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

_llseek - reposition read/write file offset

#include <sys/types.h>
#include <unistd.h>
int _llseek(unsigned int fd, unsigned long offset_high,
            unsigned long offset_low, loff_t *result,
            unsigned int whence);
Note: There is no glibc wrapper for this system call; see NOTES.

The _llseek() system call repositions the offset of the open file description associated with the file descriptor fd to (offset_high<<32) | offset_low bytes 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. It returns the resulting file position in the argument result.
This system call exists on various 32-bit platforms to support seeking to large file offsets.

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

fd is not an open file descriptor.
Problem with copying results to user space.
whence is invalid.

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

Glibc does not provide a wrapper for this system call. To invoke it directly, use syscall(2). However, you probably want to use the lseek(2) wrapper function instead.

lseek(2), open(2), lseek64(3)
2017-09-15 Linux