From: "Phillip Wood via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: "Johannes Schindelin" <Johannes.Schindelin@gmx.de>,
"Carlo Marcelo Arenas Belón" <carenas@gmail.com>,
"Phillip Wood" <phillip.wood@dunelm.org.uk>,
"Phillip Wood" <phillip.wood@dunelm.org.uk>
Subject: [PATCH v2 2/4] terminal: pop signal handler when terminal is restored
Date: Tue, 22 Feb 2022 18:53:33 +0000 [thread overview]
Message-ID: <0020953f1cf901e66883853392915ba8ce07ca61.1645556015.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.1146.v2.git.1645556015.gitgitgadget@gmail.com>
From: Phillip Wood <phillip.wood@dunelm.org.uk>
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>
---
compat/terminal.c | 17 +++++++++++++----
compat/terminal.h | 8 ++++++++
2 files changed, 21 insertions(+), 4 deletions(-)
diff --git a/compat/terminal.c b/compat/terminal.c
index fb8c70a6251..11288cfe5c9 100644
--- a/compat/terminal.c
+++ b/compat/terminal.c
@@ -11,7 +11,7 @@
static void restore_term_on_signal(int sig)
{
restore_term();
- sigchain_pop(sig);
+ /* restore_term calls sigchain_pop_common */
raise(sig);
}
@@ -31,14 +31,20 @@ void restore_term(void)
tcsetattr(term_fd, TCSAFLUSH, &old_term);
close(term_fd);
term_fd = -1;
+ sigchain_pop_common();
}
int save_term(int full_duplex)
{
if (term_fd < 0)
term_fd = open("/dev/tty", O_RDWR);
+ if (term_fd < 0)
+ return -1;
+ if (tcgetattr(term_fd, &old_term) < 0)
+ return -1;
+ sigchain_push_common(restore_term_on_signal);
- return (term_fd < 0) ? -1 : tcgetattr(term_fd, &old_term);
+ return 0;
}
static int disable_bits(tcflag_t bits)
@@ -49,12 +55,12 @@ static int disable_bits(tcflag_t bits)
goto error;
t = old_term;
- sigchain_push_common(restore_term_on_signal);
t.c_lflag &= ~bits;
if (!tcsetattr(term_fd, TCSAFLUSH, &t))
return 0;
+ sigchain_pop_common();
error:
close(term_fd);
term_fd = -1;
@@ -100,6 +106,8 @@ void restore_term(void)
return;
}
+ sigchain_pop_common();
+
if (hconin == INVALID_HANDLE_VALUE)
return;
@@ -134,6 +142,7 @@ int save_term(int full_duplex)
GetConsoleMode(hconin, &cmode_in);
use_stty = 0;
+ sigchain_push_common(restore_term_on_signal);
return 0;
error:
CloseHandle(hconin);
@@ -177,10 +186,10 @@ static int disable_bits(DWORD bits)
if (save_term(0) < 0)
return -1;
- sigchain_push_common(restore_term_on_signal);
if (!SetConsoleMode(hconin, cmode_in & ~bits)) {
CloseHandle(hconin);
hconin = INVALID_HANDLE_VALUE;
+ sigchain_pop_common();
return -1;
}
diff --git a/compat/terminal.h b/compat/terminal.h
index e1770c575b2..0fb9fa147c4 100644
--- a/compat/terminal.h
+++ b/compat/terminal.h
@@ -1,7 +1,15 @@
#ifndef COMPAT_TERMINAL_H
#define COMPAT_TERMINAL_H
+/*
+ * Save the terminal attributes so they can be restored later by a
+ * call to restore_term(). Note that every successful call to
+ * save_term() must be matched by a call to restore_term() even if the
+ * attributes have not been changed. Returns 0 on success, -1 on
+ * failure.
+ */
int save_term(int full_duplex);
+/* Restore the terminal attributes that were saved with save_term() */
void restore_term(void);
char *git_terminal_prompt(const char *prompt, int echo);
--
gitgitgadget
next prev parent reply other threads:[~2022-02-22 18:53 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-16 10:54 [PATCH 0/3] a couple of read_key_without_echo() fixes Phillip Wood via GitGitGadget
2022-02-16 10:54 ` [PATCH 1/3] terminal: pop signal handler when terminal is restored Phillip Wood via GitGitGadget
2022-02-16 10:54 ` [PATCH 2/3] terminal: set VMIN and VTIME in non-canonical mode Phillip Wood via GitGitGadget
2022-02-16 21:40 ` Junio C Hamano
2022-02-17 10:59 ` Phillip Wood
2022-02-16 10:54 ` [PATCH 3/3] add -p: disable stdin buffering when interactive.singlekey is set Phillip Wood via GitGitGadget
2022-02-16 21:43 ` Junio C Hamano
2022-02-22 18:53 ` [PATCH v2 0/4] a couple of read_key_without_echo() fixes Phillip Wood via GitGitGadget
2022-02-22 18:53 ` [PATCH v2 1/4] terminal: always reset terminal when reading without echo Phillip Wood via GitGitGadget
2022-02-22 18:53 ` Phillip Wood via GitGitGadget [this message]
2022-02-22 18:53 ` [PATCH v2 3/4] terminal: set VMIN and VTIME in non-canonical mode Phillip Wood via GitGitGadget
2022-02-22 18:53 ` [PATCH v2 4/4] add -p: disable stdin buffering when interactive.singlekey is set Phillip Wood via GitGitGadget
2022-02-23 21:34 ` [PATCH v2 0/4] a couple of read_key_without_echo() fixes Junio C Hamano
2022-02-24 14:30 ` Phillip Wood
2022-03-22 20:18 ` Carlo Arenas
2022-03-23 9:03 ` Junio C Hamano
2022-03-24 13:29 ` Johannes Schindelin
2022-03-28 10:51 ` Phillip Wood
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