Fix various potential null ptr deref and int32 overflows

This fix errors that can happen when ingesting very large JSON files
when hitting the maximum heap size of the process.

arraylist.c

@@ -11,6 +11,8 @@
 
 #include "config.h"
 
+#include <limits.h>
+
 #ifdef STDC_HEADERS
 # include <stdlib.h>
 # include <string.h>
@@ -62,10 +64,17 @@ static int array_list_expand_internal(struct array_list *arr, int max)
   int new_size;
 
   if(max < arr->size) return 0;
-  new_size = arr->size << 1;
-  if (new_size < max)
+  /* Avoid undefined behaviour on int32 overflow */
+  if( arr->size >= INT_MAX / 2 )
     new_size = max;
-  if(!(t = realloc(arr->array, new_size*sizeof(void*)))) return -1;
+  else
+  {
+    new_size = arr->size << 1;
+    if (new_size < max)
+      new_size = max;
+  }
+  if((size_t)new_size > (~((size_t)0)) / sizeof(void*)) return -1;
+  if(!(t = realloc(arr->array, ((size_t)new_size)*sizeof(void*)))) return -1;
   arr->array = (void**)t;
   (void)memset(arr->array + arr->size, 0, (new_size-arr->size)*sizeof(void*));
   arr->size = new_size;
@@ -75,6 +84,7 @@ static int array_list_expand_internal(struct array_list *arr, int max)
 int
 array_list_put_idx(struct array_list *arr, int idx, void *data)
 {
+  if( idx < 0 || idx > INT_MAX - 1 ) return -1;
   if(array_list_expand_internal(arr, idx+1)) return -1;
   if(arr->array[idx]) arr->free_fn(arr->array[idx]);
   arr->array[idx] = data;