cmd/kgz: linter fixes.

cmd/kgz/main.go

@@ -8,12 +8,14 @@ import (
 	"flag"
 	"fmt"
 	"io"
+	"math"
 	"os"
 	"path/filepath"
 	"strings"
 
-	goutilslib "git.wntrmute.dev/kyle/goutils/lib"
 	"golang.org/x/sys/unix"
+
+	goutilslib "git.wntrmute.dev/kyle/goutils/lib"
 )
 
 const gzipExt = ".gz"
@@ -59,16 +61,61 @@ func buildKGExtra(uid, gid, mode uint32, ctimeS int64, ctimeNs int32) []byte {
 	}
 
 	// Wrap in gzip subfield: [ID1 ID2 LEN(lo) LEN(hi) PAYLOAD]
+	// Guard against payload length overflow to uint16 for the extra subfield length.
+	if len(payload) > int(math.MaxUint16) {
+		return nil
+	}
 	extra := make([]byte, 4+len(payload))
 	extra[0] = kgzExtraID[0]
 	extra[1] = kgzExtraID[1]
-	binary.LittleEndian.PutUint16(extra[2:], uint16(len(payload)))
+	binary.LittleEndian.PutUint16(extra[2:], uint16(len(payload)&0xFFFF)) //#nosec G115 - masked
 	copy(extra[4:], payload)
 	return extra
 }
 
+// clampToInt32 clamps an int value into the int32 range using a switch to
+// satisfy linters that prefer switch over if-else chains for ordered checks.
+func clampToInt32(v int) int32 {
+	switch {
+	case v > int(math.MaxInt32):
+		return math.MaxInt32
+	case v < int(math.MinInt32):
+		return math.MinInt32
+	default:
+		return int32(v)
+	}
+}
+
+// buildExtraForPath prepares the gzip Extra field for kgz by collecting
+// uid/gid/mode and ctime information, applying any overrides, and encoding it.
+func buildExtraForPath(st unix.Stat_t, path string, setUID, setGID int) []byte {
+	uid := st.Uid
+	gid := st.Gid
+	if setUID >= 0 {
+		if uint64(setUID) <= math.MaxUint32 {
+			uid = uint32(setUID & 0xFFFFFFFF) //#nosec G115 - masked
+		}
+	}
+	if setGID >= 0 {
+		if uint64(setGID) <= math.MaxUint32 {
+			gid = uint32(setGID & 0xFFFFFFFF) //#nosec G115 - masked
+		}
+	}
+	mode := uint32(st.Mode & 0o7777)
+
+	// Use portable helper to gather ctime
+	var cts int64
+	var ctns int32
+	if ft, err := goutilslib.LoadFileTime(path); err == nil {
+		cts = ft.Changed.Unix()
+		ctns = clampToInt32(ft.Changed.Nanosecond())
+	}
+
+	return buildKGExtra(uid, gid, mode, cts, ctns)
+}
+
 // parseKGExtra scans a gzip Extra blob and returns kgz metadata if present.
-func parseKGExtra(extra []byte) (uid, gid, mode uint32, ctimeS int64, ctimeNs int32, ok bool) {
+func parseKGExtra(extra []byte) (uint32, uint32, uint32, int64, int32, bool) {
 	i := 0
 	for i+4 <= len(extra) {
 		id1 := extra[i]
@@ -95,7 +142,16 @@ func parseKGExtra(extra []byte) (uid, gid, mode uint32, ctimeS int64, ctimeNs in
 			if s.Version != 1 {
 				return 0, 0, 0, 0, 0, false
 			}
-			return uint32(s.UID), uint32(s.GID), uint32(s.Mode), s.CTimeSec, s.CTimeNSec, true
+			// Validate ranges before converting from int -> uint32 to avoid overflow.
+			if s.UID < 0 || s.GID < 0 || s.Mode < 0 {
+				return 0, 0, 0, 0, 0, false
+			}
+			if uint64(s.UID) > math.MaxUint32 || uint64(s.GID) > math.MaxUint32 || uint64(s.Mode) > math.MaxUint32 {
+				return 0, 0, 0, 0, 0, false
+			}
+
+			return uint32(s.UID & 0xFFFFFFFF), uint32(s.GID & 0xFFFFFFFF),
+				uint32(s.Mode & 0xFFFFFFFF), s.CTimeSec, s.CTimeNSec, true //#nosec G115 - masked
 		}
 		i += l
 	}
@@ -111,7 +167,7 @@ func compress(path, target string, level int, includeExtra bool, setUID, setGID
 
 	// Gather file metadata
 	var st unix.Stat_t
-	if err := unix.Stat(path, &st); err != nil {
+	if err = unix.Stat(path, &st); err != nil {
 		return fmt.Errorf("stat source: %w", err)
 	}
 	fi, err := sourceFile.Stat()
@@ -132,23 +188,7 @@ func compress(path, target string, level int, includeExtra bool, setUID, setGID
 	// Set header metadata
 	gzipCompressor.ModTime = fi.ModTime()
 	if includeExtra {
-		uid := uint32(st.Uid)
+		gzipCompressor.Extra = buildExtraForPath(st, path, setUID, setGID)
-		gid := uint32(st.Gid)
-		if setUID >= 0 {
-			uid = uint32(setUID)
-		}
-		if setGID >= 0 {
-			gid = uint32(setGID)
-		}
-		mode := uint32(st.Mode & 0o7777)
-		// Use portable helper to gather ctime
-		var cts int64
-		var ctns int32
-		if ft, err := goutilslib.LoadFileTime(path); err == nil {
-			cts = ft.Changed.Unix()
-			ctns = int32(ft.Changed.Nanosecond())
-		}
-		gzipCompressor.Extra = buildKGExtra(uid, gid, mode, cts, ctns)
 	}
 	defer gzipCompressor.Close()