osdep: add qemu_set_tty_echo()

Using stdin with readline.c requires disabling echo and line buffering.
Add a portable wrapper to set the terminal attributes under Linux and
Windows.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

include/qemu/osdep.h

@@ -240,4 +240,6 @@ static inline void qemu_init_auxval(char **envp) { }
 void qemu_init_auxval(char **envp);
 #endif
 
+void qemu_set_tty_echo(int fd, bool echo);
+
 #endif

util/oslib-posix.c

@@ -47,6 +47,9 @@ extern int daemon(int, int);
 #  define QEMU_VMALLOC_ALIGN getpagesize()
 #endif
 
+#include <termios.h>
+#include <unistd.h>
+
 #include <glib/gprintf.h>
 
 #include "config-host.h"
@@ -251,3 +254,18 @@ qemu_get_local_state_pathname(const char *relative_pathname)
     return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
                            relative_pathname);
 }
+
+void qemu_set_tty_echo(int fd, bool echo)
+{
+    struct termios tty;
+
+    tcgetattr(fd, &tty);
+
+    if (echo) {
+        tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
+    } else {
+        tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
+    }
+
+    tcsetattr(fd, TCSANOW, &tty);
+}

util/oslib-win32.c

@@ -189,3 +189,22 @@ qemu_get_local_state_pathname(const char *relative_pathname)
     return g_strdup_printf("%s" G_DIR_SEPARATOR_S "%s", base_path,
                            relative_pathname);
 }
+
+void qemu_set_tty_echo(int fd, bool echo)
+{
+    HANDLE handle = (HANDLE)_get_osfhandle(fd);
+    DWORD dwMode = 0;
+
+    if (handle == INVALID_HANDLE_VALUE) {
+        return;
+    }
+
+    GetConsoleMode(handle, &dwMode);
+
+    if (echo) {
+        SetConsoleMode(handle, dwMode | ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT);
+    } else {
+        SetConsoleMode(handle,
+                       dwMode & ~(ENABLE_ECHO_INPUT | ENABLE_LINE_INPUT));
+    }
+}