);
execvp(pager, pager_cmd);
// error out if exec fails
perror("execvp()");
exit(127);
} else {
close(pipes[0]);
p->file = fdopen(pipes[1], "w");
if (p->file == NULL) {
perror("fdopen()");
return rv;
}
rv = 0;
posix_spawn_file_actions_t actions;
if (posix_spawn_file_actions_init(&actions) < 0) {
perror("posix_spawn_file_actions_init()");
goto spawn_out;
}
if (posix_spawn_file_actions_adddup2(&actions, pipes[0], STDIN_FILENO) < 0
|| posix_spawn_file_actions_addclose(&actions, pipes[1]) < 0) {
perror("posix_spawn_file_actions_add*()");
goto actions_out;
}
extern char **environ;
pid_t pid;
if (posix_spawnp(&pid, pager, &actions, &spawn, pager_cmd, environ) != 0) {
perror("posix_spawnp()");
goto actions_out;
}
p->file = fdopen(pipes[1], "w");
if (p->file == NULL) {
perror("fdopen()");
goto actions_out;
}
p->pid = pid;
rv = 0;
actions_out:
posix_spawn_file_actions_destroy(&actions);
spawn_out:
posix_spawnattr_destroy(&spawn);
err_out:
close(pipes[0]);
if (rv) close(pipes[1]);
return rv;
}