Fail cleanly on allocation failures

Previously code in the SWIG tool didn't handle allocation failures
well.  Most places didn't check for NULL return from
malloc()/realloc()/calloc() at all, typically resulting in undefined
behaviour, and some places used assert() to check for a NULL return
(which is a misuse of assert() and such checks disappear if built with
NDEBUG defined leaving us back with undefined behaviour).

All C allocations are now done via wrapper functions (Malloc(),
Realloc() and Calloc()) which emit and error and exit with non-zero
status on failure, so a non-NULL return can be relied upon.

Fixes #1901.

Source/Swig/error.c

@@ -209,14 +209,14 @@ void Swig_warnfilter(const_String_or_char_ptr wlist, int add) {
 	  Insert(filter, 0, "-");
 	}
       } else {
-	char *temp = (char *)malloc(sizeof(char)*strlen(c) + 2);
+	char *temp = (char *)Malloc(sizeof(char)*strlen(c) + 2);
 	if (isdigit((int) *c)) {
 	  sprintf(temp, "-%s", c);
 	} else {
 	  strcpy(temp, c);
 	}
 	Replace(filter, temp, "", DOH_REPLACE_FIRST);
-        free(temp);
+	Free(temp);
       }
     }
     c = strtok(NULL, ", ");

Source/Swig/getopt.c

@@ -32,16 +32,12 @@ static int *marked;
  * ----------------------------------------------------------------------------- */
 
 void Swig_init_args(int argc, char **argv) {
-  int i;
   assert(argc > 0);
   assert(argv);
 
   numargs = argc;
   args = argv;
-  marked = (int *) malloc(numargs * sizeof(int));
-  for (i = 0; i < argc; i++) {
-    marked[i] = 0;
-  }
+  marked = (int *) Calloc(numargs, sizeof(int));
   marked[0] = 1;
 }
 

Source/Swig/misc.c

@@ -36,7 +36,7 @@ static char *fake_version = 0;
 char *Swig_copy_string(const char *s) {
   char *c = 0;
   if (s) {
-    c = (char *) malloc(strlen(s) + 1);
+    c = (char *) Malloc(strlen(s) + 1);
     strcpy(c, s);
   }
   return c;
@@ -1251,7 +1251,7 @@ void Swig_offset_string(String *s, int number) {
   if ((Char(s))[len-1] == '\n')
     --lines;
   /* allocate a temporary storage for a padded string */
-  res = (char*)malloc(len + lines * number * 2 + 1);
+  res = (char*)Malloc(len + lines * number * 2 + 1);
   res[len + lines * number * 2] = 0;
 
   /* copy lines to res, prepending tabs to each line */
@@ -1275,7 +1275,7 @@ void Swig_offset_string(String *s, int number) {
   /* replace 's' contents with 'res' */
   Clear(s);
   Append(s, res);
-  free(res);
+  Free(res);
 }
 
 
@@ -1458,11 +1458,11 @@ String *Swig_string_regex(String *s) {
 
 String *Swig_pcre_version(void) {
   int len = pcre2_config(PCRE2_CONFIG_VERSION, NULL);
-  char *buf = malloc(len);
+  char *buf = Malloc(len);
   String *result;
   pcre2_config(PCRE2_CONFIG_VERSION, buf);
   result = NewStringf("PCRE2 Version: %s", buf);
-  free(buf);
+  Free(buf);
   return result;
 }
 

Source/Swig/scanner.c

@@ -56,7 +56,7 @@ static void brackets_clear(Scanner *);
 
 Scanner *NewScanner(void) {
   Scanner *s;
-  s = (Scanner *) malloc(sizeof(Scanner));
+  s = (Scanner *) Malloc(sizeof(Scanner));
   s->line = 1;
   s->file = 0;
   s->nexttoken = -1;
@@ -88,8 +88,8 @@ void DelScanner(Scanner *s) {
   Delete(s->file);
   Delete(s->error);
   Delete(s->str);
-  free(s->idstart);
-  free(s); 
+  Free(s->idstart);
+  Free(s);
 }
 
 /* -----------------------------------------------------------------------------
@@ -202,7 +202,7 @@ int Scanner_start_line(Scanner *s) {
  * ----------------------------------------------------------------------------- */
 
 void Scanner_idstart(Scanner *s, const char *id) {
-  free(s->idstart);
+  Free(s->idstart);
   s->idstart = Swig_copy_string(id);
 }
 
@@ -336,9 +336,9 @@ static void brackets_reset(Scanner *s) {
  * Usually called when '(' is found.
  * ----------------------------------------------------------------------------- */
 static void brackets_push(Scanner *s) {
-  int *newInt = (int *)malloc(sizeof(int));
+  int *newInt = (int *)Malloc(sizeof(int));
   *newInt = 0;
-  Push(s->brackets, NewVoid(newInt, free));
+  Push(s->brackets, NewVoid(newInt, Free));
 }
 
 /* -----------------------------------------------------------------------------
@@ -1811,14 +1811,14 @@ void Scanner_locator(Scanner *s, String *loc) {
 	cparse_file = locs->filename;
 	cparse_line = locs->line_number;
 	l = locs->next;
-	free(locs);
+	Free(locs);
 	locs = l;
       }
       return;
     }
 
     /* We're going to push a new location */
-    l = (Locator *) malloc(sizeof(Locator));
+    l = (Locator *) Malloc(sizeof(Locator));
     l->filename = cparse_file;
     l->line_number = cparse_line;
     l->next = locs;

Source/Swig/wrapfunc.c

@@ -27,7 +27,7 @@ static int Max_line_size = 128;
 
 Wrapper *NewWrapper(void) {
   Wrapper *w;
-  w = (Wrapper *) malloc(sizeof(Wrapper));
+  w = (Wrapper *) Malloc(sizeof(Wrapper));
   w->localh = NewHash();
   w->locals = NewStringEmpty();
   w->code = NewStringEmpty();
@@ -46,7 +46,7 @@ void DelWrapper(Wrapper *w) {
   Delete(w->locals);
   Delete(w->code);
   Delete(w->def);
-  free(w);
+  Free(w);
 }
 
 /* -----------------------------------------------------------------------------