C malloc segmentation fault - c

Question

In the function RenameSubs() when I try debugging I get segmentation fault at this line of code
subsdir[i] = (char*)malloc((GetStringSize(moviesdir[i]) + 1 + 4) * sizeof(char));
I don't understand why — can you explain?
int main()
{
int number;
char *mainDirectory = NULL,**names = NULL;
printf("Give the movies directory: ");
mainDirectory = ReadMainDirectory();
if(GetFiles(&mainDirectory,&names,&number) != 0)
{
RenameSubs(number,mainDirectory,names);
system("PAUSE");
return 1;
}
system("PAUSE");
return 0;
}
char* ReadMainDirectory()
{
char *dir,c;
int size = 1;
dir = (char*)malloc(size+1);
dir[size-1] = '\0';
while((c = getchar()) != '\n')
{
dir[size-1] = c;
size++;
dir = (char*)realloc(dir,size+1);
dir[size-1] = '\0';
}
return dir;
}
int GetFiles(char **dir,char ***names,int *number)
{
struct dirent *dp;
DIR *fd;
if ((fd = opendir(*dir)) == NULL)
{
printf("Can't open directory %s!\n",*dir);
return 0;
}
*number = 0;
*names = (char**)malloc(((*number)+1) * sizeof(char*));
while ((dp = readdir(fd)) != NULL)
{
if (!strcmp(dp->d_name, ".") || !strcmp(dp->d_name, ".."))
{
continue;
}
(*names)[*number] = strdup(dp->d_name);
(*number)++;
*names = (char**)realloc(*names,((*number)+1) * sizeof(char*));
}
closedir(fd);
return 1;
}
int GetStringSize(char *string)
{
int size = 0;
while(string[size] != '\0')
{
size++;
}
return size;
}
int StringEndsWith(char* string,char* extension)
{
int size;
char *strextension = NULL;
size = GetStringSize(string);
strextension = (char*)malloc(5 * sizeof(char));
strextension[0] = string[size-4];
strextension[1] = string[size-3];
strextension[2] = string[size-2];
strextension[3] = string[size-1];
strextension[4] = '\0';
if(strcmp(strextension,extension) == 0)
{
return 1;
}
return 0;
}
void RenameSubs(int number,char* mainDir,char** filenames)
{
int i,mainDirSize,movieDirSize[number],moviesdirnumber,subsdirnumber,j,y;
char **moviesdir = NULL,**subsdir = NULL,**subsdest = NULL,**moviesdirfilenames = NULL,**subsdirfilenames = NULL,*moviesname = NULL;
moviesdir = (char**)malloc(number * sizeof(char*));
mainDirSize = GetStringSize(mainDir);
for(i=0;i<number;i++)
{
movieDirSize[i] = mainDirSize + 1 + GetStringSize(filenames[i]);
moviesdir[i] = (char*)malloc((movieDirSize[i]+1) * sizeof(char));
strcpy(moviesdir[i],mainDir);
strcat(moviesdir[i],"\\");
strcat(moviesdir[i],filenames[i]);
GetFiles(&moviesdir[i],&moviesdirfilenames,&moviesdirnumber);
subsdir[i] = (char*)malloc((GetStringSize(moviesdir[i]) + 1 + 4) * sizeof(char));
strcpy(subsdir[i],moviesdir[i]);
strcat(subsdir[i],"\\");
strcat(subsdir[i],"Subs");
GetFiles(&subsdir[i],&subsdirfilenames,&subsdirnumber);
subsdest[i] = (char*)malloc((GetStringSize(subsdir[i]) + GetStringSize(subsdirfilenames[0]) + 1) * sizeof(char));
strcpy(subsdest[i],subsdir[i]);
strcat(subsdest[i],"\\");
strcat(subsdest[i],subsdirfilenames[0]);
for(j=0;j<moviesdirnumber;j++)
{
if(StringEndsWith(moviesdirfilenames[j],".mkv") || StringEndsWith(moviesdirfilenames[j],".mp4") || StringEndsWith(moviesdirfilenames[j],".avi"))
{
moviesname = (char*)malloc((GetStringSize(moviesdirfilenames[j]) - 4 + 1) * sizeof(char));
for(y=0;y<(GetStringSize(moviesdirfilenames[j]) - 4);y++)
{
moviesname[y] = moviesdirfilenames[j][y];
}
moviesname[y] = '\0';
break;
}
}
}
}

Answer 1

You are using array of pointers without initializing it first . initialize it.
In loop
subsdir[i] = malloc((GetStringSize(moviesdir[i]) + 1 + 4) * sizeof(char));
This is the second step . First u need to initialize
subsdir = malloc (sizeof(char*) * number);