Add staticcheck tool

vendor/honnef.co/go/tools/staticcheck/sa1031/sa1031.go

@@ -0,0 +1,81 @@
+package sa1031
+
+import (
+	"go/constant"
+	"go/token"
+
+	"honnef.co/go/tools/analysis/callcheck"
+	"honnef.co/go/tools/analysis/lint"
+	"honnef.co/go/tools/go/ir"
+	"honnef.co/go/tools/go/ir/irutil"
+	"honnef.co/go/tools/internal/passes/buildir"
+	"honnef.co/go/tools/knowledge"
+
+	"golang.org/x/tools/go/analysis"
+)
+
+var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
+	Analyzer: &analysis.Analyzer{
+		Name:     "SA1031",
+		Requires: []*analysis.Analyzer{buildir.Analyzer},
+		Run:      callcheck.Analyzer(checkEncodeRules),
+	},
+	Doc: &lint.RawDocumentation{
+		Title: `Overlapping byte slices passed to an encoder`,
+		Text: `In an encoding function of the form \'Encode(dst, src)\', \'dst\' and
+\'src\' were found to reference the same memory. This can result in
+\'src\' bytes being overwritten before they are read, when the encoder
+writes more than one byte per \'src\' byte.`,
+		Since:    "2024.1",
+		Severity: lint.SeverityWarning,
+		MergeIf:  lint.MergeIfAny,
+	},
+})
+
+var Analyzer = SCAnalyzer.Analyzer
+
+var checkEncodeRules = map[string]callcheck.Check{
+	"encoding/ascii85.Encode":            checkNonOverlappingDstSrc(knowledge.Arg("encoding/ascii85.Encode.dst"), knowledge.Arg("encoding/ascii85.Encode.src")),
+	"(*encoding/base32.Encoding).Encode": checkNonOverlappingDstSrc(knowledge.Arg("(*encoding/base32.Encoding).Encode.dst"), knowledge.Arg("(*encoding/base32.Encoding).Encode.src")),
+	"(*encoding/base64.Encoding).Encode": checkNonOverlappingDstSrc(knowledge.Arg("(*encoding/base64.Encoding).Encode.dst"), knowledge.Arg("(*encoding/base64.Encoding).Encode.src")),
+	"encoding/hex.Encode":                checkNonOverlappingDstSrc(knowledge.Arg("encoding/hex.Encode.dst"), knowledge.Arg("encoding/hex.Encode.src")),
+}
+
+func checkNonOverlappingDstSrc(dstArg, srcArg int) callcheck.Check {
+	return func(call *callcheck.Call) {
+		dst := call.Args[dstArg]
+		src := call.Args[srcArg]
+		_, dstConst := irutil.Flatten(dst.Value.Value).(*ir.Const)
+		_, srcConst := irutil.Flatten(src.Value.Value).(*ir.Const)
+		if dstConst || srcConst {
+			// one of the arguments is nil, therefore overlap is not possible
+			return
+		}
+		if dst.Value == src.Value {
+			// simple case of f(b, b)
+			dst.Invalid("overlapping dst and src")
+			return
+		}
+		dstSlice, ok := irutil.Flatten(dst.Value.Value).(*ir.Slice)
+		if !ok {
+			return
+		}
+		srcSlice, ok := irutil.Flatten(src.Value.Value).(*ir.Slice)
+		if !ok {
+			return
+		}
+		if irutil.Flatten(dstSlice.X) != irutil.Flatten(srcSlice.X) {
+			// differing underlying arrays, all is well
+			return
+		}
+		l1 := irutil.Flatten(dstSlice.Low)
+		l2 := irutil.Flatten(srcSlice.Low)
+		c1, ok1 := l1.(*ir.Const)
+		c2, ok2 := l2.(*ir.Const)
+		if l1 == l2 || (ok1 && ok2 && constant.Compare(c1.Value, token.EQL, c2.Value)) {
+			// dst and src are the same slice, and have the same lower bound
+			dst.Invalid("overlapping dst and src")
+			return
+		}
+	}
+}