Drop all contexts the same way.

* Handle multiple calls to fz_drop_colorspace_context() and
  fz_drop_font_context().
* Allow missing context in call to fz_drop_aa_context()
  and fz_drop_glyph_cache_context().
* Only drop font context objects when dropping the last reference.
* Avoid unnecessary NULL checks.

7 files changed, 20 insertions, 13 deletions

diff --git a/source/fitz/colorspace.c b/source/fitz/colorspace.c
index 6313fb70..84e9b36c 100644
--- a/source/fitz/colorspace.c
+++ b/source/fitz/colorspace.c
@@ -257,7 +257,10 @@ void fz_drop_colorspace_context(fz_context *ctx)
 	if (!ctx)
 		return;
 	if (fz_drop_imp(ctx, ctx->colorspace, &ctx->colorspace->ctx_refs))
+	{
 		fz_free(ctx, ctx->colorspace);
+		ctx->colorspace = NULL;
+	}
 }
 
 fz_colorspace *
diff --git a/source/fitz/document.c b/source/fitz/document.c
index fdf4d2b7..43fcb133 100644
--- a/source/fitz/document.c
+++ b/source/fitz/document.c
@@ -31,7 +31,7 @@ fz_document_handler_context *fz_keep_document_handler_context(fz_context *ctx)
 
 void fz_drop_document_handler_context(fz_context *ctx)
 {
-	if (!ctx || !ctx->handler)
+	if (!ctx)
 		return;
 
 	if (fz_drop_imp(ctx, ctx->handler, &ctx->handler->refs))
diff --git a/source/fitz/draw-edge.c b/source/fitz/draw-edge.c
index cd6a525f..0da45331 100644
--- a/source/fitz/draw-edge.c
+++ b/source/fitz/draw-edge.c
@@ -53,6 +53,8 @@ void fz_copy_aa_context(fz_context *dst, fz_context *src)
 
 void fz_drop_aa_context(fz_context *ctx)
 {
+	if (!ctx)
+		return;
 #ifndef AA_BITS
 	fz_free(ctx, ctx->aa);
 	ctx->aa = NULL;
diff --git a/source/fitz/draw-glyph.c b/source/fitz/draw-glyph.c
index a0c47b74..1eb89093 100644
--- a/source/fitz/draw-glyph.c
+++ b/source/fitz/draw-glyph.c
@@ -107,7 +107,7 @@ fz_purge_glyph_cache(fz_context *ctx)
 void
 fz_drop_glyph_cache_context(fz_context *ctx)
 {
-	if (!ctx->glyph_cache)
+	if (!ctx || !ctx->glyph_cache)
 		return;
 
 	fz_lock(ctx, FZ_LOCK_GLYPHCACHE);
diff --git a/source/fitz/font.c b/source/fitz/font.c
index 88d5e358..93546042 100644
--- a/source/fitz/font.c
+++ b/source/fitz/font.c
@@ -235,21 +235,23 @@ fz_keep_font_context(fz_context *ctx)
 
 void fz_drop_font_context(fz_context *ctx)
 {
-	int i;
-
 	if (!ctx)
 		return;
 
-	for (i = 0; i < nelem(ctx->font->fallback); ++i)
+	if (fz_drop_imp(ctx, ctx->font, &ctx->font->ctx_refs))
 	{
-		fz_drop_font(ctx, ctx->font->fallback[i].serif);
-		fz_drop_font(ctx, ctx->font->fallback[i].sans);
-	}
-	fz_drop_font(ctx, ctx->font->symbol);
-	fz_drop_font(ctx, ctx->font->emoji);
+		int i;
 
-	if (fz_drop_imp(ctx, ctx->font, &ctx->font->ctx_refs))
+		for (i = 0; i < nelem(ctx->font->fallback); ++i)
+		{
+			fz_drop_font(ctx, ctx->font->fallback[i].serif);
+			fz_drop_font(ctx, ctx->font->fallback[i].sans);
+		}
+		fz_drop_font(ctx, ctx->font->symbol);
+		fz_drop_font(ctx, ctx->font->emoji);
 		fz_free(ctx, ctx->font);
+		ctx->font = NULL;
+	}
 }
 
 void fz_install_load_system_font_funcs(fz_context *ctx, fz_load_system_font_func f, fz_load_system_cjk_font_func f_cjk)
diff --git a/source/fitz/output.c b/source/fitz/output.c
index d5dfb47e..ee3f5b6f 100644
--- a/source/fitz/output.c
+++ b/source/fitz/output.c
@@ -45,7 +45,7 @@ fz_keep_output_context(fz_context *ctx)
 void
 fz_drop_output_context(fz_context *ctx)
 {
-	if (!ctx || !ctx->output)
+	if (!ctx)
 		return;
 
 	if (fz_drop_imp(ctx, ctx->output, &ctx->output->refs))
diff --git a/source/fitz/store.c b/source/fitz/store.c
index 2c8a7022..c85ceab2 100644
--- a/source/fitz/store.c
+++ b/source/fitz/store.c
@@ -661,7 +661,7 @@ fz_keep_store_context(fz_context *ctx)
 void
 fz_drop_store_context(fz_context *ctx)
 {
-	if (ctx == NULL || ctx->store == NULL)
+	if (!ctx)
 		return;
 	if (fz_drop_imp(ctx, ctx->store, &ctx->store->refs))
 	{