Make parsing of types and GPS tags more robust

Don't assume that we cannot encounter type IDs other than the specification says. It does happen. Also, don't assume that the string values for GPSProcessingMethod and GPSAreaInformation will always be correctly formatted strings.
mattiasw · Oct 20, 2014 · 84ddc9f · 84ddc9f
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Showing 5 changed files with 96 additions and 49 deletions.
diff --git a/bower.json b/bower.json
@@ -1,6 +1,6 @@
 {
   "name": "exifreader",
-  "version": "1.1.0",
+  "version": "1.1.1",
   "homepage": "https://github.com/mattiasw/ExifReader",
   "authors": [
     "Mattias Wallander <mattias@wallander.eu>"

diff --git a/component.json b/component.json
@@ -2,7 +2,7 @@
   "name": "exifreader",
   "repo": "mattiasw/ExifReader",
   "description": "Client-side Exif parser",
-  "version": "1.1.0",
+  "version": "1.1.1",
   "keywords": ["exif", "image", "jpg", "jpeg", "meta"],
   "dependencies": {},
   "license": "GNU LGPL",

diff --git a/js/ExifReader.js b/js/ExifReader.js
diff --git a/spec/ExifReader.spec.coffee b/spec/ExifReader.spec.coffee
@@ -1,7 +1,7 @@
 ###
-# ExifReader 1.1.0
+# ExifReader 1.1.1
 # http://github.com/mattiasw/exifreader
-# Copyright (C) 2011  Mattias Wallander <mattias@wallander.eu>
+# Copyright (C) 2011-2014  Mattias Wallander <mattias@wallander.eu>
 # Licensed under the GNU Lesser General Public License version 3 or later
 # See license text at http://www.gnu.org/licenses/lgpl.txt
 ###
@@ -230,6 +230,11 @@ describe 'ExifReader', ->
     @exif._dataView = getDataView '\x47\x11\x00\x02\x00\x00\x00\x06\x00\x00\x00\x0c\x41\x42\x43\x44\x45\x00'
     expect(@exif._readTag('0th', 0).description).toEqual 'ABCDE'
 
+  it 'should be able to handle tag with faulty type', ->
+    @exif._tagNames['0th'][0x4711] = 'MyFaultyTypeTag'
+    @exif._dataView = getDataView '\x47\x11\x00\x08\x00\x00\x00\x00'
+    expect(@exif._readTag('0th', 0)).toBeUndefined()
+
   it 'should return undefined value for undefined tag names', ->
     exif = @exif
     expect(exif.getTagValue('MyUndefinedTagName')).toBeUndefined()
@@ -317,6 +322,14 @@ describe 'ExifReader', ->
     @exif._dataView = getDataView '\x92\x86\x00\x07\x00\x00\x00\x08\x00\x00\x00\x0c\x00\x00\x00\x00\x00\x00\x00\x00'
     expect(@exif._readTag('exif', 0).description).toEqual '[Undefined encoding]'
 
+  it 'should report correct name for FNumber', ->
+    @exif._dataView = getDataView '\x82\x9d\x00\x05\x00\x00\x00\x01\x00\x00\x00\x0c\x00\x00\x01\x02\x00\x00\x03\x04'
+    expect(@exif._readTag('exif', 0).name).toEqual 'FNumber'
+
+  it 'should report correct description for FNumber', ->
+    @exif._dataView = getDataView '\x82\x9d\x00\x05\x00\x00\x00\x01\x00\x00\x00\x0c\x00\x00\x01\x02\x00\x00\x03\x04'
+    expect(@exif._readTag('exif', 0).description).toEqual 0x102 / 0x304
+
   it 'should report correct description for ExposureProgram', ->
     @exif._dataView = getDataView '\x88\x22\x00\x03\x00\x00\x00\x01\x00\x00\x00\x00'
     expect(@exif._readTag('exif', 0).description).toEqual 'Undefined'
@@ -583,6 +596,10 @@ describe 'ExifReader', ->
     @exif._dataView = getDataView '\x00\x00\x00\x01\x00\x00\x00\x04\x02\x02\x00\x00'
     expect(@exif._readTag('gps', 0).description).toEqual 'Version 2.2'
 
+  it 'should handle empty GPSVersionID', ->
+    @exif._dataView = getDataView '\x00\x00\x00\x01\x00\x00\x00\x01\x00'
+    expect(@exif._readTag('gps', 0).description).toEqual 'Unknown'
+
   it 'should report correct description for GPSLatitudeRef', ->
     @exif._dataView = getDataView '\x00\x01\x00\x02\x00\x00\x00\x02N\x00\x00\x00'
     expect(@exif._readTag('gps', 0).description).toEqual 'North latitude'
@@ -707,6 +724,10 @@ describe 'ExifReader', ->
     @exif._dataView = getDataView '\x00\x1b\x00\x07\x00\x00\x00\x08\x00\x00\x00\x0c\x00\x00\x00\x00\x00\x00\x00\x00'
     expect(@exif._readTag('gps', 0).description).toEqual '[Undefined encoding]'
 
+  it 'should handle empty GPSProcessingMethod', ->
+    @exif._dataView = getDataView '\x00\x1b\x00\x07\x00\x00\x00\x01\x00'
+    expect(@exif._readTag('gps', 0).description).toEqual 'Undefined'
+
   it 'should report correct text for ASCII GPSAreaInformation', ->
     @exif._dataView = getDataView '\x00\x1c\x00\x07\x00\x00\x00\x0b\x00\x00\x00\x0cASCII\x00\x00\x00ABC'
     expect(@exif._readTag('gps', 0).description).toEqual 'ABC'
@@ -718,3 +739,7 @@ describe 'ExifReader', ->
     expect(@exif._readTag('gps', 0).description).toEqual '[Unicode encoded text]'
     @exif._dataView = getDataView '\x00\x1c\x00\x07\x00\x00\x00\x08\x00\x00\x00\x0c\x00\x00\x00\x00\x00\x00\x00\x00'
     expect(@exif._readTag('gps', 0).description).toEqual '[Undefined encoding]'
+
+  it 'should handle empty GPSAreaInformation', ->
+    @exif._dataView = getDataView '\x00\x1c\x00\x07\x00\x00\x00\x01\x00'
+    expect(@exif._readTag('gps', 0).description).toEqual 'Undefined'
diff --git a/src/ExifReader.coffee b/src/ExifReader.coffee
@@ -1,7 +1,7 @@
 ###
-# ExifReader 1.1.0
+# ExifReader 1.1.1
 # http://github.com/mattiasw/exifreader
-# Copyright (C) 2011-2013  Mattias Wallander <mattias@wallander.eu>
+# Copyright (C) 2011-2014  Mattias Wallander <mattias@wallander.eu>
 # Licensed under the GNU Lesser General Public License version 3 or later
 # See license text at http://www.gnu.org/licenses/lgpl.txt
 ###
@@ -127,13 +127,16 @@ class (exports ? this).ExifReader
     offset += 2
     for fieldIndex in [0...numberOfFields]
       tag = @_readTag(ifdType, offset)
-      @_tags[tag.name] = {'value': tag.value, 'description': tag.description}
+      if tag != undefined
+        @_tags[tag.name] = {'value': tag.value, 'description': tag.description}
       offset += 12
 
   _readTag: (ifdType, offset) ->
     tagCode = @_getShortAt offset
     tagType = @_getShortAt(offset + 2)
     tagCount = @_getLongAt(offset + 4)
+    if @_typeSizes[tagType] == undefined
+      return undefined
     if @_typeSizes[tagType] * tagCount <= 4
       # If the value itself fits in four bytes, it is recorded instead of just
       # the offset.
@@ -663,18 +666,24 @@ class (exports ? this).ExifReader
       }
       0x001a: 'GPSDestDistance',
       0x001b: {'name': 'GPSProcessingMethod', 'description': (value) ->
-        switch value[0...8].map((charCode) -> String.fromCharCode(charCode)).join ''
-          when 'ASCII\x00\x00\x00' then value[8...value.length].map((charCode) -> String.fromCharCode(charCode)).join ''
-          when 'JIS\x00\x00\x00\x00\x00' then '[JIS encoded text]'
-          when 'UNICODE\x00' then '[Unicode encoded text]'
-          when '\x00\x00\x00\x00\x00\x00\x00\x00' then '[Undefined encoding]'
+        if value == 0
+          'Undefined'
+        else
+          switch value[0...8].map((charCode) -> String.fromCharCode(charCode)).join ''
+            when 'ASCII\x00\x00\x00' then value[8...value.length].map((charCode) -> String.fromCharCode(charCode)).join ''
+            when 'JIS\x00\x00\x00\x00\x00' then '[JIS encoded text]'
+            when 'UNICODE\x00' then '[Unicode encoded text]'
+            when '\x00\x00\x00\x00\x00\x00\x00\x00' then '[Undefined encoding]'
       }
       0x001c: {'name': 'GPSAreaInformation', 'description': (value) ->
-        switch value[0...8].map((charCode) -> String.fromCharCode(charCode)).join ''
-          when 'ASCII\x00\x00\x00' then value[8...value.length].map((charCode) -> String.fromCharCode(charCode)).join ''
-          when 'JIS\x00\x00\x00\x00\x00' then '[JIS encoded text]'
-          when 'UNICODE\x00' then '[Unicode encoded text]'
-          when '\x00\x00\x00\x00\x00\x00\x00\x00' then '[Undefined encoding]'
+        if value == 0
+          'Undefined'
+        else
+          switch value[0...8].map((charCode) -> String.fromCharCode(charCode)).join ''
+            when 'ASCII\x00\x00\x00' then value[8...value.length].map((charCode) -> String.fromCharCode(charCode)).join ''
+            when 'JIS\x00\x00\x00\x00\x00' then '[JIS encoded text]'
+            when 'UNICODE\x00' then '[Unicode encoded text]'
+            when '\x00\x00\x00\x00\x00\x00\x00\x00' then '[Undefined encoding]'
       }
       0x001d: 'GPSDateStamp',
       0x001e: {'name': 'GPSDifferential', 'description': (value) ->