UTF-8 / system / filesystem encoding bugs

Bumping priority of this bug, because it's a genuine issue that needs addressing with increased internationalisation in the suite.

Are there specific known cases or do we need to audit the code to find them? I've found a few string operations in the code (i18n and otherwise) I'm unhappy with, I just wonder the best place to capture them.

Split second part into 1083076.

A commit was made which affects this bug
git master commit f9140160a1ba1a2d76f97aa0371dd02093130bb2
http://git.geda-project.org/geda-gaf/commit/?id=f9140160a1ba1a2d76f97aa0371dd02093130bb2

commit f9140160a1ba1a2d76f97aa0371dd02093130bb2
Author: Peter TB Brett <email address hidden>
Commit: Peter TB Brett <email address hidden>

    libgeda: Require gEDA files to be valid UTF-8.

    Affects-bug: lp-698498

One way to tackle this in general might be to use GFile objects (https://developer.gnome.org/gio/2.36/GFile.html) whenever we need to work with filenames, rather than just using raw character array filenames.

I've tested many dialogs using the 8-bit Russian encoding KOI8-R.

I installed the KOI8-R locale as the default one and rebooted.
I added a symbol with a name in the KOI8-R encoding:
  echo ~/gaf/symbols/passive/фыва.sym |recode ..koi8-r| xargs touch
Then I opened gschem (built from current git) in KOI8-R
environment (using the special KOI8-R terminal though I could do
it just using LANG=KOI8-R):
  koi8rxterm -e gschem

Then I've tested as much gschem dialogs as I could:

COMPSELECT
  I found the symbol in my library which name is shown with
  characters displayed as diagonally crossed rectangles. I cannot
  select it to add to the schematic.
  gschem says as I open the dialog:
    (gschem:13010): Pango-WARNING **: Invalid UTF-8 string passed
    to pango_layout_set_text()

PAGE-MANAGER
  "Pango-WARNING ..." as above and the same appearance of the file
  name.

FILE OPEN, FILE SAVE AS
  They work well and display filenames correctly.

  If I launch 'LANG=C gschem' the 'File open' dialog shows the
  file name as '<four diamonds here>.sym (invalid encoding)'

OVERWRITE FILE
  When I'm trying to overwrite the file using "file save as"
  dialog the 'Overwrite file?' dialog
  causes the same effect with "Pango-WARNING ..."

CLOSE WITHOUT SAVING
  In "close without saving" window the header "Save the changes to
  schematic <filename> before closing?" is lost.

MULTIATTRIB
  If I even add an attribute (using text editor) in KOI8-R the
  multiattrib dialog adds text in UTF-8 and works well

TEXT-ENTRY
AUTONUMBER
SINGLEATTRIB
TEXT-EDIT
SLOT-EDIT
SYMBOL TRANSLATE
  Tried to insert text, sometimes using those two encodings, the
  dialogs work well and there are no errors anywhere

LOG
  If I type ":" to type a command and enter any cyrillic symbols
  (e.g. '(фыва)') and then Enter, it outputs "Invalid UTF-8 in log
  message. See stderr or gschem.log." in the log window and
  outputs the backtrace in terminal, whereas when I type in English
  it outputs the backtrace in the log window (this behaviour is
  the same for any locale, with UTF-8 it behaves the same way, so
  I believe this is another bug).

HOTKEYS
COLOR-EDIT
SNAP-SIZE
TEXT-SIZE
LINE-TYPE
PIN-TYPE-EDIT
  OK (cannot add any text here)

If I launch 'LANG=C gschem' with the above file name gschem
outputs in the log window
  ** Invalid UTF-8 in log message. See stderr or gschem.log.
and barfs to stderr (I suspect this is because of the "Loading
schematic ..." string where the name is in KOI8-R).