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, 25 insertions, 33 deletions

diff --git a/pdf/pdf_crypt.c b/pdf/pdf_crypt.c
index 523fabc1..1ae16b37 100644
--- a/pdf/pdf_crypt.c
+++ b/pdf/pdf_crypt.c
@@ -47,11 +47,10 @@ static fz_error pdf_parse_crypt_filter(fz_context *ctx, pdf_crypt_filter *cf, fz
  * given the Encryption and ID objects.
  */
 
-fz_error
-pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
+pdf_crypt *
+pdf_new_crypt(fz_context *ctx, fz_obj *dict, fz_obj *id)
 {
 	pdf_crypt *crypt;
-	fz_error error;
 	fz_obj *obj;
 
 	crypt = fz_malloc(ctx, sizeof(pdf_crypt));
@@ -63,12 +62,12 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	if (!fz_is_name(obj))
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("unspecified encryption handler");
+		fz_throw(ctx, "unspecified encryption handler");
 	}
 	if (strcmp(fz_to_name(obj), "Standard") != 0)
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("unknown encryption handler: '%s'", fz_to_name(obj));
+		fz_throw(ctx, "unknown encryption handler: '%s'", fz_to_name(obj));
 	}
 
 	crypt->v = 0;
@@ -78,7 +77,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	if (crypt->v != 1 && crypt->v != 2 && crypt->v != 4 && crypt->v != 5)
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("unknown encryption version");
+		fz_throw(ctx, "unknown encryption version");
 	}
 
 	crypt->length = 40;
@@ -95,12 +94,12 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 		if (crypt->length % 8 != 0)
 		{
 			pdf_free_crypt(ctx, crypt);
-			return fz_error_make("invalid encryption key length");
+			fz_throw(ctx, "invalid encryption key length");
 		}
 		if (crypt->length > 256)
 		{
 			pdf_free_crypt(ctx, crypt);
-			return fz_error_make("invalid encryption key length");
+			fz_throw(ctx, "invalid encryption key length");
 		}
 	}
 
@@ -134,26 +133,20 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 			crypt->cf = NULL;
 		}
 
-		obj = fz_dict_gets(dict, "StmF");
-		if (fz_is_name(obj))
+		fz_try(ctx)
 		{
-			error = pdf_parse_crypt_filter(ctx, &crypt->stmf, crypt->cf, fz_to_name(obj), crypt->length);
-			if (error)
-			{
-				pdf_free_crypt(ctx, crypt);
-				return fz_error_note(error, "cannot parse stream crypt filter (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
-			}
-		}
+			obj = fz_dict_gets(dict, "StmF");
+			if (fz_is_name(obj))
+				pdf_parse_crypt_filter(ctx, &crypt->stmf, crypt->cf, fz_to_name(obj), crypt->length);
 
-		obj = fz_dict_gets(dict, "StrF");
-		if (fz_is_name(obj))
+			obj = fz_dict_gets(dict, "StrF");
+			if (fz_is_name(obj))
+				pdf_parse_crypt_filter(ctx, &crypt->strf, crypt->cf, fz_to_name(obj), crypt->length);
+		}
+		fz_catch(ctx)
 		{
-			error = pdf_parse_crypt_filter(ctx, &crypt->strf, crypt->cf, fz_to_name(obj), crypt->length);
-			if (error)
-			{
-				pdf_free_crypt(ctx, crypt);
-				return fz_error_note(error, "cannot parse string crypt filter (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
-			}
+			pdf_free_crypt(ctx, crypt);
+			fz_throw(ctx, "cannot parse string crypt filter (%d %d R)", fz_to_num(obj), fz_to_gen(obj));
 		}
 
 		/* in crypt revision 4, the crypt filter determines the key length */
@@ -169,7 +162,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	else
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("encryption dictionary missing revision value");
+		fz_throw(ctx, "encryption dictionary missing revision value");
 	}
 
 	obj = fz_dict_gets(dict, "O");
@@ -181,7 +174,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	else
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("encryption dictionary missing owner password");
+		fz_throw(ctx, "encryption dictionary missing owner password");
 	}
 
 	obj = fz_dict_gets(dict, "U");
@@ -197,7 +190,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	else
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("encryption dictionary missing user password");
+		fz_throw(ctx, "encryption dictionary missing user password");
 	}
 
 	obj = fz_dict_gets(dict, "P");
@@ -206,7 +199,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	else
 	{
 		pdf_free_crypt(ctx, crypt);
-		return fz_error_make("encryption dictionary missing permissions value");
+		fz_throw(ctx, "encryption dictionary missing permissions value");
 	}
 
 	if (crypt->r == 5)
@@ -215,7 +208,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 		if (!fz_is_string(obj) || fz_to_str_len(obj) != 32)
 		{
 			pdf_free_crypt(ctx, crypt);
-			return fz_error_make("encryption dictionary missing owner encryption key");
+			fz_throw(ctx, "encryption dictionary missing owner encryption key");
 		}
 		memcpy(crypt->oe, fz_to_str_buf(obj), 32);
 
@@ -223,7 +216,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 		if (!fz_is_string(obj) || fz_to_str_len(obj) != 32)
 		{
 			pdf_free_crypt(ctx, crypt);
-			return fz_error_make("encryption dictionary missing user encryption key");
+			fz_throw(ctx, "encryption dictionary missing user encryption key");
 		}
 		memcpy(crypt->ue, fz_to_str_buf(obj), 32);
 	}
@@ -244,8 +237,7 @@ pdf_new_crypt(fz_context *ctx, pdf_crypt **cryptp, fz_obj *dict, fz_obj *id)
 	else
 		fz_warn(ctx, "missing file identifier, may not be able to do decryption");
 
-	*cryptp = crypt;
-	return fz_okay;
+	return crypt;
 }
 
 void