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 <phillip.wood@dunelm.org.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

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 */
+	/* no duplex support available */
-	return -full_duplex;
+	return -!!(flags & SAVE_TERM_DUPLEX);
 }
 
 void restore_term(void)

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);