[scilab-Users] problem with free function

[Collewet Guylaine]

Hi,

 

Thank you for your help

The debugging mode allowed me to fix the problem

 

May be it can be useful for someone else :

the calloc was called in a function in one dll (the dll corresponding to the "c" files) and the free was called by a function belonging to another dll (the dll corresponding to the "sci_gateway" files). This led to an error in the heap of the pointer detected by _CtlIsValidHeadPointer

 

If the calloc  and free are called in the same function, scilab does not crash anymore

 

Guylaine

 

 

 

De : Allan CORNET [mailto:allan.cornet at scilab.org] 
Envoyé : lundi 14 février 2011 08:24
À : users at lists.scilab.org
Objet : RE: [scilab-Users] problem with free function

 

Hi,

 

You can debug your code with Visual studio :

 

http://wiki.scilab.org/How_to_debug_an_external_source_code_linked_to_scilab_with_Visual_Studio

 

Allan

 

De : Collewet Guylaine [mailto:guylaine.collewet at cemagref.fr] 
Envoyé : vendredi 11 février 2011 17:22
À : users at lists.scilab.org
Objet : [scilab-Users] problem with free function

 

Hello,

 

I have a problem with the "free" function which makes scilab crash

I wrote two functions "sci_imdilate" and "image_dilate"

sci_imdilate is the interface between scilab and the function image_dilate

 

the memory pointed by l_dilated_image (see the code below) is allocated by image_dilate and I'd like to free it in sci_imdilate

 

however, a call to free makes  scilab crash

If I remove the "free", the whole function works properly

 

I cannot undersand why

 

Does someone see my mistake ?

I am working with scilab 5.2.2  32 bits on windows 7 (64 bits machine)

 

Regards

 

Guylaine Collewet

 

 

 

/////////////////////////

// function sci_imdilate

///////////////////////

 

double *l_dilated_image;

 

.../...

 

dilate_image(&l_image[0], m_image, n_image, &l_kernel[0], m_kernel, n_kernel, &l_dilated_image, &l_mask[0], &ierr);

 

createMatrixOfDouble(pvApiCtx, 4, m_image, n_image, l_dilated_image);

 

if(l_dilated_image) {

       free(l_dilated_image);

               }

 

 

 

/////////////////////////

// function dilate_image

/////////////////////////

 

 

int dilate_image(double *image, int width, int height, double *kernel,  int kernel_width, int kernel_height, double **dilated_image, double *mask, int *ierr)

{

 

.../...

 

               if (!(*dilated_image = (double*)calloc(1, sizeof(double)*width*height)))

               {

                              *ierr=1;

                              return(-1);

               }

 

 

.../...

 

 

}

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