Grafx2 now disables safety backups (and warns the user on startup) if another instance is running or if its configuration directory is read-only. Implemented separately on Linux and Windows, tested only on Windows

git-svn-id: svn://pulkomandy.tk/GrafX2/trunk@1343 416bcca6-2ee7-4201-b75f-2eb2f807beb1

io.c

@@ -284,3 +284,72 @@ void Get_full_filename(char * output_name, char * file_name, char * directory_na
   }
   strcat(output_name,file_name);
 }
+
+/// Lock file used to prevent several instances of grafx2 from harming each others' backups
+#ifdef __WIN32__
+HANDLE Lock_file_handle = INVALID_HANDLE_VALUE;
+#else
+int Lock_file_handle = -1;
+#endif
+
+byte Create_lock_file(const char *file_directory)
+{
+  char lock_filename[MAX_PATH_CHARACTERS];
+  
+  strcpy(lock_filename,file_directory);
+  strcat(lock_filename,"gfx2.lck");
+  
+  #ifdef __WIN32__
+  // Windowzy method for creating a lock file
+  Lock_file_handle = CreateFile(
+    lock_filename,
+    GENERIC_WRITE,
+    0, // No sharing
+    NULL,
+    OPEN_ALWAYS,
+    FILE_ATTRIBUTE_NORMAL,
+    NULL);
+  if (Lock_file_handle == INVALID_HANDLE_VALUE)
+  {
+    return -1;
+  }
+  #else
+  // Unixy method for lock file
+  Lock_file_handle = open(lock_filename,O_WRONLY|O_CREAT);
+  if (Lock_file_handle == -1)
+  {
+    // Usually write-protected media
+    return -1;
+  }
+  if (lockf(Lock_file_handle, F_TLOCK, 0)==-1)
+  {
+    close(Lock_file_handle);
+    // Usually write-protected media
+    return -1;
+  }
+  #endif
+  return 0;
+}
+
+void Release_lock_file(const char *file_directory)
+{
+  char lock_filename[MAX_PATH_CHARACTERS];
+    
+  #ifdef __WIN32__
+  if (Lock_file_handle != INVALID_HANDLE_VALUE)
+  {
+    CloseHandle(Lock_file_handle);
+  }
+  #else
+  if (Lock_file_handle != -1)
+  {
+    close(Lock_file_handle);
+    Lock_file_handle = -1;
+  }  
+  #endif
+  
+  // Actual deletion
+  strcpy(lock_filename,file_directory);
+  strcat(lock_filename,"gfx2.lck");
+  remove(lock_filename);
+}

io.h

@@ -94,3 +94,12 @@ void For_each_file(const char * directory_name, void Callback(const char *));
 /// Creates a fully qualified name from a directory and filename.
 /// The point is simply to insert a PATH_SEPARATOR when needed.
 void Get_full_filename(char * output_name, char * file_name, char * directory_name);
+
+///
+/// Creates a lock file, to check if an other instance of Grafx2 is running.
+/// @return 0 on success (first instance), -1 on failure (others are running)
+byte Create_lock_file(const char *file_directory);
+
+///
+/// Release a lock file created by ::Create_Lock_file
+void Release_lock_file(const char *file_directory);

loadsave.c

@@ -1162,6 +1162,7 @@ T_String_list *Backups_main = NULL;
 /// A list of files, used for scanning a directory
 T_String_list *Backups_spare = NULL;
 
+
 // Settings for safety backup (frequency, numbers, etc)
 
 const int Rotation_safety_backup = 8;
@@ -1187,9 +1188,9 @@ void Add_backup_file(const char *name)
   Extract_filename(file_name, name);
   
   // Check first character
-  if (file_name[0]=='a')
+  if (file_name[0]==Main_safety_backup_prefix)
     list = &Backups_main;
-  else if (file_name[0]=='b')
+  else if (file_name[0]==Spare_safety_backup_prefix)
     list = &Backups_spare;
    else {
     // Not a good file
@@ -1291,13 +1292,22 @@ byte Process_backups(T_String_list **list)
 }
 
 
+/// Global indicator that tells if the safety backup system is active
+byte Safety_backup_active = 0;
+
 ///
 /// Checks if there are any pending safety backups, and then opens them.
-///
+/// @return 0 if no problem, -1 if the backup system cannot be activated, >=1 if some backups are restored
 int Check_recovery(void)
 {
   int restored_spare;
   int restored_main;
+  
+  // First check if can write backups
+  if (Create_lock_file(Config_directory))
+    return -1;
+
+  Safety_backup_active=1;
     
   Backups_main = NULL;
   Backups_spare = NULL;
@@ -1327,13 +1337,7 @@ int Check_recovery(void)
     Compute_paintbrush_coordinates();
     Redraw_layered_image();
   }
-  /*
-  if (restored_main||restored_spare)
-  {
-    Display_all_screen();
-    return 1;
-  }*/
-  return restored_main || restored_spare;
+  return restored_main + restored_spare;
 }
 
 void Rotate_safety_backups(void)
@@ -1343,6 +1347,9 @@ void Rotate_safety_backups(void)
   char file_name[12+1];
   char deleted_file[MAX_PATH_CHARACTERS];
 
+  if (!Safety_backup_active)
+    return;
+    
   now = SDL_GetTicks();
   // It's time to save if either:
   // - Many edits have taken place
@@ -1384,6 +1391,9 @@ void Delete_safety_backups(void)
 {
   T_String_list *element;
 
+  if (!Safety_backup_active)
+    return;
+  
   Backups_main = NULL;
   Backups_spare = NULL;
   
@@ -1401,4 +1411,7 @@ void Delete_safety_backups(void)
       printf("Failed to delete %s\n",element->String);
   }
   
+  // Release lock file
+  Release_lock_file(Config_directory);
+  
 }

main.c

@@ -760,54 +760,74 @@ int Init_program(int argc,char * argv[])
   *Brush=MC_White;
   
   // Test de recuperation de fichiers sauvés
-  if (Check_recovery())
-  {
-    // Some files were loaded from last crash-exit.
-    // Do not load files from command-line, nor show splash screen.
-    Compute_optimal_menu_colors(Main_palette);
-    Display_all_screen();
-    Display_menu();
-    Display_cursor();
-  }
-  else
+  switch (Check_recovery())
   {
     T_IO_Context context;
-    
-    switch (file_in_command_line)
-    {
-      case 0:
-        if (Config.Opening_message)
-          Button_Message_initial();
-        break;
 
-      case 2:
-        // Load this file
-        Init_context_layered_image(&context, spare_filename, spare_directory);
-        Load_image(&context);
-        Destroy_context(&context);
-        End_of_modification();
-        Redraw_layered_image();
-
-        Button_Page();
-        // no break ! proceed with the other file now
-      case 1:
-        Init_context_layered_image(&context, main_filename, main_directory);
-        Load_image(&context);
-        Destroy_context(&context);
-        End_of_modification();
-        Redraw_layered_image();
-        
-        Hide_cursor();
-        Compute_optimal_menu_colors(Main_palette);
-        Display_all_screen();
-        Display_menu();
-        Display_cursor();
-        Resolution_in_command_line = 0;
-        break;
+    default:    
+      // Some files were loaded from last crash-exit.
+      // Do not load files from command-line, nor show splash screen.
+      Compute_optimal_menu_colors(Main_palette);
+      Display_all_screen();
+      Display_menu();
+      Display_cursor();
+      Verbose_message("Images recovered",
+        "Grafx2 has recovered images from\n"
+        "last session, before a crash or\n"
+        "shutdown. Browse the history using\n"
+        "the Undo/Redo button, and when\n"
+        "you find a state that you want to\n"
+        "save, use the 'Save as' button to\n"
+        "save the image.\n"
+        "Some backups can be present in\n"
+        "the spare page too.\n");
+      break;
   
-      default:
-        break;
-    }
+    case -1: // Unable to write lock file
+      Verbose_message("Warning", 
+        "Safety backups (every minute) are\n"
+        "disabled because Grafx2 is running\n"
+        "from a read-only device, or other\n"
+        "instances are running.");
+      break;
+
+    case 0:
+    
+      switch (file_in_command_line)
+      {
+        case 0:
+          if (Config.Opening_message)
+            Button_Message_initial();
+          break;
+  
+        case 2:
+          // Load this file
+          Init_context_layered_image(&context, spare_filename, spare_directory);
+          Load_image(&context);
+          Destroy_context(&context);
+          End_of_modification();
+          Redraw_layered_image();
+  
+          Button_Page();
+          // no break ! proceed with the other file now
+        case 1:
+          Init_context_layered_image(&context, main_filename, main_directory);
+          Load_image(&context);
+          Destroy_context(&context);
+          End_of_modification();
+          Redraw_layered_image();
+          
+          Hide_cursor();
+          Compute_optimal_menu_colors(Main_palette);
+          Display_all_screen();
+          Display_menu();
+          Display_cursor();
+          Resolution_in_command_line = 0;
+          break;
+    
+        default:
+          break;
+      }
   }
   return(1);
 }