From 329bdb344c268f91ed726e000028cf52806ef5cb Mon Sep 17 00:00:00 2001
From: Simon Tatham <anakin@pobox.com>
Date: Sat, 8 May 2021 18:13:06 +0100
Subject: [PATCH] Make TermWin's palette_get_overrides() take a Terminal *.

Less than 12 hours after 0.75 went out of the door, a user pointed out
that enabling the 'Use system colours' config option causes an
immediate NULL-dereference crash. The reason is because a chain of
calls from term_init() ends up calling back to the Windows
implementation of the palette_get_overrides() method, which responds
by trying to call functions on the static variable 'term' in window.c,
which won't be initialised until term_init() has returned.

Simple fix: palette_get_overrides() is now given a pointer to the
Terminal that it should be updating, because it can't find it out any
other way.

(cherry picked from commit 571fa3388d61f3270d958503c62f09669665f6f8)
---
 fuzzterm.c       |  2 +-
 putty.h          | 14 ++++++++++----
 terminal.c       |  2 +-
 unix/gtkwin.c    |  2 +-
 windows/window.c |  4 ++--
 5 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/fuzzterm.c b/fuzzterm.c
index c5c29ef4..f53c0a9c 100644
--- a/fuzzterm.c
+++ b/fuzzterm.c
@@ -93,7 +93,7 @@ static void fuzz_move(TermWin *tw, int x, int y) {}
 static void fuzz_set_zorder(TermWin *tw, bool top) {}
 static void fuzz_palette_set(TermWin *tw, unsigned start, unsigned ncolours,
                              const rgb *colours) {}
-static void fuzz_palette_get_overrides(TermWin *tw) {}
+static void fuzz_palette_get_overrides(TermWin *tw, Terminal *term) {}
 
 static const TermWinVtable fuzz_termwin_vt = {
     .setup_draw_ctx = fuzz_setup_draw_ctx,
diff --git a/putty.h b/putty.h
index a73817af..6f1f914c 100644
--- a/putty.h
+++ b/putty.h
@@ -1299,8 +1299,14 @@ struct TermWinVtable {
 
     /* Query the front end for any OS-local overrides to the default
      * colours stored in Conf. The front end should set any it cares
-     * about by calling term_palette_override. */
-    void (*palette_get_overrides)(TermWin *);
+     * about by calling term_palette_override.
+     *
+     * The Terminal object is passed in as a parameter, because this
+     * can be called as a callback from term_init(). So the TermWin
+     * itself won't yet have been told where to find its Terminal
+     * object, because that doesn't happen until term_init
+     * returns. */
+    void (*palette_get_overrides)(TermWin *, Terminal *);
 };
 
 static inline bool win_setup_draw_ctx(TermWin *win)
@@ -1354,8 +1360,8 @@ static inline void win_set_zorder(TermWin *win, bool top)
 static inline void win_palette_set(
     TermWin *win, unsigned start, unsigned ncolours, const rgb *colours)
 { win->vt->palette_set(win, start, ncolours, colours); }
-static inline void win_palette_get_overrides(TermWin *win)
-{ win->vt->palette_get_overrides(win); }
+static inline void win_palette_get_overrides(TermWin *win, Terminal *term)
+{ win->vt->palette_get_overrides(win, term); }
 
 /*
  * Global functions not specific to a connection instance.
diff --git a/terminal.c b/terminal.c
index 0673623a..4bb47352 100644
--- a/terminal.c
+++ b/terminal.c
@@ -1874,7 +1874,7 @@ static void palette_reset(Terminal *term, bool overrides_only)
      */
     for (unsigned i = 0; i < OSC4_NCOLOURS; i++)
         term->subpalettes[SUBPAL_PLATFORM].present[i] = false;
-    win_palette_get_overrides(term->win);
+    win_palette_get_overrides(term->win, term);
 
     /*
      * Rebuild the composite palette.
diff --git a/unix/gtkwin.c b/unix/gtkwin.c
index 2a2353d4..61e77187 100644
--- a/unix/gtkwin.c
+++ b/unix/gtkwin.c
@@ -2614,7 +2614,7 @@ static void gtkwin_palette_set(TermWin *tw, unsigned start, unsigned ncolours,
     }
 }
 
-static void gtkwin_palette_get_overrides(TermWin *tw)
+static void gtkwin_palette_get_overrides(TermWin *tw, Terminal *term)
 {
     /* GTK has no analogue of Windows's 'standard system colours', so GTK PuTTY
      * has no config option to override the normally configured colours from
diff --git a/windows/window.c b/windows/window.c
index 091838b4..ccf7b259 100644
--- a/windows/window.c
+++ b/windows/window.c
@@ -263,7 +263,7 @@ static void wintw_set_maximised(TermWin *, bool maximised);
 static void wintw_move(TermWin *, int x, int y);
 static void wintw_set_zorder(TermWin *, bool top);
 static void wintw_palette_set(TermWin *, unsigned, unsigned, const rgb *);
-static void wintw_palette_get_overrides(TermWin *);
+static void wintw_palette_get_overrides(TermWin *, Terminal *);
 
 static const TermWinVtable windows_termwin_vt = {
     .setup_draw_ctx = wintw_setup_draw_ctx,
@@ -1214,7 +1214,7 @@ static inline rgb rgb_from_colorref(COLORREF cr)
     return toret;
 }
 
-static void wintw_palette_get_overrides(TermWin *tw)
+static void wintw_palette_get_overrides(TermWin *tw, Terminal *term)
 {
     if (conf_get_bool(conf, CONF_system_colour)) {
         rgb rgb;