path: root/contrib/libs/lcms2/src/cmserr.c

//---------------------------------------------------------------------------------
//
//  Little Color Management System
//  Copyright (c) 1998-2023 Marti Maria Saguer
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO
// THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
//
//---------------------------------------------------------------------------------

#include "lcms2_internal.h"


// This function is here to help applications to prevent mixing lcms versions on header and shared objects.
int CMSEXPORT cmsGetEncodedCMMversion(void)
{
       return LCMS_VERSION;
}

// I am so tired about incompatibilities on those functions that here are some replacements
// that hopefully would be fully portable.

// compare two strings ignoring case
int CMSEXPORT cmsstrcasecmp(const char* s1, const char* s2)
{
    CMSREGISTER const unsigned char *us1 = (const unsigned char *)s1,
                                 *us2 = (const unsigned char *)s2;

    while (toupper(*us1) == toupper(*us2++))
        if (*us1++ == '\0')
            return 0;

    return (toupper(*us1) - toupper(*--us2));
}

// long int because C99 specifies ftell in such way (7.19.9.2)
long int CMSEXPORT cmsfilelength(FILE* f)
{
    long int p , n;

    p = ftell(f); // register current file position
    if (p == -1L) 
        return -1L;

    if (fseek(f, 0, SEEK_END) != 0) {
        return -1L;
    }

    n = ftell(f);
    fseek(f, p, SEEK_SET); // file position restored

    return n;
}


// Memory handling ------------------------------------------------------------------
//
// This is the interface to low-level memory management routines. By default a simple
// wrapping to malloc/free/realloc is provided, although there is a limit on the max
// amount of memory that can be reclaimed. This is mostly as a safety feature to prevent 
// bogus or evil code to allocate huge blocks that otherwise lcms would never need.

#define MAX_MEMORY_FOR_ALLOC  ((cmsUInt32Number)(1024U*1024U*512U))

// User may override this behaviour by using a memory plug-in, which basically replaces
// the default memory management functions. In this case, no check is performed and it
// is up to the plug-in writer to keep in the safe side. There are only three functions
// required to be implemented: malloc, realloc and free, although the user may want to
// replace the optional mallocZero, calloc and dup as well.

cmsBool   _cmsRegisterMemHandlerPlugin(cmsContext ContextID, cmsPluginBase* Plugin);

// *********************************************************************************

// This is the default memory allocation function. It does a very coarse
// check of amount of memory, just to prevent exploits
static
void* _cmsMallocDefaultFn(cmsContext ContextID, cmsUInt32Number size)
{
    // Never allow 0 or over maximum
    if (size == 0 || size > MAX_MEMORY_FOR_ALLOC) return NULL;

    return (void*) malloc(size);

    cmsUNUSED_PARAMETER(ContextID);
}

// Generic allocate & zero
static
void* _cmsMallocZeroDefaultFn(cmsContext ContextID, cmsUInt32Number size)
{
    void *pt = _cmsMalloc(ContextID, size);
    if (pt == NULL) return NULL;

    memset(pt, 0, size);
    return pt;
}


// The default free function. The only check proformed is against NULL pointers
static
void _cmsFreeDefaultFn(cmsContext ContextID, void *Ptr)
{
    // free(NULL) is defined a no-op by C99, therefore it is safe to
    // avoid the check, but it is here just in case...

    if (Ptr) free(Ptr);

    cmsUNUSED_PARAMETER(ContextID);
}

// The default realloc function. Again it checks for exploits. If Ptr is NULL,
// realloc behaves the same way as malloc and allocates a new block of size bytes.
static
void* _cmsReallocDefaultFn(cmsContext ContextID, void* Ptr, cmsUInt32Number size)
{

    if (size > MAX_MEMORY_FOR_ALLOC) return NULL;  // Never realloc over 512Mb

    return realloc(Ptr, size);

    cmsUNUSED_PARAMETER(ContextID);
}


// The default calloc function. Allocates an array of num elements, each one of size bytes
// all memory is initialized to zero.
static
void* _cmsCallocDefaultFn(cmsContext ContextID, cmsUInt32Number num, cmsUInt32Number size)
{
    cmsUInt32Number Total = num * size;

    // Preserve calloc behaviour
    if (Total == 0) return NULL;

    // Safe check for overflow.
    if (num >= UINT_MAX / size) return NULL;

    // Check for overflow
    if (Total < num || Total < size) {
        return NULL;
    }

    if (Total > MAX_MEMORY_FOR_ALLOC) return NULL;  // Never alloc over 512Mb

    return _cmsMallocZero(ContextID, Total);
}

// Generic block duplication
static
void* _cmsDupDefaultFn(cmsContext ContextID, const void* Org, cmsUInt32Number size)
{
    void* mem;

    if (size > MAX_MEMORY_FOR_ALLOC) return NULL;  // Never dup over 512Mb

    mem = _cmsMalloc(ContextID, size);

    if (mem != NULL && Org != NULL)
        memmove(mem, Org, size);

    return mem;
}


// Pointers to memory manager functions in Context0
_cmsMemPluginChunkType _cmsMemPluginChunk = { _cmsMallocDefaultFn, _cmsMallocZeroDefaultFn, _cmsFreeDefaultFn, 
                                              _cmsReallocDefaultFn, _cmsCallocDefaultFn,    _cmsDupDefaultFn
                                            };


// Reset and duplicate memory manager
void _cmsAllocMemPluginChunk(struct _cmsContext_struct* ctx, const struct _cmsContext_struct* src)
{
    _cmsAssert(ctx != NULL);

    if (src != NULL) {    

        // Duplicate
        ctx ->chunks[MemPlugin] = _cmsSubAllocDup(ctx ->MemPool, src ->chunks[MemPlugin], sizeof(_cmsMemPluginChunkType));  
    }
    else {

        // To reset it, we use the default allocators, which cannot be overridden
        ctx ->chunks[MemPlugin] = &ctx ->DefaultMemoryManager;
    } 
}

// Auxiliary to fill memory management functions from plugin (or context 0 defaults)
void _cmsInstallAllocFunctions(cmsPluginMemHandler* Plugin, _cmsMemPluginChunkType* ptr)
{
    if (Plugin == NULL) {

        memcpy(ptr, &_cmsMemPluginChunk, sizeof(_cmsMemPluginChunk));
    }
    else {

        ptr ->MallocPtr  = Plugin -> MallocPtr;
        ptr ->FreePtr    = Plugin -> FreePtr;
        ptr ->ReallocPtr = Plugin -> ReallocPtr;

        // Make sure we revert to defaults
        ptr ->MallocZeroPtr= _cmsMallocZeroDefaultFn;
        ptr ->CallocPtr    = _cmsCallocDefaultFn;
        ptr ->DupPtr       = _cmsDupDefaultFn;
      
        if (Plugin ->MallocZeroPtr != NULL) ptr ->MallocZeroPtr = Plugin -> MallocZeroPtr;
        if (Plugin ->CallocPtr != NULL)     ptr ->CallocPtr     = Plugin -> CallocPtr;
        if (Plugin ->DupPtr != NULL)        ptr ->DupPtr        = Plugin -> DupPtr;
        
    }
}


// Plug-in replacement entry
cmsBool  _cmsRegisterMemHandlerPlugin(cmsContext ContextID, cmsPluginBase *Data)
{
    cmsPluginMemHandler* Plugin = (cmsPluginMemHandler*) Data;     
    _cmsMemPluginChunkType* ptr;

    // NULL forces to reset to defaults. In this special case, the defaults are stored in the context structure. 
    // Remaining plug-ins does NOT have any copy in the context structure, but this is somehow special as the
    // context internal data should be malloc'ed by using those functions. 
    if (Data == NULL) {

       struct _cmsContext_struct* ctx = ( struct _cmsContext_struct*) ContextID;

       // Return to the default allocators
        if (ContextID != NULL) {
            ctx->chunks[MemPlugin] = (void*) &ctx->DefaultMemoryManager;
        }
        return TRUE;
    }

    // Check for required callbacks
    if (Plugin -> MallocPtr == NULL ||
        Plugin -> FreePtr == NULL ||
        Plugin -> ReallocPtr == NULL) return FALSE;

    // Set replacement functions
    ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
    if (ptr == NULL) 
        return FALSE;

    _cmsInstallAllocFunctions(Plugin, ptr);
    return TRUE;
}

// Generic allocate
void* CMSEXPORT _cmsMalloc(cmsContext ContextID, cmsUInt32Number size)
{
    _cmsMemPluginChunkType* ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
    return ptr ->MallocPtr(ContextID, size);
}

// Generic allocate & zero
void* CMSEXPORT _cmsMallocZero(cmsContext ContextID, cmsUInt32Number size)
{
    _cmsMemPluginChunkType* ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
    return ptr->MallocZeroPtr(ContextID, size);
}

// Generic calloc
void* CMSEXPORT _cmsCalloc(cmsContext ContextID, cmsUInt32Number num, cmsUInt32Number size)
{
    _cmsMemPluginChunkType* ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
    return ptr->CallocPtr(ContextID, num, size);
}

// Generic reallocate
void* CMSEXPORT _cmsRealloc(cmsContext ContextID, void* Ptr, cmsUInt32Number size)
{
    _cmsMemPluginChunkType* ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
    return ptr->ReallocPtr(ContextID, Ptr, size);
}

// Generic free memory
void CMSEXPORT _cmsFree(cmsContext ContextID, void* Ptr)
{
    if (Ptr != NULL) {
        _cmsMemPluginChunkType* ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
        ptr ->FreePtr(ContextID, Ptr);
    }
}

// Generic block duplication
void* CMSEXPORT _cmsDupMem(cmsContext ContextID, const void* Org, cmsUInt32Number size)
{
    _cmsMemPluginChunkType* ptr = (_cmsMemPluginChunkType*) _cmsContextGetClientChunk(ContextID, MemPlugin);
    return ptr ->DupPtr(ContextID, Org, size);
}

// ********************************************************************************************

// Sub allocation takes care of many pointers of small size. The memory allocated in
// this way have be freed at once. Next function allocates a single chunk for linked list
// I prefer this method over realloc due to the big impact on xput realloc may have if
// memory is being swapped to disk. This approach is safer (although that may not be true on all platforms)
static
_cmsSubAllocator_chunk* _cmsCreateSubAllocChunk(cmsContext ContextID, cmsUInt32Number Initial)
{
    _cmsSubAllocator_chunk* chunk;

    // 20K by default
    if (Initial == 0)
        Initial = 20*1024;

    // Create the container
    chunk = (_cmsSubAllocator_chunk*) _cmsMallocZero(ContextID, sizeof(_cmsSubAllocator_chunk));
    if (chunk == NULL) return NULL;

    // Initialize values
    chunk ->Block     = (cmsUInt8Number*) _cmsMalloc(ContextID, Initial);
    if (chunk ->Block == NULL) {

        // Something went wrong
        _cmsFree(ContextID, chunk);
        return NULL;
    }

    chunk ->BlockSize = Initial;
    chunk ->Used      = 0;
    chunk ->next      = NULL;

    return chunk;
}

// The suballocated is nothing but a pointer to the first element in the list. We also keep
// the thread ID in this structure.
_cmsSubAllocator* _cmsCreateSubAlloc(cmsContext ContextID, cmsUInt32Number Initial)
{
    _cmsSubAllocator* sub;

    // Create the container
    sub = (_cmsSubAllocator*) _cmsMallocZero(ContextID, sizeof(_cmsSubAllocator));
    if (sub == NULL) return NULL;

    sub ->ContextID = ContextID;

    sub ->h = _cmsCreateSubAllocChunk(ContextID, Initial);
    if (sub ->h == NULL) {
        _cmsFree(ContextID, sub);
        return NULL;
    }

    return sub;
}


// Get rid of whole linked list
void _cmsSubAllocDestroy(_cmsSubAllocator* sub)
{
    _cmsSubAllocator_chunk *chunk, *n;

    for (chunk = sub ->h; chunk != NULL; chunk = n) {

        n = chunk->next;
        if (chunk->Block != NULL) _cmsFree(sub ->ContextID, chunk->Block);
        _cmsFree(sub ->ContextID, chunk);
    }

    // Free the header
    _cmsFree(sub ->ContextID, sub);
}


// Get a pointer to small memory block.
void*  _cmsSubAlloc(_cmsSubAllocator* sub, cmsUInt32Number size)
{
    cmsUInt32Number Free = sub -> h ->BlockSize - sub -> h -> Used;
    cmsUInt8Number* ptr;

    size = _cmsALIGNMEM(size);

    // Check for memory. If there is no room, allocate a new chunk of double memory size.
    if (size > Free) {

        _cmsSubAllocator_chunk* chunk;
        cmsUInt32Number newSize;

        newSize = sub -> h ->BlockSize * 2;
        if (newSize < size) newSize = size;

        chunk = _cmsCreateSubAllocChunk(sub -> ContextID, newSize);
        if (chunk == NULL) return NULL;

        // Link list
        chunk ->next = sub ->h;
        sub ->h    = chunk;

    }

    ptr =  sub -> h ->Block + sub -> h ->Used;
    sub -> h -> Used += size;

    return (void*) ptr;
}

// Duplicate in pool
void* _cmsSubAllocDup(_cmsSubAllocator* s, const void *ptr, cmsUInt32Number size)
{
    void *NewPtr;
    
    // Dup of null pointer is also NULL
    if (ptr == NULL)
        return NULL;

    NewPtr = _cmsSubAlloc(s, size);

    if (ptr != NULL && NewPtr != NULL) {
        memcpy(NewPtr, ptr, size);
    }

    return NewPtr;
}



// Error logging ******************************************************************

// There is no error handling at all. When a function fails, it returns proper value.
// For example, all create functions does return NULL on failure. Other return FALSE
// It may be interesting, for the developer, to know why the function is failing.
// for that reason, lcms2 does offer a logging function. This function does receive
// a ENGLISH string with some clues on what is going wrong. You can show this
// info to the end user, or just create some sort of log.
// The logging function should NOT terminate the program, as this obviously can leave
// resources. It is the programmer's responsibility to check each function return code
// to make sure it didn't fail.

// Error messages are limited to MAX_ERROR_MESSAGE_LEN

#define MAX_ERROR_MESSAGE_LEN   1024

// ---------------------------------------------------------------------------------------------------------

// This is our default log error
static void DefaultLogErrorHandlerFunction(cmsContext ContextID, cmsUInt32Number ErrorCode, const char *Text);

// Context0 storage, which is global
_cmsLogErrorChunkType _cmsLogErrorChunk = { DefaultLogErrorHandlerFunction };

// Allocates and inits error logger container for a given context. If src is NULL, only initializes the value
// to the default. Otherwise, it duplicates the value. The interface is standard across all context clients
void _cmsAllocLogErrorChunk(struct _cmsContext_struct* ctx, 
                            const struct _cmsContext_struct* src)
{    
    static _cmsLogErrorChunkType LogErrorChunk = { DefaultLogErrorHandlerFunction };
    void* from;
     
     if (src != NULL) {
        from = src ->chunks[Logger];       
    }
    else {
       from = &LogErrorChunk;
    }
    
    ctx ->chunks[Logger] = _cmsSubAllocDup(ctx ->MemPool, from, sizeof(_cmsLogErrorChunkType));   
}

// The default error logger does nothing.
static
void DefaultLogErrorHandlerFunction(cmsContext ContextID, cmsUInt32Number ErrorCode, const char *Text)
{
    // fprintf(stderr, "[lcms]: %s\n", Text);
    // fflush(stderr);

     cmsUNUSED_PARAMETER(ContextID);
     cmsUNUSED_PARAMETER(ErrorCode);
     cmsUNUSED_PARAMETER(Text);
}

// Change log error, context based
void CMSEXPORT cmsSetLogErrorHandlerTHR(cmsContext ContextID, cmsLogErrorHandlerFunction Fn)
{
    _cmsLogErrorChunkType* lhg = (_cmsLogErrorChunkType*) _cmsContextGetClientChunk(ContextID, Logger);

    if (lhg != NULL) {

        if (Fn == NULL)
            lhg -> LogErrorHandler = DefaultLogErrorHandlerFunction;
        else
            lhg -> LogErrorHandler = Fn;
    }
}

// Change log error, legacy
void CMSEXPORT cmsSetLogErrorHandler(cmsLogErrorHandlerFunction Fn)
{
    cmsSetLogErrorHandlerTHR(NULL, Fn);    
}

// Log an error
// ErrorText is a text holding an english description of error.
void CMSEXPORT cmsSignalError(cmsContext ContextID, cmsUInt32Number ErrorCode, const char *ErrorText, ...)
{
    va_list args;
    char Buffer[MAX_ERROR_MESSAGE_LEN];
    _cmsLogErrorChunkType* lhg;


    va_start(args, ErrorText);
    vsnprintf(Buffer, MAX_ERROR_MESSAGE_LEN-1, ErrorText, args);
    va_end(args);

    // Check for the context, if specified go there. If not, go for the global
    lhg = (_cmsLogErrorChunkType*) _cmsContextGetClientChunk(ContextID, Logger);
    if (lhg ->LogErrorHandler) {
        lhg ->LogErrorHandler(ContextID, ErrorCode, Buffer);
    }   
}

// Utility function to print signatures
void _cmsTagSignature2String(char String[5], cmsTagSignature sig)
{
    cmsUInt32Number be;

    // Convert to big endian
    be = _cmsAdjustEndianess32((cmsUInt32Number) sig);

    // Move chars
    memmove(String, &be, 4);

    // Make sure of terminator
    String[4] = 0;
}

//--------------------------------------------------------------------------------------------------


static
void* defMtxCreate(cmsContext id)
{
    _cmsMutex* ptr_mutex = (_cmsMutex*) _cmsMalloc(id, sizeof(_cmsMutex));
    _cmsInitMutexPrimitive(ptr_mutex);
    return (void*) ptr_mutex;   
}

static
void defMtxDestroy(cmsContext id, void* mtx)
{
    _cmsDestroyMutexPrimitive((_cmsMutex *) mtx); 
    _cmsFree(id, mtx);
}

static
cmsBool defMtxLock(cmsContext id, void* mtx)
{
    cmsUNUSED_PARAMETER(id);
    return _cmsLockPrimitive((_cmsMutex *) mtx) == 0;     
}

static
void defMtxUnlock(cmsContext id, void* mtx)
{
    cmsUNUSED_PARAMETER(id);
    _cmsUnlockPrimitive((_cmsMutex *) mtx); 
}



// Pointers to memory manager functions in Context0
_cmsMutexPluginChunkType _cmsMutexPluginChunk = { defMtxCreate, defMtxDestroy, defMtxLock, defMtxUnlock };

// Allocate and init mutex container.
void _cmsAllocMutexPluginChunk(struct _cmsContext_struct* ctx, 
                                        const struct _cmsContext_struct* src)
{
    static _cmsMutexPluginChunkType MutexChunk = {defMtxCreate, defMtxDestroy, defMtxLock, defMtxUnlock };
    void* from;
     
     if (src != NULL) {
        from = src ->chunks[MutexPlugin];       
    }
    else {
       from = &MutexChunk;
    }
    
    ctx ->chunks[MutexPlugin] = _cmsSubAllocDup(ctx ->MemPool, from, sizeof(_cmsMutexPluginChunkType));   
}

// Register new ways to transform
cmsBool  _cmsRegisterMutexPlugin(cmsContext ContextID, cmsPluginBase* Data)
{
    cmsPluginMutex* Plugin = (cmsPluginMutex*) Data;
    _cmsMutexPluginChunkType* ctx = ( _cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);

    if (Data == NULL) {

        // No lock routines
        ctx->CreateMutexPtr = NULL; 
        ctx->DestroyMutexPtr = NULL; 
        ctx->LockMutexPtr = NULL;
        ctx ->UnlockMutexPtr = NULL;
        return TRUE;
    }

    // Factory callback is required
    if (Plugin ->CreateMutexPtr == NULL || Plugin ->DestroyMutexPtr == NULL || 
        Plugin ->LockMutexPtr == NULL || Plugin ->UnlockMutexPtr == NULL) return FALSE;

    ctx->CreateMutexPtr  = Plugin->CreateMutexPtr;
    ctx->DestroyMutexPtr = Plugin ->DestroyMutexPtr;
    ctx ->LockMutexPtr   = Plugin ->LockMutexPtr;
    ctx ->UnlockMutexPtr = Plugin ->UnlockMutexPtr;

    // All is ok
    return TRUE;
}

// Generic Mutex fns
void* CMSEXPORT _cmsCreateMutex(cmsContext ContextID)
{
    _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);

    if (ptr ->CreateMutexPtr == NULL) return NULL;

    return ptr ->CreateMutexPtr(ContextID);
}

void CMSEXPORT _cmsDestroyMutex(cmsContext ContextID, void* mtx)
{
    _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);

    if (ptr ->DestroyMutexPtr != NULL) {

        ptr ->DestroyMutexPtr(ContextID, mtx);
    }
}

cmsBool CMSEXPORT _cmsLockMutex(cmsContext ContextID, void* mtx)
{
    _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);

    if (ptr ->LockMutexPtr == NULL) return TRUE;

    return ptr ->LockMutexPtr(ContextID, mtx);
}

void CMSEXPORT _cmsUnlockMutex(cmsContext ContextID, void* mtx)
{
    _cmsMutexPluginChunkType* ptr = (_cmsMutexPluginChunkType*) _cmsContextGetClientChunk(ContextID, MutexPlugin);

    if (ptr ->UnlockMutexPtr != NULL) {

        ptr ->UnlockMutexPtr(ContextID, mtx);
    }
}

// The global Context0 storage for parallelization plug-in
 _cmsParallelizationPluginChunkType _cmsParallelizationPluginChunk = { 0 };

// Allocate parallelization container.
void _cmsAllocParallelizationPluginChunk(struct _cmsContext_struct* ctx,
                                         const struct _cmsContext_struct* src)
{    
    if (src != NULL) {
        void* from = src->chunks[ParallelizationPlugin];
        ctx->chunks[ParallelizationPlugin] = _cmsSubAllocDup(ctx->MemPool, from, sizeof(_cmsParallelizationPluginChunkType));
    }
    else {        
        _cmsParallelizationPluginChunkType ParallelizationPluginChunk = { 0 };
        ctx->chunks[ParallelizationPlugin] = _cmsSubAllocDup(ctx->MemPool, &ParallelizationPluginChunk, sizeof(_cmsParallelizationPluginChunkType));
    }         
}

// Register parallel processing
cmsBool _cmsRegisterParallelizationPlugin(cmsContext ContextID, cmsPluginBase* Data)
{
    cmsPluginParalellization* Plugin = (cmsPluginParalellization*)Data;
    _cmsParallelizationPluginChunkType* ctx = (_cmsParallelizationPluginChunkType*)_cmsContextGetClientChunk(ContextID, ParallelizationPlugin);

    if (Data == NULL) {

        // No parallelization routines
        ctx->MaxWorkers = 0;
        ctx->WorkerFlags = 0;
        ctx->SchedulerFn = NULL;        
        return TRUE;
    }

    // callback is required
    if (Plugin->SchedulerFn == NULL) return FALSE;

    ctx->MaxWorkers = Plugin->MaxWorkers;
    ctx->WorkerFlags = Plugin->WorkerFlags;
    ctx->SchedulerFn = Plugin->SchedulerFn;
    
    // All is ok
    return TRUE;
}