#294 JPEG-XR on Linux

[Grant Boyle]

I've been trying to get FreeImage working with JPEG-XR images on Linux (Ubuntu 18.10, debian buster). I ran into an issue where the process would be unable to open such images.

I've been looking into the cause and this is what I think is happening:

• JPEG-XR uses GUIDs to specify the pixel types of the image
• LibJXR defines a GUID structure to hold such GUIDs
• the definition depends on _WINDOWS_ to select between long and int members
• FreeImage.h defines _WINDOWS_ on all platforms if it isn't already
• the resulting GUID struct is longer than on Windows
• the load process does not populate all bytes as a result
• during open, FreeImage first reads the image pixel type GUID
• the it calls CopyPixels which also reads the image pixel type GUID
• it then compares the GUIDs to see if they are identical
• this comparision uses memcmp
• since there are uninitialized bytes in the GUIDs, they don't match
• LibJXR then goes off looking for a conversion function
• it does not find one and reports the image as being in an unsupported format

If I replace _WINDOWS_ with _WIN32 in LibJXR it gets further. The api test seems to work with this change but fails on one of the memIO tests otherwise.

[Grant Boyle]

Notes:

• FreeImage.h line 132 defines WINDOWS macro
• guiddef.h line 44 uses if to set the GUID structure
• PluginJXR.cpp line 1022 uses IsEqualGUID to compare input and output formats
• guiddef.h line 184 shows it is defined in terms of memcmp
• debugging shows the type is 24-bytes long rather than 16

Source\FreeImage.h

   131  #ifndef _WINDOWS_
   132  #define _WINDOWS_
   133  
   134  #ifndef FALSE
   135  #define FALSE 0
   136  #endif
   137  #ifndef TRUE
   138  #define TRUE 1
   139  #endif
   140  #ifndef NULL
   141  #define NULL 0
   142  #endif
   143  
   144  #ifndef SEEK_SET
   145  #define SEEK_SET  0
   146  #define SEEK_CUR  1
   147  #define SEEK_END  2
   148  #endif

Source\LibJXR\common\include\guiddef.h

    33  #ifndef GUID_DEFINED
    34  #define GUID_DEFINED
    35  #if defined(__midl)
    36  typedef struct {
    37      unsigned long  Data1;
    38      unsigned short Data2;
    39      unsigned short Data3;
    40      byte           Data4[ 8 ];
    41  } GUID;
    42  #else
    43  typedef struct _GUID {
    44  #if defined(_WINDOWS_) || !__LP64__
    45      unsigned long  Data1;
    46  #else
    47      unsigned int   Data1;
    48  #endif
    49      unsigned short Data2;
    50      unsigned short Data3;
    51      unsigned char  Data4[ 8 ];
    52  } GUID;
    53  #endif
    54  #endif

  ...

   184  __inline int IsEqualGUID(REFGUID rguid1, REFGUID rguid2)
   185  {
   186      return !memcmp(&rguid1, &rguid2, sizeof(GUID));
   187  }    

FreeImage\PluginJXR.cpp

  1006  CopyPixels(PKImageDecode *pDecoder, PKPixelFormatGUID out_guid_format, FIBITMAP *dib, int width, int height) {
  1007      PKFormatConverter *pConverter = NULL;   // pixel format converter
  1008      ERR error_code = 0; // error code as returned by the interface
  1009      BYTE *pb = NULL;    // local buffer used for pixel format conversion
  1010      
  1011      // image dimensions
  1012      const PKRect rect = {0, 0, width, height};
  1013  
  1014      try {
  1015          // get input file pixel format ...
  1016          PKPixelFormatGUID in_guid_format;
  1017          error_code = pDecoder->GetPixelFormat(pDecoder, &in_guid_format);
  1018          JXR_CHECK(error_code);
  1019          
  1020          // is a format conversion needed ?
  1021  
  1022          if(IsEqualGUID(out_guid_format, in_guid_format)) {
  1023              // no conversion, load bytes "as is" ...

LibJXR\jxrgluelib\JXRGlue.h

   190  DEFINE_GUID(GUID_PKPixelFormat48bpp3Channels, 0x6fddc324, 0x4e03, 0x4bfe, 0xb1, 0x85, 0x3d, 0x77, 0x76, 0x8d, 0xc9, 0x26);

debugging

(gdb) x /24bx &out_guid_format
0x7fffffffde70:    0x24    0xc3    0xdd    0x6f    0x03    0x4e    0xfe    0x4b
0x7fffffffde78:    0xb1    0x85    0x3d    0x77    0x76    0x8d    0xc9    0x26
0x7fffffffde80:    0x24    0xc3    0xdd    0x6f    0x03    0x4e    0xfe    0x4b
(gdb) x /24bx &in_guid_format
0x7fffffffde90:    0x24    0xc3    0xdd    0x6f    0x03    0x4e    0xfe    0x4b
0x7fffffffde98:    0xb1    0x85    0x3d    0x77    0x76    0x8d    0xc9    0x26
0x7fffffffdea0:    0xe0    0x3d    0x58    0x55    0x55    0x55    0x00    0x00
(gdb) print out_guid_format
$1 = {Data1 = 5475899973597774628, Data2 = 34225, Data3 = 30525, Data4 = "v\215\311&$\303\335o"}
(gdb) print in_guid_format
$2 = {Data1 = 5475899973597774628, Data2 = 34225, Data3 = 30525, Data4 = "v\215\311&\340=XU"}
(gdb) print sizeof(out_guid_format)
$3 = 24
(gdb) print sizeof(in_guid_format)
$4 = 24

[Hervé Drolon]

fixed in the SVN