extracts FS interfaces into fsapi package and consolidates impls (#1477)

Signed-off-by: Adrian Cole <adrian@tetrate.io>
Signed-off-by: Edoardo Vacchi <evacchi@users.noreply.github.com>
Co-authored-by: Edoardo Vacchi <evacchi@users.noreply.github.com>

internal/sysfs/stat_bsd.go

@@ -0,0 +1,60 @@
+//go:build (amd64 || arm64) && (darwin || freebsd)
+
+package sysfs
+
+import (
+	"io/fs"
+	"os"
+	"syscall"
+
+	"github.com/tetratelabs/wazero/internal/fsapi"
+	"github.com/tetratelabs/wazero/internal/platform"
+)
+
+func lstat(path string) (fsapi.Stat_t, syscall.Errno) {
+	if t, err := os.Lstat(path); err != nil {
+		return fsapi.Stat_t{}, platform.UnwrapOSError(err)
+	} else {
+		return statFromFileInfo(t), 0
+	}
+}
+
+func stat(path string) (fsapi.Stat_t, syscall.Errno) {
+	if t, err := os.Stat(path); err != nil {
+		return fsapi.Stat_t{}, platform.UnwrapOSError(err)
+	} else {
+		return statFromFileInfo(t), 0
+	}
+}
+
+func statFile(f *os.File) (fsapi.Stat_t, syscall.Errno) {
+	return defaultStatFile(f)
+}
+
+func inoFromFileInfo(_ string, t fs.FileInfo) (ino uint64, err syscall.Errno) {
+	if d, ok := t.Sys().(*syscall.Stat_t); ok {
+		ino = d.Ino
+	}
+	return
+}
+
+func statFromFileInfo(t fs.FileInfo) fsapi.Stat_t {
+	if d, ok := t.Sys().(*syscall.Stat_t); ok {
+		st := fsapi.Stat_t{}
+		st.Dev = uint64(d.Dev)
+		st.Ino = d.Ino
+		st.Uid = d.Uid
+		st.Gid = d.Gid
+		st.Mode = t.Mode()
+		st.Nlink = uint64(d.Nlink)
+		st.Size = d.Size
+		atime := d.Atimespec
+		st.Atim = atime.Sec*1e9 + atime.Nsec
+		mtime := d.Mtimespec
+		st.Mtim = mtime.Sec*1e9 + mtime.Nsec
+		ctime := d.Ctimespec
+		st.Ctim = ctime.Sec*1e9 + ctime.Nsec
+		return st
+	}
+	return StatFromDefaultFileInfo(t)
+}