typedef unsigned char GifByteType;

typedef struct GifColorType
{
    GifByteType Red, Green, Blue;
} GifColorType;

typedef struct ColorMapObject
{
    int ColorCount;                        
    int BitsPerPixel;                    
    GifColorType *Colors;                
} ColorMapObject;

    ...............

    BitsPerPixel = 8;

    ColorMap = (ColorMapObject *)malloc(sizeof(ColorMapObject));        

    if(ColorMap == (ColorMapObject *) NULL)                             
    {
        FATFileClose(fd);                                                

        return 0;        
    }

    ColorMap->Colors = (GifColorType *)calloc(1 << BitsPerPixel, sizeof(GifColorType));    

    if(ColorMap->Colors == (GifColorType *) NULL)                         
    {
        free((ColorMapObject *)ColorMap);                                  
        FATFileClose(fd);                                                

        return 0;                                                        
    }

    ..........

$ cat el.c
#include <stdlib.h>
#include <stdio.h>

typedef unsigned char GifByteType;

typedef struct GifColorType {
GifByteType Red, Green, Blue;
} GifColorType;

typedef struct ColorMapObject {
int ColorCount;
int BitsPerPixel;
GifColorType *Colors;
} ColorMapObject;

static const int BitsPerPixel = 8;

int main()
{
ColorMapObject *ColorMap = malloc(sizeof(ColorMapObject));
if(!ColorMap)
abort();

ColorMap->Colors = calloc(1 << BitsPerPixel, sizeof(GifColorType));
if(!ColorMap->Colors)
abort();

exit(EXIT_SUCCESS);
}
$ gcc el.c -std=gnu99 -Wall -o el
$ ./el
$

int extcheck(char *s, char *match)
{              
    char tmp[5];
    uint8_t i;

    if(strlen(s) > 3)                                 
    {
        strncpy(tmp, s + strlen(s) - 4, 4);            
        tmp[4] = 0;                                 

        tolower(*tmp);                        
        if(strcmp(tmp, match) == 0)                     
            return 1;                                
    }
              
    return 0;                                        
}

tolower(*tmp);

for(i = 0; i < 4; i++)
    tolower(tmp[i]);

for(i = 0; i < 4; i++)


     tmp[i]=tolower(tmp[i]);