Tweak ordering of constant pdf_obj enums to make PDF_NULL == NULL.

2 files changed, 117 insertions, 149 deletions

diff --git a/source/pdf/pdf-clean-file.c b/source/pdf/pdf-clean-file.c
index 9cdd7c91..eb5505dc 100644
--- a/source/pdf/pdf-clean-file.c
+++ b/source/pdf/pdf-clean-file.c
@@ -68,9 +68,7 @@ static int dest_is_valid(fz_context *ctx, pdf_obj *o, int page_count, int *page_
 	if (p == NULL)
 	{}
 	else if (pdf_is_string(ctx, p))
-	{
 		return string_in_names_list(ctx, p, names_list);
-	}
 	else if (!dest_is_valid_page(ctx, pdf_array_get(ctx, p, 0), page_object_nums, page_count))
 		return 0;
 
@@ -278,8 +276,7 @@ static void retainpages(fz_context *ctx, globals *glo, int argc, char **argv)
 		pdf_drop_obj(ctx, olddests);
 	}
 
-	/* Edit each pages /Annot list to remove any links that point to
-	 * nowhere. */
+	/* Edit each pages /Annot list to remove any links that point to nowhere. */
 	for (i = 0; i < pagecount; i++)
 	{
 		pdf_obj *pageref = pdf_lookup_page_obj(ctx, doc, i);
diff --git a/source/pdf/pdf-object.c b/source/pdf/pdf-object.c
index 0d43e056..0efd667e 100644
--- a/source/pdf/pdf-object.c
+++ b/source/pdf/pdf-object.c
@@ -8,7 +8,7 @@
 
 #define PDF_MAKE_NAME(STRING,NAME) STRING,
 static const char *PDF_NAME_LIST[] = {
-	"", /* dummy */
+	"", "", "", /* dummy slots for null, true, and false */
 #include "mupdf/pdf/name-table.h"
 };
 #undef PDF_MAKE_NAME
@@ -159,21 +159,23 @@ pdf_new_string(fz_context *ctx, pdf_document *doc, const char *str, size_t len)
 	return &obj->super;
 }
 
-static int
-namecmp(const void *key, const void *name)
-{
-	return strcmp((char *)key, *(char **)name);
-}
-
 pdf_obj *
 pdf_new_name(fz_context *ctx, pdf_document *doc, const char *str)
 {
 	pdf_obj_name *obj;
-	const char **stdname;
-
-	stdname = bsearch(str, &PDF_NAME_LIST[1], PDF_ENUM_LIMIT_NAME-1, sizeof(char *), namecmp);
-	if (stdname != NULL)
-		return (pdf_obj *)(intptr_t)(stdname - &PDF_NAME_LIST[0]);
+	int l = 3; /* skip dummy slots */
+	int r = nelem(PDF_NAME_LIST) - 1;
+	while (l <= r)
+	{
+		int m = (l + r) >> 1;
+		int c = strcmp(str, PDF_NAME_LIST[m]);
+		if (c < 0)
+			r = m - 1;
+		else if (c > 0)
+			l = m + 1;
+		else
+			return (pdf_obj*)(intptr_t)m;
+	}
 
 	obj = Memento_label(fz_malloc(ctx, offsetof(pdf_obj_name, n) + strlen(str) + 1), "pdf_obj(name)");
 	obj->super.refs = 1;
@@ -197,34 +199,23 @@ pdf_new_indirect(fz_context *ctx, pdf_document *doc, int num, int gen)
 	return &obj->super;
 }
 
-pdf_obj *
-pdf_keep_obj(fz_context *ctx, pdf_obj *obj)
-{
-	if (obj >= PDF_OBJ_LIMIT)
-	{
-		(void)fz_keep_imp16(ctx, obj, &obj->refs);
-	}
-	return obj;
-}
-
 #define OBJ_IS_NULL(obj) (obj == PDF_NULL)
 #define OBJ_IS_BOOL(obj) (obj == PDF_TRUE || obj == PDF_FALSE)
+#define OBJ_IS_NAME(obj) ((obj > PDF_FALSE && obj < PDF_LIMIT) || (obj >= PDF_LIMIT && obj->kind == PDF_NAME))
 #define OBJ_IS_INT(obj) \
-	(obj >= PDF_OBJ_LIMIT ? obj->kind == PDF_INT : 0)
+	(obj >= PDF_LIMIT && obj->kind == PDF_INT)
 #define OBJ_IS_REAL(obj) \
-	(obj >= PDF_OBJ_LIMIT ? obj->kind == PDF_REAL : 0)
+	(obj >= PDF_LIMIT && obj->kind == PDF_REAL)
 #define OBJ_IS_NUMBER(obj) \
-	(obj >= PDF_OBJ_LIMIT ? (obj->kind == PDF_REAL || obj->kind == PDF_INT) : 0)
+	(obj >= PDF_LIMIT && (obj->kind == PDF_REAL || obj->kind == PDF_INT))
 #define OBJ_IS_STRING(obj) \
-	(obj >= PDF_OBJ_LIMIT ? obj->kind == PDF_STRING : 0)
-#define OBJ_IS_NAME(obj) \
-	((obj >= PDF_OBJ_LIMIT) ? (obj->kind == PDF_NAME) : (obj != NULL && obj < PDF_NAME_LIMIT))
+	(obj >= PDF_LIMIT && obj->kind == PDF_STRING)
 #define OBJ_IS_ARRAY(obj) \
-	(obj >= PDF_OBJ_LIMIT ? obj->kind == PDF_ARRAY : 0)
+	(obj >= PDF_LIMIT && obj->kind == PDF_ARRAY)
 #define OBJ_IS_DICT(obj) \
-	(obj >= PDF_OBJ_LIMIT ? obj->kind == PDF_DICT : 0)
+	(obj >= PDF_LIMIT && obj->kind == PDF_DICT)
 #define OBJ_IS_INDIRECT(obj) \
-	(obj >= PDF_OBJ_LIMIT ? obj->kind == PDF_INDIRECT : 0)
+	(obj >= PDF_LIMIT && obj->kind == PDF_INDIRECT)
 
 #define RESOLVE(obj) \
 	if (OBJ_IS_INDIRECT(obj)) \
@@ -298,7 +289,7 @@ int pdf_to_bool(fz_context *ctx, pdf_obj *obj)
 int pdf_to_int(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	if (obj->kind == PDF_INT)
 		return (int)NUM(obj)->u.i;
@@ -310,7 +301,7 @@ int pdf_to_int(fz_context *ctx, pdf_obj *obj)
 int64_t pdf_to_int64(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	if (obj->kind == PDF_INT)
 		return NUM(obj)->u.i;
@@ -322,7 +313,7 @@ int64_t pdf_to_int64(fz_context *ctx, pdf_obj *obj)
 float pdf_to_real(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	if (obj->kind == PDF_REAL)
 		return NUM(obj)->u.f;
@@ -334,34 +325,33 @@ float pdf_to_real(fz_context *ctx, pdf_obj *obj)
 const char *pdf_to_name(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (!OBJ_IS_NAME(obj))
-		return "";
-	if (obj < PDF_NAME_LIMIT)
-		return PDF_NAME_LIST[(intptr_t)obj];
-	return NAME(obj)->n;
+	if (obj < PDF_LIMIT)
+		return PDF_NAME_LIST[((intptr_t)obj)];
+	if (obj->kind == PDF_NAME)
+		return NAME(obj)->n;
+	return "";
 }
 
 char *pdf_to_str_buf(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (!OBJ_IS_STRING(obj))
-		return "";
-	return STRING(obj)->buf;
+	if (OBJ_IS_STRING(obj))
+		return STRING(obj)->buf;
+	return "";
 }
 
 int pdf_to_str_len(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (!OBJ_IS_STRING(obj))
-		return 0;
-	return STRING(obj)->len;
+	if (OBJ_IS_STRING(obj))
+		return STRING(obj)->len;
+	return 0;
 }
 
 void pdf_set_int(fz_context *ctx, pdf_obj *obj, int64_t i)
 {
-	if (!OBJ_IS_INT(obj))
-		return;
-	NUM(obj)->u.i = i;
+	if (OBJ_IS_INT(obj))
+		NUM(obj)->u.i = i;
 }
 
 /* for use by pdf_crypt_obj_imp to decrypt AES string in place */
@@ -377,28 +367,28 @@ void pdf_set_str_len(fz_context *ctx, pdf_obj *obj, int newlen)
 
 int pdf_to_num(fz_context *ctx, pdf_obj *obj)
 {
-	if (!OBJ_IS_INDIRECT(obj))
-		return 0;
-	return REF(obj)->num;
+	if (OBJ_IS_INDIRECT(obj))
+		return REF(obj)->num;
+	return 0;
 }
 
 int pdf_to_gen(fz_context *ctx, pdf_obj *obj)
 {
-	if (!OBJ_IS_INDIRECT(obj))
-		return 0;
-	return REF(obj)->gen;
+	if (OBJ_IS_INDIRECT(obj))
+		return REF(obj)->gen;
+	return 0;
 }
 
 pdf_document *pdf_get_indirect_document(fz_context *ctx, pdf_obj *obj)
 {
-	if (!OBJ_IS_INDIRECT(obj))
-		return NULL;
-	return REF(obj)->doc;
+	if (OBJ_IS_INDIRECT(obj))
+		return REF(obj)->doc;
+	return NULL;
 }
 
 pdf_document *pdf_get_bound_document(fz_context *ctx, pdf_obj *obj)
 {
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return NULL;
 	if (obj->kind == PDF_INDIRECT)
 		return REF(obj)->doc;
@@ -424,32 +414,25 @@ pdf_objcmp(fz_context *ctx, pdf_obj *a, pdf_obj *b)
 	if (a == b)
 		return 0;
 
-	if (!a || !b)
+	if (a <= PDF_FALSE || b <= PDF_FALSE)
 		return 1;
 
-	if (a < PDF_NAME_LIMIT)
+	if (a < PDF_LIMIT)
 	{
-		if (b < PDF_NAME_LIMIT)
+		if (b < PDF_LIMIT)
 			return a != b;
-		if (b < PDF_OBJ_LIMIT)
-			return 1;
 		if (b->kind != PDF_NAME)
 			return 1;
-		return strcmp(NAME(b)->n, PDF_NAME_LIST[(intptr_t)a]);
+		return strcmp(PDF_NAME_LIST[(intptr_t)a], NAME(b)->n);
 	}
 
-	if (b < PDF_NAME_LIMIT)
+	if (b < PDF_LIMIT)
 	{
-		if (a < PDF_OBJ_LIMIT)
-			return 1;
 		if (a->kind != PDF_NAME)
 			return 1;
 		return strcmp(NAME(a)->n, PDF_NAME_LIST[(intptr_t)b]);
 	}
 
-	if (a < PDF_OBJ_LIMIT || b < PDF_OBJ_LIMIT)
-		return a != b;
-
 	if (a->kind != b->kind)
 		return 1;
 
@@ -513,23 +496,26 @@ pdf_objcmp(fz_context *ctx, pdf_obj *a, pdf_obj *b)
 
 int pdf_name_eq(fz_context *ctx, pdf_obj *a, pdf_obj *b)
 {
-	/* A quick check in case they are constants */
-	if (a < PDF_NAME_LIMIT)
-		return a == b;
-	return !pdf_objcmp_resolve(ctx, a, b);
+	RESOLVE(a);
+	RESOLVE(b);
+	if (a <= PDF_FALSE || b <= PDF_FALSE)
+		return 0;
+	if (a < PDF_LIMIT || b < PDF_LIMIT)
+		return (a == b);
+	if (a->kind == PDF_NAME && b->kind == PDF_NAME)
+		return !strcmp(NAME(a)->n, NAME(b)->n);
+	return 0;
 }
 
 static char *
 pdf_objkindstr(pdf_obj *obj)
 {
-	if (!obj)
-		return "<NULL>";
-	if (obj < PDF_NAME_LIMIT)
-		return "name";
-	if (obj == PDF_TRUE || obj == PDF_FALSE)
-		return "boolean";
 	if (obj == PDF_NULL)
 		return "null";
+	if (obj == PDF_TRUE || obj == PDF_FALSE)
+		return "boolean";
+	if (obj < PDF_LIMIT)
+		return "name";
 	switch (obj->kind)
 	{
 	case PDF_INT: return "integer";
@@ -644,7 +630,7 @@ static void prepare_object_for_alteration(fz_context *ctx, pdf_obj *obj, pdf_obj
 		obj should be a dict or an array. We don't care about
 		any other types, as they aren't 'containers'.
 	*/
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return;
 
 	switch (obj->kind)
@@ -697,10 +683,6 @@ pdf_array_put(fz_context *ctx, pdf_obj *obj, int i, pdf_obj *item)
 	}
 	if (i < 0 || i > ARRAY(obj)->len)
 		fz_throw(ctx, FZ_ERROR_GENERIC, "index out of bounds");
-
-	if (!item)
-		item = PDF_NULL;
-
 	prepare_object_for_alteration(ctx, obj, item);
 	pdf_drop_obj(ctx, ARRAY(obj)->items[i]);
 	ARRAY(obj)->items[i] = pdf_keep_obj(ctx, item);
@@ -723,10 +705,6 @@ pdf_array_push(fz_context *ctx, pdf_obj *obj, pdf_obj *item)
 	RESOLVE(obj);
 	if (!OBJ_IS_ARRAY(obj))
 		fz_throw(ctx, FZ_ERROR_GENERIC, "not an array (%s)", pdf_objkindstr(obj));
-
-	if (!item)
-		item = PDF_NULL;
-
 	prepare_object_for_alteration(ctx, obj, item);
 	if (ARRAY(obj)->len + 1 > ARRAY(obj)->cap)
 		pdf_array_grow(ctx, ARRAY(obj));
@@ -737,16 +715,12 @@ pdf_array_push(fz_context *ctx, pdf_obj *obj, pdf_obj *item)
 void
 pdf_array_push_drop(fz_context *ctx, pdf_obj *obj, pdf_obj *item)
 {
-	RESOLVE(obj);
-	if (obj >= PDF_OBJ_LIMIT)
-	{
-		fz_try(ctx)
-			pdf_array_push(ctx, obj, item);
-		fz_always(ctx)
-			pdf_drop_obj(ctx, item);
-		fz_catch(ctx)
-			fz_rethrow(ctx);
-	}
+	fz_try(ctx)
+		pdf_array_push(ctx, obj, item);
+	fz_always(ctx)
+		pdf_drop_obj(ctx, item);
+	fz_catch(ctx)
+		fz_rethrow(ctx);
 }
 
 void
@@ -757,10 +731,6 @@ pdf_array_insert(fz_context *ctx, pdf_obj *obj, pdf_obj *item, int i)
 		fz_throw(ctx, FZ_ERROR_GENERIC, "not an array (%s)", pdf_objkindstr(obj));
 	if (i < 0 || i > ARRAY(obj)->len)
 		fz_throw(ctx, FZ_ERROR_GENERIC, "index out of bounds");
-
-	if (!item)
-		item = PDF_NULL;
-
 	prepare_object_for_alteration(ctx, obj, item);
 	if (ARRAY(obj)->len + 1 > ARRAY(obj)->cap)
 		pdf_array_grow(ctx, ARRAY(obj));
@@ -772,16 +742,12 @@ pdf_array_insert(fz_context *ctx, pdf_obj *obj, pdf_obj *item, int i)
 void
 pdf_array_insert_drop(fz_context *ctx, pdf_obj *obj, pdf_obj *item, int i)
 {
-	RESOLVE(obj);
-	if (obj >= PDF_OBJ_LIMIT)
-	{
-		fz_try(ctx)
-			pdf_array_insert(ctx, obj, item, i);
-		fz_always(ctx)
-			pdf_drop_obj(ctx, item);
-		fz_catch(ctx)
-			fz_rethrow(ctx);
-	}
+	fz_try(ctx)
+		pdf_array_insert(ctx, obj, item, i);
+	fz_always(ctx)
+		pdf_drop_obj(ctx, item);
+	fz_catch(ctx)
+		fz_rethrow(ctx);
 }
 
 void
@@ -792,7 +758,6 @@ pdf_array_delete(fz_context *ctx, pdf_obj *obj, int i)
 		fz_throw(ctx, FZ_ERROR_GENERIC, "not an array (%s)", pdf_objkindstr(obj));
 	if (i < 0 || i >= ARRAY(obj)->len)
 		fz_throw(ctx, FZ_ERROR_GENERIC, "index out of bounds");
-
 	prepare_object_for_alteration(ctx, obj, NULL);
 	pdf_drop_obj(ctx, ARRAY(obj)->items[i]);
 	ARRAY(obj)->items[i] = 0;
@@ -875,16 +840,16 @@ static int keyvalcmp(const void *ap, const void *bp)
 
 	/* We should never get a->k == NULL or b->k == NULL. If we
 	 * do, then they match. */
-	if (a->k < PDF_NAME_LIMIT)
+	if (a->k < PDF_LIMIT)
 		an = PDF_NAME_LIST[(intptr_t)a->k];
-	else if (a->k >= PDF_OBJ_LIMIT && a->k->kind == PDF_NAME)
+	else if (a->k >= PDF_LIMIT && a->k->kind == PDF_NAME)
 		an = NAME(a->k)->n;
 	else
 		return 0;
 
-	if (b->k < PDF_NAME_LIMIT)
+	if (b->k < PDF_LIMIT)
 		bn = PDF_NAME_LIST[(intptr_t)b->k];
-	else if (b->k >= PDF_OBJ_LIMIT && b->k->kind == PDF_NAME)
+	else if (b->k >= PDF_LIMIT && b->k->kind == PDF_NAME)
 		bn = NAME(b->k)->n;
 	else
 		return 0;
@@ -1064,7 +1029,7 @@ pdf_dict_find(fz_context *ctx, pdf_obj *obj, pdf_obj *key)
 		int r = len - 1;
 		pdf_obj *k = DICT(obj)->items[r].k;
 
-		if (k == key || (k >= PDF_OBJ_LIMIT && strcmp(NAME(k)->n, PDF_NAME_LIST[(intptr_t)key]) < 0))
+		if (k == key || (k >= PDF_LIMIT && strcmp(NAME(k)->n, PDF_NAME_LIST[(intptr_t)key]) < 0))
 		{
 			return -1 - (r+1);
 		}
@@ -1075,7 +1040,7 @@ pdf_dict_find(fz_context *ctx, pdf_obj *obj, pdf_obj *key)
 			int c;
 
 			k = DICT(obj)->items[m].k;
-			c = (k < PDF_OBJ_LIMIT ? (char *)key-(char *)k : -strcmp(NAME(k)->n, PDF_NAME_LIST[(intptr_t)key]));
+			c = (k < PDF_LIMIT ? (char *)key-(char *)k : -strcmp(NAME(k)->n, PDF_NAME_LIST[(intptr_t)key]));
 			if (c < 0)
 				r = m - 1;
 			else if (c > 0)
@@ -1091,7 +1056,7 @@ pdf_dict_find(fz_context *ctx, pdf_obj *obj, pdf_obj *key)
 		for (i = 0; i < len; i++)
 		{
 			pdf_obj *k = DICT(obj)->items[i].k;
-			if (k < PDF_OBJ_LIMIT)
+			if (k < PDF_LIMIT)
 			{
 				if (k == key)
 					return i;
@@ -1185,7 +1150,7 @@ pdf_dict_get(fz_context *ctx, pdf_obj *obj, pdf_obj *key)
 	if (!OBJ_IS_NAME(key))
 		return NULL;
 
-	if (key < PDF_NAME_LIMIT)
+	if (key < PDF_LIMIT)
 		i = pdf_dict_find(ctx, obj, key);
 	else
 		i = pdf_dict_finds(ctx, obj, pdf_to_name(ctx, key));
@@ -1228,13 +1193,10 @@ pdf_dict_get_put(fz_context *ctx, pdf_obj *obj, pdf_obj *key, pdf_obj *val, pdf_
 	if (!OBJ_IS_NAME(key))
 		fz_throw(ctx, FZ_ERROR_GENERIC, "key is not a name (%s)", pdf_objkindstr(obj));
 
-	if (!val)
-		val = PDF_NULL;
-
 	if (DICT(obj)->len > 100 && !(obj->flags & PDF_FLAGS_SORTED))
 		pdf_sort_dict(ctx, obj);
 
-	if (key < PDF_NAME_LIMIT)
+	if (key < PDF_LIMIT)
 		i = pdf_dict_find(ctx, obj, key);
 	else
 		i = pdf_dict_finds(ctx, obj, pdf_to_name(ctx, key));
@@ -1522,7 +1484,7 @@ pdf_dict_del(fz_context *ctx, pdf_obj *obj, pdf_obj *key)
 	if (!OBJ_IS_NAME(key))
 		fz_throw(ctx, FZ_ERROR_GENERIC, "key is not a name (%s)", pdf_objkindstr(key));
 
-	if (key < PDF_NAME_LIMIT)
+	if (key < PDF_LIMIT)
 		pdf_dict_dels(ctx, obj, PDF_NAME_LIST[(intptr_t)key]);
 	else
 		pdf_dict_dels(ctx, obj, NAME(key)->n);
@@ -1544,9 +1506,9 @@ pdf_sort_dict(fz_context *ctx, pdf_obj *obj)
 pdf_obj *
 pdf_deep_copy_obj(fz_context *ctx, pdf_obj *obj)
 {
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 	{
-		return pdf_keep_obj(ctx, obj);
+		return obj;
 	}
 	if (obj->kind == PDF_DICT)
 	{
@@ -1600,7 +1562,7 @@ int
 pdf_obj_marked(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	return !!(obj->flags & PDF_FLAGS_MARKED);
 }
@@ -1610,7 +1572,7 @@ pdf_mark_obj(fz_context *ctx, pdf_obj *obj)
 {
 	int marked;
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	marked = !!(obj->flags & PDF_FLAGS_MARKED);
 	obj->flags |= PDF_FLAGS_MARKED;
@@ -1621,7 +1583,7 @@ void
 pdf_unmark_obj(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return;
 	obj->flags &= ~PDF_FLAGS_MARKED;
 }
@@ -1629,9 +1591,8 @@ pdf_unmark_obj(fz_context *ctx, pdf_obj *obj)
 void
 pdf_set_obj_memo(fz_context *ctx, pdf_obj *obj, int bit, int memo)
 {
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return;
-
 	bit <<= 1;
 	obj->flags |= PDF_FLAGS_MEMO_BASE << bit;
 	if (memo)
@@ -1643,7 +1604,7 @@ pdf_set_obj_memo(fz_context *ctx, pdf_obj *obj, int bit, int memo)
 int
 pdf_obj_memo(fz_context *ctx, pdf_obj *obj, int bit, int *memo)
 {
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	bit <<= 1;
 	if (!(obj->flags & (PDF_FLAGS_MEMO_BASE<<bit)))
@@ -1655,7 +1616,7 @@ pdf_obj_memo(fz_context *ctx, pdf_obj *obj, int bit, int *memo)
 int pdf_obj_is_dirty(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 	return !!(obj->flags & PDF_FLAGS_DIRTY);
 }
@@ -1663,14 +1624,14 @@ int pdf_obj_is_dirty(fz_context *ctx, pdf_obj *obj)
 void pdf_dirty_obj(fz_context *ctx, pdf_obj *obj)
 {
 	RESOLVE(obj);
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return;
 	obj->flags |= PDF_FLAGS_DIRTY;
 }
 
 void pdf_clean_obj(fz_context *ctx, pdf_obj *obj)
 {
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return;
 	obj->flags &= ~PDF_FLAGS_DIRTY;
 }
@@ -1701,10 +1662,18 @@ pdf_drop_dict(fz_context *ctx, pdf_obj *obj)
 	fz_free(ctx, obj);
 }
 
+pdf_obj *
+pdf_keep_obj(fz_context *ctx, pdf_obj *obj)
+{
+	if (obj >= PDF_LIMIT)
+		return fz_keep_imp16(ctx, obj, &obj->refs);
+	return obj;
+}
+
 void
 pdf_drop_obj(fz_context *ctx, pdf_obj *obj)
 {
-	if (obj >= PDF_OBJ_LIMIT)
+	if (obj >= PDF_LIMIT)
 	{
 		if (fz_drop_imp16(ctx, obj, &obj->refs))
 		{
@@ -1723,10 +1692,10 @@ pdf_set_obj_parent(fz_context *ctx, pdf_obj *obj, int num)
 {
 	int n, i;
 
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return;
 
-	switch(obj->kind)
+	switch (obj->kind)
 	{
 	case PDF_ARRAY:
 		ARRAY(obj)->parent_num = num;
@@ -1745,10 +1714,10 @@ pdf_set_obj_parent(fz_context *ctx, pdf_obj *obj, int num)
 
 int pdf_obj_parent_num(fz_context *ctx, pdf_obj *obj)
 {
-	if (obj < PDF_OBJ_LIMIT)
+	if (obj < PDF_LIMIT)
 		return 0;
 
-	switch(obj->kind)
+	switch (obj->kind)
 	{
 	case PDF_INDIRECT:
 		return REF(obj)->num;
@@ -2180,9 +2149,11 @@ void pdf_debug_obj(fz_context *ctx, pdf_obj *obj)
 	putchar('\n');
 }
 
-int pdf_obj_refs(fz_context *ctx, pdf_obj *ref)
+int pdf_obj_refs(fz_context *ctx, pdf_obj *obj)
 {
-	return (ref >= PDF_OBJ_LIMIT ? ref->refs : 0);
+	if (obj < PDF_LIMIT)
+		return 0;
+	return obj->refs;
 }
 
 /* Convenience functions */