Informatik/Assets/Betriebssysteme_uebung/u6-a2-anlage/helpers.c
2021-03-01 16:39:46 +01:00

104 lines
1.7 KiB
C

/*
* This is just some code behind the curtain.
* You really don't need to touch this.
*
*/
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
#include "helpers.h"
int do_quit = 0;
int do_reload = 0;
int load_config(void) {
static char firsttime_message[] = "Loading";
static char subsequent_message[] = "Reloading";
static char *message = firsttime_message;
fprintf(stderr, "%s configuration... ", message);
fprintf(stderr, "done.\n");
message = subsequent_message;
do_reload = 0;
return 1;
}
int main_loop(void) {
fd_set rfds;
struct timeval tv;
int retval;
char buf[1024];
ssize_t len;
#if 0
/* fork() to the background */
if(fork()) return 0;
#endif
fprintf(stderr, "I'm just a simple daemon, my PID is: %i\n",
getpid());
while (!do_quit) {
/*
* Let's just do our really simple job:
* Copy stdin to stdout (just another cat(1)).
*/
if (do_reload) {
load_config();
}
/* Watch stdin (fd 0) to see when it has input. */
FD_ZERO(&rfds);
FD_SET(0, &rfds);
/* Wait up to five seconds. */
tv.tv_sec = 5;
tv.tv_usec = 0;
retval = select(1, &rfds, NULL, NULL, &tv);
/* Don't rely on the value of tv now! */
if (retval == -1) {
if (errno == EINTR) {
continue;
}
perror("select()");
continue;
}
if (retval == 0) {
/* fprintf(stderr, "Timeout reached.\n"); */
continue;
}
if (!FD_ISSET(0, &rfds)) {
fprintf(stderr, "BUG: Empty read-set, this should"
" never happen. Never ever. Really! :-)\n");
continue;
}
len = read(0, buf, sizeof(buf) - 1);
if (len < 0) {
perror("read()");
continue;
}
buf[len] = 0;
printf("%s", buf);
if (len == 0) {
do_quit = 1;
}
}
return 1;
}