impl last error

_cgo/types.h

@@ -21,6 +21,8 @@
   WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 
+#include <stdbool.h>
+
 typedef struct exif_value {
 	char *name;
 	char *value;
@@ -30,3 +32,8 @@ typedef struct exif_value {
 typedef struct exif_stack {
 	struct exif_value* head;
 } exif_stack_t;
+
+typedef struct logging_option {
+  bool show_debug_message;
+  bool detail_error;
+} logging_option_t;

exif.go

@@ -33,7 +33,8 @@ package exif
 exif_value_t* pop_exif_value(exif_stack_t *);
 void free_exif_value(exif_value_t* n);
 exif_stack_t* exif_dump(ExifData *);
-void set_exif_log(ExifLog *log);
+void set_exif_log(ExifLog *log, logging_option_t* opt);
+ExifLogCode last_exif_log_code();
 */
 import "C"
 
@@ -48,13 +49,16 @@ import (
 var (
 	ErrNoExifData      = errors.New(`no EXIF data found`)
 	ErrFoundExifInData = errors.New(`found EXIF header. OK to call Parse`)
+	ErrNoMemory        = errors.New(`not enough memory`)
+	ErrCorruptData     = errors.New(`data provided does not follow the specification`)
 )
 
 // Data stores the EXIF tags of a file.
 type Data struct {
 	exifLoader     *C.ExifLoader
 	exifLog        *C.ExifLog
 	loggingEnabled bool
+	option         *LoggingOption
 	Tags           map[string]string
 }
 
@@ -116,9 +120,16 @@ func (d *Data) Write(p []byte) (n int, err error) {
 		runtime.SetFinalizer(d, (*Data).cleanup)
 	}
 	if d.loggingEnabled && d.exifLog == nil {
+		if d.option == nil {
+			d.option = &LoggingOption{}
+		}
 		d.exifLog = C.exif_log_new()
 		C.exif_loader_log(d.exifLoader, d.exifLog)
-		C.set_exif_log(d.exifLog)
+		opt := C.logging_option_t{
+			show_debug_message: (C.bool)(d.option.ShowDebugMessage),
+			detail_error:       (C.bool)(d.option.DetailError),
+		}
+		C.set_exif_log(d.exifLog, (*C.logging_option_t)(unsafe.Pointer(&opt)))
 		C.exif_log_ref(d.exifLog)
 		// cleanup will be defered by above
 	}
@@ -128,7 +139,17 @@ func (d *Data) Write(p []byte) (n int, err error) {
 	if res == 1 {
 		return len(p), nil
 	}
-	return len(p), ErrFoundExifInData
+
+	// if logging not enabled, code is always EXIF_LOG_CODE_NONE. so return ErrFoundExifInData(successful value)
+	code := C.last_exif_log_code()
+	if code == C.EXIF_LOG_CODE_NO_MEMORY {
+		err = ErrNoMemory
+	} else if code == C.EXIF_LOG_CODE_CORRUPT_DATA {
+		err = ErrCorruptData
+	} else {
+		err = ErrFoundExifInData
+	}
+	return len(p), err
 }
 
 // Parse finalizes the data loader and sets the tags
@@ -158,12 +179,12 @@ func (d *Data) cleanup() {
 	}
 }
 
-type LoggingOption struct{}
+type LoggingOption struct {
+	ShowDebugMessage bool
+	DetailError      bool
+}
 
 func (d *Data) EnableLogging(opt *LoggingOption) {
 	d.loggingEnabled = true
-}
-
-func (d *Data) DisableLogging() {
-	d.loggingEnabled = false
+	d.option = opt
 }

exif_c.c

@@ -108,12 +108,35 @@ exif_stack_t* exif_dump(ExifData* data) {
   return user_data;
 }
 
-void show_log(ExifLog *log, ExifLogCode code, const char *domain, const char *format, va_list args, void* _) {
-	printf("domain %s: %s: %s\n  ", domain, exif_log_code_get_title(code),	exif_log_code_get_message (code));
-	vprintf(format, args);
-	puts("");
+typedef struct {
+  logging_option_t* opt;
+  ExifLogCode* last_code;
+} logfunc_data_t;
+
+void show_log(ExifLog *log, ExifLogCode code, const char *domain, const char *format, va_list args, void* vdata) {
+  logfunc_data_t* data = vdata;
+  if (data->opt->show_debug_message) {
+    printf("domain %s: %s: %s\n  ", domain, exif_log_code_get_title(code),	exif_log_code_get_message (code));
+	  vprintf(format, args);
+	  puts("");
+  }
+  if (data->opt->detail_error && code != EXIF_LOG_CODE_NONE) {
+    *(data->last_code) = code;
+  }
+}
+
+logfunc_data_t* logfunc_data() { // hold logfunc_data_t like global val
+  static ExifLogCode code = EXIF_LOG_CODE_NONE;
+  static logfunc_data_t data = {NULL, &code};
+  return &data;
+}
+
+ExifLogCode last_exif_log_code() {
+  return *(logfunc_data()->last_code);
 }
 
-void set_exif_log(ExifLog *log) {
-	exif_log_set_func(log, show_log, NULL);
+void set_exif_log(ExifLog *log, logging_option_t* opt) {
+  logfunc_data_t* d = logfunc_data();
+  d->opt = opt;
+	exif_log_set_func(log, show_log, d);
 }

exif_test.go

@@ -2,10 +2,11 @@ package exif
 
 import (
 	"fmt"
-	"github.com/stretchr/testify/assert"
 	"io"
 	"os"
 	"testing"
+
+	"github.com/stretchr/testify/assert"
 )
 
 func TestOpen(t *testing.T) {
@@ -76,3 +77,14 @@ func TestGetLatitude(t *testing.T) {
 
 	assert.Equal(t, "25, 21, 32.6101", latitude)
 }
+
+func TestBrokenExif(t *testing.T) {
+	exif := New()
+	exif.EnableLogging(&LoggingOption{ShowDebugMessage: true, DetailError: true})
+	file, err := os.Open("_examples/resources/broken_exif.jpg")
+	assert.NoError(t, err)
+	defer file.Close()
+	_, err = io.Copy(exif, file)
+	assert.Error(t, err)
+	assert.Equal(t, ErrCorruptData, err)
+}