Problem with malloc ...

[BeePM]

Hey guys !

First thing first, i am sorry about this post about malloc ... but i have serious problem with it ... I am programming Sokoban Console Game and i need to load levels from file (levels.dat) and then read line by line and parse every line in some blocks ...
Example of level : <name>;<password>;<description>;<map>
chicago;addie;story begins here;-----#####-----------|-----#@$.#-----------|-----#####-----------
I have the struct :

typedef struct level 
{
char * name;
char * password;
char * description;
char * map;
struct level * next;
}

My problem is, when i am tryin to allocate memory for map ...
Do not read the comments , i am from slovakia ...
Here is the code :

Level * load_levels(const char * path)
{
    // docasne udaje
    Level *prvy, *posl, *novy;
    // nacitaj subor
    FILE * f = fopen(path, "r");
    // ak subor neexistuje tak ukonci
    if(!f) 
        return NULL;
    // nacitaj riadok
    int i = 0,j;
    // sem citam retazce
    char t[128][512];
    // citaj retazce
    while(fgets(t[i], 512, f) != NULL) 
        i++;
    
     // rozparsuj level
        prvy = NULL;
        prvy= parse_level(t[0]);
         prvy->next_level = NULL;
        posl = prvy;
        //pokial som nacital level nacitaj dalsi
        for(j = 1; j < i; j++)
        {
            novy = parse_level(t[j]);
            if(novy != NULL)
            {
               novy->next_level = NULL;
               //posl->next_level = novy;
               posl = novy;    
            }
            else 
                return NULL;
        }
      
     // zatvor subor
     fclose(f);   
        
    // nacital som levely 
    return (prvy);
     
}


Level * parse_level(char s[])
{
    // pridel pamat
    Level * t  = (Level*)malloc(sizeof(Level)) ;
    // ak sa nepodarilo naalokovat pamat tak skoncime s NULL
    if(t == NULL) 
        return NULL;
    // docasne premenne
    int i;
    // alokuj potrebnu pamat
    char * buffer = malloc( sizeof *s + 1);
    
    // ak sa nenaalokoval buffer konci
    if(buffer == NULL) 
        return NULL;
    // kopiruj do bafra 
    strcpy(buffer , "");
    // hladaci algoritmus
    // hladaj meno
    for(i = 0; i < strlen(s); i++)
    {
        if(s[i] != ';')
        {
            char znak = s[i];
            strcat(buffer, &znak);
        }
        else break;
    }
    // ak som nenacital nic do buffra skonci
    if(!strcmp(buffer, "") || !strcmp(buffer, " ")) 
        return NULL;
    // pridel pamat 
    if((t->name) != NULL) free(t->name);
    t->name = malloc( sizeof *buffer + 1 );
    // ak sa pamat neda pridelit tak skonci
    if(t->name == NULL) 
        return NULL;
    // skopiruj obsah z buffra do name
    strcpy(t->name, buffer);
    // kopiruj do buffra
    strcpy(buffer , "");
    
    // hladaj heslo
    for(i++; i < strlen(s); i++)
    {
        if(s[i] != ';')
        {
            char znak = s[i];
            strcat(buffer, &znak);
        }
        else break;
    }
    // ak som nic nenasiel konci
     if(!strcmp(buffer, "")  || !strcmp(buffer, " ")) 
         return NULL;
    // pridel pamat
    if((t->password) != NULL) free(t->password);
    t->password = malloc( sizeof *buffer + 1  );
    // ak sa nepridelila pamat konci
    if(t->password == NULL)
        return NULL;
    // kopiruj obsah buffra
    strcpy(t->password, buffer);
    // kopiruj do buffra
    strcpy(buffer , "");
    
    // hladaj description
    for(i++; i < strlen(s); i++)
    {
        if(s[i] != ';')
        {
            char znak = s[i];
            strcat(buffer, &znak);
        }
        else break;
    }
    // ak sa v buffrinic nenachadya konci
    if(!strcmp(buffer, "")  || !strcmp(buffer, "'")) 
        return NULL;
    // vyhrad pamat
    if((t->description) != NULL) free(t->description);
    t->description = malloc( sizeof *buffer + 1 );
    // ak nemam nic v description
    if(t->description == NULL)
        return NULL;
    // kopirujobsah z buffra
    strcpy(t->description, buffer);
    // kopiruj do buffra
    strcpy(buffer , "");
    
    // hladaj mapu
    for(i++; i < strlen(s); i++)
    {
        char znak = s[i];
        strcat(buffer, &znak);
    }
    // ak nemam nic v buffri konci
    if(!strcmp(buffer, "")  || !strcmp(buffer, " ")) 
        return NULL;
    // vyhrad pamat
    if((t->map) != NULL) free(t->map);
    t->map = malloc( sizeof  *buffer + 1 );
    //   t->map = malloc( (strlen(buffer) + 1) * sizeof  *t->map ); ak nemam pamatkonci
    if(t->map == NULL)
        return NULL;
    // kopiruj obsah buffra
    strcpy(t->map, buffer);
    
    // vrat rozparsovany level
    return (t);
}

[ZuK]

in parse_level

char * buffer = malloc( sizeof *s + 1);

sizeof s gives you the size of a char *
You have to either pass the size of the buffer to parse_level or use strlen()

Kurt

[BeePM]

Ok i changed the allocation of all pointers ....
I run debugger and there is something very interesting ...
when prvy = parse_level ( t[0] ); is called everything is OK , system alloc memory for all members ... but when i reach the code in the for, novy = parse_level ( t[i] ); , it alloc memory for all members , but not for map ... when the malloc for map is calling it send me segmentation fault ...

[ZuK]

You're doing it all over the place to call sizof on a pointer and strcpy() ing things into it.
Kurt

[BeePM]

size = strlen(buffer) + 1;
t->map = (char*)malloc( sizeof(char) * size );

i have something like this ... is that problem ?

[ZuK]

    char * buffer = malloc( sizeof *s + 1);   // size of a pointer +1 ( 5 or 9 on 64 bits )
    ....
    if((t->password) != NULL) free(t->password);
    t->password = malloc( sizeof *buffer + 1  );   // size of a pointer +1 ( 5 or 9 on 64 bits )
    // ak sa nepridelila pamat konci
    if(t->password == NULL)
        return NULL;
    // kopiruj obsah buffra
    strcpy(t->password, buffer);

Kurt

[Salem]

Well getting strlen() and sizeof() mixed up certainly is one problem.

Another biggie is this code, copy/pasted in several places (make it a function, then you only have to debug it once).

    for(i++; i < strlen(s); i++)
    {
        char znak = s[i];
        strcat(buffer, &znak);
    }

This is NOT how you append a single character to a string, since znak has no \0 character.

At the very least, you need something like

    for(i++; i < strlen(s); i++)
    {
        char znak[2] = { 0 };
        znak[0] = s[i];
        strcat(buffer, znak);
    }

However, since you're trying to append the whole string, you can do it all with something like

strcat( buffer, &s[i+1] );