Exception handling changes

In preparation for work on progressive loading, update the exception
handling scheme slightly.

Until now, exceptions (as thrown with fz_throw, and caught with
fz_try/fz_catch) have merely had an informative string. They have
never had anything that can be compared to see if an error is of
a particular type.

We now introduce error codes; when we fz_throw, we now always
give an error code, and can optionally (using fz_throw_message)
give both an error code and an informative string.

When we fz_rethrow from within a fz_catch, both the error code and
the error message is maintained. Using fz_rethrow_message we can
'improve' the error message, but the code is maintained.

The error message can be read out using fz_caught_message() and the
error code can be read as fz_caught().

Currently we only define a 'generic' error. This will expand in future
versions to include other error types that may be tested for.

1 files changed, 9 insertions, 9 deletions

diff --git a/fitz/filt_faxd.c b/fitz/filt_faxd.c
index fab66f1a..8ac98f42 100644
--- a/fitz/filt_faxd.c
+++ b/fitz/filt_faxd.c
@@ -401,13 +401,13 @@ dec1d(fz_context *ctx, fz_faxd *fax)
 		code = get_code(fax, cf_white_decode, cfd_white_initial_bits);
 
 	if (code == UNCOMPRESSED)
-		fz_throw(ctx, "uncompressed data in faxd");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "uncompressed data in faxd");
 
 	if (code < 0)
-		fz_throw(ctx, "negative code in 1d faxd");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "negative code in 1d faxd");
 
 	if (fax->a + code > fax->columns)
-		fz_throw(ctx, "overflow in 1d faxd");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "overflow in 1d faxd");
 
 	if (fax->c)
 		setbits(fax->dst, fax->a, fax->a + code);
@@ -440,13 +440,13 @@ dec2d(fz_context *ctx, fz_faxd *fax)
 			code = get_code(fax, cf_white_decode, cfd_white_initial_bits);
 
 		if (code == UNCOMPRESSED)
-			fz_throw(ctx, "uncompressed data in faxd");
+			fz_throw(ctx, FZ_ERROR_GENERIC, "uncompressed data in faxd");
 
 		if (code < 0)
-			fz_throw(ctx, "negative code in 2d faxd");
+			fz_throw(ctx, FZ_ERROR_GENERIC, "negative code in 2d faxd");
 
 		if (fax->a + code > fax->columns)
-			fz_throw(ctx, "overflow in 2d faxd");
+			fz_throw(ctx, FZ_ERROR_GENERIC, "overflow in 2d faxd");
 
 		if (fax->c)
 			setbits(fax->dst, fax->a, fax->a + code);
@@ -539,13 +539,13 @@ dec2d(fz_context *ctx, fz_faxd *fax)
 		break;
 
 	case UNCOMPRESSED:
-		fz_throw(ctx, "uncompressed data in faxd");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "uncompressed data in faxd");
 
 	case ERROR:
-		fz_throw(ctx, "invalid code in 2d faxd");
+		fz_throw(ctx, FZ_ERROR_GENERIC, "invalid code in 2d faxd");
 
 	default:
-		fz_throw(ctx, "invalid code in 2d faxd (%d)", code);
+		fz_throw(ctx, FZ_ERROR_GENERIC, "invalid code in 2d faxd (%d)", code);
 	}
 }