fuzzing, template, unsafe

Author: postmannen

template/02-call-function/main.go

@@ -0,0 +1,29 @@
+package main
+
+import (
+	"os"
+	"text/template"
+)
+
+func main() {
+
+	t := `{{ horse 32 }}`
+
+	echo := func(in any) any {
+		return in
+	}
+
+	funcs := template.FuncMap{
+		"horse": echo,
+	}
+
+	tmpl, err := template.New("test").Funcs(funcs).Parse(t)
+	if err != nil {
+		panic(err)
+	}
+
+	err = tmpl.Execute(os.Stdout, nil)
+	if err != nil {
+		panic(err)
+	}
+}

testing/10-fuzz/convert_test.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"testing"
+	"unicode/utf8"
+)
+
+func FuzzConvert(f *testing.F) {
+	f.Add("ABCD")
+
+	f.Fuzz(func(t *testing.T, orig string) {
+		r := Reverse(orig)
+		rr := Reverse(r)
+
+		//t.Log(s)
+
+		if utf8.ValidString(orig) && !utf8.ValidString(r) {
+			t.Errorf("Reverse produced invalid UTF-8 string %q", r)
+		}
+
+		if orig != rr {
+			t.Errorf("double reverse failed: Orig: %x, double reverse: %x\n", orig, rr)
+		}
+	})
+}

testing/10-fuzz/main.go

@@ -0,0 +1,36 @@
+package main
+
+import (
+	"fmt"
+	"unicode/utf8"
+)
+
+func Reverse(s string) string {
+	// var result string
+	// for _, v := range s {
+	// 	result = string(v) + result
+	// }
+
+	b := []byte(s)
+	// if len(b) <= 1 {
+	// 	return s
+	// }
+
+	for i, j := 0, len(b)-1; i < len(b)/2; i, j = i+1, j-1 {
+		b[i], b[j] = b[j], b[i]
+	}
+
+	if !utf8.ValidString(string(b)) {
+		return s
+	}
+
+	return string(b)
+}
+
+func main() {
+	s := "Hesten spiser gress og ikke andre dyr som f.eks. apekatter."
+	fmt.Printf("%q\n", s)
+	fmt.Printf("%q\n", Reverse(s))
+	fmt.Printf("%q\n", Reverse(Reverse(s)))
+
+}

unsafe/10-edit-struct-with-unsafe/main.go

@@ -0,0 +1,24 @@
+package main
+
+import (
+	"fmt"
+	"unsafe"
+)
+
+type Programmer struct {
+	name     string
+	language string
+}
+
+func main() {
+	p := Programmer{"stefno", "go"}
+	fmt.Println(p)
+
+	name := (*string)(unsafe.Pointer(&p))
+	*name = "qcrao"
+
+	lang := (*string)(unsafe.Pointer(uintptr(unsafe.Pointer(&p)) + unsafe.Offsetof(p.language)))
+	*lang = "Golang"
+
+	fmt.Println(p)
+}

unsafe/11/main.go

@@ -0,0 +1,18 @@
+package main
+
+import (
+	"fmt"
+	"reflect"
+	"unsafe"
+)
+
+func main() {
+	aString := [8]byte{'a', 's', 't', 'r', 'i', 'n', 'g'}
+	upStr := (uintptr)(unsafe.Pointer(&aString))
+
+	sh := reflect.SliceHeader{Data: upStr, Len: len(aString)}
+
+	s := *(*string)(unsafe.Pointer(&sh))
+
+	fmt.Printf("%v, %T\n", s, s)
+}