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From: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Johannes Schindelin <johannes.schindelin@gmx.de>,
	Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: [PATCH v3 06/10] terminal: add a new function to read a single keystroke
Date: Mon, 13 Jan 2020 08:29:27 +0000	[thread overview]
Message-ID: <74593b51157c49f1785e217446f3af0889b0fdf2.1578904171.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.175.v3.git.1578904171.gitgitgadget@gmail.com>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

Typically, input on the command-line is line-based. It is actually not
really easy to get single characters (or better put: keystrokes).

We provide two implementations here:

- One that handles `/dev/tty` based systems as well as native Windows.
  The former uses the `tcsetattr()` function to put the terminal into
  "raw mode", which allows us to read individual keystrokes, one by one.
  The latter uses `stty.exe` to do the same, falling back to direct
  Win32 Console access.

  Thanks to the refactoring leading up to this commit, this is a single
  function, with the platform-specific details hidden away in
  conditionally-compiled code blocks.

- A fall-back which simply punts and reads back an entire line.

Note that the function writes the keystroke into an `strbuf` rather than
a `char`, in preparation for reading Escape sequences (e.g. when the
user hit an arrow key). This is also required for UTF-8 sequences in
case the keystroke corresponds to a non-ASCII letter.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 compat/terminal.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++
 compat/terminal.h |  3 +++
 2 files changed, 58 insertions(+)

diff --git a/compat/terminal.c b/compat/terminal.c
index 16e9949da1..1b2564042a 100644
--- a/compat/terminal.c
+++ b/compat/terminal.c
@@ -60,6 +60,11 @@ static int disable_echo(void)
 	return disable_bits(ECHO);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ICANON | ECHO);
+}
+
 #elif defined(GIT_WINDOWS_NATIVE)
 
 #define INPUT_PATH "CONIN$"
@@ -151,6 +156,10 @@ static int disable_echo(void)
 	return disable_bits(ENABLE_ECHO_INPUT);
 }
 
+static int enable_non_canonical(void)
+{
+	return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT);
+}
 
 #endif
 
@@ -198,6 +207,33 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return buf.buf;
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	int ch;
+
+	if (warning_displayed || enable_non_canonical() < 0) {
+		if (!warning_displayed) {
+			warning("reading single keystrokes not supported on "
+				"this platform; reading line instead");
+			warning_displayed = 1;
+		}
+
+		return strbuf_getline(buf, stdin);
+	}
+
+	strbuf_reset(buf);
+	ch = getchar();
+	if (ch == EOF) {
+		restore_term();
+		return EOF;
+	}
+
+	strbuf_addch(buf, ch);
+	restore_term();
+	return 0;
+}
+
 #else
 
 char *git_terminal_prompt(const char *prompt, int echo)
@@ -205,4 +241,23 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	return getpass(prompt);
 }
 
+int read_key_without_echo(struct strbuf *buf)
+{
+	static int warning_displayed;
+	const char *res;
+
+	if (!warning_displayed) {
+		warning("reading single keystrokes not supported on this "
+			"platform; reading line instead");
+		warning_displayed = 1;
+	}
+
+	res = getpass("");
+	strbuf_reset(buf);
+	if (!res)
+		return EOF;
+	strbuf_addstr(buf, res);
+	return 0;
+}
+
 #endif
diff --git a/compat/terminal.h b/compat/terminal.h
index 97db7cd69d..a9d52b8464 100644
--- a/compat/terminal.h
+++ b/compat/terminal.h
@@ -3,4 +3,7 @@
 
 char *git_terminal_prompt(const char *prompt, int echo);
 
+/* Read a single keystroke, without echoing it to the terminal */
+int read_key_without_echo(struct strbuf *buf);
+
 #endif /* COMPAT_TERMINAL_H */
-- 
gitgitgadget


  parent reply	other threads:[~2020-01-13  8:29 UTC|newest]

Thread overview: 63+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-21 22:41 [PATCH 0/9] built-in add -p: add support for the same config settings as the Perl version Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 1/9] built-in add -p: support interactive.diffFilter Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 2/9] built-in add -p: handle diff.algorithm Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 3/9] terminal: make the code of disable_echo() reusable Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 4/9] terminal: accommodate Git for Windows' default terminal Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 5/9] terminal: add a new function to read a single keystroke Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 6/9] built-in add -p: respect the `interactive.singlekey` config setting Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 7/9] built-in add -p: handle Escape sequences in interactive.singlekey mode Johannes Schindelin via GitGitGadget
2019-12-21 22:41 ` [PATCH 8/9] built-in add -p: handle Escape sequences more efficiently Johannes Schindelin via GitGitGadget
2019-12-21 22:42 ` [PATCH 9/9] ci: include the built-in `git add -i` in the `linux-gcc` job Johannes Schindelin via GitGitGadget
2019-12-21 22:53   ` SZEDER Gábor
2019-12-25 11:56     ` Johannes Schindelin
2019-12-22  0:11   ` Junio C Hamano
2019-12-25 11:57     ` Johannes Schindelin
2019-12-24 18:23 ` [PATCH 0/9] built-in add -p: add support for the same config settings as the Perl version Junio C Hamano
2019-12-24 18:39   ` Junio C Hamano
2019-12-25  8:46     ` Simon Ruderich
2019-12-25 12:09     ` Johannes Schindelin
2019-12-25 12:02   ` Johannes Schindelin
2019-12-25 11:56 ` [PATCH v2 " Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 1/9] built-in add -p: support interactive.diffFilter Johannes Schindelin via GitGitGadget
2020-01-07 22:57     ` SZEDER Gábor
2020-01-13  6:47       ` Johannes Schindelin
2019-12-25 11:56   ` [PATCH v2 2/9] built-in add -p: handle diff.algorithm Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 3/9] terminal: make the code of disable_echo() reusable Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 4/9] terminal: accommodate Git for Windows' default terminal Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 5/9] terminal: add a new function to read a single keystroke Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 6/9] built-in add -p: respect the `interactive.singlekey` config setting Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 7/9] built-in add -p: handle Escape sequences in interactive.singlekey mode Johannes Schindelin via GitGitGadget
2019-12-25 11:56   ` [PATCH v2 8/9] built-in add -p: handle Escape sequences more efficiently Johannes Schindelin via GitGitGadget
2019-12-25 11:57   ` [PATCH v2 9/9] ci: include the built-in `git add -i` in the `linux-gcc` job Johannes Schindelin via GitGitGadget
2019-12-26 20:48     ` Derrick Stolee
2020-01-01 22:10       ` Johannes Schindelin
2019-12-26 20:45   ` [PATCH v2 0/9] built-in add -p: add support for the same config settings as the Perl version Junio C Hamano
2020-01-13  8:29   ` [PATCH v3 00/10] " Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 01/10] built-in add -i/-p: treat SIGPIPE as EOF Johannes Schindelin via GitGitGadget
2020-01-13 17:04       ` SZEDER Gábor
2020-01-13 18:33         ` Jeff King
2020-01-15 18:32           ` Junio C Hamano
2020-01-15 19:03             ` Jeff King
2020-01-14 12:47         ` Johannes Schindelin
2020-01-17 14:32         ` SZEDER Gábor
2020-01-17 18:58           ` Jeff King
2020-01-13  8:29     ` [PATCH v3 02/10] built-in add -p: support interactive.diffFilter Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 03/10] built-in add -p: handle diff.algorithm Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 04/10] terminal: make the code of disable_echo() reusable Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 05/10] terminal: accommodate Git for Windows' default terminal Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` Johannes Schindelin via GitGitGadget [this message]
2020-01-13  8:29     ` [PATCH v3 07/10] built-in add -p: respect the `interactive.singlekey` config setting Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 08/10] built-in add -p: handle Escape sequences in interactive.singlekey mode Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 09/10] built-in add -p: handle Escape sequences more efficiently Johannes Schindelin via GitGitGadget
2020-01-13  8:29     ` [PATCH v3 10/10] ci: include the built-in `git add -i` in the `linux-gcc` job Johannes Schindelin via GitGitGadget
2020-01-14 18:43     ` [PATCH v4 00/10] built-in add -p: add support for the same config settings as the Perl version Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 01/10] t3701: adjust difffilter test Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 02/10] built-in add -p: support interactive.diffFilter Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 03/10] built-in add -p: handle diff.algorithm Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 04/10] terminal: make the code of disable_echo() reusable Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 05/10] terminal: accommodate Git for Windows' default terminal Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 06/10] terminal: add a new function to read a single keystroke Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 07/10] built-in add -p: respect the `interactive.singlekey` config setting Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 08/10] built-in add -p: handle Escape sequences in interactive.singlekey mode Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 09/10] built-in add -p: handle Escape sequences more efficiently Johannes Schindelin via GitGitGadget
2020-01-14 18:43       ` [PATCH v4 10/10] ci: include the built-in `git add -i` in the `linux-gcc` job Johannes Schindelin via GitGitGadget

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