webp fix v1

internal/storage/gif_test.go

@@ -0,0 +1,86 @@
+package storage
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/gif"
+	"testing"
+)
+
+// buildGIF 生成指定帧数的动画 GIF。
+func buildGIF(t *testing.T, frames int) []byte {
+	t.Helper()
+	g := &gif.GIF{}
+	for i := 0; i < frames; i++ {
+		pal := color.Palette{color.Black, color.White}
+		img := image.NewPaletted(image.Rect(0, 0, 4, 4), pal)
+		if i%2 == 1 {
+			for y := 0; y < 4; y++ {
+				for x := 0; x < 4; x++ {
+					img.SetColorIndex(x, y, 1)
+				}
+			}
+		}
+		g.Image = append(g.Image, img)
+		g.Delay = append(g.Delay, 10)
+	}
+	var b bytes.Buffer
+	if err := gif.EncodeAll(&b, g); err != nil {
+		t.Fatalf("encode gif: %v", err)
+	}
+	return b.Bytes()
+}
+
+func TestGIFFrameCount(t *testing.T) {
+	cases := []struct {
+		name   string
+		frames int
+	}{
+		{"单帧", 1},
+		{"多帧", 12},
+		{"恰好等于上限", maxGIFFrames},
+		{"超过上限", maxGIFFrames + 1},
+	}
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			data := buildGIF(t, c.frames)
+			if got := gifFrameCount(data); got != c.frames {
+				t.Fatalf("gifFrameCount = %d, want %d", got, c.frames)
+			}
+		})
+	}
+}
+
+// 帧数统计必须能承受构造超大 GIF 的场景而不过度消耗内存。
+func TestGIFFrameCount_RejectsGarbage(t *testing.T) {
+	cases := map[string][]byte{
+		"空数据":     nil,
+		"非 GIF":   []byte("not a gif at all, just some bytes"),
+		"仅有文件头":   []byte("GIF89a"),
+		"截断的 LSD": []byte("GIF89a\x01\x00"),
+		"截断的色表":   append([]byte("GIF89a"), bytes.Repeat([]byte{0xFF}, 8)...),
+	}
+	for name, data := range cases {
+		t.Run(name, func(t *testing.T) {
+			if n := gifFrameCount(data); n < 0 || n > 3 {
+				t.Fatalf("gifFrameCount = %d, out of sane range", n)
+			}
+		})
+	}
+}
+
+// 转换入口在帧数超限时必须返回错误（而不是把超大 GIF 丢给 cwebp）。
+// 注意本机无 cwebp 时该测试只能覆盖「帧数检查发生在 LookPath 之后」这条路径，
+// 故直接针对判定逻辑断言，不依赖外部二进制。
+func TestGIFFrameLimitConstant(t *testing.T) {
+	if maxGIFFrames <= 0 {
+		t.Fatalf("maxGIFFrames = %d, must be positive", maxGIFFrames)
+	}
+	if gifFrameCount(buildGIF(t, maxGIFFrames+1)) <= maxGIFFrames {
+		t.Fatal("oversized GIF should be detected as over limit")
+	}
+	if gifFrameCount(buildGIF(t, 3)) > maxGIFFrames {
+		t.Fatal("small GIF should not be flagged as over limit")
+	}
+}