From ce82537df9e4b832213138d942be4482418b9e50 Mon Sep 17 00:00:00 2001
From: Sebastian Rasmussen <sebras@gmail.com>
Date: Sat, 15 Oct 2016 01:55:05 +0800
Subject: All external drop functions handles NULL.

---
 source/fitz/hash.c         | 3 +++
 source/fitz/image.c        | 3 +++
 source/fitz/link.c         | 3 +++
 source/fitz/pool.c         | 7 ++++++-
 source/fitz/writer.c       | 3 +++
 source/fitz/zip.c          | 2 ++
 source/html/html-font.c    | 3 +++
 source/pdf/pdf-resources.c | 7 +++++--
 8 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/source/fitz/hash.c b/source/fitz/hash.c
index 31a692c0..e16aefd1 100644
--- a/source/fitz/hash.c
+++ b/source/fitz/hash.c
@@ -96,6 +96,9 @@ fz_hash_get_val(fz_context *ctx, fz_hash_table *table, int idx)
 void
 fz_drop_hash(fz_context *ctx, fz_hash_table *table)
 {
+	if (!table)
+		return;
+
 	fz_free(ctx, table->ents);
 	fz_free(ctx, table);
 }
diff --git a/source/fitz/image.c b/source/fitz/image.c
index 48420a81..7373147f 100644
--- a/source/fitz/image.c
+++ b/source/fitz/image.c
@@ -376,6 +376,9 @@ fz_drop_image_imp(fz_context *ctx, fz_storable *image_)
 void
 fz_drop_image_base(fz_context *ctx, fz_image *image)
 {
+	if (!image)
+		return;
+
 	fz_drop_colorspace(ctx, image->colorspace);
 	fz_drop_image(ctx, image->mask);
 	fz_free(ctx, image);
diff --git a/source/fitz/link.c b/source/fitz/link.c
index 20668ab1..eaed1402 100644
--- a/source/fitz/link.c
+++ b/source/fitz/link.c
@@ -3,6 +3,9 @@
 void
 fz_drop_link_dest(fz_context *ctx, fz_link_dest *dest)
 {
+	if (!dest)
+		return;
+
 	switch (dest->kind)
 	{
 	case FZ_LINK_NONE:
diff --git a/source/fitz/pool.c b/source/fitz/pool.c
index 2591c563..90c405dc 100644
--- a/source/fitz/pool.c
+++ b/source/fitz/pool.c
@@ -41,7 +41,12 @@ char *fz_pool_strdup(fz_context *ctx, fz_pool *pool, const char *s)
 
 void fz_drop_pool(fz_context *ctx, fz_pool *pool)
 {
-	fz_pool_node *node = pool->head;
+	fz_pool_node *node;
+
+	if (!pool)
+		return;
+
+	node = pool->head;
 	while (node)
 	{
 		fz_pool_node *next = node->next;
diff --git a/source/fitz/writer.c b/source/fitz/writer.c
index d7fd60f9..fe9e8635 100644
--- a/source/fitz/writer.c
+++ b/source/fitz/writer.c
@@ -82,6 +82,9 @@ fz_close_document_writer(fz_context *ctx, fz_document_writer *wri)
 void
 fz_drop_document_writer(fz_context *ctx, fz_document_writer *wri)
 {
+	if (!wri)
+		return;
+
 	if (wri->close_writer)
 		fz_warn(ctx, "dropping unclosed document writer");
 	if (wri->drop_writer)
diff --git a/source/fitz/zip.c b/source/fitz/zip.c
index 599d2954..95f1bd03 100644
--- a/source/fitz/zip.c
+++ b/source/fitz/zip.c
@@ -87,6 +87,8 @@ fz_close_zip_writer(fz_context *ctx, fz_zip_writer *zip)
 void
 fz_drop_zip_writer(fz_context *ctx, fz_zip_writer *zip)
 {
+	if (!zip)
+		return;
 	if (!zip->closed)
 		fz_warn(ctx, "dropping unclosed zip writer");
 	fz_drop_output(ctx, zip->output);
diff --git a/source/html/html-font.c b/source/html/html-font.c
index 01ec10f5..48c04b73 100644
--- a/source/html/html-font.c
+++ b/source/html/html-font.c
@@ -86,6 +86,9 @@ void fz_drop_html_font_set(fz_context *ctx, fz_html_font_set *set)
 	fz_html_font_face *font, *next;
 	int i;
 
+	if (!set)
+		return;
+
 	font = set->custom;
 	while (font)
 	{
diff --git a/source/pdf/pdf-resources.c b/source/pdf/pdf-resources.c
index 7c1f36ad..ad195393 100644
--- a/source/pdf/pdf-resources.c
+++ b/source/pdf/pdf-resources.c
@@ -147,6 +147,9 @@ res_table_free(fz_context *ctx, fz_hash_table *hash)
 void
 pdf_drop_resource_tables(fz_context *ctx, pdf_document *doc)
 {
-	res_table_free(ctx, doc->resources.fonts);
-	res_table_free(ctx, doc->resources.images);
+	if (doc)
+	{
+		res_table_free(ctx, doc->resources.fonts);
+		res_table_free(ctx, doc->resources.images);
+	}
 }
-- 
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