Eliminate the termsize handling from common.h

Finish the transition to termsize.h. Remove the scary termsize bits
from common.cpp, which can throw off events at arbitrary calls and are
dangerously reentrant. Migrate everyone to the new termsize.h.

src/reader.cpp

@@ -74,6 +74,7 @@
 #include "sanity.h"
 #include "screen.h"
 #include "signal.h"
+#include "termsize.h"
 #include "tnode.h"
 #include "tokenizer.h"
 #include "wutil.h"  // IWYU pragma: keep
@@ -621,6 +622,9 @@ class reader_data_t : public std::enable_shared_from_this<reader_data_t> {
     void update_command_line_from_history_search();
     void set_buffer_maintaining_pager(const wcstring &b, size_t pos, bool transient = false);
     void delete_char(bool backward = true);
+
+    /// Called to update the termsize, including $COLUMNS and $LINES, as necessary.
+    void update_termsize() { (void)termsize_container_t::shared().updating(parser()); }
 };
 
 /// This variable is set to a signal by the signal handler when ^C is pressed.
@@ -695,7 +699,7 @@ static void term_steal() {
             break;
     }
 
-    invalidate_termsize();
+    termsize_container_t::shared().invalidate_tty();
 }
 
 bool reader_exit_forced() { return s_exit_forced; }
@@ -800,8 +804,7 @@ void reader_data_t::repaint() {
     size_t cursor_position = focused_on_pager ? pager.cursor_position() : cmd_line->position();
 
     // Prepend the mode prompt to the left prompt.
-    int screen_width = common_get_width();
-    s_write(&screen, screen_width, mode_prompt_buff + left_prompt_buff, right_prompt_buff,
+    s_write(&screen, termsize_last().width, mode_prompt_buff + left_prompt_buff, right_prompt_buff,
             full_line, cmd_line->size(), colors, indents, cursor_position, current_page_rendering,
             focused_on_pager);
 
@@ -1053,9 +1056,9 @@ void reader_data_t::exec_prompt() {
     // Do not allow the exit status of the prompts to leak through.
     const bool apply_exit_status = false;
 
-    // HACK: Query winsize again because it might have changed.
+    // Update the termsize now.
     // This allows prompts to react to $COLUMNS.
-    (void)get_current_winsize();
+    update_termsize();
 
     // If we have any prompts, they must be run non-interactively.
     if (!left_prompt.empty() || !right_prompt.empty()) {
@@ -1091,7 +1094,8 @@ void reader_data_t::exec_prompt() {
 }
 
 void reader_init() {
-    auto &vars = parser_t::principal_parser().vars();
+    parser_t &parser = parser_t::principal_parser();
+    auto &vars = parser.vars();
 
     // Ensure this var is present even before an interactive command is run so that if it is used
     // in a function like `fish_prompt` or `fish_right_prompt` it is defined at the time the first
@@ -1121,7 +1125,7 @@ void reader_init() {
 
     // We do this not because we actually need the window size but for its side-effect of correctly
     // setting the COLUMNS and LINES env vars.
-    get_current_winsize();
+    termsize_container_t::shared().updating(parser);
 }
 
 /// Restore the term mode if we own the terminal. It's important we do this before
@@ -1972,7 +1976,7 @@ static void reader_interactive_init(parser_t &parser) {
         }
     }
 
-    invalidate_termsize();
+    termsize_container_t::shared().invalidate_tty();
 
     // For compatibility with fish 2.0's $_, now replaced with `status current-command`
     parser.vars().set_one(L"_", ENV_GLOBAL, L"fish");
@@ -2329,7 +2333,7 @@ void reader_pop() {
         reader_interactive_destroy();
     } else {
         s_end_current_loop = false;
-        s_reset_abandoning_line(&new_reader->screen, common_get_width());
+        s_reset_abandoning_line(&new_reader->screen, termsize_last().width);
     }
 }
 
@@ -2964,7 +2968,7 @@ void reader_data_t::handle_readline_command(readline_cmd_t c, readline_loop_stat
                 // already be printed, all we need to do is repaint.
                 wcstring_list_t argv(1, el->text());
                 event_fire_generic(parser(), L"fish_posterror", &argv);
-                s_reset_abandoning_line(&screen, common_get_width());
+                s_reset_abandoning_line(&screen, termsize_last().width);
                 mark_repaint_needed();
             }
 
@@ -3485,7 +3489,7 @@ maybe_t<wcstring> reader_data_t::readline(int nchars_or_0) {
 
     history_search.reset();
 
-    s_reset_abandoning_line(&screen, common_get_width());
+    s_reset_abandoning_line(&screen, termsize_last().width);
     event_fire_generic(parser(), L"fish_prompt");
     exec_prompt();
 
@@ -3510,6 +3514,9 @@ maybe_t<wcstring> reader_data_t::readline(int nchars_or_0) {
     }
 
     while (!rls.finished && !shell_is_exiting()) {
+        // Perhaps update the termsize. This is cheap if it has not changed.
+        update_termsize();
+
         if (rls.nchars <= command_line.size()) {
             // We've already hit the specified character limit.
             rls.finished = true;