Exception handling fixes.

Various tweaks to ensure the exception handling works as expected
when throwing error values. The key thing is not to reset the
error value on a try, as this can cause problems when code calls
trys in the always section.

2 files changed, 7 insertions, 6 deletions

diff --git a/fitz/base_context.c b/fitz/base_context.c
index 231d9104..c65377a8 100644
--- a/fitz/base_context.c
+++ b/fitz/base_context.c
@@ -93,7 +93,7 @@ new_context_phase1(fz_alloc_context *alloc, fz_locks_context *locks)
 	if (!ctx->error)
 		goto cleanup;
 	ctx->error->top = -1;
-	ctx->error->errcode = 0;
+	ctx->error->errcode = FZ_ERROR_NONE;
 	ctx->error->message[0] = 0;
 
 	ctx->warn = fz_malloc_no_throw(ctx, sizeof(fz_warn_context));
diff --git a/fitz/base_error.c b/fitz/base_error.c
index f16dd4d0..50b3c5aa 100644
--- a/fitz/base_error.c
+++ b/fitz/base_error.c
@@ -89,7 +89,6 @@ int fz_push_try(fz_error_context *ex)
 {
 	assert(ex);
 	ex->top++;
-	ex->errcode = FZ_ERROR_NONE;
 	/* Normal case, get out of here quick */
 	if (ex->top < nelem(ex->stack)-1)
 		return 1; /* We exit here, and the setjmp sets the code to 0 */
@@ -107,15 +106,13 @@ int fz_push_try(fz_error_context *ex)
 
 int fz_caught(fz_context *ctx)
 {
-	assert(ctx);
-	assert(ctx->error);
+	assert(ctx && ctx->error && ctx->error->errcode >= FZ_ERROR_NONE);
 	return ctx->error->errcode;
 }
 
 const char *fz_caught_message(fz_context *ctx)
 {
-	assert(ctx);
-	assert(ctx->error);
+	assert(ctx && ctx->error && ctx->error->errcode >= FZ_ERROR_NONE);
 	return ctx->error->message;
 }
 
@@ -136,12 +133,16 @@ void fz_throw(fz_context *ctx, int code, const char *fmt, ...)
 
 void fz_rethrow(fz_context *ctx)
 {
+	assert(ctx && ctx->error && ctx->error->errcode >= FZ_ERROR_NONE);
 	throw(ctx->error);
 }
 
 void fz_rethrow_message(fz_context *ctx, const char *fmt, ...)
 {
 	va_list args;
+
+	assert(ctx && ctx->error && ctx->error->errcode >= FZ_ERROR_NONE);
+
 	va_start(args, fmt);
 	vsnprintf(ctx->error->message, sizeof ctx->error->message, fmt, args);
 	va_end(args);