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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When we need to prompt the user for input interactively, we
want to access their terminal directly. We can't rely on
stdio because it may be connected to pipes or files, rather
than the terminal. Instead, we use "getpass()", because it
abstracts the idea of prompting and reading from the
terminal. However, it has some problems:
1. It never echoes the typed characters, which makes it OK
for passwords but annoying for other input (like usernames).
2. Some implementations of getpass() have an extremely
small input buffer (e.g., Solaris 8 is reported to
support only 8 characters).
3. Some implementations of getpass() will fall back to
reading from stdin (e.g., glibc). We explicitly don't
want this, because our stdin may be connected to a pipe
speaking a particular protocol, and reading will
disrupt the protocol flow (e.g., the remote-curl
helper).
4. Some implementations of getpass() turn off signals, so
that hitting "^C" on the terminal does not break out of
the password prompt. This can be a mild annoyance.
Instead, let's provide an abstract "git_terminal_prompt"
function that addresses these concerns. This patch includes
an implementation based on /dev/tty, enabled by setting
HAVE_DEV_TTY. The fallback is to use getpass() as before.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
