@matheusbsbs / matheus-bagliano / commits / 21aeafceda

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 <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>

Jeff King committed Dec 10, 2011 at 05:41 UTC 21aeafceda2382d26bfa73a98ba45a937d65d77a
3 files changed +96
Makefile
+9
@@ -229,6 +229,9 @@ all::
229 #
230 # Define NO_REGEX if you have no or inferior regex support in your C library.
231 #
232 +# Define HAVE_DEV_TTY if your system can open /dev/tty to interact with the
233 +# user.
234 +#
235 # Define GETTEXT_POISON if you are debugging the choice of strings marked
236 # for translation. In a GETTEXT_POISON build, you can turn all strings marked
237 # for translation into gibberish by setting the GIT_GETTEXT_POISON variable
@@ -523,6 +526,7 @@ LIB_H += compat/bswap.h
526 LIB_H += compat/cygwin.h
527 LIB_H += compat/mingw.h
528 LIB_H += compat/obstack.h
529 +LIB_H += compat/terminal.h
530 LIB_H += compat/win32/pthread.h
531 LIB_H += compat/win32/syslog.h
532 LIB_H += compat/win32/poll.h
@@ -610,6 +614,7 @@ LIB_OBJS += color.o
614 LIB_OBJS += combine-diff.o
615 LIB_OBJS += commit.o
616 LIB_OBJS += compat/obstack.o
617 +LIB_OBJS += compat/terminal.o
618 LIB_OBJS += config.o
619 LIB_OBJS += connect.o
620 LIB_OBJS += connected.o
@@ -1646,6 +1651,10 @@ ifdef HAVE_PATHS_H
1651 BASIC_CFLAGS += -DHAVE_PATHS_H
1652 endif
1653
1654 +ifdef HAVE_DEV_TTY
1655 + BASIC_CFLAGS += -DHAVE_DEV_TTY
1656 +endif
1657 +
1658 ifdef DIR_HAS_BSD_GROUP_SEMANTICS
1659 COMPAT_CFLAGS += -DDIR_HAS_BSD_GROUP_SEMANTICS
1660 endif
compat/terminal.c new
+81
@@ -0,0 +1,81 @@
1 +#include "git-compat-util.h"
2 +#include "compat/terminal.h"
3 +#include "sigchain.h"
4 +#include "strbuf.h"
5 +
6 +#ifdef HAVE_DEV_TTY
7 +
8 +static int term_fd = -1;
9 +static struct termios old_term;
10 +
11 +static void restore_term(void)
12 +{
13 + if (term_fd < 0)
14 + return;
15 +
16 + tcsetattr(term_fd, TCSAFLUSH, &old_term);
17 + term_fd = -1;
18 +}
19 +
20 +static void restore_term_on_signal(int sig)
21 +{
22 + restore_term();
23 + sigchain_pop(sig);
24 + raise(sig);
25 +}
26 +
27 +char *git_terminal_prompt(const char *prompt, int echo)
28 +{
29 + static struct strbuf buf = STRBUF_INIT;
30 + int r;
31 + FILE *fh;
32 +
33 + fh = fopen("/dev/tty", "w+");
34 + if (!fh)
35 + return NULL;
36 +
37 + if (!echo) {
38 + struct termios t;
39 +
40 + if (tcgetattr(fileno(fh), &t) < 0) {
41 + fclose(fh);
42 + return NULL;
43 + }
44 +
45 + old_term = t;
46 + term_fd = fileno(fh);
47 + sigchain_push_common(restore_term_on_signal);
48 +
49 + t.c_lflag &= ~ECHO;
50 + if (tcsetattr(fileno(fh), TCSAFLUSH, &t) < 0) {
51 + term_fd = -1;
52 + fclose(fh);
53 + return NULL;
54 + }
55 + }
56 +
57 + fputs(prompt, fh);
58 + fflush(fh);
59 +
60 + r = strbuf_getline(&buf, fh, '\n');
61 + if (!echo) {
62 + putc('\n', fh);
63 + fflush(fh);
64 + }
65 +
66 + restore_term();
67 + fclose(fh);
68 +
69 + if (r == EOF)
70 + return NULL;
71 + return buf.buf;
72 +}
73 +
74 +#else
75 +
76 +char *git_terminal_prompt(const char *prompt, int echo)
77 +{
78 + return getpass(prompt);
79 +}
80 +
81 +#endif
compat/terminal.h new
+6
@@ -0,0 +1,6 @@
1 +#ifndef COMPAT_TERMINAL_H
2 +#define COMPAT_TERMINAL_H
3 +
4 +char *git_terminal_prompt(const char *prompt, int echo);
5 +
6 +#endif /* COMPAT_TERMINAL_H */