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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/event.h>
#include <sys/time.h>
#include <errno.h>
#include <err.h>
#include <dirent.h>
#include <string.h>
#include <fcntl.h>
#include <sys/wait.h>
#include <signal.h>
#define DEFAULT_QUEUE_DIR "."
#define MAX_JOBS 2
struct job {
pid_t pid;
char *file;
};
int cur_jobs = 0;
struct job jobs[MAX_JOBS];
pid_t
run_job(char *queuedir, int fd)
{
char *run;
pid_t pid;
switch((pid = fork())) {
case -1:
return -1;
case 0:
asprintf(&run, "%s/run", queuedir);
dup2(fd, STDIN_FILENO);
close(fd);
execl(run, "run", (char*)NULL);
perror("execle()");
_exit(1);
break;
default:
return pid;
}
}
void
process_queue(char *queuedir, int dfd)
{
int fd, i;
DIR *dir;
struct dirent *de;
char *name, *work, *failed;
pid_t pid;
dir = fdopendir(dfd);
while ((de = readdir(dir))) {
if (cur_jobs >= MAX_JOBS)
break;
if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
continue;
asprintf(&name, "new/%s", de->d_name);
asprintf(&work, "work/%s", de->d_name);
asprintf(&failed, "failed/%s", de->d_name);
fd = open(name, O_RDONLY);
if (fd == -1) {
goto next;
}
rename(name, work);
pid = run_job(queuedir, fd);
if (pid == -1) {
rename(work, failed);
free(name);
free(work);
free(failed);
break;
}
for (i = 0; i < MAX_JOBS; i++) {
if (jobs[i].pid == -1) {
jobs[i].pid = pid;
jobs[i].file = strdup(de->d_name);
}
}
close(fd);
cur_jobs++;
next:
free(name);
free(work);
free(failed);
}
rewinddir(dir);
fdclosedir(dir);
}
void
wait_all()
{
int i, status;
char *work, *done, *failed;
for (;;) {
pid_t r = waitpid(-1, &status, WNOHANG);
if (r == 0)
break;
else if (r == -1) {
if (errno == ECHILD)
break;
else
err(1, "waitpid()");
}
for (i = 0; i < MAX_JOBS; i++) {
if (jobs[i].pid == r) {
asprintf(&work, "work/%s", jobs[i].file);
asprintf(&done, "done/%s", jobs[i].file);
asprintf(&failed, "failed/%s", jobs[i].file);
if (WEXITSTATUS(status) == 0)
rename(work, done);
else
rename(work, failed);
jobs[i].pid = -1;
free(jobs[i].file);
jobs[i].file = NULL;
cur_jobs--;
free(work);
free(done);
free(failed);
break;
}
}
}
}
int
main(int argc, char **argv)
{
int kq, dfd, ret, i;
struct kevent kv[2];
char *queuedir = NULL, *newdir = NULL;
for (i = 0; i < MAX_JOBS; i++) {
jobs[i].pid = -1;
jobs[i].file = NULL;
}
if (argc > 1) {
queuedir = strdup(argv[1]);
} else {
queuedir = strdup(DEFAULT_QUEUE_DIR);
}
asprintf(&newdir, "%s/new", queuedir);
dfd = open(newdir, O_RDONLY | O_DIRECTORY);
if (dfd == -1)
err(1, "open()");
kq = kqueue();
if (kq == -1)
err(1, "kqueue()");
EV_SET(&kv[0], dfd, EVFILT_VNODE, EV_ADD | EV_CLEAR, NOTE_WRITE, 0, NULL);
EV_SET(&kv[1], SIGCHLD, EVFILT_SIGNAL, EV_ADD | EV_CLEAR, 0, 0, NULL);
if (kevent(kq, kv, 2, NULL, 0, NULL) == -1)
err(1, "kevent()");
process_queue(queuedir, dfd);
for (;;) {
ret = kevent(kq, NULL, 0, kv, 2, NULL);
if (ret == 0)
continue;
else if (ret == -1) {
if (errno == EINTR)
continue;
else
break;
}
int i;
for (i = 0; i < ret; i++) {
if (kv[i].filter == EVFILT_SIGNAL) {
if (kv[i].ident == SIGCHLD) {
wait_all();
process_queue(queuedir, dfd);
}
} else if (kv[i].filter == EVFILT_VNODE) {
process_queue(queuedir, dfd);
}
}
}
return 0;
}
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