Similar to the xterm AllowWindowOps option, this is an option to allow or
disallow certain (non-interactive) operations that can be insecure or
exploited.

NOTE: xsettitle() is not guarded by this because st does not support printing
the window title. Else this could be exploitable (arbitrary code execution).
Similar problems have been found in the past in other terminal emulators.

The sequence for base64-encoded clipboard copy is now guarded because it allows
a sequence written to the terminal to manipulate the clipboard of the running
user non-interactively, for example:

printf '\x1b]52;0;ZWNobyBoaQ0=\a'

St uses a very good hack where mouse wheel genereates ^Y and ^E,
that are the same keys that less and vi uses for backward and
fordward scrolling. Scroll, as many terminal emulators, use
shift+Prev/Next for scrolling, but it is also using ^E and ^Y
for scroling, characters that are reserved in the POSIX shell
in emacs mode for end of line and yanking, making scroll unsable
in st.

This patch adds a new hack, making shift+wheel returning the
same sequences than shift+Prev/Next, meaning that scroll or
any other similar program will not be able to differentiate
between them.

st could easily tear/flicker with animation or other unattended
output. This commit eliminates most of the tear/flicker.

Before this commit, the display timing had two "modes":

- Interactively, st was waiting fixed `1000/xfps` ms after forwarding
  the kb/mouse event to the application and before drawing.

- Unattended, and specifically with animations, the draw frequency was
  throttled to `actionfps`. Animation at a higher rate would throttle
  and likely tear, and at lower rates it was tearing big frames
  (specifically, when one `read` didn't get a full "frame").

The interactive behavior was decent, but it was impossible to get good
unattended-draw behavior even with carefully chosen configuration.

This commit changes the behavior such that it draws on idle instead of
using fixed latency/frequency. This means that it tries to draw only
when it's very likely that the application has completed its output
(or after some duration without idle), so it mostly succeeds to avoid
tear, flicker, and partial drawing.

The config values minlatency/maxlatency replace xfps/actionfps and
define the range which the algorithm is allowed to wait from the
initial draw-trigger until the actual draw. The range enables the
flexibility to choose when to draw - when least likely to flicker.

It also unifies the interactive and unattended behavior and config
values, which makes the code simpler as well - without sacrificing
latency during interactive use, because typically interactively idle
arrives very quickly, so the wait is typically minlatency.

While it only slighly improves interactive behavior, for animations
and other unattended-drawing it improves greatly, as it effectively
adapts to any [animation] output rate without tearing, throttling,
redundant drawing, or unnecessary delays (sounds impossible, but it
works).

Scroll is a program that stores all the lines of its child and be used in st as
a way of implementing scrollback.

This solution is much better than implementing the scrollback in st itself
because having a different program allows to use it in any other program
without doing modifications to those programs.

Because selpaste is activated on release, a release flag was added to
mouse shortcuts which controls whether activation is on press/release,
and selpaste binding to button2 was moved to config.h .

button1 remains the only hardcoded mouse button - for selection + copy.

Allow forceselmod to override all mouse shortcuts rather than only
selection, and rename it to forcemousemod as it's now more appropriate.

This will affect mouse shortcuts which use mask other than XK_ANY_MOD.

This does not affect the default behavior because the default mouse
shortcuts (wheel) use XK_ANY_MOD, where forceselmod already activated
the override also before this change.

Previously, if a mouse shortcut was configured with a specific mod and
forceselmod was held, then the shortcut did not execute unless the
configured mod included forceselmod.

Previously mouse shortcuts supported only ttywrite.

This required adding an "Arg" function ttysend - which does what the
original mouse shortcuts did.

this is not used anymore.

patch sent as an ed script using RFC2549 by k0ga.

"use iswspace()/iswpunct() to find word delimiters

    this inverts the configuration logic: you no longer provide a list of
    delimiters -- all space and punctuation characters are considered
    delimiters, unless listed in extrawordchars."

Feedback from IRC and personal preference.

This changes the selection more like xterm.
To test try: "find /" and select a path.

this inverts the configuration logic: you no longer provide a list of
delimiters -- all space and punctuation characters are considered
delimiters, unless listed in extrawordchars.

This was changed before in:
commit 20f713548d on Wed Jan 25 19:17:38 2017

And move it to the patches section.
Keeping it would force to add an exec pledge on OpenBSD, and some
people think it's bloated, so bye!

This reverts commit b51bcd5553.

Prefer passing arguments to declaring external global variables.  The
only remaining usage of extern is for config.h variables which are
needed in st.c instead of x.c (where it is now included).

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

This also allows us to remove the crlf field from the Key struct, since
the only difference it made was converting "\r" to "\r\n" (which is now
done automatically in ttywrite).  In addition, MODE_CRLF is no longer
referenced from x.c.

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

config.h includes references to KeySyms and other X stuff.  Until we
come up with a cleaner way to separate configuration, it is simpler
(leads to more code removal) to have this here.

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

Modifiers and keysyms are specific to X, and the functions match and
kmap are only used in x.c.  Needed to global-ize the key arrays and
lengths from config.h (for now).

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

This allows us to make xseturgency internal.

Signed-off-by: Devin J. Pohly <djpohly@gmail.com>

CTRL+SHIFT is an impossible combination in the terminal world
(0x20 | x & 0x1F), so it is perfect to be used for internals
shortcuts of terminals, and being a double combination
reduces the prossibility of having comflicts.

When using st with screen, I've bound next, prev, new screen to
combinations like Ctrl-Alt-Right,Left,Down; xterm and (u)rxvt work fine
when this combination of modifiers is pressed, st does not seem to
transport all of them; a single modifier key is fine (e.g. Ctrl-Up,
Alt-Down etc., but combinations are not). While I'm not terribly
familiar with this, I have tried to hack config.h in a more or less
systematic way to generate the expected sequences.

If fontconfig gives us a font without the attributes we asked for,
display an alternative color instead.

We launch dmenu for getting a codepoint, then convert it and send it to
the terminal.

If you don't make sure that the terminal does not expand tabs to spaces, of
course such a setting won't work.

st.info needs to be changed too, when tabspaces are changed.

The default config specifies BackSpace as "\177". The default behavior
should persist across modifier keys, commonly Mod1 (Alt or Meta) which
is widely used to delete a word on readline and text editors, notably
Emacs.

This will make Alt+BackSpace behaves as expected, i.e. sends "\033\177"
instead of "\033\010" as previous default behavior.

Signed-off-by: Christoph Lohmann <20h@r-36.net>

This fix is needed to use dual-width fonts, which have double-width
glyphs (e.g. CJK unified ideographs).

Signed-off-by: Ryusei Yamaguchi <mandel59@gmail.com>
Signed-off-by: Christoph Lohmann <20h@r-36.net>

Keep the debile happy.

»IBeam« is now »Bar« because it's named like that in the source code.

This adds an awareness commit for the big key array too.

The antialiasing was false due to circumstances that do not exist anymore. We
need antialiasing on big screens with big fonts. Autohinting too.

Signed-off-by: Christoph Lohmann <20h@r-36.net>