x/sys/unix: should support Dup2 on Solaris

[pyhalov]

Current go versions don't implement Dup2 for Solaris.
The fix is simple

--- golang-1.6.3/src/syscall/zsyscall_solaris_amd64.go.1        2016-09-09 17:36:48.176495144 +0300
+++ golang-1.6.3/src/syscall/zsyscall_solaris_amd64.go  2016-09-09 17:41:06.974986783 +0300
@@ -21,6 +21,7 @@
 //go:cgo_import_dynamic libc_Chroot chroot "libc.so"
 //go:cgo_import_dynamic libc_Close close "libc.so"
 //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_Fchdir fchdir "libc.so"
 //go:cgo_import_dynamic libc_Fchmod fchmod "libc.so"
@@ -104,6 +105,7 @@
 //go:linkname libc_Chroot libc_Chroot
 //go:linkname libc_Close libc_Close
 //go:linkname libc_Dup libc_Dup
+//go:linkname libc_Dup2 libc_Dup2
 //go:linkname libc_Exit libc_Exit
 //go:linkname libc_Fchdir libc_Fchdir
 //go:linkname libc_Fchmod libc_Fchmod
@@ -190,6 +192,7 @@
        libc_Chroot,
        libc_Close,
        libc_Dup,
+       libc_Dup2,
        libc_Exit,
        libc_Fchdir,
        libc_Fchmod,
@@ -412,6 +415,14 @@
        return
 }

+func Dup2(oldfd int, newfd int) (err error) {
+        _, _, e1 := sysvicall6(uintptr(unsafe.Pointer(&libc_Dup2)), 2, uintptr(oldfd), uintptr(newfd), 0, 0, 0, 0)
+        if e1 != 0 {
+                err = errnoErr(e1)
+        }
+        return
+}
+
 func Exit(code int) {
        sysvicall6(uintptr(unsafe.Pointer(&libc_Exit)), 1, uintptr(code), 0, 0, 0, 0, 0)
        return

[bradfitz]

The syscall package is frozen. See the notes at https://golang.org/pkg/syscall/#pkg-overview

But it doesn't look like it exists in golang.org/x/sys/unix either, so I'll repurpose this bug for that instead.

[ianlancetaylor]

Admittedly Dup2 is supported by all other Unix systems. Is there some popular program that requires it? I suppose we could consider this to be a special case for the syscall package.

Can you send your patch as a change as described at https://golang.org/doc/contribute.html? If not, please don't send us patches in the issue tracker. It complicates the copyright history. Thanks.

[pyhalov]

I've found that it's missing when tried to build mongo tools, which rely on https://github.com/spacemonkeygo/spacelog. And this one uses Dup2

[minux]

The syscall package is frozen, please add it to x/sys/unix instead.

[binarycrusader]

I already added Dup2 among others for Solaris in this commit to sys/unix in revision 68a71b6 for #8609: golang/sys@68a71b6

So the real answer is that spacelog should be using the sys/unix package instead of the syscall package.

[bradfitz]

@pyhalov, please file a bug against https://github.com/spacemonkeygo/spacelog to ask them to use golang.org/x/sys/unix instead of the syscall package.

That said, this is still a little sad for Solaris.