--- /dev/null
+/* files.c: Glulxe file-handling code.
+ Designed by Andrew Plotkin <erkyrath@eblong.com>
+ http://eblong.com/zarf/glulx/index.html
+*/
+
+#include "glk.h"
+#include "gi_blorb.h"
+#include "glulxe.h"
+
+/* is_gamefile_valid():
+ Check guess what.
+*/
+int is_gamefile_valid()
+{
+ unsigned char buf[8];
+ int res;
+ glui32 version;
+
+ glk_stream_set_position(gamefile, gamefile_start, seekmode_Start);
+ res = glk_get_buffer_stream(gamefile, (char *)buf, 8);
+
+ if (res != 8) {
+ fatal_error("This is too short to be a valid Glulx file.");
+ return FALSE;
+ }
+
+ if (buf[0] != 'G' || buf[1] != 'l' || buf[2] != 'u' || buf[3] != 'l') {
+ fatal_error("This is not a valid Glulx file.");
+ return FALSE;
+ }
+
+ /* We support version 2.0 through 3.1.*. */
+
+ version = Read4(buf+4);
+ if (version < 0x20000) {
+ fatal_error("This Glulx file is too old a version to execute.");
+ return FALSE;
+ }
+ if (version >= 0x30200) {
+ fatal_error("This Glulx file is too new a version to execute.");
+ return FALSE;
+ }
+
+ return TRUE;
+}
+
+/* locate_gamefile:
+ Given that gamefile contains a Glk stream, which may be a Glulx
+ file or a Blorb archive containing one, locate the beginning and
+ end of the Glulx data.
+*/
+int locate_gamefile(int isblorb)
+{
+ if (!isblorb) {
+ /* The simple case. A bare Glulx file was opened, so we don't use
+ Blorb at all. */
+ gamefile_start = 0;
+ glk_stream_set_position(gamefile, 0, seekmode_End);
+ gamefile_len = glk_stream_get_position(gamefile);
+ return TRUE;
+ }
+ else {
+ /* A Blorb file. We now have to open it and find the Glulx chunk. */
+ giblorb_err_t err;
+ giblorb_result_t blorbres;
+ giblorb_map_t *map;
+
+ err = giblorb_set_resource_map(gamefile);
+ if (err) {
+ init_err = "This Blorb file seems to be invalid.";
+ return FALSE;
+ }
+ map = giblorb_get_resource_map();
+ err = giblorb_load_resource(map, giblorb_method_FilePos,
+ &blorbres, giblorb_ID_Exec, 0);
+ if (err) {
+ init_err = "This Blorb file does not contain an executable Glulx chunk.";
+ return FALSE;
+ }
+ if (blorbres.chunktype != giblorb_make_id('G', 'L', 'U', 'L')) {
+ init_err = "This Blorb file contains an executable chunk, but it is not a Glulx file.";
+ return FALSE;
+ }
+ gamefile_start = blorbres.data.startpos;
+ gamefile_len = blorbres.length;
+ return TRUE;
+ }
+}
+