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Top Forums UNIX for Advanced & Expert Users System Call Wrapper of 'open' Post 302328837 by mgessner on Thursday 25th of June 2009 09:41:14 AM
Old 06-25-2009
This looks to me like you found a stub that's intended for someone to fill in for a specific system, given that no matter what you do to call it, it will return -1 and set errno. That said, I'm not sure why they would do all the other stuff just to return -1.

You need to be looking in a different place, I think.
 

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

NAME
_llseek - reposition read/write file offset SYNOPSIS
#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. DESCRIPTION
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. RETURN VALUE
Upon successful completion, _llseek() returns 0. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS
EBADF fd is not an open file descriptor. EFAULT Problem with copying results to user space. EINVAL whence is invalid. CONFORMING TO
This function is Linux-specific, and should not be used in programs intended to be portable. NOTES
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. SEE ALSO
lseek(2), open(2), lseek64(3) COLOPHON
This page is part of release 4.15 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 2017-09-15 LLSEEK(2)
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