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utility.go
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utility.go
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package exif
import (
"fmt"
"io"
"math"
"github.com/dsoprea/go-logging"
"github.com/dsoprea/go-utility/v2/filesystem"
"github.com/dsoprea/go-exif/v3/common"
"github.com/dsoprea/go-exif/v3/undefined"
)
var (
utilityLogger = log.NewLogger("exif.utility")
)
// ExifTag is one simple representation of a tag in a flat list of all of them.
type ExifTag struct {
// IfdPath is the fully-qualified IFD path (even though it is not named as
// such).
IfdPath string `json:"ifd_path"`
// TagId is the tag-ID.
TagId uint16 `json:"id"`
// TagName is the tag-name. This is never empty.
TagName string `json:"name"`
// UnitCount is the recorded number of units constution of the value.
UnitCount uint32 `json:"unit_count"`
// TagTypeId is the type-ID.
TagTypeId exifcommon.TagTypePrimitive `json:"type_id"`
// TagTypeName is the type name.
TagTypeName string `json:"type_name"`
// Value is the decoded value.
Value interface{} `json:"value"`
// ValueBytes is the raw, encoded value.
ValueBytes []byte `json:"value_bytes"`
// Formatted is the human representation of the first value (tag values are
// always an array).
FormattedFirst string `json:"formatted_first"`
// Formatted is the human representation of the complete value.
Formatted string `json:"formatted"`
// ChildIfdPath is the name of the child IFD this tag represents (if it
// represents any). Otherwise, this is empty.
ChildIfdPath string `json:"child_ifd_path"`
}
// String returns a string representation.
func (et ExifTag) String() string {
return fmt.Sprintf(
"ExifTag<"+
"IFD-PATH=[%s] "+
"TAG-ID=(0x%02x) "+
"TAG-NAME=[%s] "+
"TAG-TYPE=[%s] "+
"VALUE=[%v] "+
"VALUE-BYTES=(%d) "+
"CHILD-IFD-PATH=[%s]",
et.IfdPath, et.TagId, et.TagName, et.TagTypeName, et.FormattedFirst,
len(et.ValueBytes), et.ChildIfdPath)
}
// GetFlatExifData returns a simple, flat representation of all tags.
func GetFlatExifData(exifData []byte, so *ScanOptions) (exifTags []ExifTag, med *MiscellaneousExifData, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
sb := rifs.NewSeekableBufferWithBytes(exifData)
exifTags, med, err = getFlatExifDataUniversalSearchWithReadSeeker(sb, so, false)
log.PanicIf(err)
return exifTags, med, nil
}
// RELEASE(dustin): GetFlatExifDataUniversalSearch is a kludge to allow univeral tag searching in a backwards-compatible manner. For the next release, undo this and simply add the flag to GetFlatExifData.
// GetFlatExifDataUniversalSearch returns a simple, flat representation of all
// tags.
func GetFlatExifDataUniversalSearch(exifData []byte, so *ScanOptions, doUniversalSearch bool) (exifTags []ExifTag, med *MiscellaneousExifData, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
sb := rifs.NewSeekableBufferWithBytes(exifData)
exifTags, med, err = getFlatExifDataUniversalSearchWithReadSeeker(sb, so, doUniversalSearch)
log.PanicIf(err)
return exifTags, med, nil
}
// RELEASE(dustin): GetFlatExifDataUniversalSearchWithReadSeeker is a kludge to allow using a ReadSeeker in a backwards-compatible manner. For the next release, drop this and refactor GetFlatExifDataUniversalSearch to take a ReadSeeker.
// GetFlatExifDataUniversalSearchWithReadSeeker returns a simple, flat
// representation of all tags given a ReadSeeker.
func GetFlatExifDataUniversalSearchWithReadSeeker(rs io.ReadSeeker, so *ScanOptions, doUniversalSearch bool) (exifTags []ExifTag, med *MiscellaneousExifData, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
exifTags, med, err = getFlatExifDataUniversalSearchWithReadSeeker(rs, so, doUniversalSearch)
log.PanicIf(err)
return exifTags, med, nil
}
// getFlatExifDataUniversalSearchWithReadSeeker returns a simple, flat
// representation of all tags given a ReadSeeker.
func getFlatExifDataUniversalSearchWithReadSeeker(rs io.ReadSeeker, so *ScanOptions, doUniversalSearch bool) (exifTags []ExifTag, med *MiscellaneousExifData, err error) {
defer func() {
if state := recover(); state != nil {
err = log.Wrap(state.(error))
}
}()
headerData := make([]byte, ExifSignatureLength)
if _, err = io.ReadFull(rs, headerData); err != nil {
if err == io.EOF {
return nil, nil, err
}
log.Panic(err)
}
eh, err := ParseExifHeader(headerData)
log.PanicIf(err)
im, err := exifcommon.NewIfdMappingWithStandard()
log.PanicIf(err)
ti := NewTagIndex()
if doUniversalSearch == true {
ti.SetUniversalSearch(true)
}
ebs := NewExifReadSeeker(rs)
ie := NewIfdEnumerate(im, ti, ebs, eh.ByteOrder)
exifTags = make([]ExifTag, 0)
visitor := func(ite *IfdTagEntry) (err error) {
// This encodes down to base64. Since this an example tool and we do not
// expect to ever decode the output, we are not worried about
// specifically base64-encoding it in order to have a measure of
// control.
valueBytes, err := ite.GetRawBytes()
if err != nil {
if err == exifundefined.ErrUnparseableValue {
return nil
}
log.Panic(err)
}
value, err := ite.Value()
if err != nil {
if err == exifcommon.ErrUnhandledUndefinedTypedTag {
value = exifundefined.UnparseableUnknownTagValuePlaceholder
} else if log.Is(err, exifcommon.ErrParseFail) == true {
utilityLogger.Warningf(nil,
"Could not parse value for tag [%s] (%04x) [%s].",
ite.IfdPath(), ite.TagId(), ite.TagName())
return nil
} else {
log.Panic(err)
}
}
et := ExifTag{
IfdPath: ite.IfdPath(),
TagId: ite.TagId(),
TagName: ite.TagName(),
UnitCount: ite.UnitCount(),
TagTypeId: ite.TagType(),
TagTypeName: ite.TagType().String(),
Value: value,
ValueBytes: valueBytes,
ChildIfdPath: ite.ChildIfdPath(),
}
et.Formatted, err = ite.Format()
log.PanicIf(err)
et.FormattedFirst, err = ite.FormatFirst()
log.PanicIf(err)
exifTags = append(exifTags, et)
return nil
}
med, err = ie.Scan(exifcommon.IfdStandardIfdIdentity, eh.FirstIfdOffset, visitor, nil)
log.PanicIf(err)
return exifTags, med, nil
}
// GpsDegreesEquals returns true if the two `GpsDegrees` are identical.
func GpsDegreesEquals(gi1, gi2 GpsDegrees) bool {
if gi2.Orientation != gi1.Orientation {
return false
}
degreesRightBound := math.Nextafter(gi1.Degrees, gi1.Degrees+1)
minutesRightBound := math.Nextafter(gi1.Minutes, gi1.Minutes+1)
secondsRightBound := math.Nextafter(gi1.Seconds, gi1.Seconds+1)
if gi2.Degrees < gi1.Degrees || gi2.Degrees >= degreesRightBound {
return false
} else if gi2.Minutes < gi1.Minutes || gi2.Minutes >= minutesRightBound {
return false
} else if gi2.Seconds < gi1.Seconds || gi2.Seconds >= secondsRightBound {
return false
}
return true
}