Move to exception handling rather than error passing throughout.

This frees us from passing errors back everywhere, and hence enables us
to pass results back as return values.

Rather than having to explicitly check for errors everywhere and bubble
them, we now allow exception handling to do the work for us; the
downside to this is that we no longer emit as much debugging information
as we did before (though this could be put back in). For now, the
debugging information we have lost has been retained in comments
with 'RJW:' at the start.

This code needs fuller testing, but is being committed as a work in
progress.

1 files changed, 70 insertions, 84 deletions

diff --git a/pdf/pdf_colorspace.c b/pdf/pdf_colorspace.c
index 4c4368cc..c386b34c 100644
--- a/pdf/pdf_colorspace.c
+++ b/pdf/pdf_colorspace.c
@@ -3,8 +3,8 @@
 
 /* ICCBased */
 
-static fz_error
-load_icc_based(fz_colorspace **csp, pdf_xref *xref, fz_obj *dict)
+static fz_colorspace *
+load_icc_based(pdf_xref *xref, fz_obj *dict)
 {
 	int n;
 
@@ -12,12 +12,13 @@ load_icc_based(fz_colorspace **csp, pdf_xref *xref, fz_obj *dict)
 
 	switch (n)
 	{
-	case 1: *csp = fz_device_gray; return fz_okay;
-	case 3: *csp = fz_device_rgb; return fz_okay;
-	case 4: *csp = fz_device_cmyk; return fz_okay;
+	case 1: return fz_device_gray;
+	case 3: return fz_device_rgb;
+	case 4: return fz_device_cmyk;
 	}
 
-	return fz_error_make("syntaxerror: ICCBased must have 1, 3 or 4 components");
+	fz_throw(xref->ctx, "syntaxerror: ICCBased must have 1, 3 or 4 components");
+	return NULL; /* Stupid MSVC */
 }
 
 /* Lab */
@@ -89,10 +90,9 @@ free_separation(fz_context *ctx, fz_colorspace *cs)
 	fz_free(ctx, sep);
 }
 
-static fz_error
-load_separation(fz_colorspace **csp, pdf_xref *xref, fz_obj *array)
+static fz_colorspace *
+load_separation(pdf_xref *xref, fz_obj *array)
 {
-	fz_error error;
 	fz_colorspace *cs;
 	struct separation *sep;
 	fz_context *ctx = xref->ctx;
@@ -109,18 +109,14 @@ load_separation(fz_colorspace **csp, pdf_xref *xref, fz_obj *array)
 		n = 1;
 
 	if (n > FZ_MAX_COLORS)
-		return fz_error_make("too many components in colorspace");
+		fz_throw(ctx, "too many components in colorspace");
 
-	error = pdf_load_colorspace(&base, xref, baseobj);
-	if (error)
-		return fz_error_note(error, "cannot load base colorspace (%d %d R)", fz_to_num(baseobj), fz_to_gen(baseobj));
+	base = pdf_load_colorspace(xref, baseobj);
+	/* RJW: "cannot load base colorspace (%d %d R)", fz_to_num(baseobj), fz_to_gen(baseobj) */
 
-	error = pdf_load_function(&tint, xref, tintobj);
-	if (error)
-	{
-		fz_drop_colorspace(ctx, base);
-		return fz_error_note(error, "cannot load tint function (%d %d R)", fz_to_num(tintobj), fz_to_gen(tintobj));
-	}
+	tint = pdf_load_function(xref, tintobj);
+	/* RJW: fz_drop_colorspace(ctx, base);
+	 * "cannot load tint function (%d %d R)", fz_to_num(tintobj), fz_to_gen(tintobj) */
 
 	sep = fz_malloc(ctx, sizeof(struct separation));
 	sep->base = base;
@@ -131,8 +127,7 @@ load_separation(fz_colorspace **csp, pdf_xref *xref, fz_obj *array)
 	cs->free_data = free_separation;
 	cs->data = sep;
 
-	*csp = cs;
-	return fz_okay;
+	return cs;
 }
 
 /* Indexed */
@@ -208,22 +203,19 @@ pdf_expand_indexed_pixmap(fz_context *ctx, fz_pixmap *src)
 	return dst;
 }
 
-static fz_error
-load_indexed(fz_colorspace **csp, pdf_xref *xref, fz_obj *array)
+static fz_colorspace *
+load_indexed(pdf_xref *xref, fz_obj *array)
 {
-	fz_error error;
-	fz_colorspace *cs;
 	struct indexed *idx;
 	fz_context *ctx = xref->ctx;
 	fz_obj *baseobj = fz_array_get(array, 1);
 	fz_obj *highobj = fz_array_get(array, 2);
 	fz_obj *lookup = fz_array_get(array, 3);
-	fz_colorspace *base;
+	fz_colorspace *base, *cs;
 	int i, n;
 
-	error = pdf_load_colorspace(&base, xref, baseobj);
-	if (error)
-		return fz_error_note(error, "cannot load base colorspace (%d %d R)", fz_to_num(baseobj), fz_to_gen(baseobj));
+	base = pdf_load_colorspace(xref, baseobj);
+	/* "cannot load base colorspace (%d %d R)", fz_to_num(baseobj), fz_to_gen(baseobj) */
 
 	idx = fz_malloc(ctx, sizeof(struct indexed));
 	idx->base = base;
@@ -247,18 +239,21 @@ load_indexed(fz_colorspace **csp, pdf_xref *xref, fz_obj *array)
 	{
 		fz_stream *file;
 
-		error = pdf_open_stream(&file, xref, fz_to_num(lookup), fz_to_gen(lookup));
-		if (error)
+		fz_try(ctx)
+		{
+			file = pdf_open_stream(xref, fz_to_num(lookup), fz_to_gen(lookup));
+		}
+		fz_catch(ctx)
 		{
 			fz_drop_colorspace(ctx, cs);
-			return fz_error_note(error, "cannot open colorspace lookup table (%d 0 R)", fz_to_num(lookup));
+			fz_throw(ctx, "cannot open colorspace lookup table (%d 0 R)", fz_to_num(lookup));
 		}
 
 		i = fz_read(file, idx->lookup, n);
 		if (i < 0)
 		{
 			fz_drop_colorspace(ctx, cs);
-			return fz_error_make("cannot read colorspace lookup table (%d 0 R)", fz_to_num(lookup));
+			fz_throw(ctx, "cannot read colorspace lookup table (%d 0 R)", fz_to_num(lookup));
 		}
 
 		fz_close(file);
@@ -266,37 +261,35 @@ load_indexed(fz_colorspace **csp, pdf_xref *xref, fz_obj *array)
 	else
 	{
 		fz_drop_colorspace(ctx, cs);
-		return fz_error_make("cannot parse colorspace lookup table");
+		fz_throw(ctx, "cannot parse colorspace lookup table");
 	}
 
-	*csp = cs;
-	return fz_okay;
+	return cs;
 }
 
 /* Parse and create colorspace from PDF object */
 
-static fz_error
-pdf_load_colorspace_imp(fz_colorspace **csp, pdf_xref *xref, fz_obj *obj)
+static fz_colorspace *
+pdf_load_colorspace_imp(pdf_xref *xref, fz_obj *obj)
 {
 	if (fz_is_name(obj))
 	{
 		if (!strcmp(fz_to_name(obj), "Pattern"))
-			*csp = fz_device_gray;
+			return fz_device_gray;
 		else if (!strcmp(fz_to_name(obj), "G"))
-			*csp = fz_device_gray;
+			return fz_device_gray;
 		else if (!strcmp(fz_to_name(obj), "RGB"))
-			*csp = fz_device_rgb;
+			return fz_device_rgb;
 		else if (!strcmp(fz_to_name(obj), "CMYK"))
-			*csp = fz_device_cmyk;
+			return fz_device_cmyk;
 		else if (!strcmp(fz_to_name(obj), "DeviceGray"))
-			*csp = fz_device_gray;
+			return fz_device_gray;
 		else if (!strcmp(fz_to_name(obj), "DeviceRGB"))
-			*csp = fz_device_rgb;
+			return fz_device_rgb;
 		else if (!strcmp(fz_to_name(obj), "DeviceCMYK"))
-			*csp = fz_device_cmyk;
+			return fz_device_cmyk;
 		else
-			return fz_error_make("unknown colorspace: %s", fz_to_name(obj));
-		return fz_okay;
+			fz_throw(xref->ctx, "unknown colorspace: %s", fz_to_name(obj));
 	}
 
 	else if (fz_is_array(obj))
@@ -308,82 +301,75 @@ pdf_load_colorspace_imp(fz_colorspace **csp, pdf_xref *xref, fz_obj *obj)
 			/* load base colorspace instead */
 			if (!strcmp(fz_to_name(name), "Pattern"))
 			{
-				fz_error error;
-
 				obj = fz_array_get(obj, 1);
 				if (!obj)
 				{
-					*csp = fz_device_gray;
-					return fz_okay;
+					return fz_device_gray;
 				}
 
-				error = pdf_load_colorspace(csp, xref, obj);
-				if (error)
-					return fz_error_note(error, "cannot load pattern (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
+				return pdf_load_colorspace(xref, obj);
+				/* RJW: "cannot load pattern (%d %d R)", fz_to_num(obj), fz_to_gen(obj) */
 			}
 
 			else if (!strcmp(fz_to_name(name), "G"))
-				*csp = fz_device_gray;
+				return fz_device_gray;
 			else if (!strcmp(fz_to_name(name), "RGB"))
-				*csp = fz_device_rgb;
+				return fz_device_rgb;
 			else if (!strcmp(fz_to_name(name), "CMYK"))
-				*csp = fz_device_cmyk;
+				return fz_device_cmyk;
 			else if (!strcmp(fz_to_name(name), "DeviceGray"))
-				*csp = fz_device_gray;
+				return fz_device_gray;
 			else if (!strcmp(fz_to_name(name), "DeviceRGB"))
-				*csp = fz_device_rgb;
+				return fz_device_rgb;
 			else if (!strcmp(fz_to_name(name), "DeviceCMYK"))
-				*csp = fz_device_cmyk;
+				return fz_device_cmyk;
 			else if (!strcmp(fz_to_name(name), "CalGray"))
-				*csp = fz_device_gray;
+				return fz_device_gray;
 			else if (!strcmp(fz_to_name(name), "CalRGB"))
-				*csp = fz_device_rgb;
+				return fz_device_rgb;
 			else if (!strcmp(fz_to_name(name), "CalCMYK"))
-				*csp = fz_device_cmyk;
+				return fz_device_cmyk;
 			else if (!strcmp(fz_to_name(name), "Lab"))
-				*csp = fz_device_lab;
+				return fz_device_lab;
 
 			else if (!strcmp(fz_to_name(name), "ICCBased"))
-				return load_icc_based(csp, xref, fz_array_get(obj, 1));
+				return load_icc_based(xref, fz_array_get(obj, 1));
 
 			else if (!strcmp(fz_to_name(name), "Indexed"))
-				return load_indexed(csp, xref, obj);
+				return load_indexed(xref, obj);
 			else if (!strcmp(fz_to_name(name), "I"))
-				return load_indexed(csp, xref, obj);
+				return load_indexed(xref, obj);
 
 			else if (!strcmp(fz_to_name(name), "Separation"))
-				return load_separation(csp, xref, obj);
+				return load_separation(xref, obj);
 
 			else if (!strcmp(fz_to_name(name), "DeviceN"))
-				return load_separation(csp, xref, obj);
+				return load_separation(xref, obj);
 
 			else
-				return fz_error_make("syntaxerror: unknown colorspace %s", fz_to_name(name));
-
-			return fz_okay;
+				fz_throw(xref->ctx, "syntaxerror: unknown colorspace %s", fz_to_name(name));
 		}
 	}
 
-	return fz_error_make("syntaxerror: could not parse color space (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
+	fz_throw(xref->ctx, "syntaxerror: could not parse color space (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
+	return NULL; /* Stupid MSVC */
 }
 
-fz_error
-pdf_load_colorspace(fz_colorspace **csp, pdf_xref *xref, fz_obj *obj)
+fz_colorspace *
+pdf_load_colorspace(pdf_xref *xref, fz_obj *obj)
 {
-	fz_error error;
 	fz_context *ctx = xref->ctx;
+	fz_colorspace *cs;
 
-	if ((*csp = pdf_find_item(ctx, xref->store, (pdf_store_drop_fn *)fz_drop_colorspace, obj)))
+	if ((cs = pdf_find_item(ctx, xref->store, (pdf_store_drop_fn *)fz_drop_colorspace, obj)))
 	{
-		fz_keep_colorspace(*csp);
-		return fz_okay;
+		return fz_keep_colorspace(cs);
 	}
 
-	error = pdf_load_colorspace_imp(csp, xref, obj);
-	if (error)
-		return fz_error_note(error, "cannot load colorspace (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
+	cs = pdf_load_colorspace_imp(xref, obj);
+	/* RJW: "cannot load colorspace (%d %d R)", fz_to_num(obj), fz_to_gen(obj) */
 
-	pdf_store_item(ctx, xref->store, (pdf_store_keep_fn *)fz_keep_colorspace, (pdf_store_drop_fn *)fz_drop_colorspace, obj, *csp);
+	pdf_store_item(ctx, xref->store, (pdf_store_keep_fn *)fz_keep_colorspace, (pdf_store_drop_fn *)fz_drop_colorspace, obj, cs);
 
-	return fz_okay;
+	return cs;
 }