v0.2.2 fixes: split only text sources, report a mode change once, don't block on open

fuzz_test.go

@@ -0,0 +1,61 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+type fuzzTarget struct {
+	Name  string            `toml:"name"`
+	Port  int64             `toml:"port"`
+	Ratio float64           `toml:"ratio"`
+	On    bool              `toml:"on"`
+	Tags  []string          `toml:"tags"`
+	IDs   []uint16          `toml:"ids"`
+	Meta  map[string]string `toml:"meta"`
+	Sub   struct {
+		Level string `toml:"level"`
+	} `toml:"sub"`
+}
+
+// Arguments never panic the parser, and what a load accepts decodes
+func FuzzLoadCLI(f *testing.F) {
+	for _, s := range []string{"--name=x", "--port\x009000", "--on\x00--tags=a,b", "-q\x00x\x00--\x00--name", "--sub.level\x00--on", "--ids=1,65536"} {
+		f.Add(s)
+	}
+	f.Fuzz(func(t *testing.T, s string) {
+		cfg, err := NewBuilder().WithTarget(&fuzzTarget{}).WithArgs(strings.Split(s, "\x00")).Build()
+		if err != nil {
+			return
+		}
+		if _, err := cfg.AsStruct(); err != nil {
+			t.Fatalf("accepted %q, then: %v", s, err)
+		}
+	})
+}
+
+// File contents never panic the loader, and what LoadFile accepts decodes
+func FuzzLoadFile(f *testing.F) {
+	for _, s := range []string{"name = \"x\"\nport = 1", "tags = \"a,b\"\n[sub]\nlevel = \"debug\"", "ids = [1, 2]\n[meta]\nk = \"v\"", "on = true # c\r\n"} {
+		f.Add([]byte(s))
+	}
+	// One file and one Config per worker: each LoadFile replaces the file source
+	path := filepath.Join(f.TempDir(), "c.toml")
+	cfg, err := NewBuilder().WithTarget(&fuzzTarget{}).Build()
+	if err != nil {
+		f.Fatal(err)
+	}
+	f.Fuzz(func(t *testing.T, data []byte) {
+		if err := os.WriteFile(path, data, 0600); err != nil {
+			t.Fatal(err)
+		}
+		if cfg.LoadFile(path) != nil {
+			return
+		}
+		if _, err := cfg.AsStruct(); err != nil {
+			t.Fatalf("accepted %q, then: %v", data, err)
+		}
+	})
+}