Question

For example,
I need to malloc two pieces of memory, so:

void *a = malloc (1);

if (!a)
  return -1;

void *b = malloc (1);

if (!b)
{
  free (a);
  return -1;
}

Notice if the second malloc fails, I have to free “a” first. The problem is, this can be very messy if there are many such malloc’s and error checking’s, unless I use the notorious “goto” clause and carefully arrange the order of free’s along with the labels:

void *a = malloc (1);

if (!a)
  goto X;

void *b = malloc (1);

if (!b)
  goto Y;

return 0; //normal exit

Y:
  free (a);
X:
  return -1;

Do you have any better solution to this situation? Thanks in advance.

Answer 1

We do like this:

void *a = NULL;
void *b = NULL;
void *c = NULL;
a = malloc(1);
if (!a) goto errorExit;
b = malloc(1);
if (!b) goto errorExit;
c = malloc(1);
if (!b) goto errorExit;

return 0;
errorExit:
//free a null pointer is safe.
free(a);
free(b);
free(c);
return -1;