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/DOH/doh.h

@@ -122,6 +122,10 @@
 #define DohIterator        DOH_NAMESPACE(Iterator)
 #define DohFirst           DOH_NAMESPACE(First)
 #define DohNext            DOH_NAMESPACE(Next)
+#define DohMalloc          DOH_NAMESPACE(Malloc)
+#define DohRealloc         DOH_NAMESPACE(Realloc)
+#define DohCalloc          DOH_NAMESPACE(Calloc)
+#define DohFree            DOH_NAMESPACE(Free)
 #endif
 
 #define DOH_MAJOR_VERSION 0
@@ -163,12 +167,11 @@ typedef struct {
 
 /* Memory management */
 
-#ifndef DohMalloc
-#define DohMalloc malloc
-#endif
-#ifndef DohRealloc
-#define DohRealloc realloc
-#endif
+/* Wrappers around malloc(), realloc() and calloc() which never return NULL. */
+extern void *DohMalloc(size_t size);
+extern void *DohRealloc(void *ptr, size_t size);
+extern void *DohCalloc(size_t n, size_t size);
+
 #ifndef DohFree
 #define DohFree free
 #endif
@@ -440,6 +443,10 @@ extern void DohMemoryDebug(void);
 #define Next               DohNext
 #define Iterator           DohIterator
 #define SortList           DohSortList
+#define Malloc             DohMalloc
+#define Realloc            DohRealloc
+#define Calloc             DohCalloc
+#define Free               DohFree
 #endif
 
 #ifdef NIL

Source/DOH/file.c

@@ -291,10 +291,6 @@ DOH *DohNewFile(DOHString *filename, const char *mode, DOHList *newfiles) {
     return 0;
 
   f = (DohFile *) DohMalloc(sizeof(DohFile));
-  if (!f) {
-    fclose(file);
-    return 0;
-  }
   if (newfiles)
     Append(newfiles, filename);
   f->filep = file;
@@ -314,8 +310,6 @@ DOH *DohNewFile(DOHString *filename, const char *mode, DOHList *newfiles) {
 DOH *DohNewFileFromFile(FILE *file) {
   DohFile *f;
   f = (DohFile *) DohMalloc(sizeof(DohFile));
-  if (!f)
-    return 0;
   f->filep = file;
   f->fd = 0;
   f->closeondel = 0;
@@ -331,8 +325,6 @@ DOH *DohNewFileFromFile(FILE *file) {
 DOH *DohNewFileFromFd(int fd) {
   DohFile *f;
   f = (DohFile *) DohMalloc(sizeof(DohFile));
-  if (!f)
-    return 0;
   f->filep = 0;
   f->fd = fd;
   f->closeondel = 0;

Source/DOH/hash.c

@@ -173,10 +173,7 @@ static void resize(Hash *h) {
     p = p + 2;
   }
 
-  table = (HashNode **) DohMalloc(newsize * sizeof(HashNode *));
-  for (i = 0; i < newsize; i++) {
-    table[i] = 0;
-  }
+  table = (HashNode **) DohCalloc(newsize, sizeof(HashNode *));
 
   /* Walk down the old set of nodes and re-place */
   h->hashsize = newsize;

Source/DOH/list.c

@@ -27,7 +27,6 @@ extern DohObjInfo DohListType;
 static
 void more(List *l) {
   l->items = (void **) DohRealloc(l->items, l->maxitems * 2 * sizeof(void *));
-  assert(l->items);
   l->maxitems *= 2;
 }
 
@@ -346,15 +345,10 @@ DohObjInfo DohListType = {
 #define MAXLISTITEMS 8
 
 DOH *DohNewList(void) {
-  List *l;
-  int i;
-  l = (List *) DohMalloc(sizeof(List));
+  List *l = (List *) DohMalloc(sizeof(List));
   l->nitems = 0;
   l->maxitems = MAXLISTITEMS;
-  l->items = (void **) DohMalloc(l->maxitems * sizeof(void *));
-  for (i = 0; i < MAXLISTITEMS; i++) {
-    l->items[i] = 0;
-  }
+  l->items = (void **) DohCalloc(l->maxitems, sizeof(void *));
   l->file = 0;
   l->line = 0;
   return DohObjMalloc(&DohListType, l);

Source/DOH/memory.c

@@ -14,6 +14,9 @@
 
 #include "dohint.h"
 
+#include <stdio.h>
+#include <stdlib.h>
+
 #ifndef DOH_POOL_SIZE
 #define DOH_POOL_SIZE         4194304
 #endif
@@ -48,10 +51,7 @@ static int pools_initialized = 0;
 static void CreatePool() {
   Pool *p = 0;
   p = (Pool *) DohMalloc(sizeof(Pool));
-  assert(p);
-  p->ptr = (DohBase *) DohMalloc(sizeof(DohBase) * PoolSize);
-  assert(p->ptr);
-  memset(p->ptr, 0, sizeof(DohBase) * PoolSize);
+  p->ptr = (DohBase *) DohCalloc(PoolSize, sizeof(DohBase));
   p->len = PoolSize;
   p->blen = PoolSize * sizeof(DohBase);
   p->current = 0;
@@ -234,3 +234,40 @@ void DohMemoryDebug(void) {
 #endif
 
 }
+
+static void allocation_failed(size_t n, size_t size) {
+  /* Report and exit as directly as possible to try to avoid further issues due
+   * to lack of memory. */
+  if (n == 1) {
+#if defined __STDC_VERSION__ && __STDC_VERSION__-0 >= 19901L
+    fprintf(stderr, "Failed to allocate %zu bytes\n", size);
+#else
+    fprintf(stderr, "Failed to allocate %lu bytes\n", (unsigned long)size);
+#endif
+  } else {
+#if defined __STDC_VERSION__ && __STDC_VERSION__-0 >= 19901L
+    fprintf(stderr, "Failed to allocate %zu*%zu bytes\n", n, size);
+#else
+    fprintf(stderr, "Failed to allocate %lu*%lu bytes\n", (unsigned long)n, (unsigned long)size);
+#endif
+  }
+  exit(EXIT_FAILURE);
+}
+
+void *DohMalloc(size_t size) {
+  void *p = malloc(size);
+  if (!p) allocation_failed(1, size);
+  return p;
+}
+
+void *DohRealloc(void *ptr, size_t size) {
+  void *p = realloc(ptr, size);
+  if (!p) allocation_failed(1, size);
+  return p;
+}
+
+void *DohCalloc(size_t n, size_t size) {
+  void *p = calloc(n, size);
+  if (!p) allocation_failed(n, size);
+  return p;
+}

Source/DOH/string.c

@@ -229,7 +229,6 @@ static void DohString_append(DOH *so, const DOHString_or_char *str) {
     if (newlen >= newmaxsize - 1)
       newmaxsize = newlen + 1;
     s->str = (char *) DohRealloc(s->str, newmaxsize);
-    assert(s->str);
     s->maxsize = newmaxsize;
   }
   tc = s->str;
@@ -296,7 +295,6 @@ static int String_insert(DOH *so, int pos, DOH *str) {
   while (s->maxsize <= s->len + len) {
     int newsize = 2 * s->maxsize;
     s->str = (char *) DohRealloc(s->str, newsize);
-    assert(s->str);
     s->maxsize = newsize;
   }
   memmove(s->str + pos + len, s->str + pos, (s->len - pos));
@@ -424,7 +422,6 @@ static int String_write(DOH *so, const void *buffer, int len) {
   newlen = s->sp + len + 1;
   if (newlen > s->maxsize) {
     s->str = (char *) DohRealloc(s->str, newlen);
-    assert(s->str);
     s->maxsize = newlen;
     s->len = s->sp + len;
   }
@@ -517,7 +514,6 @@ static int String_putc(DOH *so, int ch) {
     if (len > (maxsize - 2)) {
       maxsize *= 2;
       tc = (char *) DohRealloc(tc, maxsize);
-      assert(tc);
       s->maxsize = (int) maxsize;
       s->str = tc;
     }
@@ -923,7 +919,6 @@ static int replace_simple(String *str, char *token, char *rep, int flags, int co
       newsize *= 2;
 
     ns = (char *) DohMalloc(newsize);
-    assert(ns);
     t = ns;
     s = first;