first release

2026-09-18 13:05:49 +08:00
commit b327bc1230
123 changed files with 30003 additions and 0 deletions
@@ -0,0 +1,215 @@
+package exif
+
+import (
+	"bytes"
+	"encoding/binary"
+	"math"
+	"testing"
+	"time"
+)
+
+// buildTIFF 拼出小端 TIFF（IFD0 + ExifIFD + GPS IFD），JPEG 与 HEIC 共用。
+func buildTIFF(lat, lon float64, shot string) []byte {
+	tiff := &bytes.Buffer{}
+	tiff.WriteString("II")
+	binary.Write(tiff, binary.LittleEndian, uint16(0x002A))
+	binary.Write(tiff, binary.LittleEndian, uint32(8)) // IFD0 偏移
+
+	const (
+		ifd0Off = 8
+		exifOff = ifd0Off + 30 // IFD0: 2 条目 = 2 + 24 + 4
+		shotOff = exifOff + 18 // ExifIFD: 1 条目 = 2 + 12 + 4
+		shotLen = len("2006:01:02 15:04:05") + 1
+		gpsOff  = shotOff + shotLen
+		ratOff  = gpsOff + 54 // GPS IFD: 4 条目 = 2 + 48 + 4
+	)
+	// IFD0
+	binary.Write(tiff, binary.LittleEndian, uint16(2))
+	tiff.Write(entryBytes(0x8769, 4, 1, uint32(exifOff)))
+	tiff.Write(entryBytes(0x8825, 4, 1, uint32(gpsOff)))
+	binary.Write(tiff, binary.LittleEndian, uint32(0))
+	// ExifIFD：DateTimeOriginal
+	binary.Write(tiff, binary.LittleEndian, uint16(1))
+	tiff.Write(entryBytes(0x9003, 2, uint32(shotLen), uint32(shotOff)))
+	binary.Write(tiff, binary.LittleEndian, uint32(0))
+	tiff.WriteString(shot + "\x00")
+	// GPS IFD
+	binary.Write(tiff, binary.LittleEndian, uint16(4))
+	latRef, lonRef := byte('N'), byte('E')
+	alat, alon := math.Abs(lat), math.Abs(lon)
+	if lat < 0 {
+		latRef = 'S'
+	}
+	if lon < 0 {
+		lonRef = 'W'
+	}
+	tiff.Write(entryBytes(1, 2, 2, uint32(latRef)))
+	tiff.Write(entryBytes(2, 5, 3, uint32(ratOff)))
+	tiff.Write(entryBytes(3, 2, 2, uint32(lonRef)))
+	tiff.Write(entryBytes(4, 5, 3, uint32(ratOff+24)))
+	binary.Write(tiff, binary.LittleEndian, uint32(0))
+	writeDMS(tiff, alat)
+	writeDMS(tiff, alon)
+	return tiff.Bytes()
+}
+
+// buildJPEG 拼一张最小 JPEG：SOI + APP1(EXIF) + EOI。
+// 只有 EXIF 段是真的，后面不需要有效图像数据——解析器读到 APP1 就返回。
+func buildJPEG(t *testing.T, lat, lon float64, shot string) []byte {
+	t.Helper()
+	body := &bytes.Buffer{}
+	body.Write([]byte("Exif\x00\x00"))
+	body.Write(buildTIFF(lat, lon, shot))
+	out := &bytes.Buffer{}
+	out.Write([]byte{0xFF, 0xD8, 0xFF, 0xE1})
+	binary.Write(out, binary.BigEndian, uint16(body.Len()+2))
+	out.Write(body.Bytes())
+	out.Write([]byte{0xFF, 0xD9})
+	return out.Bytes()
+}
+
+// mkBox 拼一个 ISO BMFF 盒子（32 位长度）。
+func mkBox(typ string, payload []byte) []byte {
+	b := make([]byte, 8+len(payload))
+	binary.BigEndian.PutUint32(b[0:4], uint32(8+len(payload)))
+	copy(b[4:8], typ)
+	copy(b[8:], payload)
+	return b
+}
+
+// buildHEIC 拼一个最小 HEIC：ftyp + meta(iinf + iloc) + Exif item。
+// Exif item 放在文件末尾，iloc 里填它的绝对偏移——真实文件也是这样定位的。
+func buildHEIC(t *testing.T, lat, lon float64, shot string) []byte {
+	t.Helper()
+	tiff := buildTIFF(lat, lon, shot)
+	// HEIF 的 Exif item = 4 字节 TIFF 偏移 + TIFF 本体
+	item := append([]byte{0, 0, 0, 4}, tiff...)
+	ftyp := mkBox("ftyp", append([]byte("heic"), []byte{0, 0, 0, 0, 'h', 'e', 'i', 'c'}...))
+
+	// infe v2：version+flags + item_ID + protection + item_type + 空名字
+	infe := mkBox("infe", append([]byte{2, 0, 0, 0, 0, 1, 0, 0}, append([]byte("Exif"), 0)...))
+	iinf := mkBox("iinf", append([]byte{0, 0, 0, 0, 0, 1}, infe...))
+
+	// iloc v0：offsetSize=4 lengthSize=4 baseSize=0，一条数据段
+	ilocPayload := []byte{0, 0, 0, 0, 0x44, 0x00, 0, 1, 0, 1, 0, 0, 0, 1}
+	offPos := len(ilocPayload)
+	ilocPayload = append(ilocPayload, 0, 0, 0, 0) // extent_offset 待回填
+	ilocPayload = append(ilocPayload,
+		byte(len(item)>>24), byte(len(item)>>16), byte(len(item)>>8), byte(len(item)))
+	iloc := mkBox("iloc", ilocPayload)
+
+	meta := mkBox("meta", append([]byte{0, 0, 0, 0}, append(iinf, iloc...)...))
+	// extent_offset 的绝对位置：meta 头(8) + fullbox(4) + iinf + iloc 头(8) + 段内偏移
+	pos := 8 + 4 + len(iinf) + 8 + offPos
+	binary.BigEndian.PutUint32(meta[pos:pos+4], uint32(len(ftyp)+len(meta)))
+
+	out := &bytes.Buffer{}
+	out.Write(ftyp)
+	out.Write(meta)
+	out.Write(item)
+	return out.Bytes()
+}
+
+func entryBytes(tag, typ uint16, count uint32, val uint32) []byte {
+	b := make([]byte, 12)
+	binary.LittleEndian.PutUint16(b[0:2], tag)
+	binary.LittleEndian.PutUint16(b[2:4], typ)
+	binary.LittleEndian.PutUint32(b[4:8], count)
+	binary.LittleEndian.PutUint32(b[8:12], val)
+	return b
+}
+
+// writeDMS 把十进制度拆成 度/分/秒 三个 rational。
+func writeDMS(w *bytes.Buffer, v float64) {
+	d := math.Floor(v)
+	m := math.Floor((v - d) * 60)
+	s := ((v-d)*60 - m) * 60
+	for _, p := range [][2]uint32{{uint32(d), 1}, {uint32(m), 1}, {uint32(math.Round(s * 10000)), 10000}} {
+		binary.Write(w, binary.LittleEndian, p[0])
+		binary.Write(w, binary.LittleEndian, p[1])
+	}
+}
+
+func TestParseGPSAndTime(t *testing.T) {
+	// 大理古城附近，EXIF 存的是 WGS-84
+	jpg := buildJPEG(t, 25.6890, 100.1560, "2026:08:14 12:40:33")
+	info, err := Parse(bytes.NewReader(jpg))
+	if err != nil {
+		t.Fatalf("解析失败: %v", err)
+	}
+	if !info.HasGPS {
+		t.Fatal("没读到 GPS")
+	}
+	if math.Abs(info.Lat-25.6890) > 1e-4 || math.Abs(info.Lon-100.1560) > 1e-4 {
+		t.Fatalf("坐标不对: %v, %v", info.Lat, info.Lon)
+	}
+	if !info.HasTime {
+		t.Fatal("没读到拍摄时间")
+	}
+	want := time.Date(2026, 8, 14, 12, 40, 33, 0, time.Local)
+	if !info.ShotAt.Equal(want) {
+		t.Fatalf("时间不对: %v 期望 %v", info.ShotAt, want)
+	}
+}
+
+func TestParseSouthWest(t *testing.T) {
+	jpg := buildJPEG(t, -33.8688, -70.6693, "2025:01:02 03:04:05")
+	info, err := Parse(bytes.NewReader(jpg))
+	if err != nil {
+		t.Fatalf("解析失败: %v", err)
+	}
+	if info.Lat > 0 || info.Lon > 0 {
+		t.Fatalf("南纬/西经应该是负数: %v, %v", info.Lat, info.Lon)
+	}
+}
+
+func TestParseRejectsNonImage(t *testing.T) {
+	if _, err := Parse(bytes.NewReader([]byte("PNG\x89 not a jpeg"))); err == nil {
+		t.Fatal("非图片应该报错")
+	}
+	bare := []byte{0xFF, 0xD8, 0xFF, 0xD9} // 合法 JPEG 但没有 EXIF 段
+	if _, err := Parse(bytes.NewReader(bare)); err == nil {
+		t.Fatal("没有 EXIF 应该报错")
+	}
+}
+
+func TestParseHEIC(t *testing.T) {
+	// 喜洲古镇附近，EXIF 存 WGS-84
+	heic := buildHEIC(t, 25.8560, 100.1310, "2026:08:15 15:43:00")
+	info, err := Parse(bytes.NewReader(heic))
+	if err != nil {
+		t.Fatalf("HEIC 解析失败: %v", err)
+	}
+	if !info.HasGPS || math.Abs(info.Lat-25.8560) > 1e-4 || math.Abs(info.Lon-100.1310) > 1e-4 {
+		t.Fatalf("坐标不对: %v, %v", info.Lat, info.Lon)
+	}
+	if !info.HasTime || info.ShotAt.Format("2006-01-02 15:04:05") != "2026-08-15 15:43:00" {
+		t.Fatalf("时间不对: %v", info.ShotAt)
+	}
+}
+
+func TestParseHEICNoExifItem(t *testing.T) {
+	// 有 meta/iinf/iloc 但没有 Exif item：应报「没有 EXIF」而不是崩
+	infe := mkBox("infe", append([]byte{2, 0, 0, 0, 0, 1, 0, 0}, append([]byte("hvc1"), 0)...))
+	iinf := mkBox("iinf", append([]byte{0, 0, 0, 0, 0, 1}, infe...))
+	meta := mkBox("meta", append([]byte{0, 0, 0, 0}, iinf...))
+	ftyp := mkBox("ftyp", append([]byte("heic"), []byte{0, 0, 0, 0, 'h', 'e', 'i', 'c'}...))
+	buf := append(ftyp, meta...)
+	if _, err := Parse(bytes.NewReader(buf)); err == nil {
+		t.Fatal("没有 Exif item 应该报错")
+	}
+}
+
+func TestParseTruncatedDoesNotPanic(t *testing.T) {
+	// 截断到各种长度都不该 panic（上传中断、文件损坏在真实世界里都会出现）
+	full := buildHEIC(t, 25.8560, 100.1310, "2026:08:15 15:43:00")
+	for _, n := range []int{1, 5, 12, 20, len(full) / 2, len(full) - 1} {
+		if n <= len(full) {
+			_, _ = Parse(bytes.NewReader(full[:n]))
+		}
+	}
+	jpg := buildJPEG(t, 25.6890, 100.1560, "2026:08:14 12:40:33")
+	for _, n := range []int{1, 4, 10, len(jpg) / 2, len(jpg) - 1} {
+		_, _ = Parse(bytes.NewReader(jpg[:n]))
+	}
+}