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#include <unistd.h>
#include <fcntl.h>
#include <utmp.h> /*EXTRACT_UNMOD*/
#include "utmp_defs.h"
#define UTMP_SIZE (sizeof(struct utmp)) /*EXTRACT_UNMOD*/
/* type: F_RDLCK or F_WRLCK */
struct utmp *utmp_io(int fd, struct utmp *ut, int type) /*EXTRACT_INCL*/ {
int ret;
struct flock fl;
int (*op)() = (type==F_WRLCK) ? (int(*)())write : (int(*)())read;
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;
ret = SAFE_IO(op, fd, ut, UTMP_SIZE);
fl.l_start = -UTMP_SIZE;
fl.l_type = F_UNLCK;
fcntl(fd, F_SETLK, &fl);
if (ret != UTMP_SIZE) return 0;
return ut;
}
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