Merge #13716: bitcoin-cli: -stdinwalletpassphrase and non-echo stdin passwords

50c4afa3c420f11329cffb091b62beeb96b39183 add newline after -stdin* (Karl-Johan Alm)
7f11fba2e3c7b1e00ffb98504cdcfc2ded9c09cf cli: add -stdinwalletpassphrase for (slightly more) secure CLI (Karl-Johan Alm)
0da503e9475fea5644168544668581796bf66334 add stdin helpers for password input support (Karl-Johan Alm)

Pull request description:

  This PR
  * adds `-stdinwalletpassphrase` for use with `walletpasshprase(change)`
  * adds no-echo for passwords (`-stdinrpcpass` and above)

  It may not be ideal, but it's better than having to clear the screen whenever you unlock the wallet.

ACKs for top commit:
  laanwj:
    code review ACK 50c4afa3c420f11329cffb091b62beeb96b39183

Tree-SHA512: 473db8a303ff360ffaa36ac81a2f82be2136fa82696df0bc4f33cb44033a3ae258b5aa5bbcc1f101f88ae9abe9598ed564ce52877ab139bd5d709833f5275ec6

2 files changed, 90 insertions, 0 deletions

diff --git a/src/compat/stdin.cpp b/src/compat/stdin.cpp
new file mode 100644
index 0000000000..4f2ba1e9c4
--- /dev/null
+++ b/src/compat/stdin.cpp
@@ -0,0 +1,72 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#if defined(HAVE_CONFIG_H)
+#include <config/bitcoin-config.h>
+#endif
+
+#include <cstdio>       // for fileno(), stdin
+
+#ifdef WIN32
+#include <windows.h>    // for SetStdinEcho()
+#include <io.h>         // for isatty()
+#else
+#include <termios.h>    // for SetStdinEcho()
+#include <unistd.h>     // for SetStdinEcho(), isatty()
+#include <sys/poll.h>   // for StdinReady()
+#endif
+
+#include <compat/stdin.h>
+
+// https://stackoverflow.com/questions/1413445/reading-a-password-from-stdcin
+void SetStdinEcho(bool enable)
+{
+#ifdef WIN32
+    HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
+    DWORD mode;
+    GetConsoleMode(hStdin, &mode);
+    if (!enable) {
+        mode &= ~ENABLE_ECHO_INPUT;
+    } else {
+        mode |= ENABLE_ECHO_INPUT;
+    }
+    SetConsoleMode(hStdin, mode);
+#else
+    struct termios tty;
+    tcgetattr(STDIN_FILENO, &tty);
+    if (!enable) {
+        tty.c_lflag &= ~ECHO;
+    } else {
+        tty.c_lflag |= ECHO;
+    }
+    (void)tcsetattr(STDIN_FILENO, TCSANOW, &tty);
+#endif
+}
+
+bool StdinTerminal()
+{
+#ifdef WIN32
+    return _isatty(_fileno(stdin));
+#else
+    return isatty(fileno(stdin));
+#endif
+}
+
+bool StdinReady()
+{
+    if (!StdinTerminal()) {
+        return true;
+    }
+#ifdef WIN32
+    return false;
+#else
+    struct pollfd fds;
+    fds.fd = 0; /* this is STDIN */
+    fds.events = POLLIN;
+    return poll(&fds, 1, 0) == 1;
+#endif
+}
+
+NoechoInst::NoechoInst() { SetStdinEcho(false); }
+NoechoInst::~NoechoInst() { SetStdinEcho(true); }
diff --git a/src/compat/stdin.h b/src/compat/stdin.h
new file mode 100644
index 0000000000..468fe4d6a6
--- /dev/null
+++ b/src/compat/stdin.h
@@ -0,0 +1,18 @@
+// Copyright (c) 2018 The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_COMPAT_STDIN_H
+#define BITCOIN_COMPAT_STDIN_H
+
+struct NoechoInst {
+    NoechoInst();
+    ~NoechoInst();
+};
+
+#define NO_STDIN_ECHO() NoechoInst _no_echo
+
+bool StdinTerminal();
+bool StdinReady();
+
+#endif // BITCOIN_COMPAT_STDIN_H