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POC programming problems with realloc and memcpy
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copied!<p>I'm new to this forum. I thank you in advance for the help.</p> <p>every time I call to this function "agregar_segmento" my global pointer named "segment" should resize to contain new data values. data are defined as a "struct" named "typeSeg".</p> <p>the problem is that every time I run the code I have different error messages. note: I tried to use valgrind but do not understand what is returned.</p> <p>my code is:</p> <pre><code>typedef struct { char cmd[2];int nEnt; float x1;float y1;float z1; float x2;float y2;float z2; } typeSeg; static typeSeg *segmentos; static int posSeg=0; static int cantSeg=0; void agregar_segmento(char *cmd,int nEnt, float x1,float y1,float z1,float x2,float y2,float z2){ typeSeg aux; long new_size; long offset; strcpy(aux.cmd,(char*)cmd); aux.nEnt = nEnt; aux.x1=x1; aux.y1=y1; aux.z1=z1; aux.x2=x2; aux.y2=y2; aux.z2=z2; posSeg++;cantSeg++; new_size = sizeof(typeSeg) * posSeg; offset = (new_size - sizeof(typeSeg)); printf("new_size = %lu , offset = %lu, size of my struct = %d\n",new_size,offset,sizeof(aux)); if(posSeg==1){ segmentos = (typeSeg*) malloc(new_size); }else{ segmentos = (typeSeg*) realloc(segmentos,new_size); } memcpy((segmentos + offset), &aux,sizeof(typeSeg)); } </code></pre> <p>in my program this function is called many times (usually more than 5000) from many parts.</p> <p>the example:</p> <pre><code>agregar_segmento("P",nEntidad,(xant1 == 0?px1:xant1),((yant1 == 0?py1:yant1)),atof("0.0"),px1,py1,atof("0.0")); </code></pre> <p>below the error messages obtained.</p> <p>error 1</p> <pre><code>new_size = 32 , offset = 0, size of my struct = 32 new_size = 64 , offset = 32, size of my struct = 32 new_size = 96 , offset = 64, size of my struct = 32 new_size = 128 , offset = 96, size of my struct = 32 new_size = 160 , offset = 128, size of my struct = 32 ...... ...... new_size = 13024 , offset = 12992, size of my struct = 32 new_size = 13056 , offset = 13024, size of my struct = 32 new_size = 13088 , offset = 13056, size of my struct = 32 Segmentation fault </code></pre> <p>error 2</p> <pre><code>new_size = 32 , offset = 0, size of my struct = 32 new_size = 64 , offset = 32, size of my struct = 32 new_size = 96 , offset = 64, size of my struct = 32 new_size = 128 , offset = 96, size of my struct = 32 new_size = 160 , offset = 128, size of my struct = 32 new_size = 192 , offset = 160, size of my struct = 32 ...... ...... new_size = 5440 , offset = 5408, size of my struct = 32 new_size = 5472 , offset = 5440, size of my struct = 32 Segmentation fault </code></pre> <p>error 3</p> <pre><code>new_size = 32 , offset = 0, size of my struct = 32 new_size = 64 , offset = 32, size of my struct = 32 new_size = 96 , offset = 64, size of my struct = 32 new_size = 128 , offset = 96, size of my struct = 32 ...... ...... new_size = 1216 , offset = 1184, size of my struct = 32 new_size = 1248 , offset = 1216, size of my struct = 32 new_size = 1280 , offset = 1248, size of my struct = 32 craster: malloc.c:4630: _int_malloc: Assertion `(unsigned long)(size) >= (unsigned long)(nb)' failed. Aborted </code></pre> <p>Can anyone take the trouble to see the code of my function and giving me his opinion?</p> <p>I print to debug the values of "new_size" and "offset" to make sure no corrupt memory but something is wrong.</p> <p>thanks!</p>

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