First pass at fixing issue 99

A lot of code touched because low level functions needed to pass up
error messages reliably, and this had to propagate up the entire
driver hierarchy.

Tested OK *in English* on:
     > Linux
     > OSX 10.10.x
     > Windows VS2017
     > Windows mingw64
I have no way to test on Android, but it might work.

TODO: Needs testing in other languages to verify proper UTF8 error messages,
      esp. with Windows VS, due to complexities with FormatMessage() -- see get_ms_errmsg()

2 files changed, 14 insertions, 6 deletions

diff --git a/src/drivers/Android/Fl_Android_System_Driver.H b/src/drivers/Android/Fl_Android_System_Driver.H
index 2a8682ddb..198d7a2b3 100644
--- a/src/drivers/Android/Fl_Android_System_Driver.H
+++ b/src/drivers/Android/Fl_Android_System_Driver.H
@@ -70,7 +70,9 @@ public:
   // these 2 are in Fl_get_key_win32.cxx
   virtual int event_key(int k);
   virtual int get_key(int k);
-  virtual int filename_list(const char *d, dirent ***list, int (*sort)(struct dirent **, struct dirent **) );
+  virtual int filename_list(const char *d, dirent ***list,
+                            int (*sort)(struct dirent **, struct dirent **),
+                            char *errmsg, int errmsg_sz);
   virtual int filename_expand(char *to,int tolen, const char *from);
   virtual int filename_relative(char *to, int tolen, const char *from, const char *base);
   virtual int filename_absolute(char *to, int tolen, const char *from);
@@ -80,7 +82,9 @@ public:
   virtual int open_uri(const char *uri, char *msg, int msglen);
   virtual int use_recent_tooltip_fix() {return 1;}
   virtual int file_browser_load_filesystem(Fl_File_Browser *browser, char *filename, int lname, Fl_File_Icon *icon);
-  virtual int file_browser_load_directory(const char *directory, char *filename, size_t name_size, dirent ***pfiles, Fl_File_Sort_F *sort);
+  virtual int file_browser_load_directory(const char *directory, char *filename, size_t name_size,
+                                          dirent ***pfiles, Fl_File_Sort_F *sort,
+                                          char *errmsg=NULL, int errmsg_sz=0);
   virtual void newUUID(char *uuidBuffer);
   virtual char *preference_rootnode(Fl_Preferences *prefs, Fl_Preferences::Root root, const char *vendor,
                                     const char *application);
diff --git a/src/drivers/Android/Fl_Android_System_Driver.cxx b/src/drivers/Android/Fl_Android_System_Driver.cxx
index e6aa970e4..0fa9671c5 100644
--- a/src/drivers/Android/Fl_Android_System_Driver.cxx
+++ b/src/drivers/Android/Fl_Android_System_Driver.cxx
@@ -486,11 +486,13 @@ int Fl_WinAPI_System_Driver::clocale_printf(FILE *output, const char *format, va
   return retval;
 }
 
-int Fl_WinAPI_System_Driver::filename_list(const char *d, dirent ***list, int (*sort)(struct dirent **, struct dirent **) ) {
+int Fl_WinAPI_System_Driver::filename_list(const char *d, dirent ***list,
+                                           int (*sort)(struct dirent **, struct dirent **),
+                                           char *errmsg, int errmsg_sz ) {
   // For Windows we have a special scandir implementation that uses
   // the Win32 "wide" functions for lookup, avoiding the code page mess
   // entirely. It also fixes up the trailing '/'.
-  return fl_scandir(d, list, 0, sort);
+  return fl_scandir(d, list, 0, sort, errmsg, errmsg_sz);
 }
 
 int Fl_WinAPI_System_Driver::filename_expand(char *to, int tolen, const char *from) {
@@ -747,7 +749,9 @@ int Fl_WinAPI_System_Driver::file_browser_load_filesystem(Fl_File_Browser *brows
 }
 
 int Fl_WinAPI_System_Driver::file_browser_load_directory(const char *directory, char *filename,
-                                                         size_t name_size, dirent ***pfiles, Fl_File_Sort_F *sort)
+                                                         size_t name_size, dirent ***pfiles,
+                                                         Fl_File_Sort_F *sort,
+                                                         char *errmsg, int errmsg_sz)
 {
   strlcpy(filename, directory, name_size);
   int i = (int) (strlen(filename) - 1);
@@ -756,7 +760,7 @@ int Fl_WinAPI_System_Driver::file_browser_load_directory(const char *directory,
     filename[2] = '/';
   else if (filename[i] != '/' && filename[i] != '\\')
     strlcat(filename, "/", name_size);
-  return filename_list(filename, pfiles, sort);
+  return filename_list(filename, pfiles, sort, errmsg, errmsg_sz);
 }
 
 void Fl_WinAPI_System_Driver::newUUID(char *uuidBuffer)