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#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "lib.h"
/* type: F_RDLCK or F_WRLCK */
struct utmp_type *utmp_io(int fd, struct utmp_type *ut, int type) /*EXTRACT_INCL*/ {
struct flock fl;
int len;
fl.l_whence = SEEK_CUR;
fl.l_start = 0;
fl.l_len = UTMP_SIZE;
fl.l_pid = 0;
fl.l_type = type;
if (fcntl(fd, F_SETLKW, &fl)) return 0;
len = const_io((type==F_WRLCK) ? (int(*)())write : (int(*)())read,
fd, ut, UTMP_SIZE);
fl.l_start = -UTMP_SIZE;
fl.l_type = F_UNLCK;
fcntl(fd, F_SETLK, &fl);
return (len) ? 0 : ut;
}
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