[PATCH v3 1/2] add interface for /dev/tty interaction

[Tay Ray Chuan <rctay89@gmail.com>]

Factor out the opening and closing of /dev/tty from
git_terminal_prompt(), so that callers may first test if a controlling
terminal is available before proceeding with prompting proper.

When HAVE_DEV_TTY is not defined, terminal_open() falls back to checking
tty-ness of stdin and stderr, as getpass() uses them both.

Signed-off-by: Tay Ray Chuan <rctay89@gmail.com>
---
 compat/terminal.c | 52 ++++++++++++++++++++++++++++++++++++++++++++--------
 compat/terminal.h | 10 ++++++++++
 2 files changed, 54 insertions(+), 8 deletions(-)

diff --git a/compat/terminal.c b/compat/terminal.c
index 6d16c8f..c85d5c7 100644
--- a/compat/terminal.c
+++ b/compat/terminal.c
@@ -24,15 +24,21 @@ static void restore_term_on_signal(int sig)
 	raise(sig);
 }
 
-char *git_terminal_prompt(const char *prompt, int echo)
+term_t terminal_open(void)
+{
+	return fopen("/dev/tty", "w+");
+}
+
+int terminal_close(term_t term)
+{
+	return fclose(term);
+}
+
+char *terminal_prompt(term_t term, const char *prompt, int echo)
 {
 	static struct strbuf buf = STRBUF_INIT;
 	int r;
-	FILE *fh;
-
-	fh = fopen("/dev/tty", "w+");
-	if (!fh)
-		return NULL;
+	FILE *fh = term;
 
 	if (!echo) {
 		struct termios t;
@@ -64,18 +70,48 @@ char *git_terminal_prompt(const char *prompt, int echo)
 	}
 
 	restore_term();
-	fclose(fh);
 
 	if (r == EOF)
 		return NULL;
 	return buf.buf;
 }
 
+char *git_terminal_prompt(const char *prompt, int echo)
+{
+	char *ret;
+	term_t term;
+
+	term = terminal_open();
+	if (!term)
+		return NULL;
+
+	ret = terminal_prompt(term, prompt, echo);
+
+	terminal_close(term);
+
+	return ret;
+}
+
 #else
 
-char *git_terminal_prompt(const char *prompt, int echo)
+term_t terminal_open()
+{
+	return isatty(0) && isatty(2);
+}
+
+int terminal_close(term_t term)
+{
+	return 0;
+}
+
+char *terminal_prompt(term_t term, const char *prompt, int echo)
 {
 	return getpass(prompt);
 }
 
+char *git_terminal_prompt(const char *prompt, int echo)
+{
+	return terminal_prompt(prompt, echo);
+}
+
 #endif
diff --git a/compat/terminal.h b/compat/terminal.h
index 97db7cd..cf2aa10 100644
--- a/compat/terminal.h
+++ b/compat/terminal.h
@@ -1,6 +1,16 @@
 #ifndef COMPAT_TERMINAL_H
 #define COMPAT_TERMINAL_H
 
+#ifdef HAVE_DEV_TTY
+typedef FILE *term_t;
+#else
+typedef int term_t;
+#endif
+
+term_t terminal_open();
+int terminal_close(term_t term);
+char *terminal_prompt(term_t term, const char *prompt, int echo);
+
 char *git_terminal_prompt(const char *prompt, int echo);
 
 #endif /* COMPAT_TERMINAL_H */
-- 
1.7.12.rc1.187.g6dd9156