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https://github.com/fish-shell/fish-shell
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c7160d7cb4
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.
116 lines
4 KiB
C++
116 lines
4 KiB
C++
// Support for exposing the terminal size.
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#include "config.h" // IWYU pragma: keep
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#ifndef FISH_TERMSIZE_H
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#define FISH_TERMSIZE_H
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#include <stdint.h>
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#include "common.h"
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#include "global_safety.h"
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class environment_t;
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class parser_t;
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struct termsize_tester_t;
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/// A simple value type wrapping up a terminal size.
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struct termsize_t {
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/// Default width and height.
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static constexpr int DEFAULT_WIDTH = 80;
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static constexpr int DEFAULT_HEIGHT = 24;
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/// width of the terminal, in columns.
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int width{DEFAULT_WIDTH};
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/// height of the terminal, in rows.
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int height{DEFAULT_HEIGHT};
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/// Construct from width and height.
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termsize_t(int w, int h) : width(w), height(h) {}
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/// Return a default-sized termsize.
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static termsize_t defaults() { return termsize_t{DEFAULT_WIDTH, DEFAULT_HEIGHT}; }
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bool operator==(termsize_t rhs) const {
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return this->width == rhs.width && this->height == rhs.height;
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}
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bool operator!=(termsize_t rhs) const { return !(*this == rhs); }
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};
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/// Termsize monitoring is more complicated than one may think.
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/// The main source of complexity is the interaction between the environment variables COLUMNS/ROWS,
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/// the WINCH signal, and the TIOCGWINSZ ioctl.
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/// Our policy is "last seen wins": if COLUMNS or LINES is modified, we respect that until we get a
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/// SIGWINCH.
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struct termsize_container_t {
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/// \return the termsize without applying any updates.
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/// Return the default termsize if none.
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termsize_t last() const;
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/// If our termsize is stale, update it, using \p parser firing any events that may be
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/// registered for COLUMNS and LINES.
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/// \return the updated termsize.
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termsize_t updating(parser_t &parser);
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/// Initialize our termsize, using the given environment stack.
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/// This will prefer to use COLUMNS and LINES, but will fall back to the tty size reader.
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/// This does not change any variables in the environment.
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termsize_t initialize(const environment_t &vars);
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/// Note that a WINCH signal is received.
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/// Naturally this may be called from within a signal handler.
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static void handle_winch();
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/// Invalidate the tty in the sense that we need to re-fetch its termsize.
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static void invalidate_tty();
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/// Note that COLUMNS and/or LINES global variables changed.
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void handle_columns_lines_var_change(const environment_t &vars);
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/// \return the singleton shared container.
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static termsize_container_t &shared();
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private:
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/// A function used for accessing the termsize from the tty. This is only exposed for testing.
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using tty_size_reader_func_t = maybe_t<termsize_t> (*)();
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struct data_t {
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// The last termsize returned by TIOCGWINSZ, or none if none.
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maybe_t<termsize_t> last_from_tty{};
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// The last termsize seen from the environment (COLUMNS/LINES), or none if none.
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maybe_t<termsize_t> last_from_env{};
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// The last-seen tty-invalidation generation count.
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// Set to a huge value so it's initially stale.
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uint32_t last_tty_gen_count{UINT32_MAX};
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/// \return the current termsize from this data.
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termsize_t current() const;
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/// Mark that our termsize is (for the time being) from the environment, not the tty.
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void mark_override_from_env(termsize_t ts);
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};
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// Construct from a reader function.
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explicit termsize_container_t(tty_size_reader_func_t func) : tty_size_reader_(func) {}
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// Update COLUMNS and LINES in the parser's stack.
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void set_columns_lines_vars(termsize_t val, parser_t &parser);
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// Our lock-protected data.
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mutable owning_lock<data_t> data_{};
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// An indication that we are currently in the process of setting COLUMNS and LINES, and so do
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// not react to any changes.
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relaxed_atomic_bool_t setting_env_vars_{false};
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const tty_size_reader_func_t tty_size_reader_;
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friend termsize_tester_t;
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};
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/// Convenience helper to return the last known termsize.
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inline termsize_t termsize_last() { return termsize_container_t::shared().last(); }
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#endif // FISH_TERMSIZE_H
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