disabling cache; it's not really necessary.

conf/funcs_permspec.go

@@ -0,0 +1,123 @@
+package conf
+
+import (
+	`errors`
+	`io/fs`
+	`os`
+	`os/user`
+	`strconv`
+)
+
+// chmod applies the PermSpec.Mode to path.
+func (p *PermSpec) chmod(path string, isNew bool) (err error) {
+
+	if p.Mode == nil || (!isNew && p.explicitMode == false) {
+		return
+	}
+
+	if err = os.Chmod(path, *p.Mode); err != nil {
+		return
+	}
+
+	return
+}
+
+// chown applies the Permspec.User and PermSpec.Group to path.
+func (p *PermSpec) chown(path string) (err error) {
+
+	/*
+		ORIGINALLY, I thought I'd have to fetch the original UID/GID from fs.FileInfo.Sys().
+		Linux uses https://pkg.go.dev/syscall?GOOS=linux#Stat_t
+		macOS uses a https://pkg.go.dev/syscall?GOOS=darwin#Stat_t
+		Windows uses a https://pkg.go.dev/syscall?GOOS=windows#Win32FileAttributeData which is completely useless.
+		(And AIX, Plan9, JS don't have a Stat_t.)
+		But per os.Chown, a -1 means "do not change", which is what we want.
+	*/
+
+	if (p.realUid == -1) || (p.realGid == -1) {
+		// This evaluates as a no-op.
+		return
+	}
+
+	if err = os.Chown(path, p.realUid, p.realGid); err != nil {
+		return
+	}
+
+	return
+}
+
+// setMissing populates missing information from a PermSpec. It should only be invoked by the parent Perms.SetMissing.
+func (p *PermSpec) setMissing(isDir bool) (err error) {
+
+	var tmpUser *user.User
+	var tmpGroup *user.Group
+	var unameUnknown user.UnknownUserError
+	// var uidUnknown user.UnknownUserIdError
+	var gnameUnknown user.UnknownGroupError
+	// var gidUnknown user.UnknownGroupIdError
+
+	if p.idsSet {
+		return
+	}
+
+	// MODE
+	if p.Mode == nil {
+		p.Mode = new(fs.FileMode)
+		if isDir {
+			*p.Mode = fs.FileMode(0o0700)
+		} else {
+			*p.Mode = fs.FileMode(0o0600)
+		}
+	} else {
+		p.explicitMode = true
+	}
+
+	// OWNER/GROUP
+	// If nil, no change from current on-disk.
+	switch p.User {
+	case "":
+		p.realUid = p.parent.curUid
+	case "-1":
+		p.realUid = -1
+	default:
+		// Lookup, try username first then uid.
+		if tmpUser, err = user.Lookup(p.User); err != nil {
+			if errors.As(err, &unameUnknown) {
+				err = nil
+				if tmpUser, err = user.LookupId(p.User); err != nil {
+					return
+				}
+			} else {
+				return
+			}
+		}
+		if p.realUid, err = strconv.Atoi(tmpUser.Uid); err != nil {
+			return
+		}
+	}
+	switch p.Group {
+	case "":
+		p.realGid = p.parent.curGid
+	case "-1":
+		p.realGid = -1
+	default:
+		// Lookup, try groupname first then gid.
+		if tmpGroup, err = user.LookupGroup(p.Group); err != nil {
+			if errors.As(err, &gnameUnknown) {
+				err = nil
+				if tmpGroup, err = user.LookupGroupId(p.Group); err != nil {
+					return
+				}
+			} else {
+				return
+			}
+		}
+		if p.realGid, err = strconv.Atoi(tmpGroup.Gid); err != nil {
+			return
+		}
+	}
+
+	p.idsSet = true
+
+	return
+}