commit b10968a4460ed90e1d0dcd386a49ba964cd21f23
author Ian Lance Taylor <iant@golang.org> Wed May 13 13:50:00 2015 -0700
committer Ian Lance Taylor <iant@golang.org> Wed May 13 21:31:04 2015 +0000
tree 08afd5c3c1d22d4b25ee98874a6a8ccea03191e4
parent 082a6a3a8b1835efccee8ec44ce37678b0ecb33e

unix: split Pipe/Pipe2/Dup2, use *at replacement calls

This brings over three CLs from the main syscall package:
http://golang.org/cl/5833
http://golang.org/cl/5835
http://golang.org/cl/5837

Pipe, Pipe2, and Dup2 are moved from syscall_linux.go to the GOARCH
specific variants.  On 386 and amd64, Linux kernel version 2.6.23 (the
documented minimum Linux kernel version the Go distribution supports)
does not support the pipe2 system call, so Pipe continues to call
pipe.  On ARM, Pipe now calls pipe2.

Several system calls are reimplemented in terms of the *at syscalls,
passing AT_FDCWD to indicate that pathnames are to be interpreted
relative to the current directory.  The *at syscalls were added in
Linux kernel version 2.6.16.

This is in preparation for arm64 support, as the arm64 Linux kernel
does not provide the traditional syscall variants.

Change-Id: Id6bc6097dc5f4324cd9e429c5e1f3a411a08ce42
Reviewed-on: https://go-review.googlesource.com/10032
Reviewed-by: Rob Pike <r@golang.org>