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