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built-in add -p: handle Escape sequences in interactive.singlekey mode
This recapitulates part of b5cc003253
(add -i: ignore terminal escape
sequences, 2011-05-17):
add -i: ignore terminal escape sequences
On the author's terminal, the up-arrow input sequence is ^[[A, and
thus fat-fingering an up-arrow into 'git checkout -p' is quite
dangerous: git-add--interactive.perl will ignore the ^[ and [
characters and happily treat A as "discard everything".
As a band-aid fix, use Term::Cap to get all terminal capabilities.
Then use the heuristic that any capability value that starts with ^[
(i.e., \e in perl) must be a key input sequence. Finally, given an
input that starts with ^[, read more characters until we have read a
full escape sequence, then return that to the caller. We use a
timeout of 0.5 seconds on the subsequent reads to avoid getting stuck
if the user actually input a lone ^[.
Since none of the currently recognized keys start with ^[, the net
result is that the sequence as a whole will be ignored and the help
displayed.
Note that we leave part for later which uses "Term::Cap to get all
terminal capabilities", for several reasons:
1. it is actually not really necessary, as the timeout of 0.5 seconds
should be plenty sufficient to catch Escape sequences,
2. it is cleaner to keep the change to special-case Escape sequences
separate from the change that reads all terminal capabilities to
speed things up, and
3. in practice, relying on the terminal capabilities is a bit overrated,
as the information could be incomplete, or plain wrong. For example,
in this developer's tmux sessions, the terminal capabilities claim
that the "cursor up" sequence is ^[M, but the actual sequence
produced by the "cursor up" key is ^[[A.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
parent
04f816b125
commit
e118f06396
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@ -161,6 +161,37 @@ static int enable_non_canonical(void)
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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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@ -228,8 +259,31 @@ int read_key_without_echo(struct strbuf *buf)
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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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for (;;) {
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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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