sd-terminal: save cursor settings per-page rather than per-screenterminal

This is how xterm works:
<http://invisible-island.net/xterm/xterm.log.html#xterm_90>.

2 files changed, 64 insertions, 51 deletions

diff --git a/src/libsystemd-terminal/term-internal.h b/src/libsystemd-terminal/term-internal.h
index f0f4432c8..c5e0be6b7 100644
--- a/src/libsystemd-terminal/term-internal.h
+++ b/src/libsystemd-terminal/term-internal.h
@@ -600,6 +600,17 @@ enum {
         TERM_CONFORMANCE_LEVEL_CNT,
 };
 
+struct term_cursor {
+        unsigned int cursor_x;
+        unsigned int cursor_y;
+        term_attr attr;
+        term_charset **gl;
+        term_charset **gr;
+        term_charset **glt;
+        term_charset **grt;
+        unsigned int flags;
+};
+
 struct term_screen {
         unsigned long ref;
         term_age_t age;
@@ -621,32 +632,26 @@ struct term_screen {
         term_screen_cmd_fn cmd_fn;
         void *cmd_fn_data;
 
-        unsigned int flags;
         unsigned int conformance_level;
+        term_attr default_attr;
+
+        term_charset *g0;
+        term_charset *g1;
+        term_charset *g2;
+        term_charset *g3;
+
         unsigned int cursor_x;
         unsigned int cursor_y;
         term_attr attr;
-        term_attr default_attr;
-
         term_charset **gl;
         term_charset **gr;
         term_charset **glt;
         term_charset **grt;
-        term_charset *g0;
-        term_charset *g1;
-        term_charset *g2;
-        term_charset *g3;
+        unsigned int flags;
 
-        char *answerback;
+        struct term_cursor *saved;
+        struct term_cursor saved_main;
+        struct term_cursor saved_alt;
 
-        struct {
-                unsigned int cursor_x;
-                unsigned int cursor_y;
-                term_attr attr;
-                term_charset **gl;
-                term_charset **gr;
-                term_charset **glt;
-                term_charset **grt;
-                unsigned int flags;
-        } saved;
+        char *answerback;
 };
diff --git a/src/libsystemd-terminal/term-screen.c b/src/libsystemd-terminal/term-screen.c
index ec6c14d98..3aeb6ed39 100644
--- a/src/libsystemd-terminal/term-screen.c
+++ b/src/libsystemd-terminal/term-screen.c
@@ -77,11 +77,13 @@ int term_screen_new(term_screen **out, term_screen_write_fn write_fn, void *writ
         screen->g2 = &term_unicode_lower;
         screen->g3 = &term_unicode_upper;
 
-        screen->saved.cursor_x = 0;
-        screen->saved.cursor_y = 0;
-        screen->saved.attr = screen->attr;
-        screen->saved.gl = screen->gl;
-        screen->saved.gr = screen->gr;
+        screen->saved_main.cursor_x = 0;
+        screen->saved_main.cursor_y = 0;
+        screen->saved_main.attr = screen->attr;
+        screen->saved_main.gl = screen->gl;
+        screen->saved_main.gr = screen->gr;
+
+        screen->saved_alt = screen->saved_main;
 
         r = term_page_new(&screen->page_main);
         if (r < 0)
@@ -101,6 +103,7 @@ int term_screen_new(term_screen **out, term_screen_write_fn write_fn, void *writ
 
         screen->page = screen->page_main;
         screen->history = screen->history_main;
+        screen->saved = &screen->saved_main;
 
         *out = screen;
         screen = NULL;
@@ -374,6 +377,11 @@ static int screen_DECSC(term_screen *screen, const term_seq *seq);
 static int screen_DECRC(term_screen *screen, const term_seq *seq);
 
 static inline void screen_clear_alt(term_screen *screen) {
+        zero(screen->saved_alt);
+        screen->saved_main.attr = screen->attr;
+        screen->saved_main.gl = screen->gl;
+        screen->saved_main.gr = screen->gr;
+
         term_page_set_scroll_region(screen->page_alt, 0, screen->page->height);
         term_page_erase(screen->page_alt, 0, 0, screen->page->width, screen->page->height, &screen->attr, screen->age, false);
 }
@@ -460,24 +468,23 @@ static void screen_mode_change(term_screen *screen, unsigned int mode, bool dec,
         case 1048:
                 if (dec) {
                         if (set)
-                                screen_DECSC(screen, seq);
+                                screen_DECSC(screen, NULL);
                         else
-                                screen_DECRC(screen, seq);
+                                screen_DECRC(screen, NULL);
                 }
 
                 break;
         case 1049:
                 if (dec) {
-                        /* TODO: should DEC{S,R}C be done per-page, rather than per-screen? */
                         if (set) {
-                                screen_DECSC(screen, seq);
+                                screen_DECSC(screen, NULL);
                                 screen_clear_alt(screen);
                         }
 
                         screen_set_alt(screen, set);
 
                         if (!set)
-                                screen_DECRC(screen, seq);
+                                screen_DECRC(screen, NULL);
                 }
 
                 break;
@@ -1312,14 +1319,14 @@ int screen_DECRC(term_screen *screen, const term_seq *seq) {
          * state for the main display and the status line.
          */
 
-        screen->attr = screen->saved.attr;
-        screen->gl = screen->saved.gl;
-        screen->gr = screen->saved.gr;
-        screen->glt = screen->saved.glt;
-        screen->grt = screen->saved.grt;
-        set_reset(screen, TERM_FLAG_AUTO_WRAP, screen->saved.flags & TERM_FLAG_AUTO_WRAP);
-        set_reset(screen, TERM_FLAG_ORIGIN_MODE, screen->saved.flags & TERM_FLAG_ORIGIN_MODE);
-        screen_cursor_set(screen, screen->saved.cursor_x, screen->saved.cursor_y);
+        screen->attr = screen->saved->attr;
+        screen->gl = screen->saved->gl;
+        screen->gr = screen->saved->gr;
+        screen->glt = screen->saved->glt;
+        screen->grt = screen->saved->grt;
+        set_reset(screen, TERM_FLAG_AUTO_WRAP, screen->saved->flags & TERM_FLAG_AUTO_WRAP);
+        set_reset(screen, TERM_FLAG_ORIGIN_MODE, screen->saved->flags & TERM_FLAG_ORIGIN_MODE);
+        screen_cursor_set(screen, screen->saved->cursor_x, screen->saved->cursor_y);
 
         return 0;
 }
@@ -1526,14 +1533,14 @@ int screen_DECSC(term_screen *screen, const term_seq *seq) {
          *   * Any single shift 2 (SS2) or single shift 3 (SS3) functions sent
          */
 
-        screen->saved.cursor_x = screen->cursor_x;
-        screen->saved.cursor_y = screen->cursor_y;
-        screen->saved.attr = screen->attr;
-        screen->saved.gl = screen->gl;
-        screen->saved.gr = screen->gr;
-        screen->saved.glt = screen->glt;
-        screen->saved.grt = screen->grt;
-        screen->saved.flags = screen->flags & (TERM_FLAG_AUTO_WRAP
+        screen->saved->cursor_x = screen->cursor_x;
+        screen->saved->cursor_y = screen->cursor_y;
+        screen->saved->attr = screen->attr;
+        screen->saved->gl = screen->gl;
+        screen->saved->gr = screen->gr;
+        screen->saved->glt = screen->glt;
+        screen->saved->grt = screen->grt;
+        screen->saved->flags = screen->flags & (TERM_FLAG_AUTO_WRAP
                                                | TERM_FLAG_ORIGIN_MODE);
 
         return 0;
@@ -4208,17 +4215,18 @@ void term_screen_soft_reset(term_screen *screen) {
 
         screen->page = screen->page_main;
         screen->history = screen->history_main;
+        screen->saved = &screen->saved_main;
         screen->flags = TERM_FLAG_7BIT_MODE;
         screen->conformance_level = TERM_CONFORMANCE_LEVEL_VT400;
         screen->attr = screen->default_attr;
 
-        screen->saved.cursor_x = 0;
-        screen->saved.cursor_y = 0;
-        screen->saved.attr = screen->attr;
-        screen->saved.gl = screen->gl;
-        screen->saved.gr = screen->gr;
-        screen->saved.glt = NULL;
-        screen->saved.grt = NULL;
+        zero(screen->saved_main);
+        screen->saved_main.attr = screen->attr;
+        screen->saved_main.gl = screen->gl;
+        screen->saved_main.gr = screen->gr;
+
+        screen->saved_alt = screen->saved_main;
+
         screen->flags = 0;
 
         for (i = 0; i < screen->page->width; i += 8)