[binutils-gdb] gdb/tui: fix unexpected reuse of color pairs

https://sourceware.org/git/gitweb.cgi?p=3Dbinutils-gdb.git;h=3Dfbe7f20a0f09=
8ca03913452b29f50f0dc8568f77

commit fbe7f20a0f098ca03913452b29f50f0dc8568f77
Author: Jakob Sch=C3=A4ffeler <[email protected]>
Date:   Sat May 9 23:27:43 2026 +0200

    gdb/tui: fix unexpected reuse of color pairs
   =20
    TUI translates ANSI styling sequences to curses color pairs.
    Currently, this process uses COLOR_PAIR, which only returns values
    from 0 to 255 which results in unexpected reuse of color pairs.
   =20
    Replacing wattron/wattroff with wcolor_set avoids the 256 color pair
    limit imposed by the COLOR_PAIR macro.  However, wcolor_set takes a
    short for the pair index, limiting pairs to SHRT_MAX.
   =20
    To support the full range of COLOR_PAIRS (up to 65536 with ncurses
    6.1+), init_pair is replaced with init_extended_pair, and the pair
    index is passed to wcolor_set via the opts parameter as an extended
    color pair, a documented ncurses extension.
   =20
    This also results in last_color_pair no longer being needed, and so it
    is removed.
   =20
    The extended color pair extension requires ncurses 6.1+, so a
    configure check has been added.  The fallback path uses the older
    color pair API which limits GDB to SHRT_MAX (32767) color pairs.
   =20
    This patch was tested with make check-gdb TESTS=3D"gdb.tui/*.exp"
    Additionally, I tested this with the python extension from the bug
    report.
   =20
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=3D34134
   =20
    Approved-By: Andrew Burgess <[email protected]>

Diff:
---
 gdb/config.in    |  3 +++
 gdb/configure    |  1 +
 gdb/configure.ac |  1 +
 gdb/tui/tui-io.c | 23 +++++++++++------------
 4 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/gdb/config.in b/gdb/config.in
index 73d0b1913ce..1ef5dc5c2f4 100644
--- a/gdb/config.in
+++ b/gdb/config.in
@@ -250,6 +250,9 @@
 /* Define to 1 if you have the `iconvlist' function. */
 #undef HAVE_ICONVLIST
=20
+/* Define to 1 if you have the `init_extended_pair' function. */
+#undef HAVE_INIT_EXTENDED_PAIR
+
 /* Define to 1 if you have the <inttypes.h> header file. */
 #undef HAVE_INTTYPES_H
=20
diff --git a/gdb/configure b/gdb/configure
index 3733ef76948..303d6ea011c 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -30238,6 +30238,7 @@ for ac_func in  \
   getrlimit \
   getuid \
   iconvlist \
+  init_extended_pair \
   libiconvlist \
   posix_madvise \
   pread \
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 5296d76f2cf..e55a733fba7 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1520,6 +1520,7 @@ AC_CHECK_FUNCS([ \
   getrlimit \
   getuid \
   iconvlist \
+  init_extended_pair \
   libiconvlist \
   posix_madvise \
   pread \
diff --git a/gdb/tui/tui-io.c b/gdb/tui/tui-io.c
index 642b88ead0c..896d00f44c8 100644
--- a/gdb/tui/tui-io.c
+++ b/gdb/tui/tui-io.c
@@ -265,10 +265,6 @@ get_color (const ui_file_style::color &color, int *res=
ult)
   return true;
 }
=20
-/* The most recently emitted color pair.  */
-
-static int last_color_pair =3D -1;
-
 /* The most recently applied style.  */
=20
 static ui_file_style last_style;
@@ -299,7 +295,11 @@ get_color_pair (int fg, int bg)
 	 back to the default if we've used too many.  */
       if (next >=3D COLOR_PAIRS)
 	return 0;
+#ifdef HAVE_INIT_EXTENDED_PAIR
+      init_extended_pair (next, fg, bg);
+#else
       init_pair (next, fg, bg);
+#endif
       color_pair_map[c] =3D next;
       return next;
     }
@@ -320,9 +320,8 @@ tui_apply_style (WINDOW *w, ui_file_style style)
 #endif
   wattroff (w, A_UNDERLINE);
   wattroff (w, A_REVERSE);
-  if (last_color_pair !=3D -1)
-    wattroff (w, COLOR_PAIR (last_color_pair));
-  wattron (w, COLOR_PAIR (0));
+
+  wcolor_set (w, 0, nullptr);
=20
   const ui_file_style::color &fg =3D style.get_foreground ();
   const ui_file_style::color &bg =3D style.get_background ();
@@ -342,10 +341,11 @@ tui_apply_style (WINDOW *w, ui_file_style style)
 	    bgi =3D (ncurses_norm_attr >> 4) & 15;
 #endif
 	  int pair =3D get_color_pair (fgi, bgi);
-	  if (last_color_pair !=3D -1)
-	    wattroff (w, COLOR_PAIR (last_color_pair));
-	  wattron (w, COLOR_PAIR (pair));
-	  last_color_pair =3D pair;
+#ifdef HAVE_INIT_EXTENDED_PAIR
+	  wcolor_set (w, 0, &pair);
+#else
+	  wcolor_set (w, pair, nullptr);
+#endif
 	}
     }
=20
@@ -907,7 +907,6 @@ tui_setup_io (int mode)
       savetty ();
=20
       /* Clean up color information.  */
-      last_color_pair =3D -1;
       last_style =3D ui_file_style ();
       color_map.clear ();
       color_pair_map.clear ();