From 02af15dec5bf0114b03c4c3bec5d8f60890a1c58 Mon Sep 17 00:00:00 2001 From: Phillip Wood Date: Wed, 16 Mar 2022 18:54:02 +0000 Subject: [PATCH 1/4] terminal: use flags for save_term() 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 Signed-off-by: Junio C Hamano --- compat/terminal.c | 41 +++++++++++++++++++++-------------------- compat/terminal.h | 7 ++++++- 2 files changed, 27 insertions(+), 21 deletions(-) diff --git a/compat/terminal.c b/compat/terminal.c index 3620184e79..da2f788137 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -34,7 +34,7 @@ void restore_term(void) sigchain_pop_common(); } -int save_term(int full_duplex) +int save_term(enum save_term_flags flags) { if (term_fd < 0) term_fd = open("/dev/tty", O_RDWR); @@ -47,11 +47,11 @@ int save_term(int full_duplex) return 0; } -static int disable_bits(tcflag_t bits) +static int disable_bits(enum save_term_flags flags, tcflag_t bits) { struct termios t; - if (save_term(0) < 0) + if (save_term(flags) < 0) goto error; t = old_term; @@ -71,14 +71,14 @@ error: return -1; } -static int disable_echo(void) +static int disable_echo(enum save_term_flags flags) { - return disable_bits(ECHO); + return disable_bits(flags, ECHO); } -static int enable_non_canonical(void) +static int enable_non_canonical(enum save_term_flags flags) { - return disable_bits(ICANON | ECHO); + return disable_bits(flags, ICANON | ECHO); } #elif defined(GIT_WINDOWS_NATIVE) @@ -126,7 +126,7 @@ void restore_term(void) hconin = hconout = INVALID_HANDLE_VALUE; } -int save_term(int full_duplex) +int save_term(enum save_term_flags flags) { hconin = CreateFileA("CONIN$", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, NULL, OPEN_EXISTING, @@ -134,7 +134,7 @@ int save_term(int full_duplex) if (hconin == INVALID_HANDLE_VALUE) return -1; - if (full_duplex) { + if (flags & SAVE_TERM_DUPLEX) { hconout = CreateFileA("CONOUT$", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_WRITE, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); @@ -154,7 +154,7 @@ error: return -1; } -static int disable_bits(DWORD bits) +static int disable_bits(enum save_term_flags flags, DWORD bits) { if (use_stty) { struct child_process cp = CHILD_PROCESS_INIT; @@ -191,7 +191,7 @@ static int disable_bits(DWORD bits) use_stty = 0; } - if (save_term(0) < 0) + if (save_term(flags) < 0) return -1; if (!SetConsoleMode(hconin, cmode_in & ~bits)) { @@ -204,14 +204,15 @@ static int disable_bits(DWORD bits) return 0; } -static int disable_echo(void) +static int disable_echo(enum save_term_flags flags) { - return disable_bits(ENABLE_ECHO_INPUT); + return disable_bits(flags, ENABLE_ECHO_INPUT); } -static int enable_non_canonical(void) +static int enable_non_canonical(enum save_term_flags flags) { - return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT); + return disable_bits(flags, + ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT); } /* @@ -267,7 +268,7 @@ char *git_terminal_prompt(const char *prompt, int echo) return NULL; } - if (!echo && disable_echo()) { + if (!echo && disable_echo(0)) { fclose(input_fh); fclose(output_fh); return NULL; @@ -361,7 +362,7 @@ int read_key_without_echo(struct strbuf *buf) static int warning_displayed; int ch; - if (warning_displayed || enable_non_canonical() < 0) { + if (warning_displayed || enable_non_canonical(0) < 0) { if (!warning_displayed) { warning("reading single keystrokes not supported on " "this platform; reading line instead"); @@ -413,10 +414,10 @@ int read_key_without_echo(struct strbuf *buf) #else -int save_term(int full_duplex) +int save_term(enum save_term_flags flags) { - /* full_duplex == 1, but no support available */ - return -full_duplex; + /* no duplex support available */ + return -!!(flags & SAVE_TERM_DUPLEX); } void restore_term(void) diff --git a/compat/terminal.h b/compat/terminal.h index 0fb9fa147c..aeb24c9478 100644 --- a/compat/terminal.h +++ b/compat/terminal.h @@ -1,6 +1,11 @@ #ifndef COMPAT_TERMINAL_H #define COMPAT_TERMINAL_H +enum save_term_flags { + /* Save input and output settings */ + SAVE_TERM_DUPLEX = 1 << 0, +}; + /* * Save the terminal attributes so they can be restored later by a * call to restore_term(). Note that every successful call to @@ -8,7 +13,7 @@ * attributes have not been changed. Returns 0 on success, -1 on * failure. */ -int save_term(int full_duplex); +int save_term(enum save_term_flags flags); /* Restore the terminal attributes that were saved with save_term() */ void restore_term(void); From e4938ce3cc5967c2366db289ca854b0b796a5afd Mon Sep 17 00:00:00 2001 From: Phillip Wood Date: Wed, 16 Mar 2022 18:54:03 +0000 Subject: [PATCH 2/4] terminal: don't assume stdin is /dev/tty 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] https://github.com/jonathanstowe/TermReadKey/blob/b061c913bbf7ff9bad9b4eea6caae189eacd6063/ReadKey.xs#L1090 Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano --- compat/terminal.c | 29 ++++++++++++++++++++--------- compat/terminal.h | 2 ++ 2 files changed, 22 insertions(+), 9 deletions(-) diff --git a/compat/terminal.c b/compat/terminal.c index da2f788137..4893294eb6 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -20,28 +20,41 @@ static void restore_term_on_signal(int sig) #define INPUT_PATH "/dev/tty" #define OUTPUT_PATH "/dev/tty" +static volatile sig_atomic_t term_fd_needs_closing; static int term_fd = -1; static struct termios old_term; +static void close_term_fd(void) +{ + if (term_fd_needs_closing) + close(term_fd); + term_fd_needs_closing = 0; + term_fd = -1; +} + void restore_term(void) { if (term_fd < 0) return; tcsetattr(term_fd, TCSAFLUSH, &old_term); - close(term_fd); - term_fd = -1; + close_term_fd(); sigchain_pop_common(); } int save_term(enum save_term_flags flags) { if (term_fd < 0) - term_fd = open("/dev/tty", O_RDWR); + term_fd = ((flags & SAVE_TERM_STDIN) + ? 0 + : open("/dev/tty", O_RDWR)); if (term_fd < 0) return -1; - if (tcgetattr(term_fd, &old_term) < 0) + term_fd_needs_closing = !(flags & SAVE_TERM_STDIN); + if (tcgetattr(term_fd, &old_term) < 0) { + close_term_fd(); return -1; + } sigchain_push_common(restore_term_on_signal); return 0; @@ -52,7 +65,7 @@ static int disable_bits(enum save_term_flags flags, tcflag_t bits) struct termios t; if (save_term(flags) < 0) - goto error; + return -1; t = old_term; @@ -65,9 +78,7 @@ static int disable_bits(enum save_term_flags flags, tcflag_t bits) return 0; sigchain_pop_common(); -error: - close(term_fd); - term_fd = -1; + close_term_fd(); return -1; } @@ -362,7 +373,7 @@ int read_key_without_echo(struct strbuf *buf) static int warning_displayed; int ch; - if (warning_displayed || enable_non_canonical(0) < 0) { + if (warning_displayed || enable_non_canonical(SAVE_TERM_STDIN) < 0) { if (!warning_displayed) { warning("reading single keystrokes not supported on " "this platform; reading line instead"); diff --git a/compat/terminal.h b/compat/terminal.h index aeb24c9478..79ed00cf61 100644 --- a/compat/terminal.h +++ b/compat/terminal.h @@ -4,6 +4,8 @@ enum save_term_flags { /* Save input and output settings */ SAVE_TERM_DUPLEX = 1 << 0, + /* Save stdin rather than /dev/tty (fails if stdin is not a terminal) */ + SAVE_TERM_STDIN = 1 << 1, }; /* From 6606d99bae4161289d498b51a21acd11aa09e6ef Mon Sep 17 00:00:00 2001 From: Phillip Wood Date: Wed, 16 Mar 2022 18:54:04 +0000 Subject: [PATCH 3/4] terminal: work around macos poll() bug On macos the builtin "add -p" does not handle keys that generate escape sequences because poll() does not work with terminals there. Switch to using select() on non-windows platforms to work around this. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano --- compat/terminal.c | 42 ++++++++++++++++++++++++++++++++++++------ 1 file changed, 36 insertions(+), 6 deletions(-) diff --git a/compat/terminal.c b/compat/terminal.c index 4893294eb6..2ae8a6f13e 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -92,6 +92,31 @@ static int enable_non_canonical(enum save_term_flags flags) return disable_bits(flags, ICANON | ECHO); } +/* + * On macos it is not possible to use poll() with a terminal so use select + * instead. + */ +static int getchar_with_timeout(int timeout) +{ + struct timeval tv, *tvp = NULL; + fd_set readfds; + int res; + + if (timeout >= 0) { + tv.tv_sec = timeout / 1000; + tv.tv_usec = (timeout % 1000) * 1000; + tvp = &tv; + } + + FD_ZERO(&readfds); + FD_SET(0, &readfds); + res = select(1, &readfds, NULL, NULL, tvp); + if (res <= 0) + return EOF; + + return getchar(); +} + #elif defined(GIT_WINDOWS_NATIVE) #define INPUT_PATH "CONIN$" @@ -257,6 +282,16 @@ static int mingw_getchar(void) } #define getchar mingw_getchar +static int getchar_with_timeout(int timeout) +{ + struct pollfd pfd = { .fd = 0, .events = POLLIN }; + + if (poll(&pfd, 1, timeout) < 1) + return EOF; + + return getchar(); +} + #endif #ifndef FORCE_TEXT @@ -407,12 +442,7 @@ int read_key_without_echo(struct strbuf *buf) * half a second when we know that the sequence is complete. */ while (!is_known_escape_sequence(buf->buf)) { - struct pollfd pfd = { .fd = 0, .events = POLLIN }; - - if (poll(&pfd, 1, 500) < 1) - break; - - ch = getchar(); + ch = getchar_with_timeout(500); if (ch == EOF) break; strbuf_addch(buf, ch); From 0f584debc74afefdd24449136ffb2c77859e38c9 Mon Sep 17 00:00:00 2001 From: Phillip Wood Date: Wed, 16 Mar 2022 18:54:05 +0000 Subject: [PATCH 4/4] terminal: restore settings on SIGTSTP If the user suspends git while it is waiting for a keypress reset the terminal before stopping and restore the settings when git resumes. If the user tries to resume in the background print an error message (taking care to use async safe functions) before stopping again. Ideally we would reprint the prompt for the user when git resumes but this patch just restarts the read(). The signal handler is established with sigaction() rather than using sigchain_push() as this allows us to control the signal mask when the handler is invoked and ensure SA_RESTART is used to restart the read() when resuming. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano --- compat/terminal.c | 132 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 129 insertions(+), 3 deletions(-) diff --git a/compat/terminal.c b/compat/terminal.c index 2ae8a6f13e..7db330c52d 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -1,4 +1,4 @@ -#include "git-compat-util.h" +#include "cache.h" #include "compat/terminal.h" #include "sigchain.h" #include "strbuf.h" @@ -24,6 +24,102 @@ static volatile sig_atomic_t term_fd_needs_closing; static int term_fd = -1; static struct termios old_term; +static const char *background_resume_msg; +static const char *restore_error_msg; +static volatile sig_atomic_t ttou_received; + +/* async safe error function for use by signal handlers. */ +static void write_err(const char *msg) +{ + write_in_full(2, "error: ", strlen("error: ")); + write_in_full(2, msg, strlen(msg)); + write_in_full(2, "\n", 1); +} + +static void print_background_resume_msg(int signo) +{ + int saved_errno = errno; + sigset_t mask; + struct sigaction old_sa; + struct sigaction sa = { .sa_handler = SIG_DFL }; + + ttou_received = 1; + write_err(background_resume_msg); + sigaction(signo, &sa, &old_sa); + raise(signo); + sigemptyset(&mask); + sigaddset(&mask, signo); + sigprocmask(SIG_UNBLOCK, &mask, NULL); + /* Stopped here */ + sigprocmask(SIG_BLOCK, &mask, NULL); + sigaction(signo, &old_sa, NULL); + errno = saved_errno; +} + +static void restore_terminal_on_suspend(int signo) +{ + int saved_errno = errno; + int res; + struct termios t; + sigset_t mask; + struct sigaction old_sa; + struct sigaction sa = { .sa_handler = SIG_DFL }; + int can_restore = 1; + + if (tcgetattr(term_fd, &t) < 0) + can_restore = 0; + + if (tcsetattr(term_fd, TCSAFLUSH, &old_term) < 0) + write_err(restore_error_msg); + + sigaction(signo, &sa, &old_sa); + raise(signo); + sigemptyset(&mask); + sigaddset(&mask, signo); + sigprocmask(SIG_UNBLOCK, &mask, NULL); + /* Stopped here */ + sigprocmask(SIG_BLOCK, &mask, NULL); + sigaction(signo, &old_sa, NULL); + if (!can_restore) { + write_err(restore_error_msg); + goto out; + } + /* + * If we resume in the background then we receive SIGTTOU when calling + * tcsetattr() below. Set up a handler to print an error message in that + * case. + */ + sigemptyset(&mask); + sigaddset(&mask, SIGTTOU); + sa.sa_mask = old_sa.sa_mask; + sa.sa_handler = print_background_resume_msg; + sa.sa_flags = SA_RESTART; + sigaction(SIGTTOU, &sa, &old_sa); + again: + ttou_received = 0; + sigprocmask(SIG_UNBLOCK, &mask, NULL); + res = tcsetattr(term_fd, TCSAFLUSH, &t); + sigprocmask(SIG_BLOCK, &mask, NULL); + if (ttou_received) + goto again; + else if (res < 0) + write_err(restore_error_msg); + sigaction(SIGTTOU, &old_sa, NULL); + out: + errno = saved_errno; +} + +static void reset_job_signals(void) +{ + if (restore_error_msg) { + signal(SIGTTIN, SIG_DFL); + signal(SIGTTOU, SIG_DFL); + signal(SIGTSTP, SIG_DFL); + restore_error_msg = NULL; + background_resume_msg = NULL; + } +} + static void close_term_fd(void) { if (term_fd_needs_closing) @@ -40,10 +136,13 @@ void restore_term(void) tcsetattr(term_fd, TCSAFLUSH, &old_term); close_term_fd(); sigchain_pop_common(); + reset_job_signals(); } int save_term(enum save_term_flags flags) { + struct sigaction sa; + if (term_fd < 0) term_fd = ((flags & SAVE_TERM_STDIN) ? 0 @@ -56,6 +155,26 @@ int save_term(enum save_term_flags flags) return -1; } sigchain_push_common(restore_term_on_signal); + /* + * If job control is disabled then the shell will have set the + * disposition of SIGTSTP to SIG_IGN. + */ + sigaction(SIGTSTP, NULL, &sa); + if (sa.sa_handler == SIG_IGN) + return 0; + + /* avoid calling gettext() from signal handler */ + background_resume_msg = _("cannot resume in the background, please use 'fg' to resume"); + restore_error_msg = _("cannot restore terminal settings"); + sa.sa_handler = restore_terminal_on_suspend; + sa.sa_flags = SA_RESTART; + sigemptyset(&sa.sa_mask); + sigaddset(&sa.sa_mask, SIGTSTP); + sigaddset(&sa.sa_mask, SIGTTIN); + sigaddset(&sa.sa_mask, SIGTTOU); + sigaction(SIGTSTP, &sa, NULL); + sigaction(SIGTTIN, &sa, NULL); + sigaction(SIGTTOU, &sa, NULL); return 0; } @@ -78,6 +197,7 @@ static int disable_bits(enum save_term_flags flags, tcflag_t bits) return 0; sigchain_pop_common(); + reset_job_signals(); close_term_fd(); return -1; } @@ -102,6 +222,7 @@ static int getchar_with_timeout(int timeout) fd_set readfds; int res; + again: if (timeout >= 0) { tv.tv_sec = timeout / 1000; tv.tv_usec = (timeout % 1000) * 1000; @@ -111,9 +232,14 @@ static int getchar_with_timeout(int timeout) FD_ZERO(&readfds); FD_SET(0, &readfds); res = select(1, &readfds, NULL, NULL, tvp); - if (res <= 0) + if (!res) return EOF; - + if (res < 0) { + if (errno == EINTR) + goto again; + else + return EOF; + } return getchar(); }