Implement Windows password reading

And backfilled a missing function that wasn't introduced until LiteCore hydrogen

Tool.cc

@@ -31,6 +31,7 @@
 #endif
 #include <windows.h>
 #include <io.h>
+#include <conio.h>
 #define isatty _isatty
 #define STDIN_FILENO _fileno(stdin)
 #define STDOUT_FILENO _fileno(stdout)
@@ -181,7 +182,33 @@ bool Tool::dumbReadLine(const char *prompt) {
 
 string Tool::readPassword(const char *prompt) {
 #if defined(_MSC_VER)
-    fail("Sorry, password input is unimplemented on Windows");  //FIX //TODO
+    cout << prompt;
+    string pass;
+    const char BACKSPACE = 8;
+    const char CARRIAGE_RETURN = 13;
+    const char CTRL_C = 3;
+    int next;
+    while((next = _getch()) != CARRIAGE_RETURN) {
+        if(next == CTRL_C) {
+            pass.clear();
+            break;
+        }
+
+        if(next == BACKSPACE) {
+            pass.resize(pass.length() - 1);
+            continue;
+        }
+
+        if(next < ' ') {
+            // Disregard other non-printables
+            continue;
+        }
+
+        pass += static_cast<char>(next);
+    }
+
+    cout << endl;
+    return pass;
 #else
     char *cpass = getpass(prompt);
     string password = cpass;

cblite/cbliteTool.cc

@@ -17,7 +17,6 @@
 //
 
 #include "cbliteTool.hh"
-#include "StringUtil.hh"            // for digittoint(), on non-BSD-like systems
 
 using namespace litecore;
 
@@ -108,6 +107,25 @@ bool CBLiteTool::isDatabasePath(const string &path) {
     return hasSuffix(FilePath(path).fileOrDirName(), kC4DatabaseFilenameExtension);
 }
 
+// TEMP:  Mercury only.  Hydrogen and later have this in StringUtil.hh
+#if defined(__ANDROID__) || defined(__GLIBC__) || defined(_MSC_VER)
+// digittoint is a BSD function, not available on Android, Linux, etc.
+int digittoint(char ch) {
+    int d = ch - '0';
+    if ((unsigned) d < 10) {
+        return d;
+    }
+    d = ch - 'a';
+    if ((unsigned) d < 6) {
+        return d + 10;
+    }
+    d = ch - 'A';
+    if ((unsigned) d < 6) {
+        return d + 10;
+    }
+    return 0;
+}
+#endif // defined(__ANDROID__) || defined(__GLIBC__) || defined(_MSC_VER)
 
 static bool setHexKey(C4EncryptionKey *key, const string &str) {
     if (str.size() != 2 * kC4EncryptionKeySizeAES256)

cblite/cbliteTool.hh

@@ -67,6 +67,8 @@ struct CBLiteFlags {
     C4ListenerConfig        _listenerConfig {};  // all false/0
 };
 
+// Mercury only, remove in Hydrogen
+int digittoint(char ch);
 
 class CBLiteTool : public Tool, public CBLiteFlags {
 public: