unix: add Faccessat on Solaris

Change-Id: Ie720f7c4d496e67f2a81de379374c2ec1f95bb96
Reviewed-on: https://go-review.googlesource.com/119556
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

unix/syscall_solaris.go

@@ -595,6 +595,7 @@ func Poll(fds []PollFd, timeout int) (n int, err error) {
 //sys	Dup(fd int) (nfd int, err error)
 //sys	Dup2(oldfd int, newfd int) (err error)
 //sys	Exit(code int)
+//sys	Faccessat(dirfd int, path string, mode uint32, flags int) (err error)
 //sys	Fchdir(fd int) (err error)
 //sys	Fchmod(fd int, mode uint32) (err error)
 //sys	Fchmodat(dirfd int, path string, mode uint32, flags int) (err error)

unix/zsyscall_solaris_amd64.go

@@ -41,6 +41,7 @@ import (
 //go:cgo_import_dynamic libc_dup dup "libc.so"
 //go:cgo_import_dynamic libc_dup2 dup2 "libc.so"
 //go:cgo_import_dynamic libc_exit exit "libc.so"
+//go:cgo_import_dynamic libc_faccessat faccessat "libc.so"
 //go:cgo_import_dynamic libc_fchdir fchdir "libc.so"
 //go:cgo_import_dynamic libc_fchmod fchmod "libc.so"
 //go:cgo_import_dynamic libc_fchmodat fchmodat "libc.so"
@@ -169,6 +170,7 @@ import (
 //go:linkname procDup libc_dup
 //go:linkname procDup2 libc_dup2
 //go:linkname procExit libc_exit
+//go:linkname procFaccessat libc_faccessat
 //go:linkname procFchdir libc_fchdir
 //go:linkname procFchmod libc_fchmod
 //go:linkname procFchmodat libc_fchmodat
@@ -298,6 +300,7 @@ var (
 	procDup,
 	procDup2,
 	procExit,
+	procFaccessat,
 	procFchdir,
 	procFchmod,
 	procFchmodat,
@@ -695,6 +698,19 @@ func Exit(code int) {
 	return
 }
 
+func Faccessat(dirfd int, path string, mode uint32, flags int) (err error) {
+	var _p0 *byte
+	_p0, err = BytePtrFromString(path)
+	if err != nil {
+		return
+	}
+	_, _, e1 := sysvicall6(uintptr(unsafe.Pointer(&procFaccessat)), 4, uintptr(dirfd), uintptr(unsafe.Pointer(_p0)), uintptr(mode), uintptr(flags), 0, 0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
 func Fchdir(fd int) (err error) {
 	_, _, e1 := sysvicall6(uintptr(unsafe.Pointer(&procFchdir)), 1, uintptr(fd), 0, 0, 0, 0, 0)
 	if e1 != 0 {