read_key_without_echo() reads from stdin but uses /dev/tty when it
disables echo. This is unfortunate as there no guarantee that stdin is
the same device as /dev/tty. The perl version of "add -p" uses stdin
when it sets the terminal mode, this commit does the same for the
builtin version. There is still a difference between the perl and
builtin versions though - the perl version will ignore any errors when
setting the terminal mode[1] and will still read single bytes when
stdin is not a terminal. The builtin version displays a warning if
setting the terminal mode fails and switches to reading a line at a
time.
[1] b061c913bb/ReadKey.xs (L1090)
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The next commit will add another flag in addition to the existing
full_duplex so change the function signature to take a flags
argument. Also alter the functions that call save_term() so that they
can pass flags down to it.
The choice to use an enum for tho bitwise flags is because gdb will
display the symbolic names of all the flags that are set rather than
the integer value.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When disable_bits() changes the terminal attributes it uses
sigchain_push_common() to restore the terminal if a signal is received
before restore_term() is called. However there is no corresponding
call to sigchain_pop_common() when the settings are restored so the
signal handler is left on the sigchain stack. This leaves the stack
unbalanced so code such as
sigchain_push_common(my_handler);
...
read_key_without_echo(...);
...
sigchain_pop_common();
pops the handler pushed by disable_bits() rather than the one it
intended to. Additionally "git add -p" changes the terminal settings
every time it reads a key press so the stack can grow significantly.
In order to fix this save_term() now sets up the signal handler so
restore_term() can unconditionally call sigchain_pop_common(). There
are no callers of save_term() outside of terminal.c as the only
external caller was removed by e3f7e01b50 ("Revert "editor: save and
reset terminal after calling EDITOR"", 2021-11-22). Any future callers
of save_term() should benefit from having the signal handler set up
for them.
Signed-off-by: Phillip Wood <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, git will share its console with all its children (unless
they create their own), and is therefore possible that any of them
that might change the settings for it could affect its operations once
completed.
Refactor the platform specific functionality to save the terminal
settings and expand it to also do so for the output handler.
This will allow for the state of the terminal to be saved and
restored around a child that might misbehave (ex vi) which will
be implemented next.
Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
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>
