From 94ac3c31f730ab278e1373a942fb4503829f4279 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 14 Jan 2020 18:43:47 +0000 Subject: terminal: make the code of disable_echo() reusable We are about to introduce the function `enable_non_canonical()`, which shares almost the complete code with `disable_echo()`. Let's prepare for that, by refactoring out that shared code. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/terminal.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'compat') diff --git a/compat/terminal.c b/compat/terminal.c index fa13ee672d..1fb40b3a0a 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -32,7 +32,7 @@ static void restore_term(void) term_fd = -1; } -static int disable_echo(void) +static int disable_bits(tcflag_t bits) { struct termios t; @@ -43,7 +43,7 @@ static int disable_echo(void) old_term = t; sigchain_push_common(restore_term_on_signal); - t.c_lflag &= ~ECHO; + t.c_lflag &= ~bits; if (!tcsetattr(term_fd, TCSAFLUSH, &t)) return 0; @@ -53,6 +53,11 @@ error: return -1; } +static int disable_echo(void) +{ + return disable_bits(ECHO); +} + #elif defined(GIT_WINDOWS_NATIVE) #define INPUT_PATH "CONIN$" @@ -72,7 +77,7 @@ static void restore_term(void) hconin = INVALID_HANDLE_VALUE; } -static int disable_echo(void) +static int disable_bits(DWORD bits) { hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, NULL, OPEN_EXISTING, @@ -82,7 +87,7 @@ static int disable_echo(void) GetConsoleMode(hconin, &cmode); sigchain_push_common(restore_term_on_signal); - if (!SetConsoleMode(hconin, cmode & (~ENABLE_ECHO_INPUT))) { + if (!SetConsoleMode(hconin, cmode & ~bits)) { CloseHandle(hconin); hconin = INVALID_HANDLE_VALUE; return -1; @@ -91,6 +96,12 @@ static int disable_echo(void) return 0; } +static int disable_echo(void) +{ + return disable_bits(ENABLE_ECHO_INPUT); +} + + #endif #ifndef FORCE_TEXT -- cgit v1.2.3 From 9ea416cb511e87f830462b08ae74b8a78fcca223 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 14 Jan 2020 18:43:48 +0000 Subject: terminal: accommodate Git for Windows' default terminal Git for Windows' Git Bash runs in MinTTY by default, which does not have a Win32 Console instance, but uses MSYS2 pseudo terminals instead. This is a problem, as Git for Windows does not want to use the MSYS2 emulation layer for Git itself, and therefore has no direct way to interact with that pseudo terminal. As a workaround, use the `stty` utility (which is included in Git for Windows, and which *is* an MSYS2 program, so it knows how to deal with the pseudo terminal). Note: If Git runs in a regular CMD or PowerShell window, there *is* a regular Win32 Console to work with. This is not a problem for the MSYS2 `stty`: it copes with this scenario just fine. Also note that we introduce support for more bits than would be necessary for a mere `disable_echo()` here, in preparation for the upcoming `enable_non_canonical()` function. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/terminal.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) (limited to 'compat') diff --git a/compat/terminal.c b/compat/terminal.c index 1fb40b3a0a..16e9949da1 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -2,6 +2,8 @@ #include "compat/terminal.h" #include "sigchain.h" #include "strbuf.h" +#include "run-command.h" +#include "string-list.h" #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE) @@ -64,11 +66,28 @@ static int disable_echo(void) #define OUTPUT_PATH "CONOUT$" #define FORCE_TEXT "t" +static int use_stty = 1; +static struct string_list stty_restore = STRING_LIST_INIT_DUP; static HANDLE hconin = INVALID_HANDLE_VALUE; static DWORD cmode; static void restore_term(void) { + if (use_stty) { + int i; + struct child_process cp = CHILD_PROCESS_INIT; + + if (stty_restore.nr == 0) + return; + + argv_array_push(&cp.args, "stty"); + for (i = 0; i < stty_restore.nr; i++) + argv_array_push(&cp.args, stty_restore.items[i].string); + run_command(&cp); + string_list_clear(&stty_restore, 0); + return; + } + if (hconin == INVALID_HANDLE_VALUE) return; @@ -79,6 +98,37 @@ static void restore_term(void) static int disable_bits(DWORD bits) { + if (use_stty) { + struct child_process cp = CHILD_PROCESS_INIT; + + argv_array_push(&cp.args, "stty"); + + if (bits & ENABLE_LINE_INPUT) { + string_list_append(&stty_restore, "icanon"); + argv_array_push(&cp.args, "-icanon"); + } + + if (bits & ENABLE_ECHO_INPUT) { + string_list_append(&stty_restore, "echo"); + argv_array_push(&cp.args, "-echo"); + } + + if (bits & ENABLE_PROCESSED_INPUT) { + string_list_append(&stty_restore, "-ignbrk"); + string_list_append(&stty_restore, "intr"); + string_list_append(&stty_restore, "^c"); + argv_array_push(&cp.args, "ignbrk"); + argv_array_push(&cp.args, "intr"); + argv_array_push(&cp.args, ""); + } + + if (run_command(&cp) == 0) + return 0; + + /* `stty` could not be executed; access the Console directly */ + use_stty = 0; + } + hconin = CreateFile("CONIN$", GENERIC_READ | GENERIC_WRITE, FILE_SHARE_READ, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL); -- cgit v1.2.3 From a5e46e6b0101b960c131dd39b50999cc0e69ed2b Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 14 Jan 2020 18:43:49 +0000 Subject: terminal: add a new function to read a single keystroke 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 Signed-off-by: Junio C Hamano --- compat/terminal.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ compat/terminal.h | 3 +++ 2 files changed, 58 insertions(+) (limited to 'compat') 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 */ -- cgit v1.2.3 From e118f06396bb298f2852070f648c6b4bb221a925 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 14 Jan 2020 18:43:51 +0000 Subject: built-in add -p: handle Escape sequences in interactive.singlekey mode This recapitulates part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17): add -i: ignore terminal escape sequences On the author's terminal, the up-arrow input sequence is ^[[A, and thus fat-fingering an up-arrow into 'git checkout -p' is quite dangerous: git-add--interactive.perl will ignore the ^[ and [ characters and happily treat A as "discard everything". As a band-aid fix, use Term::Cap to get all terminal capabilities. Then use the heuristic that any capability value that starts with ^[ (i.e., \e in perl) must be a key input sequence. Finally, given an input that starts with ^[, read more characters until we have read a full escape sequence, then return that to the caller. We use a timeout of 0.5 seconds on the subsequent reads to avoid getting stuck if the user actually input a lone ^[. Since none of the currently recognized keys start with ^[, the net result is that the sequence as a whole will be ignored and the help displayed. Note that we leave part for later which uses "Term::Cap to get all terminal capabilities", for several reasons: 1. it is actually not really necessary, as the timeout of 0.5 seconds should be plenty sufficient to catch Escape sequences, 2. it is cleaner to keep the change to special-case Escape sequences separate from the change that reads all terminal capabilities to speed things up, and 3. in practice, relying on the terminal capabilities is a bit overrated, as the information could be incomplete, or plain wrong. For example, in this developer's tmux sessions, the terminal capabilities claim that the "cursor up" sequence is ^[M, but the actual sequence produced by the "cursor up" key is ^[[A. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/terminal.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 55 insertions(+), 1 deletion(-) (limited to 'compat') diff --git a/compat/terminal.c b/compat/terminal.c index 1b2564042a..b7f58d1781 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -161,6 +161,37 @@ static int enable_non_canonical(void) return disable_bits(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT | ENABLE_PROCESSED_INPUT); } +/* + * Override `getchar()`, as the default implementation does not use + * `ReadFile()`. + * + * This poses a problem when we want to see whether the standard + * input has more characters, as the default of Git for Windows is to start the + * Bash in a MinTTY, which uses a named pipe to emulate a pty, in which case + * our `poll()` emulation calls `PeekNamedPipe()`, which seems to require + * `ReadFile()` to be called first to work properly (it only reports 0 + * available bytes, otherwise). + * + * So let's just override `getchar()` with a version backed by `ReadFile()` and + * go our merry ways from here. + */ +static int mingw_getchar(void) +{ + DWORD read = 0; + unsigned char ch; + + if (!ReadFile(GetStdHandle(STD_INPUT_HANDLE), &ch, 1, &read, NULL)) + return EOF; + + if (!read) { + error("Unexpected 0 read"); + return EOF; + } + + return ch; +} +#define getchar mingw_getchar + #endif #ifndef FORCE_TEXT @@ -228,8 +259,31 @@ int read_key_without_echo(struct strbuf *buf) restore_term(); return EOF; } - strbuf_addch(buf, ch); + + if (ch == '\033' /* ESC */) { + /* + * We are most likely looking at an Escape sequence. Let's try + * to read more bytes, waiting at most half a second, assuming + * that the sequence is complete if we did not receive any byte + * within that time. + * + * Start by replacing the Escape byte with ^[ */ + strbuf_splice(buf, buf->len - 1, 1, "^[", 2); + + for (;;) { + struct pollfd pfd = { .fd = 0, .events = POLLIN }; + + if (poll(&pfd, 1, 500) < 1) + break; + + ch = getchar(); + if (ch == EOF) + return 0; + strbuf_addch(buf, ch); + } + } + restore_term(); return 0; } -- cgit v1.2.3 From 12acdf573aafb8633f710fdbe5ac1282165fc6cc Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Tue, 14 Jan 2020 18:43:52 +0000 Subject: built-in add -p: handle Escape sequences more efficiently When `interactive.singlekey = true`, we react immediately to keystrokes, even to Escape sequences (e.g. when pressing a cursor key). The problem with Escape sequences is that we do not really know when they are done, and as a heuristic we poll standard input for half a second to make sure that we got all of it. While waiting half a second is not asking for a whole lot, it can become quite annoying over time, therefore with this patch, we read the terminal capabilities (if available) and extract known Escape sequences from there, then stop polling immediately when we detected that the user pressed a key that generated such a known sequence. This recapitulates the remaining part of b5cc003253c8 (add -i: ignore terminal escape sequences, 2011-05-17). Note: We do *not* query the terminal capabilities directly. That would either require a lot of platform-specific code, or it would require linking to a library such as ncurses. Linking to a library in the built-ins is something we try very hard to avoid (we even kicked the libcurl dependency to a non-built-in remote helper, just to shave off a tiny fraction of a second from Git's startup time). And the platform-specific code would be a maintenance nightmare. Even worse: in Git for Windows' case, we would need to query MSYS2 pseudo terminals, which `git.exe` simply cannot do (because it is intentionally *not* an MSYS2 program). To address this, we simply spawn `infocmp -L -1` and parse its output (which works even in Git for Windows, because that helper is included in the end-user facing installations). This is done only once, as in the Perl version, but it is done only when the first Escape sequence is encountered, not upon startup of `git add -i`; This saves on startup time, yet makes reacting to the first Escape sequence slightly more sluggish. But it allows us to keep the terminal-related code encapsulated in the `compat/terminal.c` file. Signed-off-by: Johannes Schindelin Signed-off-by: Junio C Hamano --- compat/terminal.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 72 insertions(+), 1 deletion(-) (limited to 'compat') diff --git a/compat/terminal.c b/compat/terminal.c index b7f58d1781..35bca03d14 100644 --- a/compat/terminal.c +++ b/compat/terminal.c @@ -4,6 +4,7 @@ #include "strbuf.h" #include "run-command.h" #include "string-list.h" +#include "hashmap.h" #if defined(HAVE_DEV_TTY) || defined(GIT_WINDOWS_NATIVE) @@ -238,6 +239,71 @@ char *git_terminal_prompt(const char *prompt, int echo) return buf.buf; } +/* + * The `is_known_escape_sequence()` function returns 1 if the passed string + * corresponds to an Escape sequence that the terminal capabilities contains. + * + * To avoid depending on ncurses or other platform-specific libraries, we rely + * on the presence of the `infocmp` executable to do the job for us (failing + * silently if the program is not available or refused to run). + */ +struct escape_sequence_entry { + struct hashmap_entry entry; + char sequence[FLEX_ARRAY]; +}; + +static int sequence_entry_cmp(const void *hashmap_cmp_fn_data, + const struct escape_sequence_entry *e1, + const struct escape_sequence_entry *e2, + const void *keydata) +{ + return strcmp(e1->sequence, keydata ? keydata : e2->sequence); +} + +static int is_known_escape_sequence(const char *sequence) +{ + static struct hashmap sequences; + static int initialized; + + if (!initialized) { + struct child_process cp = CHILD_PROCESS_INIT; + struct strbuf buf = STRBUF_INIT; + char *p, *eol; + + hashmap_init(&sequences, (hashmap_cmp_fn)sequence_entry_cmp, + NULL, 0); + + argv_array_pushl(&cp.args, "infocmp", "-L", "-1", NULL); + if (pipe_command(&cp, NULL, 0, &buf, 0, NULL, 0)) + strbuf_setlen(&buf, 0); + + for (eol = p = buf.buf; *p; p = eol + 1) { + p = strchr(p, '='); + if (!p) + break; + p++; + eol = strchrnul(p, '\n'); + + if (starts_with(p, "\\E")) { + char *comma = memchr(p, ',', eol - p); + struct escape_sequence_entry *e; + + p[0] = '^'; + p[1] = '['; + FLEX_ALLOC_MEM(e, sequence, p, comma - p); + hashmap_entry_init(&e->entry, + strhash(e->sequence)); + hashmap_add(&sequences, &e->entry); + } + if (!*eol) + break; + } + initialized = 1; + } + + return !!hashmap_get_from_hash(&sequences, strhash(sequence), sequence); +} + int read_key_without_echo(struct strbuf *buf) { static int warning_displayed; @@ -271,7 +337,12 @@ int read_key_without_echo(struct strbuf *buf) * Start by replacing the Escape byte with ^[ */ strbuf_splice(buf, buf->len - 1, 1, "^[", 2); - for (;;) { + /* + * Query the terminal capabilities once about all the Escape + * sequences it knows about, so that we can avoid waiting for + * 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) -- cgit v1.2.3