Add the ability to bail before EOF to get_line_alloc();

If we stop reading a file before getting to the end, get_line_alloc()
will not clean up the memory it allocated. Give get_line_alloc()
the ability to do a forced cleanup by calling it with a NULL file,
and use that ability where we stop reading a file early.

Also clear the state variables when we free the memory, to
pre-empt use-after-free.

src/option.c

@@ -6270,7 +6270,11 @@ void read_opts(int argc, char **argv, char *compile_opts)
 	  
 	  if ((token = strtok(NULL, " \t\n\r")) &&  
 	      (daemon->domain_suffix = canonicalise_opt(token)))
-	    break;
+	    {
+	      /* We don't call get_line_alloc() until it returns false and frees the automatically */
+	      get_line_alloc(NULL, &line, &linesz);
+	      break;
+	    }
 	}
 
       fclose(f);

src/util.c

@@ -1038,16 +1038,15 @@ void free_real(const char *func, unsigned int line, void *ptr)
 }
 
 /* get lines from f, expand buffer as required. Buffer is freed when
-   EOF reached and we return zero. */
+   EOF reached and we return zero. Buffer also freed if f == NULL. */
 int get_line_alloc(FILE *f, char **buffp, size_t *sizep)
 {
-  int c;
   size_t cnt = 0;
   char *buff = *buffp;
-  
-  while (1) {
-    c = getc(f);
 
+  while (1) {
+    int c = f ? getc(f) : EOF;
+        
     if (cnt == *sizep)
       {
 	void *new;
@@ -1081,6 +1080,8 @@ int get_line_alloc(FILE *f, char **buffp, size_t *sizep)
 	  return 1;
 
 	free(buff);
+	*buffp = NULL;
+	*sizep = 0;
 	return 0;
       }