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#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <errno.h>
#include <getopt.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static char *progname;
static const key_t key_astribanks = 0xAB11A0;
static int debug;
static void usage(void)
{
fprintf(stderr, "Usage: %s [-d] [-a] [-r]\n", progname);
exit(1);
}
static int absem_get(int createit)
{
int flags = (createit) ? IPC_CREAT | 0644 : 0;
int absem;
if((absem = semget(key_astribanks, 1, flags)) < 0)
absem = -errno;
return absem;
}
static int absem_touch(void)
{
int absem;
if((absem = absem_get(1)) < 0) {
perror(__FUNCTION__);
return absem;
}
if(semctl(absem, 0, SETVAL, 0) < 0) {
perror("SETVAL");
return -errno;
}
if(debug)
fprintf(stderr, "%s: touched absem\n", progname);
return 0;
}
static int absem_remove(void)
{
int absem;
if((absem = absem_get(0)) < 0) {
if(absem == -ENOENT) {
if(debug)
fprintf(stderr, "%s: absem already removed\n", progname);
return 0;
}
perror(__FUNCTION__);
return absem;
}
if(semctl(absem, 0, IPC_RMID, 0) < 0) {
perror("RMID");
return -errno;
}
if(debug)
fprintf(stderr, "%s: removed absem\n", progname);
return 0;
}
static int absem_detected(void)
{
int absem;
if((absem = absem_get(0)) < 0) {
if(debug)
fprintf(stderr, "%s: absem does not exist\n", progname);
return absem;
}
if(debug)
fprintf(stderr, "%s: absem exists\n", progname);
return 0;
}
int main(int argc, char *argv[])
{
const char options[] = "darh";
int val;
progname = argv[0];
while (1) {
int c;
c = getopt (argc, argv, options);
if (c == -1)
break;
switch (c) {
case 'd':
debug++;
break;
case 'a':
if((val = absem_touch()) < 0) {
fprintf(stderr, "%s: Add failed: %d\n", progname, val);
return 1;
}
return 0;
case 'r':
if((val = absem_remove()) < 0) {
fprintf(stderr, "%s: Remove failed: %d\n", progname, val);
return 1;
}
return 0;
case 'h':
default:
fprintf(stderr, "Unknown option '%c'\n", c);
usage();
}
}
val = absem_detected();
return (val == 0) ? 0 : 1;
}
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