toplevel-icon: implement OSC-1, CSI 20/21/22/23 t

* The toplevel icon is now set to the app-id, unless "overridden" by
  OSC-1 or OSC-0.
* Implemented OSC-1
* OSC-0 extended to also set the icon
* Implemented CSI 20 t - report window icon
* Implemented CSI 21 t - report window title
* Implemented CSI 22 ; 1 t - push window icon
* Implemented CS 23 ; 1 t - pop window icon
* Extended CSI 22/23 ; 0 t to also push/pop the icon
* Verify app-id set by OSC-176 is valid UTF-8
* Verify icon set by OSC-0/1 is valid UTF-8

CHANGELOG.md

@@ -62,6 +62,11 @@
   ([#1807][1807]).
 * `strikeout-thickness` option.
 * Implemented the new `xdg-toplevel-icon-v1` protocol.
+* Implemented `CSI 20 t`: report window icon.
+* Implemented `CSI 21 t`: report window title.
+* Implemented `CSI 22 ; 1 t`: push window icon.
+* Implemented `CSI 23 ; 1 t`: pop window icon.
+* Implemented `OSC 1`: set window icon.
 
 [1807]: https://codeberg.org/dnkl/foot/issues/1807
 

csi.c

@@ -1249,8 +1249,6 @@ csi_dispatch(struct terminal *term, uint8_t final)
             case 8: LOG_WARN("unimplemented: resize window in chars"); break;
             case 9: LOG_WARN("unimplemented: maximize/unmaximize window"); break;
             case 10: LOG_WARN("unimplemented: to/from full screen"); break;
-            case 20: LOG_WARN("unimplemented: report icon label"); break;
-            case 21: LOG_WARN("unimplemented: report window title"); break;
             case 24: LOG_WARN("unimplemented: resize window (DECSLPP)"); break;
 
             case 11:   /* report if window is iconified */
@@ -1354,6 +1352,24 @@ csi_dispatch(struct terminal *term, uint8_t final)
                 break;
             }
 
+            case 20: {
+                const char *icon = term_icon(term);
+
+                char reply[3 + strlen(icon) + 2 + 1];
+                int chars = xsnprintf(
+                    reply, sizeof(reply), "\033]L%s\033\\", icon);
+                term_to_slave(term, reply, chars);
+                break;
+            }
+
+            case 21: {
+                char reply[3 + strlen(term->window_title) + 2 + 1];
+                int chars = xsnprintf(
+                    reply, sizeof(reply), "\033]l%s\033\\", term->window_title);
+                term_to_slave(term, reply, chars);
+                break;
+            }
+
             case 22: { /* push window title */
                 /* 0 - icon + title, 1 - icon, 2 - title */
                 unsigned what = vt_param_get(term, 1, 0);
@@ -1361,6 +1377,10 @@ csi_dispatch(struct terminal *term, uint8_t final)
                     tll_push_back(
                         term->window_title_stack, xstrdup(term->window_title));
                 }
+                if (what == 0 || what == 1) {
+                    tll_push_back(
+                        term->window_icon_stack, xstrdup(term->window_icon));
+                }
                 break;
             }
 
@@ -1374,6 +1394,13 @@ csi_dispatch(struct terminal *term, uint8_t final)
                         free(title);
                     }
                 }
+                if (what == 0 || what == 1) {
+                    if (tll_length(term->window_icon_stack) > 0) {
+                        char *icon = tll_pop_back(term->window_icon_stack);
+                        term_set_icon(term, icon);
+                        free(icon);
+                    }
+                }
                 break;
             }
 

doc/foot-ctlseqs.7.scd

@@ -388,15 +388,27 @@ manipulation sequences. The generic format is:
 |  19
 :  -
 :  Report screen size, in characters.
+|  20
+:  -
+:  Report icon label.
+|  21
+:  -
+:  Report window title.
 |  22
 :  -
-:  Push window title+icon. Foot does not support pushing the icon.
+:  Push window title+icon.
+|  22
+:  1
+:  Push window icon.
 |  22
 :  2
 :  Push window title.
 |  23
 :  -
-:  Pop window title+icon. Foot does not support popping the icon.
+:  Pop window title+icon.
+|  23
+:  1
+:  Pop window icon.
 |  23
 :  2
 :  Pop window title.
@@ -659,8 +671,10 @@ All _OSC_ sequences begin with *\\E]*, sometimes abbreviated _OSC_.
 :< *Description*
 |  \\E] 0 ; _Pt_ \\E\\ 
 :  xterm
-:  Set window icon and title to _Pt_ (foot does not support setting the
+:  Set window icon and title to _Pt_.
-   icon)
+|  \\E] 1 ; _Pt_ \\E\\ 
+:  xterm
+:  Set window icon to _Pt_.
 |  \\E] 2 ; _Pt_ \\E\\ 
 :  xterm
 :  Set window title to _Pt_

misc.c

@@ -42,3 +42,10 @@ timespec_sub(const struct timespec *a, const struct timespec *b,
         res->tv_nsec += one_sec_in_ns;
     }
 }
+
+bool
+is_valid_utf8(const char *value)
+{
+    return value != NULL &&
+           mbsntoc32(NULL, value, strlen(value), 0) != (size_t)-1;
+}

misc.h

@@ -8,3 +8,5 @@ bool isword(char32_t wc, bool spaces_only, const char32_t *delimiters);
 
 void timespec_add(const struct timespec *a, const struct timespec *b, struct timespec *res);
 void timespec_sub(const struct timespec *a, const struct timespec *b, struct timespec *res);
+
+bool is_valid_utf8(const char *value);

osc.c

@@ -1145,9 +1145,18 @@ osc_dispatch(struct terminal *term)
     char *string = (char *)&term->vt.osc.data[data_ofs];
 
     switch (param) {
-    case 0: term_set_window_title(term, string); break;  /* icon + title */
+    case 0:  /* icon + title */
-    case 1: break;                                       /* icon */
+        term_set_window_title(term, string);
-    case 2: term_set_window_title(term, string); break;  /* title */
+        term_set_icon(term, string);
+        break;
+
+    case 1:  /* icon */
+        term_set_icon(term, string);
+        break;
+
+    case 2:  /* title */
+        term_set_window_title(term, string);
+        break;
 
     case 4: {
         /* Set color<idx> */

render.c

@@ -12,15 +12,19 @@
 
 #include "macros.h"
 #if HAS_INCLUDE(<pthread_np.h>)
-#include <pthread_np.h>
+ #include <pthread_np.h>
-#define pthread_setname_np(thread, name) (pthread_set_name_np(thread, name), 0)
+ #define pthread_setname_np(thread, name) (pthread_set_name_np(thread, name), 0)
 #elif defined(__NetBSD__)
-#define pthread_setname_np(thread, name) pthread_setname_np(thread, "%s", (void *)name)
+ #define pthread_setname_np(thread, name) pthread_setname_np(thread, "%s", (void *)name)
 #endif
 
+#include <presentation-time.h>
 #include <wayland-cursor.h>
 #include <xdg-shell.h>
-#include <presentation-time.h>
+
+#if defined(HAVE_XDG_TOPLEVEL_ICON)
+#include <xdg-toplevel-icon-v1.h>
+#endif
 
 #include <fcft/fcft.h>
 
@@ -4951,26 +4955,49 @@ render_refresh_app_id(struct terminal *term)
         term->app_id != NULL ? term->app_id : term->conf->app_id;
 
     xdg_toplevel_set_app_id(term->window->xdg_toplevel, app_id);
-
-#if defined(HAVE_XDG_TOPLEVEL_ICON)
-    if (term->wl->toplevel_icon_manager != NULL) {
-        struct xdg_toplevel_icon_v1 *icon =
-            xdg_toplevel_icon_manager_v1_create_icon(
-                term->wl->toplevel_icon_manager);
-
-        xdg_toplevel_icon_v1_set_name(
-            icon, streq(app_id, "footclient") ? "foot" : app_id);
-
-        xdg_toplevel_icon_manager_v1_set_icon(
-            term->wl->toplevel_icon_manager, term->window->xdg_toplevel, icon);
-
-        xdg_toplevel_icon_v1_destroy(icon);
-    }
-#endif
-
     term->render.app_id.last_update = now;
 }
 
+void
+render_refresh_icon(struct terminal *term)
+{
+#if defined(HAVE_XDG_TOPLEVEL_ICON)
+    if (term->wl->toplevel_icon_manager == NULL) {
+        LOG_DBG("compositor does not implement xdg-toplevel-icon: "
+                "ignoring request to refresh window icon");
+        return;
+    }
+
+    struct timespec now;
+    if (clock_gettime(CLOCK_MONOTONIC, &now) < 0)
+        return;
+
+    struct timespec diff;
+    timespec_sub(&now, &term->render.icon.last_update, &diff);
+
+    if (diff.tv_sec == 0 && diff.tv_nsec < 8333 * 1000) {
+        const struct itimerspec timeout = {
+            .it_value = {.tv_nsec = 8333 * 1000 - diff.tv_nsec},
+        };
+
+        timerfd_settime(term->render.icon.timer_fd, 0, &timeout, NULL);
+        return;
+    }
+
+    const char *icon_name = term_icon(term);
+    LOG_DBG("setting toplevel icon: %s", icon_name);
+
+    struct xdg_toplevel_icon_v1 *icon =
+        xdg_toplevel_icon_manager_v1_create_icon(term->wl->toplevel_icon_manager);
+    xdg_toplevel_icon_v1_set_name(icon, icon_name);
+    xdg_toplevel_icon_manager_v1_set_icon(
+        term->wl->toplevel_icon_manager, term->window->xdg_toplevel, icon);
+    xdg_toplevel_icon_v1_destroy(icon);
+
+    term->render.icon.last_update = now;
+#endif
+}
+
 void
 render_refresh(struct terminal *term)
 {

render.h

@@ -22,6 +22,7 @@ bool render_resize(
 
 void render_refresh(struct terminal *term);
 void render_refresh_app_id(struct terminal *term);
+void render_refresh_icon(struct terminal *term);
 void render_refresh_csd(struct terminal *term);
 void render_refresh_search(struct terminal *term);
 void render_refresh_title(struct terminal *term);

terminal.c

@@ -639,6 +639,30 @@ fdm_title_update_timeout(struct fdm *fdm, int fd, int events, void *data)
     return true;
 }
 
+static bool
+fdm_icon_update_timeout(struct fdm *fdm, int fd, int events, void *data)
+{
+    if (events & EPOLLHUP)
+        return false;
+
+    struct terminal *term = data;
+    uint64_t unused;
+    ssize_t ret = read(term->render.icon.timer_fd, &unused, sizeof(unused));
+
+    if (ret < 0) {
+        if (errno == EAGAIN)
+            return true;
+        LOG_ERRNO("failed to read icon update throttle timer");
+        return false;
+    }
+
+    struct itimerspec reset = {{0}};
+    timerfd_settime(term->render.icon.timer_fd, 0, &reset, NULL);
+
+    render_refresh_icon(term);
+    return true;
+}
+
 static bool
 fdm_app_id_update_timeout(struct fdm *fdm, int fd, int events, void *data)
 {
@@ -1114,6 +1138,7 @@ term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
     int delay_upper_fd = -1;
     int app_sync_updates_fd = -1;
     int title_update_fd = -1;
+    int icon_update_fd = -1;
     int app_id_update_fd = -1;
 
     struct terminal *term = malloc(sizeof(*term));
@@ -1150,6 +1175,12 @@ term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
         goto close_fds;
     }
 
+    if ((icon_update_fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK)) < 0)
+    {
+        LOG_ERRNO("failed to create icon update throttle timer FD");
+        goto close_fds;
+    }
+
     if ((app_id_update_fd = timerfd_create(CLOCK_MONOTONIC, TFD_CLOEXEC | TFD_NONBLOCK)) < 0)
     {
         LOG_ERRNO("failed to create app ID update throttle timer FD");
@@ -1187,6 +1218,7 @@ term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
         !fdm_add(fdm, delay_upper_fd, EPOLLIN, &fdm_delayed_render, term) ||
         !fdm_add(fdm, app_sync_updates_fd, EPOLLIN, &fdm_app_sync_updates_timeout, term) ||
         !fdm_add(fdm, title_update_fd, EPOLLIN, &fdm_title_update_timeout, term) ||
+        !fdm_add(fdm, icon_update_fd, EPOLLIN, &fdm_icon_update_timeout, term) ||
         !fdm_add(fdm, app_id_update_fd, EPOLLIN, &fdm_app_id_update_timeout, term))
     {
         goto err;
@@ -1288,6 +1320,9 @@ term_init(const struct config *conf, struct fdm *fdm, struct reaper *reaper,
             .title = {
                 .timer_fd = title_update_fd,
             },
+            .icon = {
+                .timer_fd = icon_update_fd,
+            },
             .app_id = {
                 .timer_fd = app_id_update_fd,
             },
@@ -1406,6 +1441,7 @@ close_fds:
     fdm_del(fdm, delay_upper_fd);
     fdm_del(fdm, app_sync_updates_fd);
     fdm_del(fdm, title_update_fd);
+    fdm_del(fdm, icon_update_fd);
     fdm_del(fdm, app_id_update_fd);
 
     free(term);
@@ -1626,6 +1662,7 @@ term_shutdown(struct terminal *term)
     fdm_del(term->fdm, term->selection.auto_scroll.fd);
     fdm_del(term->fdm, term->render.app_sync_updates.timer_fd);
     fdm_del(term->fdm, term->render.app_id.timer_fd);
+    fdm_del(term->fdm, term->render.icon.timer_fd);
     fdm_del(term->fdm, term->render.title.timer_fd);
     fdm_del(term->fdm, term->delayed_render_timer.lower_fd);
     fdm_del(term->fdm, term->delayed_render_timer.upper_fd);
@@ -1677,6 +1714,7 @@ term_shutdown(struct terminal *term)
     term->selection.auto_scroll.fd = -1;
     term->render.app_sync_updates.timer_fd = -1;
     term->render.app_id.timer_fd = -1;
+    term->render.icon.timer_fd = -1;
     term->render.title.timer_fd = -1;
     term->delayed_render_timer.lower_fd = -1;
     term->delayed_render_timer.upper_fd = -1;
@@ -1731,6 +1769,7 @@ term_destroy(struct terminal *term)
     fdm_del(term->fdm, term->selection.auto_scroll.fd);
     fdm_del(term->fdm, term->render.app_sync_updates.timer_fd);
     fdm_del(term->fdm, term->render.app_id.timer_fd);
+    fdm_del(term->fdm, term->render.icon.timer_fd);
     fdm_del(term->fdm, term->render.title.timer_fd);
     fdm_del(term->fdm, term->delayed_render_timer.lower_fd);
     fdm_del(term->fdm, term->delayed_render_timer.upper_fd);
@@ -1775,7 +1814,9 @@ term_destroy(struct terminal *term)
     composed_free(term->composed);
 
     free(term->app_id);
+    free(term->window_icon);
     free(term->window_title);
+    tll_free_and_free(term->window_icon_stack, free);
     tll_free_and_free(term->window_title_stack, free);
 
     for (size_t i = 0; i < sizeof(term->fonts) / sizeof(term->fonts[0]); i++)
@@ -2007,6 +2048,9 @@ term_reset(struct terminal *term, bool hard)
     term->saved_charsets = term->charsets;
     tll_free_and_free(term->window_title_stack, free);
     term_set_window_title(term, term->conf->title);
+    tll_free_and_free(term->window_icon_stack, free);
+    term_set_app_id(term, NULL);
+    term_set_icon(term, NULL);
 
     term_set_user_mouse_cursor(term, NULL);
 
@@ -3528,7 +3572,7 @@ term_set_window_title(struct terminal *term, const char *title)
     if (term->window_title != NULL && streq(term->window_title, title))
         return;
 
-    if (mbsntoc32(NULL, title, strlen(title), 0) == (size_t)-1) {
+    if (!is_valid_utf8(title)) {
         /* It's an xdg_toplevel::set_title() protocol violation to set
            a title with an invalid UTF-8 sequence */
         LOG_WARN("%s: title is not valid UTF-8, ignoring", title);
@@ -3548,9 +3592,14 @@ term_set_app_id(struct terminal *term, const char *app_id)
         app_id = NULL;
     if (term->app_id == NULL && app_id == NULL)
         return;
-    if (term->app_id != NULL && app_id != NULL && strcmp(term->app_id, app_id) == 0)
+    if (term->app_id != NULL && app_id != NULL && streq(term->app_id, app_id))
         return;
 
+    if (app_id != NULL && !is_valid_utf8(app_id)) {
+        LOG_WARN("%s: app-id is not valid UTF-8, ignoring", app_id);
+        return;
+    }
+
     free(term->app_id);
     if (app_id != NULL) {
         term->app_id = xstrdup(app_id);
@@ -3558,6 +3607,44 @@ term_set_app_id(struct terminal *term, const char *app_id)
         term->app_id = NULL;
     }
     render_refresh_app_id(term);
+    render_refresh_icon(term);
+}
+
+void
+term_set_icon(struct terminal *term, const char *icon)
+{
+    if (icon != NULL && *icon == '\0')
+        icon = NULL;
+    if (term->window_icon == NULL && icon == NULL)
+        return;
+    if (term->window_icon != NULL && icon != NULL && streq(term->window_icon, icon))
+        return;
+
+    if (icon != NULL && !is_valid_utf8(icon)) {
+        LOG_WARN("%s: icon label is not valid UTF-8, ignoring", icon);
+        return;
+    }
+
+    free(term->window_icon);
+    if (icon != NULL) {
+        term->window_icon = xstrdup(icon);
+    } else {
+        term->window_icon = NULL;
+    }
+    render_refresh_icon(term);
+}
+
+const char *
+term_icon(const struct terminal *term)
+{
+    const char *app_id =
+        term->app_id != NULL ? term->app_id : term->conf->app_id;
+
+    return term->window_icon != NULL
+        ? term->window_icon
+        : streq(app_id, "footclient")
+            ? "foot"
+            : app_id;
 }
 
 void

terminal.h

@@ -552,6 +552,8 @@ struct terminal {
     bool window_title_has_been_set;
     char *window_title;
     tll(char *) window_title_stack;
+    char *window_icon;
+    tll(char *)window_icon_stack;
     char *app_id;
 
     struct {
@@ -670,6 +672,11 @@ struct terminal {
             int timer_fd;
         } title;
 
+        struct {
+            struct timespec last_update;
+            int timer_fd;
+        } icon;
+
         struct {
             struct timespec last_update;
             int timer_fd;
@@ -925,6 +932,8 @@ void term_set_user_mouse_cursor(struct terminal *term, const char *cursor);
 
 void term_set_window_title(struct terminal *term, const char *title);
 void term_set_app_id(struct terminal *term, const char *app_id);
+void term_set_icon(struct terminal *term, const char *icon);
+const char *term_icon(const struct terminal *term);
 void term_flash(struct terminal *term, unsigned duration_ms);
 void term_bell(struct terminal *term);
 bool term_spawn_new(const struct terminal *term);