From 21aeafceda2382d26bfa73a98ba45a937d65d77a Mon Sep 17 00:00:00 2001 From: Jeff King Date: Sat, 10 Dec 2011 05:41:01 -0500 Subject: [PATCH] add generic terminal prompt function 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 Signed-off-by: Junio C Hamano --- Makefile | 9 ++++++ compat/terminal.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++ compat/terminal.h | 6 ++++ 3 files changed, 96 insertions(+) create mode 100644 compat/terminal.c create mode 100644 compat/terminal.h diff --git a/Makefile b/Makefile index d20d0de55..7c370ea57 100644 --- a/Makefile +++ b/Makefile @@ -229,6 +229,9 @@ all:: # # Define NO_REGEX if you have no or inferior regex support in your C library. # +# Define HAVE_DEV_TTY if your system can open /dev/tty to interact with the +# user. +# # Define GETTEXT_POISON if you are debugging the choice of strings marked # for translation. In a GETTEXT_POISON build, you can turn all strings marked # for translation into gibberish by setting the GIT_GETTEXT_POISON variable @@ -523,6 +526,7 @@ LIB_H += compat/bswap.h LIB_H += compat/cygwin.h LIB_H += compat/mingw.h LIB_H += compat/obstack.h +LIB_H += compat/terminal.h LIB_H += compat/win32/pthread.h LIB_H += compat/win32/syslog.h LIB_H += compat/win32/poll.h @@ -610,6 +614,7 @@ LIB_OBJS += color.o LIB_OBJS += combine-diff.o LIB_OBJS += commit.o LIB_OBJS += compat/obstack.o +LIB_OBJS += compat/terminal.o LIB_OBJS += config.o LIB_OBJS += connect.o LIB_OBJS += connected.o @@ -1646,6 +1651,10 @@ ifdef HAVE_PATHS_H BASIC_CFLAGS += -DHAVE_PATHS_H endif +ifdef HAVE_DEV_TTY + BASIC_CFLAGS += -DHAVE_DEV_TTY +endif + ifdef DIR_HAS_BSD_GROUP_SEMANTICS COMPAT_CFLAGS += -DDIR_HAS_BSD_GROUP_SEMANTICS endif diff --git a/compat/terminal.c b/compat/terminal.c new file mode 100644 index 000000000..6d16c8fba --- /dev/null +++ b/compat/terminal.c @@ -0,0 +1,81 @@ +#include "git-compat-util.h" +#include "compat/terminal.h" +#include "sigchain.h" +#include "strbuf.h" + +#ifdef HAVE_DEV_TTY + +static int term_fd = -1; +static struct termios old_term; + +static void restore_term(void) +{ + if (term_fd < 0) + return; + + tcsetattr(term_fd, TCSAFLUSH, &old_term); + term_fd = -1; +} + +static void restore_term_on_signal(int sig) +{ + restore_term(); + sigchain_pop(sig); + raise(sig); +} + +char *git_terminal_prompt(const char *prompt, int echo) +{ + static struct strbuf buf = STRBUF_INIT; + int r; + FILE *fh; + + fh = fopen("/dev/tty", "w+"); + if (!fh) + return NULL; + + if (!echo) { + struct termios t; + + if (tcgetattr(fileno(fh), &t) < 0) { + fclose(fh); + return NULL; + } + + old_term = t; + term_fd = fileno(fh); + sigchain_push_common(restore_term_on_signal); + + t.c_lflag &= ~ECHO; + if (tcsetattr(fileno(fh), TCSAFLUSH, &t) < 0) { + term_fd = -1; + fclose(fh); + return NULL; + } + } + + fputs(prompt, fh); + fflush(fh); + + r = strbuf_getline(&buf, fh, '\n'); + if (!echo) { + putc('\n', fh); + fflush(fh); + } + + restore_term(); + fclose(fh); + + if (r == EOF) + return NULL; + return buf.buf; +} + +#else + +char *git_terminal_prompt(const char *prompt, int echo) +{ + return getpass(prompt); +} + +#endif diff --git a/compat/terminal.h b/compat/terminal.h new file mode 100644 index 000000000..97db7cd69 --- /dev/null +++ b/compat/terminal.h @@ -0,0 +1,6 @@ +#ifndef COMPAT_TERMINAL_H +#define COMPAT_TERMINAL_H + +char *git_terminal_prompt(const char *prompt, int echo); + +#endif /* COMPAT_TERMINAL_H */ -- 2.26.2