pdf: Drop generation number from public interfaces.

The generation number is only needed for decryption, and is assumed
to be zero or irrelevant for all other uses.

Store the original object number and generation in the xref slot, so
that we can decrypt them even when the objects have been renumbered,
without needing to pass the original object number around through
the stream loading APIs.

1 files changed, 43 insertions, 39 deletions

diff --git a/source/pdf/pdf-xref.c b/source/pdf/pdf-xref.c
index 17de3f60..54dbc4b6 100644
--- a/source/pdf/pdf-xref.c
+++ b/source/pdf/pdf-xref.c
@@ -99,6 +99,7 @@ static void pdf_resize_xref(fz_context *ctx, pdf_document *doc, int newlen)
 		sub->table[i].type = 0;
 		sub->table[i].ofs = 0;
 		sub->table[i].gen = 0;
+		sub->table[i].num = 0;
 		sub->table[i].stm_ofs = 0;
 		sub->table[i].stm_buf = NULL;
 		sub->table[i].obj = NULL;
@@ -826,9 +827,10 @@ pdf_read_old_xref(fz_context *ctx, pdf_document *doc, pdf_lexbuf *buf)
 
 				entry->ofs = fz_atoo(s);
 				entry->gen = fz_atoi(s + 11);
+				entry->num = (int)i;
 				entry->type = s[17];
 				if (s[17] != 'f' && s[17] != 'n' && s[17] != 'o')
-					fz_throw(ctx, FZ_ERROR_GENERIC, "unexpected xref type: %#x (%d %d R)", s[17], (int)i, entry->gen);
+					fz_throw(ctx, FZ_ERROR_GENERIC, "unexpected xref type: %#x (%d %d R)", s[17], entry->num, entry->gen);
 			}
 		}
 	}
@@ -879,6 +881,7 @@ pdf_read_new_xref_section(fz_context *ctx, pdf_document *doc, fz_stream *stm, fz
 			entry->type = t == 0 ? 'f' : t == 1 ? 'n' : t == 2 ? 'o' : 0;
 			entry->ofs = w1 ? b : 0;
 			entry->gen = w2 ? c : 0;
+			entry->num = i;
 		}
 	}
 
@@ -918,13 +921,13 @@ pdf_read_new_xref(fz_context *ctx, pdf_document *doc, pdf_lexbuf *buf)
 
 		obj = pdf_dict_get(ctx, trailer, PDF_NAME_Size);
 		if (!obj)
-			fz_throw(ctx, FZ_ERROR_GENERIC, "xref stream missing Size entry (%d %d R)", num, gen);
+			fz_throw(ctx, FZ_ERROR_GENERIC, "xref stream missing Size entry (%d 0 R)", num);
 
 		size = pdf_to_int(ctx, obj);
 
 		obj = pdf_dict_get(ctx, trailer, PDF_NAME_W);
 		if (!obj)
-			fz_throw(ctx, FZ_ERROR_GENERIC, "xref stream missing W entry (%d %d R)", num, gen);
+			fz_throw(ctx, FZ_ERROR_GENERIC, "xref stream missing W entry (%d  R)", num);
 		w0 = pdf_to_int(ctx, pdf_array_get(ctx, obj, 0));
 		w1 = pdf_to_int(ctx, pdf_array_get(ctx, obj, 1));
 		w2 = pdf_to_int(ctx, pdf_array_get(ctx, obj, 2));
@@ -942,7 +945,7 @@ pdf_read_new_xref(fz_context *ctx, pdf_document *doc, pdf_lexbuf *buf)
 
 		index = pdf_dict_get(ctx, trailer, PDF_NAME_Index);
 
-		stm = pdf_open_stream_with_offset(ctx, doc, num, gen, trailer, stm_ofs);
+		stm = pdf_open_stream_with_offset(ctx, doc, num, trailer, stm_ofs);
 
 		if (!index)
 		{
@@ -961,6 +964,7 @@ pdf_read_new_xref(fz_context *ctx, pdf_document *doc, pdf_lexbuf *buf)
 		entry = pdf_get_populating_xref_entry(ctx, doc, num);
 		entry->ofs = ofs;
 		entry->gen = gen;
+		entry->num = num;
 		entry->stm_ofs = stm_ofs;
 		pdf_drop_obj(ctx, entry->obj);
 		entry->obj = pdf_keep_obj(ctx, trailer);
@@ -1159,6 +1163,7 @@ pdf_load_xref(fz_context *ctx, pdf_document *doc, pdf_lexbuf *buf)
 	{
 		entry->type = 'f';
 		entry->gen = 65535;
+		entry->num = 0;
 	}
 	/* broken pdfs where first object is not free */
 	else if (entry->type != 'f')
@@ -1300,10 +1305,9 @@ pdf_ocg_set_config(fz_context *ctx, pdf_document *doc, int config)
 	{
 		pdf_obj *o = pdf_array_get(ctx, obj, i);
 		int n = pdf_to_num(ctx, o);
-		int g = pdf_to_gen(ctx, o);
 		for (j=0; j < len; j++)
 		{
-			if (desc->ocgs[j].num == n && desc->ocgs[j].gen == g)
+			if (desc->ocgs[j].num == n)
 			{
 				desc->ocgs[j].state = 1;
 				break;
@@ -1317,10 +1321,9 @@ pdf_ocg_set_config(fz_context *ctx, pdf_document *doc, int config)
 	{
 		pdf_obj *o = pdf_array_get(ctx, obj, i);
 		int n = pdf_to_num(ctx, o);
-		int g = pdf_to_gen(ctx, o);
 		for (j=0; j < len; j++)
 		{
-			if (desc->ocgs[j].num == n && desc->ocgs[j].gen == g)
+			if (desc->ocgs[j].num == n)
 			{
 				desc->ocgs[j].state = 0;
 				break;
@@ -1370,7 +1373,6 @@ pdf_read_ocg(fz_context *ctx, pdf_document *doc)
 		{
 			pdf_obj *o = pdf_array_get(ctx, ocg, i);
 			desc->ocgs[i].num = pdf_to_num(ctx, o);
-			desc->ocgs[i].gen = pdf_to_gen(ctx, o);
 			desc->ocgs[i].state = 1;
 		}
 		doc->ocg = desc;
@@ -1481,7 +1483,7 @@ pdf_init_document(fz_context *ctx, pdf_document *doc)
 
 				fz_try(ctx)
 				{
-					dict = pdf_load_object(ctx, doc, i, 0);
+					dict = pdf_load_object(ctx, doc, i);
 				}
 				fz_catch(ctx)
 				{
@@ -1640,7 +1642,7 @@ pdf_print_xref(fz_context *ctx, pdf_document *doc)
  */
 
 static pdf_xref_entry *
-pdf_load_obj_stm(fz_context *ctx, pdf_document *doc, int num, int gen, pdf_lexbuf *buf, int target)
+pdf_load_obj_stm(fz_context *ctx, pdf_document *doc, int num, pdf_lexbuf *buf, int target)
 {
 	fz_stream *stm = NULL;
 	pdf_obj *objstm = NULL;
@@ -1661,7 +1663,7 @@ pdf_load_obj_stm(fz_context *ctx, pdf_document *doc, int num, int gen, pdf_lexbu
 
 	fz_try(ctx)
 	{
-		objstm = pdf_load_object(ctx, doc, num, gen);
+		objstm = pdf_load_object(ctx, doc, num);
 
 		count = pdf_to_int(ctx, pdf_dict_get(ctx, objstm, PDF_NAME_N));
 		first = pdf_to_int(ctx, pdf_dict_get(ctx, objstm, PDF_NAME_First));
@@ -1674,17 +1676,17 @@ pdf_load_obj_stm(fz_context *ctx, pdf_document *doc, int num, int gen, pdf_lexbu
 		numbuf = fz_calloc(ctx, count, sizeof(*numbuf));
 		ofsbuf = fz_calloc(ctx, count, sizeof(*ofsbuf));
 
-		stm = pdf_open_stream(ctx, doc, num, gen);
+		stm = pdf_open_stream(ctx, doc, num);
 		for (i = 0; i < count; i++)
 		{
 			tok = pdf_lex(ctx, stm, buf);
 			if (tok != PDF_TOK_INT)
-				fz_throw(ctx, FZ_ERROR_GENERIC, "corrupt object stream (%d %d R)", num, gen);
+				fz_throw(ctx, FZ_ERROR_GENERIC, "corrupt object stream (%d 0 R)", num);
 			numbuf[i] = buf->i;
 
 			tok = pdf_lex(ctx, stm, buf);
 			if (tok != PDF_TOK_INT)
-				fz_throw(ctx, FZ_ERROR_GENERIC, "corrupt object stream (%d %d R)", num, gen);
+				fz_throw(ctx, FZ_ERROR_GENERIC, "corrupt object stream (%d 0 R)", num);
 			ofsbuf[i] = buf->i;
 		}
 
@@ -1863,7 +1865,8 @@ pdf_obj_read(fz_context *ctx, pdf_document *doc, fz_off_t *offset, int *nump, pd
 			DEBUGMESS((ctx, "Successfully read object %d @ %d", num, numofs));
 		}
 		entry->type = 'n';
-		entry->gen = 0;
+		entry->gen = gen; // XXX: was 0
+		entry->num = num;
 		entry->ofs = numofs;
 		entry->stm_ofs = stmofs;
 	}
@@ -1895,7 +1898,7 @@ pdf_load_hinted_page(fz_context *ctx, pdf_document *doc, int pagenum)
 	fz_try(ctx)
 	{
 		int num = doc->hint_page[pagenum].number;
-		pdf_obj *page = pdf_load_object(ctx, doc, num, 0);
+		pdf_obj *page = pdf_load_object(ctx, doc, num);
 		if (pdf_name_eq(ctx, PDF_NAME_Page, pdf_dict_get(ctx, page, PDF_NAME_Type)))
 		{
 			/* We have found the page object! */
@@ -1985,7 +1988,7 @@ read_hinted_object(fz_context *ctx, pdf_document *doc, int num)
 }
 
 pdf_xref_entry *
-pdf_cache_object(fz_context *ctx, pdf_document *doc, int num, int gen)
+pdf_cache_object(fz_context *ctx, pdf_document *doc, int num)
 {
 	pdf_xref_entry *x;
 	int rnum, rgen, try_repair;
@@ -1993,7 +1996,7 @@ pdf_cache_object(fz_context *ctx, pdf_document *doc, int num, int gen)
 	fz_var(try_repair);
 
 	if (num <= 0 || num >= pdf_xref_len(ctx, doc))
-		fz_throw(ctx, FZ_ERROR_GENERIC, "object out of range (%d %d R); xref size %d", num, gen, pdf_xref_len(ctx, doc));
+		fz_throw(ctx, FZ_ERROR_GENERIC, "object out of range (%d 0 R); xref size %d", num, pdf_xref_len(ctx, doc));
 
 object_updated:
 	try_repair = 0;
@@ -2029,6 +2032,7 @@ object_updated:
 			x->type = 'f';
 			x->ofs = -1;
 			x->gen = 0;
+			x->num = 0;
 			x->stm_ofs = 0;
 			x->obj = NULL;
 			try_repair = (doc->repair_attempted == 0);
@@ -2044,25 +2048,25 @@ object_updated:
 			fz_catch(ctx)
 			{
 				if (rnum == num)
-					fz_throw(ctx, FZ_ERROR_GENERIC, "cannot parse object (%d %d R)", num, gen);
+					fz_throw(ctx, FZ_ERROR_GENERIC, "cannot parse object (%d 0 R)", num);
 				else
-					fz_throw(ctx, FZ_ERROR_GENERIC, "found object (%d %d R) instead of (%d %d R)", rnum, rgen, num, gen);
+					fz_throw(ctx, FZ_ERROR_GENERIC, "found object (%d 0 R) instead of (%d 0 R)", rnum, num);
 			}
 			goto object_updated;
 		}
 
 		if (doc->crypt)
-			pdf_crypt_obj(ctx, doc->crypt, x->obj, num, gen);
+			pdf_crypt_obj(ctx, doc->crypt, x->obj, x->num, x->gen);
 	}
 	else if (x->type == 'o')
 	{
 		if (!x->obj)
 		{
-			x = pdf_load_obj_stm(ctx, doc, x->ofs, 0, &doc->lexbuf.base, num);
+			x = pdf_load_obj_stm(ctx, doc, x->ofs, &doc->lexbuf.base, num);
 			if (x == NULL)
-				fz_throw(ctx, FZ_ERROR_GENERIC, "cannot load object stream containing object (%d %d R)", num, gen);
+				fz_throw(ctx, FZ_ERROR_GENERIC, "cannot load object stream containing object (%d 0 R)", num);
 			if (!x->obj)
-				fz_throw(ctx, FZ_ERROR_GENERIC, "object (%d %d R) was not found in its object stream", num, gen);
+				fz_throw(ctx, FZ_ERROR_GENERIC, "object (%d 0 R) was not found in its object stream", num);
 		}
 	}
 	else if (doc->hint_obj_offsets && read_hinted_object(ctx, doc, num))
@@ -2071,11 +2075,11 @@ object_updated:
 	}
 	else if (doc->file_length && doc->linear_pos < doc->file_length)
 	{
-		fz_throw(ctx, FZ_ERROR_TRYLATER, "cannot find object in xref (%d %d R) - not loaded yet?", num, gen);
+		fz_throw(ctx, FZ_ERROR_TRYLATER, "cannot find object in xref (%d 0 R) - not loaded yet?", num);
 	}
 	else
 	{
-		fz_throw(ctx, FZ_ERROR_GENERIC, "cannot find object in xref (%d %d R)", num, gen);
+		fz_throw(ctx, FZ_ERROR_GENERIC, "cannot find object in xref (%d 0 R)", num);
 	}
 
 	pdf_set_obj_parent(ctx, x->obj, num);
@@ -2083,9 +2087,9 @@ object_updated:
 }
 
 pdf_obj *
-pdf_load_object(fz_context *ctx, pdf_document *doc, int num, int gen)
+pdf_load_object(fz_context *ctx, pdf_document *doc, int num)
 {
-	pdf_xref_entry *entry = pdf_cache_object(ctx, doc, num, gen);
+	pdf_xref_entry *entry = pdf_cache_object(ctx, doc, num);
 	assert(entry->obj != NULL);
 	return pdf_keep_obj(ctx, entry->obj);
 }
@@ -2095,7 +2099,6 @@ pdf_resolve_indirect(fz_context *ctx, pdf_obj *ref)
 {
 	int sanity = 10;
 	int num;
-	int gen;
 	pdf_xref_entry *entry;
 
 	while (pdf_is_indirect(ctx, ref))
@@ -2104,7 +2107,7 @@ pdf_resolve_indirect(fz_context *ctx, pdf_obj *ref)
 
 		if (--sanity == 0)
 		{
-			fz_warn(ctx, "too many indirections (possible indirection cycle involving %d %d R)", num, gen);
+			fz_warn(ctx, "too many indirections (possible indirection cycle involving %d 0 R)", num);
 			return NULL;
 		}
 
@@ -2112,22 +2115,21 @@ pdf_resolve_indirect(fz_context *ctx, pdf_obj *ref)
 		if (!doc)
 			return NULL;
 		num = pdf_to_num(ctx, ref);
-		gen = pdf_to_gen(ctx, ref);
 
-		if (num <= 0 || gen < 0)
+		if (num <= 0)
 		{
-			fz_warn(ctx, "invalid indirect reference (%d %d R)", num, gen);
+			fz_warn(ctx, "invalid indirect reference (%d 0 R)", num);
 			return NULL;
 		}
 
 		fz_try(ctx)
 		{
-			entry = pdf_cache_object(ctx, doc, num, gen);
+			entry = pdf_cache_object(ctx, doc, num);
 		}
 		fz_catch(ctx)
 		{
 			fz_rethrow_if(ctx, FZ_ERROR_TRYLATER);
-			fz_warn(ctx, "cannot load object (%d %d R) into cache", num, gen);
+			fz_warn(ctx, "cannot load object (%d 0 R) into cache", num);
 			return NULL;
 		}
 
@@ -2155,6 +2157,7 @@ pdf_create_object(fz_context *ctx, pdf_document *doc)
 	entry->type = 'f';
 	entry->ofs = -1;
 	entry->gen = 0;
+	entry->num = num;
 	entry->stm_ofs = 0;
 	entry->stm_buf = NULL;
 	entry->obj = NULL;
@@ -2180,6 +2183,7 @@ pdf_delete_object(fz_context *ctx, pdf_document *doc, int num)
 	x->type = 'f';
 	x->ofs = 0;
 	x->gen += 1;
+	x->num = 0;
 	x->stm_ofs = 0;
 	x->stm_buf = NULL;
 	x->obj = NULL;
@@ -2361,7 +2365,7 @@ pdf_open_document(fz_context *ctx, const char *filename)
 }
 
 static void
-pdf_load_hints(fz_context *ctx, pdf_document *doc, int objnum, int gennum)
+pdf_load_hints(fz_context *ctx, pdf_document *doc, int objnum)
 {
 	fz_stream *stream = NULL;
 	pdf_obj *dict;
@@ -2383,7 +2387,7 @@ pdf_load_hints(fz_context *ctx, pdf_document *doc, int objnum, int gennum)
 		int least_shared_group_len, shared_group_len_num_bits;
 		int max_object_num = pdf_xref_len(ctx, doc);
 
-		stream = pdf_open_stream(ctx, doc, objnum, gennum);
+		stream = pdf_open_stream(ctx, doc, objnum);
 		dict = pdf_get_xref_entry(ctx, doc, objnum)->obj;
 		if (dict == NULL || !pdf_is_dict(ctx, dict))
 			fz_throw(ctx, FZ_ERROR_GENERIC, "malformed hint object");
@@ -2604,7 +2608,7 @@ pdf_load_hint_object(fz_context *ctx, pdf_document *doc)
 			if (tok != PDF_TOK_OBJ)
 				break;
 			(void)pdf_repair_obj(ctx, doc, buf, &tmpofs, NULL, NULL, NULL, &page, &tmpofs, NULL);
-			pdf_load_hints(ctx, doc, num, gen);
+			pdf_load_hints(ctx, doc, num);
 		}
 	}
 	fz_always(ctx)