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optimize determining if can set term title

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Decide if the terminal supports setting its title only when necessary
(e.g., when TERM changes) rather than everytime we're about to write
the prompt.
This commit is contained in:
Kurtis Rader 2017-01-09 18:35:37 -08:00
parent e9de674bbd
commit 11dccccdcc
3 changed files with 45 additions and 29 deletions
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42
src/env.cpp
View file

@ -238,6 +238,47 @@ static bool var_is_curses(const wcstring &key) {
return false;
}
/// True if we think we can set the terminal title else false.
static bool can_set_term_title = false;
/// Returns true if we think the terminal supports setting its title.
bool term_supports_setting_title() {
return can_set_term_title;
}
/// This is a pretty lame heuristic for detecting terminals that do not support setting the
/// title. If we recognise the terminal name as that of a virtual terminal, we assume it supports
/// setting the title. If we recognise it as that of a console, we assume it does not support
/// setting the title. Otherwise we check the ttyname and see if we believe it is a virtual
/// terminal.
///
/// One situation in which this breaks down is with screen, since screen supports setting the
/// terminal title if the underlying terminal does so, but will print garbage on terminals that
/// don't. Since we can't see the underlying terminal below screen there is no way to fix this.
static bool does_term_support_setting_title() {
const env_var_t term_str = env_get_string(L"TERM");
if (term_str.missing()) return false;
const wchar_t *term = term_str.c_str();
bool recognized = contains(term, L"xterm", L"screen", L"tmux", L"nxterm", L"rxvt");
if (!recognized) recognized = !wcsncmp(term, L"xterm-", wcslen(L"xterm-"));
if (!recognized) recognized = !wcsncmp(term, L"screen-", wcslen(L"screen-"));
if (!recognized) recognized = !wcsncmp(term, L"tmux-", wcslen(L"tmux-"));
if (!recognized) {
if (contains(term, L"linux", L"dumb")) return false;
char *n = ttyname(STDIN_FILENO);
if (!n || strstr(n, "tty") || strstr(n, "/vc/")) return false;
}
return true;
}
/// Handle changes to the TERM env var that do not involves the curses subsystem.
static void handle_term() {
can_set_term_title = does_term_support_setting_title();
}
/// Push all curses/terminfo env vars into the global environment where they can be found by those
/// libraries.
static void handle_curses(const wchar_t *env_var_name) {
@ -264,6 +305,7 @@ static void react_to_variable_change(const wcstring &key) {
handle_locale(key.c_str());
} else if (var_is_curses(key)) {
handle_curses(key.c_str());
if (key == L"TERM") handle_term();
} else if (var_is_timezone(key)) {
handle_timezone(key.c_str());
} else if (key == L"fish_term256" || key == L"fish_term24bit") {

3
src/env.h
View file

@ -186,4 +186,7 @@ struct var_entry_t {
typedef std::map<wcstring, var_entry_t> var_table_t;
extern bool term_has_xn; // does the terminal have the "eat_newline_glitch"
/// Returns true if we think the terminal supports setting its title.
bool term_supports_setting_title();
#endif

29
src/reader.cpp
View file

@ -660,35 +660,6 @@ bool reader_thread_job_is_stale() {
return (void *)(uintptr_t)s_generation_count != pthread_getspecific(generation_count_key);
}
/// This is a pretty lame heuristic for detecting terminals that do not support setting the
/// title. If we recognise the terminal name as that of a virtual terminal, we assume it supports
/// setting the title. If we recognise it as that of a console, we assume it does not support
/// setting the title. Otherwise we check the ttyname and see if we believe it is a virtual
/// terminal.
///
/// One situation in which this breaks down is with screen, since screen supports setting the
/// terminal title if the underlying terminal does so, but will print garbage on terminals that
/// don't. Since we can't see the underlying terminal below screen there is no way to fix this.
static bool term_supports_setting_title() {
const env_var_t term_str = env_get_string(L"TERM");
if (term_str.missing()) return false;
const wchar_t *term = term_str.c_str();
bool recognized = contains(term, L"xterm", L"screen", L"tmux", L"nxterm", L"rxvt");
if (!recognized) recognized = !wcsncmp(term, L"xterm-", wcslen(L"xterm-"));
if (!recognized) recognized = !wcsncmp(term, L"screen-", wcslen(L"screen-"));
if (!recognized) recognized = !wcsncmp(term, L"tmux-", wcslen(L"tmux-"));
if (!recognized) {
if (contains(term, L"linux", L"dumb")) return false;
char *n = ttyname(STDIN_FILENO);
if (!n || strstr(n, "tty") || strstr(n, "/vc/")) return false;
}
return true;
}
void reader_write_title(const wcstring &cmd, bool reset_cursor_position) {
if (!term_supports_setting_title()) return;