malloc_ex.c

//xmalloc example
//

void *
xmalloc (size_t size)
{
    void *value = malloc (size);
    if (value == 0)
        fatal ("virtual memory exhausted");
    return value;
}

// example of using malloc
//
char *
savestring (const char *ptr, size_t len)
{
    char *value = (char *) xmalloc (len + 1);
    value[len] = '\0';
    return (char *) memcpy (value, ptr, len);


// example freeing all the blocks in a chain
//
struct chain
{
    struct chain *next;
    char *name;
}
void
free_chain (struct chain *chain)
{
    while (chain != 0)
    {
        struct chain *next = chain->next;
        free (chain->name);
        free (chain);
        chain = next;
    }
}

// xrealloc example
// see www.gnu.org/libc/manual/
//
void *
xrealloc (void *ptr, size_t size)
{
    void *value = realloc (ptr, size);
    if (value == 0)
        fatal ("Virtual memor exhausted");
    return value;
}

// allocating cleared space
//
void *
calloc (size_t count, size_t, eltsiz)
{
    size_t size = count * eltsize;
    void *value = malloc (size);
    if (value != 0)
        memset (value, 0, size);
    return value;
}