Fix cursor position after zero width space, GitHub issue 3469.

diff --git a/usr.bin/tmux/screen-write.c b/usr.bin/tmux/screen-write.c
index 99da665..945f454 100644 (file)
--- a/usr.bin/tmux/screen-write.c
+++ b/usr.bin/tmux/screen-write.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: screen-write.c,v 1.212 2022/12/16 08:19:58 nicm Exp $ */
+/* $OpenBSD: screen-write.c,v 1.213 2023/02/10 14:01:43 nicm Exp $ */
 
 /*
  * Copyright (c) 2007 Nicholas Marriott <nicholas.marriott@gmail.com>
@@ -34,7 +34,7 @@ static void   screen_write_collect_flush(struct screen_write_ctx *, int,
 static int     screen_write_overwrite(struct screen_write_ctx *,
                    struct grid_cell *, u_int);
 static const struct grid_cell *screen_write_combine(struct screen_write_ctx *,
-                   const struct utf8_data *, u_int *);
+                   const struct utf8_data *, u_int *, u_int *);
 
 struct screen_write_citem {
        u_int                           x;
@@ -1820,7 +1820,7 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
        struct grid_cell         tmp_gc, now_gc;
        struct tty_ctx           ttyctx;
        u_int                    sx = screen_size_x(s), sy = screen_size_y(s);
-       u_int                    width = gc->data.width, xx, last, cy;
+       u_int                    width = gc->data.width, xx, last, cx, cy;
        int                      selected, skip = 1;
 
        /* Ignore padding cells. */
@@ -1847,18 +1847,18 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
         */
        if (ctx->flags & SCREEN_WRITE_ZWJ) {
                screen_write_collect_flush(ctx, 0, __func__);
-               screen_write_combine(ctx, &zwj, &xx);
+               screen_write_combine(ctx, &zwj, &xx, &cx);
        }
        if (width == 0 || (ctx->flags & SCREEN_WRITE_ZWJ)) {
                ctx->flags &= ~SCREEN_WRITE_ZWJ;
                screen_write_collect_flush(ctx, 0, __func__);
-               if ((gc = screen_write_combine(ctx, ud, &xx)) != NULL) {
+               if ((gc = screen_write_combine(ctx, ud, &xx, &cx)) != NULL) {
                        cy = s->cy;
                        screen_write_set_cursor(ctx, xx, s->cy);
                        screen_write_initctx(ctx, &ttyctx, 0);
                        ttyctx.cell = gc;
                        tty_write(tty_cmd_cell, &ttyctx);
-                       s->cx = xx + 1 + gc->data.width; s->cy = cy;
+                       s->cx = cx; s->cy = cy;
                }
                return;
        }
@@ -1980,16 +1980,19 @@ screen_write_cell(struct screen_write_ctx *ctx, const struct grid_cell *gc)
 /* Combine a UTF-8 zero-width character onto the previous. */
 static const struct grid_cell *
 screen_write_combine(struct screen_write_ctx *ctx, const struct utf8_data *ud,
-    u_int *xx)
+    u_int *xx, u_int *cx)
 {
        struct screen           *s = ctx->s;
        struct grid             *gd = s->grid;
        static struct grid_cell  gc;
-       u_int                    n;
+       u_int                    n, width;
 
        /* Can't combine if at 0. */
-       if (s->cx == 0)
+       if (s->cx == 0) {
+               *xx = 0;
                return (NULL);
+       }
+       *xx = s->cx;
 
        /* Empty data is out. */
        if (ud->size == 0)
@@ -2003,30 +2006,35 @@ screen_write_combine(struct screen_write_ctx *ctx, const struct utf8_data *ud,
        }
        if (n > s->cx)
                return (NULL);
-       *xx = s->cx - n;
 
        /* Check there is enough space. */
        if (gc.data.size + ud->size > sizeof gc.data.data)
                return (NULL);
+       (*xx) -= n;
 
-       log_debug("%s: %.*s onto %.*s at %u,%u", __func__, (int)ud->size,
-           ud->data, (int)gc.data.size, gc.data.data, *xx, s->cy);
+       log_debug("%s: %.*s onto %.*s at %u,%u (width %u)", __func__,
+           (int)ud->size, ud->data, (int)gc.data.size, gc.data.data, *xx,
+           s->cy, gc.data.width);
 
        /* Append the data. */
        memcpy(gc.data.data + gc.data.size, ud->data, ud->size);
        gc.data.size += ud->size;
+       width = gc.data.width;
 
        /* If this is U+FE0F VARIATION SELECTOR-16, force the width to 2. */
        if (gc.data.width == 1 &&
-               ud->size == 3 &&
-               memcmp(ud->data, "\357\270\217", 3) == 0) {
+           ud->size == 3 &&
+           memcmp(ud->data, "\357\270\217", 3) == 0) {
                grid_view_set_padding(gd, (*xx) + 1, s->cy);
                gc.data.width = 2;
+               width += 2;
        }
 
        /* Set the new cell. */
        grid_view_set_cell(gd, *xx, s->cy, &gc);
 
+       *cx = (*xx) + width;
+       log_debug("%s: character at %u; cursor at %u", __func__, *xx, *cx);
        return (&gc);
 }