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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <signal.h>
#include "lockfile.h"
#define LOCKDIR "/var/run"
#define LOCKPREFIX "/zcip."
static void
gen_lockfile_name(char * nbuf, char * device)
{
char * p;
p = strrchr(device, '/');
strcpy(nbuf, LOCKDIR LOCKPREFIX);
if( p ) strcat(nbuf, p+1);
else strcat(nbuf, device);
}
int
lock_check(char * device)
{
FILE * fd;
char nbuf[128];
int i;
gen_lockfile_name(nbuf, device);
fd = fopen(nbuf, "r");
if( fd )
{
fscanf(fd, "%d", &i);
fclose(fd);
if( kill(i, 0) == 0 ) return 0; /* Sorry */
if( errno == EPERM ) return 0;
if( unlink(nbuf) == -1 ) return 0;
}
fd = fopen(nbuf, "w"); /* Got it! */
i = getpid();
fprintf(fd, "%d\n", i);
fclose(fd);
return 1;
}
void
lock_unlock(char * device)
{
FILE * fd;
char nbuf[128];
int i;
gen_lockfile_name(nbuf, device);
fd = fopen(nbuf, "r");
if( fd )
{
fscanf(fd, "%d", &i);
fclose(fd);
if( i == getpid() || kill(i, 0) != 0 )
unlink(nbuf);
}
}
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