Port pkg/system/mknod.go to FreeBSD

[akhramov]

fixes #42849

Because FreeBSD uses 64-bit device nodes (see
https://reviews.freebsd.org/rS318736), Linux implementation of
system.Mknod & system.Mkdev is not sufficient.

This change adds freebsd-specific implementations for Mknod and
Mkdev.

[thaJeztah]

Doing a quick diff between both, to see what the difference is. On Linux we're converting this to return an uint32. All places where it's used (currently) cast it to an int (as argument for Mknod).

Mostly wondering if we should do the same for freebsd so that the signature is the same. (Perhaps we should look at that in a follow-up, and move these utilities into pkg/archive).

@samuelkarp perhaps you have thoughts on this?

diff --git a/pkg/system/mknod.go b/pkg/system/mknod_freebsd.go
index ccb2e638bb..b1ba8320dd 100644
--- a/pkg/system/mknod.go
+++ b/pkg/system/mknod_freebsd.go
@@ -1,5 +1,5 @@
-//go:build !freebsd && !windows
-// +build !freebsd,!windows
+//go:build freebsd
+// +build freebsd

 package system // import "github.com/docker/docker/pkg/system"

@@ -10,14 +10,11 @@ import (
 // Mknod creates a filesystem node (file, device special file or named pipe) named path
 // with attributes specified by mode and dev.
 func Mknod(path string, mode uint32, dev int) error {
-       return unix.Mknod(path, mode, dev)
+       return unix.Mknod(path, mode, uint64(dev))
 }

-// Mkdev is used to build the value of linux devices (in /dev/) which specifies major
+// Mkdev is used to build the value of FreeBSD devices (in /dev/) which specifies major
 // and minor number of the newly created device special file.
-// Linux device nodes are a bit weird due to backwards compat with 16 bit device nodes.
-// They are, from low to high: the lower 8 bits of the minor, then 12 bits of the major,
-// then the top 12 bits of the minor.
-func Mkdev(major int64, minor int64) uint32 {
-       return uint32(unix.Mkdev(uint32(major), uint32(minor)))
+func Mkdev(major int64, minor int64) uint64 {
+       return unix.Mkdev(uint32(major), uint32(minor))
 }

[akhramov]

Makes sense, thanks

[thaJeztah]

LGTM, thanks!

[thaJeztah]

@samuelkarp @AkihiroSuda ptal