source: asp3_tinet_ecnl_arm/trunk/musl-1.1.18/src/misc/lockf.c@ 352

#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include "libc.h"

int lockf(int fd, int op, off_t size)
{
        struct flock l = {
                .l_type = F_WRLCK,
                .l_whence = SEEK_CUR,
                .l_len = size,
        };
        switch (op) {
        case F_TEST:
                l.l_type = F_RDLCK;
                if (fcntl(fd, F_GETLK, &l) < 0)
                        return -1;
                if (l.l_type == F_UNLCK || l.l_pid == getpid())
                        return 0;
                errno = EACCES;
                return -1;
        case F_ULOCK:
                l.l_type = F_UNLCK;
        case F_TLOCK:
                return fcntl(fd, F_SETLK, &l);
        case F_LOCK:
                return fcntl(fd, F_SETLKW, &l);
        }
        errno = EINVAL;
        return -1;
}

LFS64(lockf);