patch [#25490] Fix for [#22096] Blender tries to open non-blend file

from Alexander Kuznetsov (alexk) with edits.

From the report:
Blender assumed that all files are .blend as retval = 0;

Now retval is initialized as file cannot be open (-1) for gzopen fail and directory case
retval = -2; is defined for not supported formats
This must be assigned before #ifdef WITH_PYTHON because this part can be missing
Finally retval = 0; if it is a .blend file

---
also made other edits.

- exotic.c's blend header checking was sloppy, didn't check data was actually read, only checked first 4 bytes and had a check for "blend.gz" extension which is unnecessary.
- use defines to help readability for BKE_read_exotic & BKE_read_file return values.
- no need to check for a NULL pointer before calling BKE_reportf(). (will just print to the console)
- print better reports when the file fails to load.

1 files changed, 18 insertions, 9 deletions

diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index e7165598e38..22b10c8c618 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -276,7 +276,7 @@ void WM_read_file(bContext *C, const char *name, ReportList *reports)
 	retval= BKE_read_exotic(CTX_data_scene(C), name);
 	
 	/* we didn't succeed, now try to read Blender file */
-	if (retval== 0) {
+	if (retval == BKE_READ_EXOTIC_OK_BLEND) {
 		int G_f= G.f;
 		ListBase wmbase;
 
@@ -298,9 +298,9 @@ void WM_read_file(bContext *C, const char *name, ReportList *reports)
 		
 // XXX		mainwindow_set_filename_to_title(G.main->name);
 
-		if(retval==2) wm_init_userdef(C);	// in case a userdef is read from regular .blend
+		if(retval == BKE_READ_FILE_OK_USERPREFS) wm_init_userdef(C);	// in case a userdef is read from regular .blend
 		
-		if (retval!=0) {
+		if (retval != BKE_READ_FILE_FAIL) {
 			G.relbase_valid = 1;
 			if(!G.background) /* assume automated tasks with background, dont write recent file list */
 				write_history();
@@ -327,13 +327,22 @@ void WM_read_file(bContext *C, const char *name, ReportList *reports)
 		BKE_write_undo(C, "original");	/* save current state */
 		
 	}
-	else if(retval==1)
+	else if(retval == BKE_READ_EXOTIC_OK_OTHER)
 		BKE_write_undo(C, "Import file");
-	else if(retval == -1) {
-		if(reports)
-			BKE_reportf(reports, RPT_ERROR, "Can't read file: \"%s\", %s.", name, errno ? strerror(errno) : "Incompatible file format");
+	else if(retval == BKE_READ_EXOTIC_FAIL_OPEN) {
+		BKE_reportf(reports, RPT_ERROR, "Can't read file: \"%s\", %s.", name, errno ? strerror(errno) : "Unable to open the file");
 	}
-	
+	else if(retval == BKE_READ_EXOTIC_FAIL_FORMAT) {
+		BKE_reportf(reports, RPT_ERROR, "File format is not supported in file: \"%s\".", name);
+	}
+	else if(retval == BKE_READ_EXOTIC_FAIL_PATH) {
+		BKE_reportf(reports, RPT_ERROR, "File path invalid: \"%s\".", name);
+	}
+	else {
+		BKE_reportf(reports, RPT_ERROR, "Unknown error loading: \"%s\".", name);
+		BKE_assert(!"invalid 'retval'");
+	}
+
 	WM_cursor_wait(0);
 
 }
@@ -372,7 +381,7 @@ int WM_read_homefile(bContext *C, wmOperator *op)
 	wm_window_match_init(C, &wmbase); 
 	
 	if (!from_memory && BLI_exists(tstr)) {
-		success = BKE_read_file(C, tstr, NULL);
+		success = (BKE_read_file(C, tstr, NULL) != BKE_READ_FILE_FAIL);
 		
 		if(U.themes.first==NULL) {
 			printf("\nError: No valid startup.blend, fall back to built-in default.\n\n");