From c630e8e213f5b697b3b78989ba866fed9dd0d45f Mon Sep 17 00:00:00 2001
From: Paul Gardiner <paulg.artifex@glidos.net>
Date: Tue, 28 May 2013 13:23:38 +0100
Subject: Access the trailer via an interface

---
 apps/pdfclean.c      |  4 ++--
 apps/pdfinfo.c       |  4 ++--
 apps/pdfposter.c     |  2 +-
 apps/pdfshow.c       |  6 +++---
 pdf/mupdf-internal.h |  2 ++
 pdf/pdf_field.c      |  2 +-
 pdf/pdf_form.c       |  4 ++--
 pdf/pdf_js.c         |  2 +-
 pdf/pdf_nametree.c   |  6 +++---
 pdf/pdf_outline.c    |  2 +-
 pdf/pdf_page.c       |  2 +-
 pdf/pdf_repair.c     | 16 ++++++++++------
 pdf/pdf_write.c      | 14 +++++++-------
 pdf/pdf_xref.c       | 51 ++++++++++++++++++++++++++++++++-------------------
 14 files changed, 68 insertions(+), 49 deletions(-)

diff --git a/apps/pdfclean.c b/apps/pdfclean.c
index e892db29..78570650 100644
--- a/apps/pdfclean.c
+++ b/apps/pdfclean.c
@@ -42,7 +42,7 @@ static void retainpages(int argc, char **argv)
 
 	/* Keep only pages/type and (reduced) dest entries to avoid
 	 * references to unretained pages */
-	oldroot = pdf_dict_gets(xref->trailer, "Root");
+	oldroot = pdf_dict_gets(pdf_trailer(xref), "Root");
 	pages = pdf_dict_gets(oldroot, "Pages");
 	olddests = pdf_load_name_tree(xref, "Dests");
 
@@ -141,7 +141,7 @@ static void retainpages(int argc, char **argv)
 			pdf_drop_obj(key_str);
 		}
 
-		root = pdf_dict_gets(xref->trailer, "Root");
+		root = pdf_dict_gets(pdf_trailer(xref), "Root");
 		pdf_dict_puts(dests, "Names", names_list);
 		pdf_dict_puts(names, "Dests", dests);
 		pdf_dict_puts(root, "Names", names);
diff --git a/apps/pdfinfo.c b/apps/pdfinfo.c
index 2d47456c..18463304 100644
--- a/apps/pdfinfo.c
+++ b/apps/pdfinfo.c
@@ -172,14 +172,14 @@ showglobalinfo(void)
 
 	printf("\nPDF-%d.%d\n", xref->version / 10, xref->version % 10);
 
-	obj = pdf_dict_gets(xref->trailer, "Info");
+	obj = pdf_dict_gets(pdf_trailer(xref), "Info");
 	if (obj)
 	{
 		printf("Info object (%d %d R):\n", pdf_to_num(obj), pdf_to_gen(obj));
 		pdf_fprint_obj(stdout, pdf_resolve_indirect(obj), 0);
 	}
 
-	obj = pdf_dict_gets(xref->trailer, "Encrypt");
+	obj = pdf_dict_gets(pdf_trailer(xref), "Encrypt");
 	if (obj)
 	{
 		printf("\nEncryption object (%d %d R):\n", pdf_to_num(obj), pdf_to_gen(obj));
diff --git a/apps/pdfposter.c b/apps/pdfposter.c
index 2ef44dbb..b9514892 100644
--- a/apps/pdfposter.c
+++ b/apps/pdfposter.c
@@ -38,7 +38,7 @@ static void decimatepages(pdf_document *xref)
 
 	/* Keep only pages/type and (reduced) dest entries to avoid
 	 * references to unretained pages */
-	oldroot = pdf_dict_gets(xref->trailer, "Root");
+	oldroot = pdf_dict_gets(pdf_trailer(xref), "Root");
 	pages = pdf_dict_gets(oldroot, "Pages");
 
 	root = pdf_new_dict(ctx, 2);
diff --git a/apps/pdfshow.c b/apps/pdfshow.c
index 275c5e18..7ccfd50d 100644
--- a/apps/pdfshow.c
+++ b/apps/pdfshow.c
@@ -24,7 +24,7 @@ static void showtrailer(void)
 	if (!doc)
 		fz_throw(ctx, "no file specified");
 	printf("trailer\n");
-	pdf_fprint_obj(stdout, doc->trailer, 0);
+	pdf_fprint_obj(stdout, pdf_trailer(doc), 0);
 	printf("\n");
 }
 
@@ -34,7 +34,7 @@ static void showencrypt(void)
 
 	if (!doc)
 		fz_throw(ctx, "no file specified");
-	encrypt = pdf_dict_gets(doc->trailer, "Encrypt");
+	encrypt = pdf_dict_gets(pdf_trailer(doc), "Encrypt");
 	if (!encrypt)
 		fz_throw(ctx, "document not encrypted");
 	printf("encryption dictionary\n");
@@ -183,7 +183,7 @@ static void showgrep(char *filename)
 	}
 
 	printf("%s:trailer: ", filename);
-	pdf_fprint_obj(stdout, doc->trailer, 1);
+	pdf_fprint_obj(stdout, pdf_trailer(doc), 1);
 }
 
 int pdfshow_main(int argc, char **argv)
diff --git a/pdf/mupdf-internal.h b/pdf/mupdf-internal.h
index bea1c0d3..5b84bed7 100644
--- a/pdf/mupdf-internal.h
+++ b/pdf/mupdf-internal.h
@@ -173,6 +173,8 @@ fz_buffer *pdf_load_raw_renumbered_stream(pdf_document *doc, int num, int gen, i
 fz_buffer *pdf_load_renumbered_stream(pdf_document *doc, int num, int gen, int orig_num, int orig_gen, int *truncated);
 fz_stream *pdf_open_raw_renumbered_stream(pdf_document *doc, int num, int gen, int orig_num, int orig_gen);
 
+pdf_obj *pdf_trailer(pdf_document *doc);
+void pdf_set_xref_trailer(pdf_document *doc, pdf_obj *trailer);
 void pdf_repair_xref(pdf_document *doc, pdf_lexbuf *buf);
 void pdf_repair_obj_stms(pdf_document *doc);
 void pdf_resize_xref(pdf_document *doc, int newcap);
diff --git a/pdf/pdf_field.c b/pdf/pdf_field.c
index 4d6d9cdb..964c04c1 100644
--- a/pdf/pdf_field.c
+++ b/pdf/pdf_field.c
@@ -14,7 +14,7 @@ pdf_obj *pdf_get_inheritable(pdf_document *doc, pdf_obj *obj, char *key)
 	}
 
 	return fobj ? fobj
-				: pdf_dict_gets(pdf_dict_gets(pdf_dict_gets(doc->trailer, "Root"), "AcroForm"), key);
+				: pdf_dict_gets(pdf_dict_gets(pdf_dict_gets(pdf_trailer(doc), "Root"), "AcroForm"), key);
 }
 
 int pdf_get_field_flags(pdf_document *doc, pdf_obj *obj)
diff --git a/pdf/pdf_form.c b/pdf/pdf_form.c
index 339968a3..d7dd6503 100644
--- a/pdf/pdf_form.c
+++ b/pdf/pdf_form.c
@@ -1578,7 +1578,7 @@ static void add_field_hierarchy_to_array(pdf_obj *array, pdf_obj *field)
 static pdf_obj *specified_fields(pdf_document *doc, pdf_obj *fields, int exclude)
 {
 	fz_context *ctx = doc->ctx;
-	pdf_obj *form = pdf_dict_getp(doc->trailer, "Root/AcroForm/Fields");
+	pdf_obj *form = pdf_dict_getp(pdf_trailer(doc), "Root/AcroForm/Fields");
 	int i, n;
 	pdf_obj *result = pdf_new_array(ctx, 0);
 	pdf_obj *nil = NULL;
@@ -1924,7 +1924,7 @@ static void recalculate(pdf_document *doc)
 	doc->recalculating = 1;
 	fz_try(ctx)
 	{
-		pdf_obj *co = pdf_dict_getp(doc->trailer, "Root/AcroForm/CO");
+		pdf_obj *co = pdf_dict_getp(pdf_trailer(doc), "Root/AcroForm/CO");
 
 		if (co && doc->js)
 		{
diff --git a/pdf/pdf_js.c b/pdf/pdf_js.c
index 23b51df6..266bc1c7 100644
--- a/pdf/pdf_js.c
+++ b/pdf/pdf_js.c
@@ -778,7 +778,7 @@ pdf_js *pdf_new_js(pdf_document *doc)
 		js->doc = doc;
 
 		/* Find the form array */
-		root = pdf_dict_gets(doc->trailer, "Root");
+		root = pdf_dict_gets(pdf_trailer(doc), "Root");
 		acroform = pdf_dict_gets(root, "AcroForm");
 		js->form = pdf_dict_gets(acroform, "Fields");
 
diff --git a/pdf/pdf_nametree.c b/pdf/pdf_nametree.c
index 6677e7a2..b175456e 100644
--- a/pdf/pdf_nametree.c
+++ b/pdf/pdf_nametree.c
@@ -75,7 +75,7 @@ pdf_lookup_name(pdf_document *xref, char *which, pdf_obj *needle)
 {
 	fz_context *ctx = xref->ctx;
 
-	pdf_obj *root = pdf_dict_gets(xref->trailer, "Root");
+	pdf_obj *root = pdf_dict_gets(pdf_trailer(xref), "Root");
 	pdf_obj *names = pdf_dict_gets(root, "Names");
 	pdf_obj *tree = pdf_dict_gets(names, which);
 	return pdf_lookup_name_imp(ctx, tree, needle);
@@ -86,7 +86,7 @@ pdf_lookup_dest(pdf_document *xref, pdf_obj *needle)
 {
 	fz_context *ctx = xref->ctx;
 
-	pdf_obj *root = pdf_dict_gets(xref->trailer, "Root");
+	pdf_obj *root = pdf_dict_gets(pdf_trailer(xref), "Root");
 	pdf_obj *dests = pdf_dict_gets(root, "Dests");
 	pdf_obj *names = pdf_dict_gets(root, "Names");
 	pdf_obj *dest = NULL;
@@ -154,7 +154,7 @@ pdf_load_name_tree(pdf_document *xref, char *which)
 {
 	fz_context *ctx = xref->ctx;
 
-	pdf_obj *root = pdf_dict_gets(xref->trailer, "Root");
+	pdf_obj *root = pdf_dict_gets(pdf_trailer(xref), "Root");
 	pdf_obj *names = pdf_dict_gets(root, "Names");
 	pdf_obj *tree = pdf_dict_gets(names, which);
 	if (pdf_is_dict(tree))
diff --git a/pdf/pdf_outline.c b/pdf/pdf_outline.c
index 3a0e803e..fb750b9f 100644
--- a/pdf/pdf_outline.c
+++ b/pdf/pdf_outline.c
@@ -63,7 +63,7 @@ pdf_load_outline(pdf_document *xref)
 {
 	pdf_obj *root, *obj, *first;
 
-	root = pdf_dict_gets(xref->trailer, "Root");
+	root = pdf_dict_gets(pdf_trailer(xref), "Root");
 	obj = pdf_dict_gets(root, "Outlines");
 	first = pdf_dict_gets(obj, "First");
 	if (first)
diff --git a/pdf/pdf_page.c b/pdf/pdf_page.c
index 5d6d6bca..99776f42 100644
--- a/pdf/pdf_page.c
+++ b/pdf/pdf_page.c
@@ -157,7 +157,7 @@ pdf_load_page_tree(pdf_document *xref)
 	if (xref->page_refs)
 		return;
 
-	catalog = pdf_dict_gets(xref->trailer, "Root");
+	catalog = pdf_dict_gets(pdf_trailer(xref), "Root");
 	pages = pdf_dict_gets(catalog, "Pages");
 	count = pdf_dict_gets(pages, "Count");
 
diff --git a/pdf/pdf_repair.c b/pdf/pdf_repair.c
index c74f25af..e26baefa 100644
--- a/pdf/pdf_repair.c
+++ b/pdf/pdf_repair.c
@@ -441,21 +441,25 @@ pdf_repair_xref(pdf_document *xref, pdf_lexbuf *buf)
 
 		/* create a repaired trailer, Root will be added later */
 
-		xref->trailer = pdf_new_dict(ctx, 5);
+		obj = pdf_new_dict(ctx, 5);
+		pdf_set_xref_trailer(xref, obj);
+		pdf_drop_obj(obj);
+		obj = NULL;
 
 		obj = pdf_new_int(ctx, maxnum + 1);
-		pdf_dict_puts(xref->trailer, "Size", obj);
+		pdf_dict_puts(pdf_trailer(xref), "Size", obj);
 		pdf_drop_obj(obj);
+		obj = NULL;
 
 		if (root)
 		{
-			pdf_dict_puts(xref->trailer, "Root", root);
+			pdf_dict_puts(pdf_trailer(xref), "Root", root);
 			pdf_drop_obj(root);
 			root = NULL;
 		}
 		if (info)
 		{
-			pdf_dict_puts(xref->trailer, "Info", info);
+			pdf_dict_puts(pdf_trailer(xref), "Info", info);
 			pdf_drop_obj(info);
 			info = NULL;
 		}
@@ -469,7 +473,7 @@ pdf_repair_xref(pdf_document *xref, pdf_lexbuf *buf)
 				pdf_drop_obj(encrypt);
 				encrypt = obj;
 			}
-			pdf_dict_puts(xref->trailer, "Encrypt", encrypt);
+			pdf_dict_puts(pdf_trailer(xref), "Encrypt", encrypt);
 			pdf_drop_obj(encrypt);
 			encrypt = NULL;
 		}
@@ -483,7 +487,7 @@ pdf_repair_xref(pdf_document *xref, pdf_lexbuf *buf)
 				pdf_drop_obj(id);
 				id = obj;
 			}
-			pdf_dict_puts(xref->trailer, "ID", id);
+			pdf_dict_puts(pdf_trailer(xref), "ID", id);
 			pdf_drop_obj(id);
 			id = NULL;
 		}
diff --git a/pdf/pdf_write.c b/pdf/pdf_write.c
index b7f2bdef..5e21e7f8 100644
--- a/pdf/pdf_write.c
+++ b/pdf/pdf_write.c
@@ -763,7 +763,7 @@ static void renumberobjs(pdf_document *xref, pdf_write_options *opts)
 	fz_try(ctx)
 	{
 		/* Apply renumber map to indirect references in all objects in xref */
-		renumberobj(xref, opts, xref->trailer);
+		renumberobj(xref, opts, pdf_trailer(xref));
 		for (num = 0; num < xref->len; num++)
 		{
 			pdf_obj *obj = xref->table[num].obj;
@@ -1301,7 +1301,7 @@ pdf_localise_page_resources(pdf_document *xref)
 	if (xref->resources_localised)
 		return;
 
-	lpr(ctx, pdf_dict_getp(xref->trailer, "Root/Pages"), 0, 0);
+	lpr(ctx, pdf_dict_getp(pdf_trailer(xref), "Root/Pages"), 0, 0);
 
 	xref->resources_localised = 1;
 }
@@ -1326,7 +1326,7 @@ linearize(pdf_document *xref, pdf_write_options *opts)
 
 	/* Walk the objects for each page, marking which ones are used, where */
 	memset(opts->use_list, 0, n * sizeof(int));
-	mark_trailer(xref, opts, xref->trailer);
+	mark_trailer(xref, opts, pdf_trailer(xref));
 
 	/* Add new objects required for linearization */
 	add_linearization_objs(xref, opts);
@@ -1769,15 +1769,15 @@ static void writexref(pdf_document *xref, pdf_write_options *opts, int from, int
 
 		if (first)
 		{
-			obj = pdf_dict_gets(xref->trailer, "Info");
+			obj = pdf_dict_gets(pdf_trailer(xref), "Info");
 			if (obj)
 				pdf_dict_puts(trailer, "Info", obj);
 
-			obj = pdf_dict_gets(xref->trailer, "Root");
+			obj = pdf_dict_gets(pdf_trailer(xref), "Root");
 			if (obj)
 				pdf_dict_puts(trailer, "Root", obj);
 
-			obj = pdf_dict_gets(xref->trailer, "ID");
+			obj = pdf_dict_gets(pdf_trailer(xref), "ID");
 			if (obj)
 				pdf_dict_puts(trailer, "ID", obj);
 		}
@@ -2256,7 +2256,7 @@ void pdf_write_document(pdf_document *xref, char *filename, fz_write_options *fz
 
 		/* Sweep & mark objects from the trailer */
 		if (opts.do_garbage >= 1)
-			sweepobj(xref, &opts, xref->trailer);
+			sweepobj(xref, &opts, pdf_trailer(xref));
 		else
 			for (num = 0; num < xref->len; num++)
 				opts.use_list[num] = 1;
diff --git a/pdf/pdf_xref.c b/pdf/pdf_xref.c
index b3455773..254c0a3f 100644
--- a/pdf/pdf_xref.c
+++ b/pdf/pdf_xref.c
@@ -12,6 +12,17 @@ static inline int iswhite(int ch)
  * magic version tag and startxref
  */
 
+pdf_obj *pdf_trailer(pdf_document *doc)
+{
+	return doc->trailer;
+}
+
+void pdf_set_xref_trailer(pdf_document *doc, pdf_obj *trailer)
+{
+	pdf_drop_obj(doc->trailer);
+	doc->trailer = pdf_keep_obj(trailer);
+}
+
 static void
 pdf_load_version(pdf_document *xref)
 {
@@ -102,6 +113,7 @@ pdf_read_old_trailer(pdf_document *xref, pdf_lexbuf *buf)
 
 	fz_try(xref->ctx)
 	{
+		pdf_obj *trailer;
 		tok = pdf_lex(xref->file, buf);
 		if (tok != PDF_TOK_TRAILER)
 			fz_throw(xref->ctx, "expected trailer marker");
@@ -110,7 +122,9 @@ pdf_read_old_trailer(pdf_document *xref, pdf_lexbuf *buf)
 		if (tok != PDF_TOK_OPEN_DICT)
 			fz_throw(xref->ctx, "expected trailer dictionary");
 
-		xref->trailer = pdf_parse_dict(xref, xref->file, buf);
+		trailer = pdf_parse_dict(xref, xref->file, buf);
+		pdf_set_xref_trailer(xref, trailer);
+		pdf_drop_obj(trailer);
 	}
 	fz_catch(xref->ctx)
 	{
@@ -123,16 +137,19 @@ pdf_read_new_trailer(pdf_document *xref, pdf_lexbuf *buf)
 {
 	fz_try(xref->ctx)
 	{
+		pdf_obj *trailer;
 		int num, gen, stm_ofs, ofs;
 		ofs = fz_tell(xref->file);
-		xref->trailer = pdf_parse_ind_obj(xref, xref->file, buf, &num, &gen, &stm_ofs);
+		trailer = pdf_parse_ind_obj(xref, xref->file, buf, &num, &gen, &stm_ofs);
+		pdf_set_xref_trailer(xref, trailer);
+		pdf_drop_obj(trailer);
 		if (num >= xref->len)
 			pdf_resize_xref(xref, num+1);
 		xref->table[num].ofs = ofs;
 		xref->table[num].gen = gen;
 		xref->table[num].stm_ofs = stm_ofs;
 		pdf_drop_obj(xref->table[num].obj);
-		xref->table[num].obj = pdf_keep_obj(xref->trailer);
+		xref->table[num].obj = pdf_keep_obj(pdf_trailer(xref));
 		xref->table[num].type = 'n';
 	}
 	fz_catch(xref->ctx)
@@ -561,7 +578,7 @@ pdf_load_xref(pdf_document *xref, pdf_lexbuf *buf)
 
 	pdf_read_trailer(xref, buf);
 
-	size = pdf_to_int(pdf_dict_gets(xref->trailer, "Size"));
+	size = pdf_to_int(pdf_dict_gets(pdf_trailer(xref), "Size"));
 	if (!size)
 		fz_throw(ctx, "trailer missing Size entry");
 
@@ -600,7 +617,7 @@ pdf_ocg_set_config(pdf_document *xref, int config)
 	pdf_obj *obj, *cobj;
 	char *name;
 
-	obj = pdf_dict_gets(pdf_dict_gets(xref->trailer, "Root"), "OCProperties");
+	obj = pdf_dict_gets(pdf_dict_gets(pdf_trailer(xref), "Root"), "OCProperties");
 	if (!obj)
 	{
 		if (config == 0)
@@ -706,7 +723,7 @@ pdf_read_ocg(pdf_document *xref)
 
 	fz_var(desc);
 
-	obj = pdf_dict_gets(pdf_dict_gets(xref->trailer, "Root"), "OCProperties");
+	obj = pdf_dict_gets(pdf_dict_gets(pdf_trailer(xref), "Root"), "OCProperties");
 	if (!obj)
 		return;
 	ocg = pdf_dict_gets(obj, "OCGs");
@@ -781,11 +798,7 @@ pdf_init_document(pdf_document *xref)
 			xref->table = NULL;
 			xref->len = 0;
 		}
-		if (xref->trailer)
-		{
-			pdf_drop_obj(xref->trailer);
-			xref->trailer = NULL;
-		}
+		pdf_set_xref_trailer(xref, NULL);
 		fz_warn(xref->ctx, "trying to repair broken xref");
 		repaired = 1;
 	}
@@ -797,8 +810,8 @@ pdf_init_document(pdf_document *xref)
 		if (repaired)
 			pdf_repair_xref(xref, &xref->lexbuf.base);
 
-		encrypt = pdf_dict_gets(xref->trailer, "Encrypt");
-		id = pdf_dict_gets(xref->trailer, "ID");
+		encrypt = pdf_dict_gets(pdf_trailer(xref), "Encrypt");
+		id = pdf_dict_gets(pdf_trailer(xref), "ID");
 		if (pdf_is_dict(encrypt))
 			xref->crypt = pdf_new_crypt(ctx, encrypt, id);
 
@@ -809,8 +822,8 @@ pdf_init_document(pdf_document *xref)
 		{
 			pdf_repair_obj_stms(xref);
 
-			hasroot = (pdf_dict_gets(xref->trailer, "Root") != NULL);
-			hasinfo = (pdf_dict_gets(xref->trailer, "Info") != NULL);
+			hasroot = (pdf_dict_gets(pdf_trailer(xref), "Root") != NULL);
+			hasinfo = (pdf_dict_gets(pdf_trailer(xref), "Info") != NULL);
 
 			for (i = 1; i < xref->len; i++)
 			{
@@ -833,7 +846,7 @@ pdf_init_document(pdf_document *xref)
 					if (pdf_is_name(obj) && !strcmp(pdf_to_name(obj), "Catalog"))
 					{
 						nobj = pdf_new_indirect(ctx, i, 0, xref);
-						pdf_dict_puts(xref->trailer, "Root", nobj);
+						pdf_dict_puts(pdf_trailer(xref), "Root", nobj);
 						pdf_drop_obj(nobj);
 						nobj = NULL;
 					}
@@ -844,7 +857,7 @@ pdf_init_document(pdf_document *xref)
 					if (pdf_dict_gets(dict, "Creator") || pdf_dict_gets(dict, "Producer"))
 					{
 						nobj = pdf_new_indirect(ctx, i, 0, xref);
-						pdf_dict_puts(xref->trailer, "Info", nobj);
+						pdf_dict_puts(pdf_trailer(xref), "Info", nobj);
 						pdf_drop_obj(nobj);
 						nobj = NULL;
 					}
@@ -919,7 +932,7 @@ pdf_close_document(pdf_document *xref)
 		pdf_drop_obj(xref->focus_obj);
 	if (xref->file)
 		fz_close(xref->file);
-	pdf_drop_obj(xref->trailer);
+	pdf_drop_obj(pdf_trailer(xref));
 	if (xref->crypt)
 		pdf_free_crypt(ctx, xref->crypt);
 
@@ -1306,7 +1319,7 @@ pdf_meta(pdf_document *doc, int key, void *ptr, int size)
 	}
 	case FZ_META_INFO:
 	{
-		pdf_obj *info = pdf_dict_gets(doc->trailer, "Info");
+		pdf_obj *info = pdf_dict_gets(pdf_trailer(doc), "Info");
 		if (!info)
 		{
 			if (ptr)
-- 
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