Merge pull request #23 from cspiegel/fix-exceptions

[Bocfel] Fix exception handling

terps/bocfel/io.c

@@ -319,26 +319,14 @@ bool zterp_io_close_memory(zterp_io *io, uint8_t **buf, long *n)
   return true;
 }
 
-/* Turn on “exception handling” for this I/O object. After calling this
- * function, all future I/O calls which return a bool will now instead
- * cause this function to return false in case of error. Simple usage:
- *
- * if(!zterp_io_try(io)) return ERROR;
- * // call I/O functions here
- *
- * This *only* affects boolean functions. Those which return non-boolean
- * values, such as zterp_io_write() and zterp_io_getc() are unaffected.
- * This may be inconsistent, at least for zterp_io_getc(), which can
- * return a failure condition, but non-boolean functions are not
- * currently used with exception handling, so it’s not relevant.
- */
-bool zterp_io_try(zterp_io *io)
+void zterp_io_set_exception_mode(zterp_io *io, bool mode)
 {
-  io->exception_mode = true;
-
-  if(setjmp(io->exception) != 0) return false;
+  io->exception_mode = mode;
+}
 
-  return true;
+jmp_buf *zterp_io_get_exception(zterp_io *io)
+{
+  return &io->exception;
 }
 
 static bool wrap(zterp_io *io, bool b)

terps/bocfel/io.h

@@ -3,6 +3,7 @@
 #ifndef ZTERP_IO_H
 #define ZTERP_IO_H
 
+#include <setjmp.h>
 #include <stdio.h>
 #include <stdint.h>
 #include <stdbool.h>
@@ -24,13 +25,36 @@ enum zterp_io_purpose
   ZTERP_IO_INPUT,
 };
 
+void zterp_io_set_exception_mode(zterp_io *, bool);
+jmp_buf *zterp_io_get_exception(zterp_io *);
+
+/* Turn on “exception handling” for this I/O object. After calling this
+ * macro, all future I/O calls which return a bool will now instead
+ * cause this macro to set “ok” to false in case of error. Simple usage:
+ *
+ * bool ok;
+ * zterp_io_try(io, ok);
+ * if (!ok) return ERROR;
+ * // call I/O functions here
+ *
+ * This *only* affects boolean functions. Those which return non-boolean
+ * values, such as zterp_io_write() and zterp_io_getc() are unaffected.
+ * This may be inconsistent, at least for zterp_io_getc(), which can
+ * return a failure condition, but non-boolean functions are not
+ * currently used with exception handling, so it’s not relevant.
+ */
+#define zterp_io_try(io, ok) do { \
+  zterp_io_set_exception_mode(io, true); \
+  if (setjmp(*zterp_io_get_exception(io)) != 0) ok = false; \
+  else                                          ok = true; \
+} while (false)
+
 zterp_io *zterp_io_open(const char *, enum zterp_io_mode, enum zterp_io_purpose);
 zterp_io *zterp_io_open_memory(const void *, size_t);
 zterp_io *zterp_io_stdin(void);
 zterp_io *zterp_io_stdout(void);
 void zterp_io_close(zterp_io *);
 bool zterp_io_close_memory(zterp_io *, uint8_t **, long *);
-bool zterp_io_try(zterp_io *);
 bool zterp_io_seek(zterp_io *, long, int);
 long zterp_io_tell(zterp_io *);
 size_t zterp_io_read(zterp_io *, void *, size_t);

terps/bocfel/stack.c

@@ -747,8 +747,10 @@ static void write_chunk(zterp_io *io, char (*(*writefunc)(zterp_io *))[5])
 bool save_quetzal(zterp_io *savefile, bool is_meta, bool store_history)
 {
   long file_size;
+  bool ok;
 
-  if(!zterp_io_try(savefile)) return false;
+  zterp_io_try(savefile, ok);
+  if (!ok) return false;
 
   zterp_io_write_exact(savefile, "FORM", 4);
   zterp_io_write32(savefile, 0); /* to be filled in */