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![Johannes Schindelin](/assets/img/avatar_default.png)
When `interactive.singlekey = true`, we react immediately to keystrokes,
even to Escape sequences (e.g. when pressing a cursor key).
The problem with Escape sequences is that we do not really know when
they are done, and as a heuristic we poll standard input for half a
second to make sure that we got all of it.
While waiting half a second is not asking for a whole lot, it can become
quite annoying over time, therefore with this patch, we read the
terminal capabilities (if available) and extract known Escape sequences
from there, then stop polling immediately when we detected that the user
pressed a key that generated such a known sequence.
This recapitulates the remaining part of b5cc003253
(add -i: ignore
terminal escape sequences, 2011-05-17).
Note: We do *not* query the terminal capabilities directly. That would
either require a lot of platform-specific code, or it would require
linking to a library such as ncurses.
Linking to a library in the built-ins is something we try very hard to
avoid (we even kicked the libcurl dependency to a non-built-in remote
helper, just to shave off a tiny fraction of a second from Git's startup
time). And the platform-specific code would be a maintenance nightmare.
Even worse: in Git for Windows' case, we would need to query MSYS2
pseudo terminals, which `git.exe` simply cannot do (because it is
intentionally *not* an MSYS2 program).
To address this, we simply spawn `infocmp -L -1` and parse its output
(which works even in Git for Windows, because that helper is included in
the end-user facing installations).
This is done only once, as in the Perl version, but it is done only when
the first Escape sequence is encountered, not upon startup of `git add
-i`; This saves on startup time, yet makes reacting to the first Escape
sequence slightly more sluggish. But it allows us to keep the
terminal-related code encapsulated in the `compat/terminal.c` file.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
389 lines
8.2 KiB
C
389 lines
8.2 KiB
C
#include "git-compat-util.h"
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#include "compat/terminal.h"
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#include "sigchain.h"
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#include "strbuf.h"
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#include "run-command.h"
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#include "string-list.h"
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#include "hashmap.h"
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#if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE)
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static void restore_term(void);
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static void restore_term_on_signal(int sig)
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{
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restore_term();
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sigchain_pop(sig);
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raise(sig);
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}
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#ifdef HAVE_DEV_TTY
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#define INPUT_PATH "/dev/tty"
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#define OUTPUT_PATH "/dev/tty"
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static int term_fd = -1;
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static struct termios old_term;
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static void restore_term(void)
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{
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if (term_fd < 0)
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return;
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tcsetattr(term_fd, TCSAFLUSH, &old_term);
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close(term_fd);
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term_fd = -1;
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}
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static int disable_bits(tcflag_t bits)
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{
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struct termios t;
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term_fd = open("/dev/tty", O_RDWR);
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if (tcgetattr(term_fd, &t) < 0)
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goto error;
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old_term = t;
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sigchain_push_common(restore_term_on_signal);
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t.c_lflag &= ~bits;
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if (!tcsetattr(term_fd, TCSAFLUSH, &t))
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return 0;
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error:
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close(term_fd);
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term_fd = -1;
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return -1;
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}
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static int disable_echo(void)
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{
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return disable_bits(ECHO);
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}
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static int enable_non_canonical(void)
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{
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return disable_bits(ICANON | ECHO);
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}
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#elif defined(GIT_WINDOWS_NATIVE)
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#define INPUT_PATH "CONIN$"
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#define OUTPUT_PATH "CONOUT$"
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#define FORCE_TEXT "t"
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static int use_stty = 1;
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static struct string_list stty_restore = STRING_LIST_INIT_DUP;
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static HANDLE hconin = INVALID_HANDLE_VALUE;
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static DWORD cmode;
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static void restore_term(void)
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{
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if (use_stty) {
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int i;
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struct child_process cp = CHILD_PROCESS_INIT;
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if (stty_restore.nr == 0)
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return;
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argv_array_push(&cp.args, "stty");
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for (i = 0; i < stty_restore.nr; i++)
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argv_array_push(&cp.args, stty_restore.items[i].string);
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run_command(&cp);
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string_list_clear(&stty_restore, 0);
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return;
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}
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if (hconin == INVALID_HANDLE_VALUE)
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return;
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SetConsoleMode(hconin, cmode);
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CloseHandle(hconin);
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hconin = INVALID_HANDLE_VALUE;
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}
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static int disable_bits(DWORD bits)
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{
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if (use_stty) {
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struct child_process cp = CHILD_PROCESS_INIT;
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argv_array_push(&cp.args, "stty");
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if (bits & ENABLE_LINE_INPUT) {
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string_list_append(&stty_restore, "icanon");
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argv_array_push(&cp.args, "-icanon");
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}
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if (bits & ENABLE_ECHO_INPUT) {
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string_list_append(&stty_restore, "echo");
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argv_array_push(&cp.args, "-echo");
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}
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if (bits & ENABLE_PROCESSED_INPUT) {
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string_list_append(&stty_restore, "-ignbrk");
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string_list_append(&stty_restore, "intr");
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string_list_append(&stty_restore, "^c");
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argv_array_push(&cp.args, "ignbrk");
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argv_array_push(&cp.args, "intr");
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argv_array_push(&cp.args, "");
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}
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if (run_command(&cp) == 0)
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return 0;
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/* `stty` could not be executed; access the Console directly */
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use_stty = 0;
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}
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hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE,
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FILE_SHARE_READ, NULL, OPEN_EXISTING,
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FILE_ATTRIBUTE_NORMAL, NULL);
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if (hconin == INVALID_HANDLE_VALUE)
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return -1;
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GetConsoleMode(hconin, &cmode);
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sigchain_push_common(restore_term_on_signal);
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if (!SetConsoleMode(hconin, cmode & ~bits)) {
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CloseHandle(hconin);
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hconin = INVALID_HANDLE_VALUE;
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return -1;
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}
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return 0;
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}
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static int disable_echo(void)
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{
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return disable_bits(ENABLE_ECHO_INPUT);
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}
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static int enable_non_canonical(void)
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{
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return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
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}
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/*
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* Override `getchar()`, as the default implementation does not use
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* `ReadFile()`.
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*
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* This poses a problem when we want to see whether the standard
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* input has more characters, as the default of Git for Windows is to start the
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* Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case
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* our `poll()` emulation calls `PeekNamedPipe()`, which seems to require
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* `ReadFile()` to be called first to work properly (it only reports 0
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* available bytes, otherwise).
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*
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* So let's just override `getchar()` with a version backed by `ReadFile()` and
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* go our merry ways from here.
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*/
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static int mingw_getchar(void)
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{
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DWORD read = 0;
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unsigned char ch;
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if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL))
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return EOF;
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if (!read) {
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error("Unexpected 0 read");
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return EOF;
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}
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return ch;
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}
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#define getchar mingw_getchar
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#endif
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#ifndef FORCE_TEXT
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#define FORCE_TEXT
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#endif
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char *git_terminal_prompt(const char *prompt, int echo)
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{
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static struct strbuf buf = STRBUF_INIT;
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int r;
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FILE *input_fh, *output_fh;
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input_fh = fopen(INPUT_PATH, "r" FORCE_TEXT);
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if (!input_fh)
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return NULL;
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output_fh = fopen(OUTPUT_PATH, "w" FORCE_TEXT);
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if (!output_fh) {
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fclose(input_fh);
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return NULL;
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}
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if (!echo && disable_echo()) {
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fclose(input_fh);
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fclose(output_fh);
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return NULL;
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}
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fputs(prompt, output_fh);
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fflush(output_fh);
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r = strbuf_getline_lf(&buf, input_fh);
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if (!echo) {
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putc('\n', output_fh);
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fflush(output_fh);
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}
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restore_term();
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fclose(input_fh);
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fclose(output_fh);
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if (r == EOF)
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return NULL;
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return buf.buf;
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}
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/*
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* The `is_known_escape_sequence()` function returns 1 if the passed string
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* corresponds to an Escape sequence that the terminal capabilities contains.
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*
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* To avoid depending on ncurses or other platform-specific libraries, we rely
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* on the presence of the `infocmp` executable to do the job for us (failing
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* silently if the program is not available or refused to run).
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*/
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struct escape_sequence_entry {
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struct hashmap_entry entry;
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char sequence[FLEX_ARRAY];
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};
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static int sequence_entry_cmp(const void *hashmap_cmp_fn_data,
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const struct escape_sequence_entry *e1,
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const struct escape_sequence_entry *e2,
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const void *keydata)
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{
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return strcmp(e1->sequence, keydata ? keydata : e2->sequence);
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}
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static int is_known_escape_sequence(const char *sequence)
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{
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static struct hashmap sequences;
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static int initialized;
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if (!initialized) {
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struct child_process cp = CHILD_PROCESS_INIT;
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struct strbuf buf = STRBUF_INIT;
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char *p, *eol;
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hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp,
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NULL, 0);
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argv_array_pushl(&cp.args, "infocmp", "-L", "-1", NULL);
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if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0))
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strbuf_setlen(&buf, 0);
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for (eol = p = buf.buf; *p; p = eol + 1) {
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p = strchr(p, '=');
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if (!p)
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break;
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p++;
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eol = strchrnul(p, '\n');
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if (starts_with(p, "\\E")) {
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char *comma = memchr(p, ',', eol - p);
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struct escape_sequence_entry *e;
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p[0] = '^';
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p[1] = '[';
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FLEX_ALLOC_MEM(e, sequence, p, comma - p);
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hashmap_entry_init(&e->entry,
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strhash(e->sequence));
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hashmap_add(&sequences, &e->entry);
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}
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if (!*eol)
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break;
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}
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initialized = 1;
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}
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return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence);
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}
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int read_key_without_echo(struct strbuf *buf)
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{
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static int warning_displayed;
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int ch;
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if (warning_displayed || enable_non_canonical() < 0) {
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if (!warning_displayed) {
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warning("reading single keystrokes not supported on "
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"this platform; reading line instead");
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warning_displayed = 1;
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}
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return strbuf_getline(buf, stdin);
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}
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strbuf_reset(buf);
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ch = getchar();
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if (ch == EOF) {
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restore_term();
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return EOF;
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}
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strbuf_addch(buf, ch);
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if (ch == '\033' /* ESC */) {
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/*
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* We are most likely looking at an Escape sequence. Let's try
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* to read more bytes, waiting at most half a second, assuming
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* that the sequence is complete if we did not receive any byte
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* within that time.
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*
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* Start by replacing the Escape byte with ^[ */
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strbuf_splice(buf, buf->len - 1, 1, "^[", 2);
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/*
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* Query the terminal capabilities once about all the Escape
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* sequences it knows about, so that we can avoid waiting for
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* half a second when we know that the sequence is complete.
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*/
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while (!is_known_escape_sequence(buf->buf)) {
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struct pollfd pfd = { .fd = 0, .events = POLLIN };
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if (poll(&pfd, 1, 500) < 1)
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break;
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ch = getchar();
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if (ch == EOF)
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return 0;
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strbuf_addch(buf, ch);
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}
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}
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restore_term();
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return 0;
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}
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#else
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char *git_terminal_prompt(const char *prompt, int echo)
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{
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return getpass(prompt);
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}
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int read_key_without_echo(struct strbuf *buf)
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{
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static int warning_displayed;
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const char *res;
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if (!warning_displayed) {
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warning("reading single keystrokes not supported on this "
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"platform; reading line instead");
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warning_displayed = 1;
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}
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res = getpass("");
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strbuf_reset(buf);
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if (!res)
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return EOF;
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strbuf_addstr(buf, res);
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return 0;
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}
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#endif
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