Filenames, escaping, and GtkFileSystem

[Federico Mena Quintero <federico ximian com>]

Hi,

I started to fix #136467 and found a few interesting things:

- GtkFileSystem::make_path() is supposed to take in a folder path and a
filename without path components, and produce folder_path + "/" +
filename.  

- However, gtk_file_system_unix_make_path() just uses
g_build_filename(), which, for practical purposes, acts like
g_strconcat() --- it also turns adjacent slashes into a single slash,
but we can ignore that for now.  This means that
gtk_file_system_unix_make_path ("/foo/bar", "/baz/beep"), which should
fail because the second argument has path components, doesn't fail.

- In contrast, gtk_file_system_gnome_vfs_make_path() uses
gnome_vfs_uri_append_file_name(), which first escapes the filename, and
then appends it to the URI --- for the example above, it would yield
something like "/foo/bar/%37baz%37beep".

- Nautilus flames you if you try to rename a file to something that
contains a slash in it.  This makes people unhappy if they want to call
a file "Report from the engineering/marketing teams".

There are a few things we can do:

1. Specify that GtkFileSystem::make_path() should fail if the filename
has path components.  In the context of GtkFileChooser, this would
eventually bring up an error message box, very similar to the one
Nautilus uses when you rename a file and try to put a slash in the name.

2. Specify that GtkFileSystem::make_path() must escape the filename,
thus allowing any characters to appear in it, *and* then unescaping
filenames when reading them from the file system.  This would make it
possible to have file names like "Report from the engineering/marketing
teams" above.  If we do this, we should modify Nautilus as well.

I'm not sure what is the right thing to do.  People get unhappy if there
are useful characters that they can't put in filenames, but doing
escaping/unescaping everywhere a) goes against what every program does;
b) may break applications which do filename munging on their own.

Ideas?

  Federico