When we're displaying double-width text as a result of the VT100 ESC#6
escape sequence or its friends, and the terminal width is an odd
number of columns, we divide by 2 the number of characters we'll even
try to display, and round _down_: if there's a rightmost odd column,
it stays blank, and doesn't show the left half of a double-width char.
In the GTK redraw function, that rounding-down can set the 'len'
variable to zero. But when we're displaying a character with Unicode
combining chars on top, that fails an assertion that len == 1, because
at the top of the function we set it to 1.
The fix is just to return early if len is reduced to zero by that
rounding: if we're not displaying any characters, then we don't have
to do anything at all.
My previous dodge to make the GTK 1 headers work with modern compilers
was to manually reset to -std=gnu89, which changed the semantics of
'inline' back to what glib.h was expecting. But that doesn't work now
the PuTTY code base expects to be able to use the rest of C99, so
instead I have to manually override the specific #defines that glib.h
uses to know how 'inline' works.
Also, moved that code in configure.ac out of the fallback branch that
manually detects GTK1, so that it will fire even if autoconf is run on
a system that still has the genuine GTK1 detection code. (Amazingly,
one still exists that I have access to!)
With that fixed, there's one more problem: the nethack_mode and
app_keypad_mode flags in gtkwin.c's key_event() are only used in the
GTK >= 2 branch of the ifdefs, so they should only be declared and set
in that branch as well, on pain of a -Wunused complaint.
Now instead of taking raw arguments to configure the output
StripCtrlChars with, it takes an enumerated value giving the context
of what's being sanitised, and allows the seat to decide what the
output parameters for that context should be.
The only context currently used is SIC_BANNER (SSH login banners).
I've also added a not-yet-used one for keyboard-interactive prompts.
If centralised code like the SSH implementation wants to sanitise
escape sequences out of a piece of server-provided text, it will need
to do it by making a locale-based StripCtrlChars if it's running in a
console context, or a Terminal-based one if it's in a GUI terminal-
window application.
All the other changes of behaviour needed between those two contexts
are handled by providing reconfigurable methods in the Seat vtable;
this one is no different. So now there's a new method in the Seat
vtable that will construct a StripCtrlChars appropriate to that kind
of seat. Terminal-window seats (gtkwin.c, window.c) implement it by
calling the new stripctrl_new_term(), and console ones use the locale-
based stripctrl_new().
This is a general cleanup which has been overdue for some time: lots
of length fields are now the machine word type rather than the (in
practice) fixed 'int'.
The upcoming PRNG revamp will want to tell noise sources apart, so
that it can treat them all fairly. So I've added an extra parameter to
noise_ultralight and random_add_noise, which takes values in an
enumeration covering all the vague classes of entropy source I'm
collecting. In this commit, though, it's simply ignored.
Mostly on the Unix side: there are lots of places the Windows code was
collecting noise that the corresponding Unix/GTK code wasn't bothering
to, such as mouse movements, keystrokes and various network events.
Also, both platforms had forgotten to collect noise when reading data
from a pipe to a local proxy process, even though in that
configuration that's morally equivalent to the network packet timings
that we'd normally be collecting from.
Taking a leaf out of the LLVM code base: this macro still includes an
assert(false) so that the message will show up in a typical build, but
it follows it up with a call to a function explicitly marked as no-
return.
So this ought to do a better job of convincing compilers that once a
code path hits this function it _really doesn't_ have to still faff
about with making up a bogus return value or filling in a variable
that 'might be used uninitialised' in the following code that won't be
reached anyway.
I've gone through the existing code looking for the assert(false) /
assert(0) idiom and replaced all the ones I found with the new macro,
which also meant I could remove a few pointless return statements and
variable initialisations that I'd already had to put in to placate
compiler front ends.
In the past, I've had a lot of macros which you call with double
parentheses, along the lines of debug(("format string", params)), so
that the inner parens protect the commas and permit the macro to treat
the whole printf-style argument list as one macro argument.
That's all very well, but it's a bit inconvenient (it doesn't leave
you any way to implement such a macro by prepending another argument
to the list), and now this code base's rules allow C99isms, I can
switch all those macros to using a single pair of parens, using the
C99 ability to say '...' in the parameter list of the #define and get
at the corresponding suffix of the arguments as __VA_ARGS__.
So I'm doing it. I've made the following printf-style macros variadic:
bpp_logevent, ppl_logevent, ppl_printf and debug.
While I'm here, I've also fixed up a collection of conditioned-out
calls to debug() in the Windows front end which were clearly expecting
a macro with a different calling syntax, because they had an integer
parameter first. If I ever have a need to condition those back in,
they should actually work now.
A long time ago, in commit 4d77b6567, I moved the generation of the
arrow-key escape sequences into a function format_arrow_key(). Mostly
the reason for that was a special purpose I had in mind at the time
which involved auto-generating the same sequences in response to
things other than a keypress, but I always thought it would be nice to
centralise a lot more of PuTTY's complicated keyboard handling in the
same way - at least the handling of the function keys and their
numerous static and dynamic config options.
In this year's general spirit of tidying up and refactoring, I think
it's finally time. So here I introduce three more centralised
functions for dealing with the numbered function keys, the small
keypad (Ins, Home, PgUp etc) and the numeric keypad. Lots of horrible
and duplicated code from the key handling functions in window.c and
gtkwin.c is now more sensibly centralised: each platform keyboard
handler concerns itself with the local format of a keyboard event and
platform-specific enumeration of key codes, and once it's decided what
the logical key press actually _is_, it hands off to the new functions
in terminal.c to generate the appropriate escape code.
Mostly this is intended to be a refactoring without functional change,
leaving the keyboard handling how it's always been. But in cases where
the Windows and GTK handlers were accidentally inconsistent, I've
fixed the inconsistency rather than carefully keeping both sides how
they were. Known consistency fixes:
- swapping the arrow keys between normal (ESC [ A) and application
(ESC O A) is now done by pressing Ctrl with them, and _not_ by
pressing Shift. That was how it was always supposed to work, and
how it's worked on GTK all along, but on Windows it's been done by
Shift as well since 2010, due to a bug at the call site of
format_arrow_key() introduced when I originally wrote that function.
- in Xterm function key mode plus application keypad mode, the /*-
keys on the numeric keypad now send ESC O {o,j,m} in place of ESC O
{Q,R,S}. That's how the Windows keyboard handler has worked all
along (it was a deliberate behaviour tweak for the Xterm-like
function key mode, because in that mode ESC O {Q,R,S} are generated
by F2-F4). But the GTK keyboard handler omitted that particular
special case and was still sending ESC O {Q,R,S} for those keys in
all application keypad modes.
- also in Xterm function key mode plus app keypad mode, we only
generates the app-keypad escape sequences if Num Lock is on; with
Num Lock off, the numeric keypad becomes arrow keys and
Home/End/etc, just as it would in non-app-keypad mode. Windows has
done this all along, but again, GTK lacked that special case.
This is another cleanup I felt a need for while I was doing
boolification. If you define a function or variable in one .c file and
declare it extern in another, then nothing will check you haven't got
the types of the two declarations mismatched - so when you're
_changing_ the type, it's a pain to make sure you've caught all the
copies of it.
It's better to put all those extern declarations in header files, so
that the declaration in the header is also in scope for the
definition. Then the compiler will complain if they don't match, which
is what I want.
I came across this unexplained static variable in my boolification
trawl. It seems clearly unintentional that it has only one instance
instead of one per terminal window - the code in question closely
resembles the Windows front end, and I think this must just be a
variable that I never swept up into 'inst' in the very early days when
I was making gtkwin.c out of a cloned-and-hacked window.c in the first
place.
These days it's even a bug, now that the OS X port actually does run
multiple terminal windows in the same process: if one goes into mouse
reporting mode, I'm pretty sure this would have done confusing things
to the effects of mouse actions in the other.
My normal habit these days, in new code, is to treat int and bool as
_almost_ completely separate types. I'm still willing to use C's
implicit test for zero on an integer (e.g. 'if (!blob.len)' is fine,
no need to spell it out as blob.len != 0), but generally, if a
variable is going to be conceptually a boolean, I like to declare it
bool and assign to it using 'true' or 'false' rather than 0 or 1.
PuTTY is an exception, because it predates the C99 bool, and I've
stuck to its existing coding style even when adding new code to it.
But it's been annoying me more and more, so now that I've decided C99
bool is an acceptable thing to require from our toolchain in the first
place, here's a quite thorough trawl through the source doing
'boolification'. Many variables and function parameters are now typed
as bool rather than int; many assignments of 0 or 1 to those variables
are now spelled 'true' or 'false'.
I managed this thorough conversion with the help of a custom clang
plugin that I wrote to trawl the AST and apply heuristics to point out
where things might want changing. So I've even managed to do a decent
job on parts of the code I haven't looked at in years!
To make the plugin's work easier, I pushed platform front ends
generally in the direction of using standard 'bool' in preference to
platform-specific boolean types like Windows BOOL or GTK's gboolean;
I've left the platform booleans in places they _have_ to be for the
platform APIs to work right, but variables only used by my own code
have been converted wherever I found them.
In a few places there are int values that look very like booleans in
_most_ of the places they're used, but have a rarely-used third value,
or a distinction between different nonzero values that most users
don't care about. In these cases, I've _removed_ uses of 'true' and
'false' for the return values, to emphasise that there's something
more subtle going on than a simple boolean answer:
- the 'multisel' field in dialog.h's list box structure, for which
the GTK front end in particular recognises a difference between 1
and 2 but nearly everything else treats as boolean
- the 'urgent' parameter to plug_receive, where 1 vs 2 tells you
something about the specific location of the urgent pointer, but
most clients only care about 0 vs 'something nonzero'
- the return value of wc_match, where -1 indicates a syntax error in
the wildcard.
- the return values from SSH-1 RSA-key loading functions, which use
-1 for 'wrong passphrase' and 0 for all other failures (so any
caller which already knows it's not loading an _encrypted private_
key can treat them as boolean)
- term->esc_query, and the 'query' parameter in toggle_mode in
terminal.c, which _usually_ hold 0 for ESC[123h or 1 for ESC[?123h,
but can also hold -1 for some other intervening character that we
don't support.
In a few places there's an integer that I haven't turned into a bool
even though it really _can_ only take values 0 or 1 (and, as above,
tried to make the call sites consistent in not calling those values
true and false), on the grounds that I thought it would make it more
confusing to imply that the 0 value was in some sense 'negative' or
bad and the 1 positive or good:
- the return value of plug_accepting uses the POSIXish convention of
0=success and nonzero=error; I think if I made it bool then I'd
also want to reverse its sense, and that's a job for a separate
piece of work.
- the 'screen' parameter to lineptr() in terminal.c, where 0 and 1
represent the default and alternate screens. There's no obvious
reason why one of those should be considered 'true' or 'positive'
or 'success' - they're just indices - so I've left it as int.
ssh_scp_recv had particularly confusing semantics for its previous int
return value: its call sites used '<= 0' to check for error, but it
never actually returned a negative number, just 0 or 1. Now the
function and its call sites agree that it's a bool.
In a couple of places I've renamed variables called 'ret', because I
don't like that name any more - it's unclear whether it means the
return value (in preparation) for the _containing_ function or the
return value received from a subroutine call, and occasionally I've
accidentally used the same variable for both and introduced a bug. So
where one of those got in my way, I've renamed it to 'toret' or 'retd'
(the latter short for 'returned') in line with my usual modern
practice, but I haven't done a thorough job of finding all of them.
Finally, one amusing side effect of doing this is that I've had to
separate quite a few chained assignments. It used to be perfectly fine
to write 'a = b = c = TRUE' when a,b,c were int and TRUE was just a
the 'true' defined by stdbool.h, that idiom provokes a warning from
gcc: 'suggest parentheses around assignment used as truth value'!
I think this is the full set of things that ought logically to be
boolean.
One annoyance is that quite a few radio-button controls in config.c
address Conf fields that are now bool rather than int, which means
that the shared handler function can't just access them all with
conf_{get,set}_int. Rather than back out the rigorous separation of
int and bool in conf.c itself, I've just added a similar alternative
handler function for the bool-typed ones.
This commit includes <stdbool.h> from defs.h and deletes my
traditional definitions of TRUE and FALSE, but other than that, it's a
100% mechanical search-and-replace transforming all uses of TRUE and
FALSE into the C99-standardised lowercase spellings.
No actual types are changed in this commit; that will come next. This
is just getting the noise out of the way, so that subsequent commits
can have a higher proportion of signal.
After the recent Seat and LogContext revamps, _nearly_ all the
remaining uses of the type 'Frontend' were in terminal.c, which needs
all sorts of interactions with the GUI window the terminal lives in,
from the obvious (actually drawing text on the window, reading and
writing the clipboard) to the obscure (minimising, maximising and
moving the window in response to particular escape sequences).
All of those functions are now provided by an abstraction called
TermWin. The few remaining uses of Frontend after _that_ are internal
to a particular platform directory, so as to spread the implementation
of that particular kind of Frontend between multiple source files; so
I've renamed all of those so that they take a more specifically named
type that refers to the particular implementation rather than the
general abstraction.
So now the name 'Frontend' no longer exists in the code base at all,
and everywhere one used to be used, it's completely clear whether it
was operating in one of Frontend's three abstract roles (and if so,
which), or whether it was specific to a particular implementation.
Another type that's disappeared is 'Context', which used to be a
typedef defined to something different on each platform, describing
whatever short-lived resources were necessary to draw on the terminal
window: the front end would provide a ready-made one when calling
term_paint, and the terminal could request one with get_ctx/free_ctx
if it wanted to do proactive window updates. Now that drawing context
lives inside the TermWin itself, because there was never any need to
have two of those contexts live at the same time.
(Another minor API change is that the window-title functions - both
reading and writing - have had a missing 'const' added to their char *
parameters / return values.)
I don't expect this change to enable any particularly interesting new
functionality (in particular, I have no plans that need more than one
implementation of TermWin in the same application). But it completes
the tidying-up that began with the Seat and LogContext rework.
That's more directly useful in uxpty.c (which is currently the only
actual client of the function), and also matches the data that SSH
clients send in "pty-req". Also, it makes that method behave more like
the GUI query function get_window_pixels used by terminal.c (with the
sole exception that unlike g_w_p it's allowed to return failure), so
it becomes even more trivial to implement in the GUI front ends.
This is a new vtable-based abstraction which is passed to a backend in
place of Frontend, and it implements only the subset of the Frontend
functions needed by a backend. (Many other Frontend functions still
exist, notably the wide range of things called by terminal.c providing
platform-independent operations on the GUI terminal window.)
The purpose of making it a vtable is that this opens up the
possibility of creating a backend as an internal implementation detail
of some other activity, by providing just that one backend with a
custom Seat that implements the methods differently.
For example, this refactoring should make it feasible to directly
implement an SSH proxy type, aka the 'jump host' feature supported by
OpenSSH, aka 'open a secondary SSH session in MAINCHAN_DIRECT_TCP
mode, and then expose the main channel of that as the Socket for the
primary connection'. (Which of course you can already do by spawning
'plink -nc' as a separate proxy process, but this would permit it in
the _same_ process without anything getting confused.)
I've centralised a full set of stub methods in misc.c for the new
abstraction, which allows me to get rid of several annoying stubs in
the previous code. Also, while I'm here, I've moved a lot of
duplicated modalfatalbox() type functions from application main
program files into wincons.c / uxcons.c, which I think saves
duplication overall. (A minor visible effect is that the prefixes on
those console-based fatal error messages will now be more consistent
between applications.)
This was used by ldisc to communicate back to the front end that a key
had been pressed (or rather, that a keypress had caused a nonzero
amount of session input data). Its only nontrivial implementation was
in gtkwin.c, which used that notification to implement the Unix GUI's
"close window on keypress, if the session was already over" policy.
(Which in turn is Unix-specific, because the rationale is that
sometimes X servers don't have a functioning window manager, so it's
useful to have a way of telling any application to close without using
WM-provided facilities like a close button.)
But gtkwin.c doesn't need to be told by the ldisc that a keypress
happened - it's the one _sending_ those keypresses to ldisc in the
first place! So I've thrown away the three stub implementations of
frontend_keypress, removed the call to it in ldisc.c, and replaced it
with calls in gtkwin.c at all the points during keypress handling
that call ldisc_send.
A visible effect is that pterm's close-on-keypress behaviour will now
only trigger on an actual (input-generating) _keypress_, and not on
other input generation such as a paste action. I think that's an
improvement.
LogContext is now the owner of the logevent() function that back ends
and so forth are constantly calling. Previously, logevent was owned by
the Frontend, which would store the message into its list for the GUI
Event Log dialog (or print it to standard error, or whatever) and then
pass it _back_ to LogContext to write to the currently open log file.
Now it's the other way round: LogContext gets the message from the
back end first, writes it to its log file if it feels so inclined, and
communicates it back to the front end.
This means that lots of parts of the back end system no longer need to
have a pointer to a full-on Frontend; the only thing they needed it
for was logging, so now they just have a LogContext (which many of
them had to have anyway, e.g. for logging SSH packets or session
traffic).
LogContext itself also doesn't get a full Frontend pointer any more:
it now talks back to the front end via a little vtable of its own
called LogPolicy, which contains the method that passes Event Log
entries through, the old askappend() function that decides whether to
truncate a pre-existing log file, and an emergency function for
printing an especially prominent message if the log file can't be
created. One minor nice effect of this is that console and GUI apps
can implement that last function subtly differently, so that Unix
console apps can write it with a plain \n instead of the \r\n
(harmless but inelegant) that the old centralised implementation
generated.
One other consequence of this is that the LogContext has to be
provided to backend_init() so that it's available to backends from the
instant of creation, rather than being provided via a separate API
call a couple of function calls later, because backends have typically
started doing things that need logging (like making network
connections) before the call to backend_provide_logctx. Fortunately,
there's no case in the whole code base where we don't already have
logctx by the time we make a backend (so I don't actually remember why
I ever delayed providing one). So that shortens the backend API by one
function, which is always nice.
While I'm tidying up, I've also moved the printf-style logeventf() and
the handy logevent_and_free() into logging.c, instead of having copies
of them scattered around other places. This has also let me remove
some stub functions from a couple of outlying applications like
Pageant. Finally, I've removed the pointless "_tag" at the end of
LogContext's official struct name.
This is the structure that stores the truncated version of the Event
Log data to be displayed by the GTK Event Log dialog. It persists for
the lifetime of the parent SSH window, so it was deliberate that it
wasn't freed on destruction of the dialog itself, but I also forgot to
free it on destruction of the SSH window. (This will be more important
in multi-connection process architectures like the OS X port, of
course.)
While I'm at it, I'll follow my recent practice by exposing the
structure tag outside gtkdlg.c so that callers can more easily not
confuse it with some other kind of void *.
It's never set to anything but NULL at any call site, and there's been
a FIXME comment in uxucs.c for ages saying it should be removed. I
think it only existed in the first place because it was a facility
supported by the underlying Windows API function and we couldn't see a
reason _not_ to pass it through. But I'm cleaning up FIXMEs, so we
should get rid of it.
(It stood for 'default used', incidentally - as in 'did the function
at any point have to make use of the parameter providing a default
fallback character?'. Nothing to do with _defusing_ things :-)
In order to list cross-certifiable host keys in the GUI specials menu,
the SSH backend has been inventing new values on the end of the
Telnet_Special enumeration, starting from the value TS_LOCALSTART.
This is inelegant, and also makes it awkward to break up special
handlers (e.g. to dispatch different specials to different SSH
layers), since if all you know about a special is that it's somewhere
in the TS_LOCALSTART+n space, you can't tell what _general kind_ of
thing it is. Also, if I ever need another open-ended set of specials
in future, I'll have to remember which TS_LOCALSTART+n codes are in
which set.
So here's a revamp that causes every special to take an extra integer
argument. For all previously numbered specials, this argument is
passed as zero and ignored, but there's a new main special code for
SSH host key cross-certification, in which the integer argument is an
index into the backend's list of available keys. TS_LOCALSTART is now
a thing of the past: if I need any other open-ended sets of specials
in future, I can add a new top-level code with a nicely separated
space of arguments.
While I'm at it, I've removed the legacy misnomer 'Telnet_Special'
from the code completely; the enum is now SessionSpecialCode, the
struct containing full details of a menu entry is SessionSpecial, and
the enum values now start SS_ rather than TS_.
Now there's a centralised routine in misc.c to do the sanitisation,
which copies data on to an outgoing bufchain. This allows me to remove
from_backend_untrusted() completely from the frontend API, simplifying
code in several places.
Two use cases for untrusted-terminal-data sanitisation were in the
terminal.c prompts handler, and in the collection of SSH-2 userauth
banners. Both of those were writing output to a bufchain anyway, so
it was very convenient to just replace a bufchain_add with
sanitise_term_data and then not have to worry about it again.
There was also a simplistic sanitiser in uxcons.c, which I've now
replaced with a call to the good one - and in wincons.c there was a
FIXME saying I ought to get round to that, which now I have!
'struct draw_ctx' has a structure tag inside gtkwin.c, so as per this
week's standard practice, let's expose the tag elsewhere so that
pointers declared that way can't be confused with anything else.
This is another major source of unexplained 'void *' parameters
throughout the code.
In particular, the currently unused testback.c actually gave the wrong
pointer type to its internal store of the frontend handle - it cast
the input void * to a Terminal *, from which it got implicitly cast
back again when calling from_backend, and nobody noticed. Now it uses
the right type internally as well as externally.
Nearly every part of the code that ever handles a full backend
structure has historically done it using a pair of pointer variables,
one pointing at a constant struct full of function pointers, and the
other pointing to a 'void *' state object that's passed to each of
those.
While I'm modernising the rest of the code, this seems like a good
time to turn that into the same more or less type-safe and less
cumbersome system as I'm using for other parts of the code, such as
Socket, Plug, BinaryPacketProtocol and so forth: the Backend structure
contains a vtable pointer, and a system of macro wrappers handles
dispatching through that vtable.
Same principle again - the more of these structures have globally
visible tags (even if the structure contents are still opaque in most
places), the fewer of them I can mistake for each other.
That's one fewer anonymous 'void *' which might be accidentally
confused with some other pointer type if I misremember the order of
function arguments.
While I'm here, I've made its pointer-nature explicit - that is,
'Ldisc' is now a typedef for the structure type itself rather than a
pointer to it. A stylistic change only, but it feels more natural to
me these days for a thing you're going to eventually pass to a 'free'
function.
This is a cleanup I started to notice a need for during the BinarySink
work. It removes a lot of faffing about casting things to char * or
unsigned char * so that some API will accept them, even though lots of
such APIs really take a plain 'block of raw binary data' argument and
don't care what C thinks the signedness of that data might be - they
may well reinterpret it back and forth internally.
So I've tried to arrange for all the function call APIs that ought to
have a void * (or const void *) to have one, and those that need to do
pointer arithmetic on the parameter internally can cast it back at the
top of the function. That saves endless ad-hoc casts at the call
sites.
In commit 528513dde I absentmindedly replaced a write to the local
variable 'need_size' of drawing_area_setup with a write to
inst->drawing_area_setup_needed, imagining that they had the same
effect. But actually, need_size was doing two jobs and I only replaced
one of them: it was also the variable that indicated that the logical
terminal size had changed and so we had to call term_size() to make
the terminal.c data structures resize themselves appropriately. The
loss of that call also inhibited generation of SIGWINCH.
NFC for the moment, because the bufchain is always specially
constructed to hold exactly the same data that would have been passed
in to the function as a (pointer,length) pair. But this API change
allows get_userpass_input to express the idea that it consumed some
but not all of the data in the bufchain, which means that later on
I'll be able to point the same function at a longer-lived bufchain
containing the full stream of keyboard input and avoid dropping
keystrokes that arrive too quickly after the end of an interactive
password prompt.
Changing the window's font size with Alt-< or Alt-> was not setting
any of the flags that make drawing_area_setup consider itself to have
been non-spuriously called, so the real window would enlarge without
the backing surface also doing so.
In GTK 3.10 and above, high-DPI support is arranged by each window
having a property called a 'scale factor', which translates logical
pixels as seen by most of the GTK API (widget and window sizes and
positions, coordinates in the "draw" event, etc) into the physical
pixels on the screen. This is handled more or less transparently,
except that one side effect is that your Cairo-based drawing code had
better be able to cope with that scaling without getting confused.
PuTTY's isn't, because we do all our serious drawing on a separate
Cairo surface we made ourselves, and then blit subrectangles of that
to the window during updates. This has two bad consequences. Firstly,
our surface has a size derived from what GTK told us the drawing area
size is, i.e. corresponding to GTK's _logical_ pixels, so when the
scale factor is (say) 2, our drawing takes place at half size and then
gets scaled up by the final blit in the draw event, making it look
blurry and unpleasant. Secondly, those final blits seem to end up
offset by half a pixel, so that a second blit over the same
subrectangle doesn't _quite_ completely wipe out the previously
blitted data - so there's a ghostly rectangle left behind everywhere
the cursor has been.
It's not that GTK doesn't _let_ you find out the scale factor; it's
just that it's in an out-of-the-way piece of API that you have to call
specially. So now we do: our backing surface is now created at a pixel
resolution matching the screen's real pixels, and we translate GTK's
scale factor into an ordinary cairo_scale() before we commence
drawing. So we still end up drawing the same text at the same size -
and this strategy also means that non-text elements like cursor
outlines and underlining will be scaled up with the screen DPI rather
than stubbornly staying one physical pixel thick - but now it's nice
and sharp at full screen resolution, and the subrectangle blits in the
draw event are back to affecting the exact set of pixels we expect
them to.
One silly consequence is that, immediately after removing the last
one, I've installed a handler for the GTK "configure-event" signal!
That's because the GTK 3 docs claim that that's how you get notified
that your scale factor has changed at run time (e.g. if you
reconfigure the scale factor of a whole monitor in the GNOME settings
dialog). Actually in practice I seem to find out via the "draw" event
before "configure" bothers to tell me, but now I've got a usefully
idempotent function for 'check whether the scale factor has changed
and sort it out if so', I don't see any harm in calling it from
anywhere it _might_ be useful.
I've been using that signal since the very first commit of this source
file, as a combined way to be notified when the size of the drawing
area changes (typically due to user window resizing actions) and also
when the drawing area is first created and available to be drawn on.
Unfortunately, testing on Ubuntu 18.04, I ran into an oddity, in which
the call to gtk_widget_show(inst->window) in new_session_window() has
the side effect of delivering a spurious configure_event on the
drawing area with size 1x46 pixels. This causes the terminal to resize
itself to 1 column wide, and the mistake isn't rectified until a
followup configure-event arrives after new_session_window returns to
the GTK main loop. But that means terminal output can occur between
those two configure events (the connection-sharing "Reusing a shared
connection to host.name" is a good example), and when it does, it gets
embarrassingly wrapped at one character per line down the left column.
I briefly tried to bodge around this by trying to heuristically guess
which configure events were real and which were spurious, but I have
no faith in that strategy continuing to work. I think a better
approach is to abandon configure-event completely, and move to a
system in which the two purposes I was using it for are handled by two
_different_ GTK signals, namely "size-allocate" (for knowing when we
get resized) and "realize" (for knowing when the drawing area
physically exists for us to start setting up Cairo or GDK machinery).
The result seems to have fixed the silly one-column wrapping bug, and
retained the ability to handle window resizes, on every GTK version I
have conveniently available to test on, including GTK 3 both before
and after these spurious configures started to happen.
GTK 3 PuTTY/pterm has always assumed that if it was compiled with
_support_ for talking to the raw X11 layer underneath GTK and GDK,
then it was entitled to expect that raw X11 layer to exist at all
times, i.e. that GDK_DISPLAY_XDISPLAY would return a meaningful X
display that it could do useful things with. So if you ran it over the
GDK Wayland backend, it would immediately segfault.
Modern GTK applications need to cope with multiple GDK backends at run
time. It's fine for GTK PuTTY to _contain_ the code to find and use
underlying X11 primitives like the display and the X window id, but it
should be prepared to find that it's running on Wayland (or something
else again!) so those functions don't return anything useful - in
which case it should degrade gracefully to the subset of functionality
that can be accessed through backend-independent GTK calls.
Accordingly, I've centralised the use of GDK_DISPLAY_XDISPLAY into a
support function get_x_display() in gtkmisc.c, which starts by
checking that there actually is one first. All previous direct uses of
GDK_*_XDISPLAY now go via that function, and check the result for NULL
afterwards. (To save faffing about calling that function too many
times, I'm also caching the display pointer in more places, and
passing it as an extra argument to various subfunctions, mostly in
gtkfont.c.)
Similarly, the get_windowid() function that retrieves the window id to
put in the environment of pterm's child process has to be prepared for
there not to be a window id.
This isn't a complete fix for all Wayland-related problems. The other
one I'm currently aware of is that the default font is "server:fixed",
which is a bad default now that it won't be available on all backends.
And I expect that further problems will show up with more testing. But
it's a start.
Colin Watson reports that on pre-releases of Ubuntu 18.04, configure
events which don't actually involve a change of window size show up
annoyingly often. Our handling of configure events involves throwing
away the backing Cairo surface, making a fresh blank one, and
scheduling a top-level callback to get terminal.c to do a repaint and
populate the new surface; so a draw event before that callback occurs
causes the window contents to flicker off and on again, not to mention
wasting a lot of time.
The simplest solution is to spot spurious configures, and respond by
not throwing away the previous Cairo surface in the first place.
Except in GTK1 (which doesn't have the former), via a gtkcompat.h
workaround.
Up-to-date GTK3 has deprecated gdk_beep(), causing build failures due
to the default -Werror setting.
Looks as if I haven't retried the GTK1 build for a while, and recent
GTK frontend development has broken it. The selection revamp has
pointed out that GTK1 didn't have the accessor function
gtk_selection_data_get_selection(), the standard GdkAtom value
GDK_SELECTION_CLIPBOARD, or keysyms for alphabetic characters; and
also I had an initialisation of one of my own structure fields
(dp->selparams) accidentally not guarded by the same GTK-versioning
ifdef that controls whether or not it was defined.
This still isn't complete: I also need to add the variable collections
of things like mid-session special commands and saved session names,
and also I need to try to grey out menu items when they're not
applicable. But it's a start.
Just to avoid an endless proliferation of functions too small to see,
I've arranged an enumeration of action ids and a single
app_menu_action function on the receiving end, and in gtkapp.c, a list
macro that means I at least don't have to define the tiny callback
functions and the GActionEntry records by hand and keep them in sync.
This fixes the problem I'd previously noticed, that if you don't
configure the "Command key acts as Meta" setting, then keystrokes like
Command-Q which _ought_ to function as accelerators for the
application menu bar don't.
Turns out that this was for the totally obvious reason: the keyboard
event was still being processed by gtkwin.c's key_event() and
translated via the GTK IM into ordinary keyboard input. If instead I
return FALSE from key_event on detecting that a key event has a
non-Meta-configured Command modifier, then it will go to the next-
level key-event handler inside GTK itself which implements the menu
accelerator behaviour. Another problem ticked off the OS X checklist.
The gtkapp.c menu now has a Copy as well as Paste option; those menu
items, as well as the corresponding ones on the context menu and Copy
All, now address sets of clipboards parametrised between OS X and
ordinary GTK in unix.h. Also I've tweaked the wording of the
context-menu items to not use the X-specific terminology "CLIPBOARD"
on OS X.
