llseek(2) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON

LLSEEK(2)               Linux Programmer's Manual              LLSEEK(2)

NAME         top

       _llseek - reposition read/write file offset

SYNOPSIS         top

       #include <sys/syscall.h>      /* Definition of SYS_* constants */
       #include <unistd.h>

       int syscall(SYS__llseek, unsigned int fd, unsigned long offset_high,
                   unsigned long offset_low, loff_t *result,
                   unsigned int whence);

       Note: glibc provides no wrapper for _llseek(), necessitating the
       use of syscall(2).

DESCRIPTION         top

       Note: for information about the llseek(3) library function, see
       lseek64(3).

       The _llseek() system call repositions the offset of the open file
       description associated with the file descriptor fd to the value

              (offset_high << 32) | offset_low

       This new offset is a byte offset relative to the beginning of the
       file, the current file offset, or the end of the file, depending
       on whether whence is SEEK_SET, SEEK_CUR, or SEEK_END,
       respectively.

       The new file offset is returned in the argument result.  The
       type loff_t is a 64-bit signed type.

       This system call exists on various 32-bit platforms to support
       seeking to large file offsets.

RETURN VALUE         top

       Upon successful completion, _llseek() returns 0.  Otherwise, a
       value of -1 is returned and errno is set to indicate the error.

ERRORS         top

       EBADF  fd is not an open file descriptor.

       EFAULT Problem with copying results to user space.

       EINVAL whence is invalid.

CONFORMING TO         top

       This function is Linux-specific, and should not be used in
       programs intended to be portable.

NOTES         top

       You probably want to use the lseek(2) wrapper function instead.

SEE ALSO         top

       lseek(2), open(2), lseek64(3)

COLOPHON         top

       This page is part of release 5.12 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2021-03-22                      LLSEEK(2)

Pages that refer to this page: syscall(2)syscalls(2)lseek64(3)