MDEV-27090 Windows client - ReadConsoleA does not work correctly with UTF8 codepage

Corresponding Windows bug  https://github.com/microsoft/terminal/issues/4551

Use ReadConsoleW instead and convert to console's input codepage, to
workaround.

Also, disable VT sequences in the console output, as we do not knows what
type of data comes with SELECT, we do not want VT escapes there.

Remove my_cgets()

client/mysql.cc

@@ -88,9 +88,7 @@ extern "C" {
 #endif /* defined(HAVE_CURSES_H) && defined(HAVE_TERM_H) */
 
 #undef bcmp				// Fix problem with new readline
-#if defined(_WIN32)
-#include <conio.h>
-#else
+#if !defined(_WIN32)
 # ifdef __APPLE__
 #  include <editline/readline.h>
 # else
@@ -104,6 +102,98 @@ extern "C" {
 #endif
 }
 
+static CHARSET_INFO *charset_info= &my_charset_latin1;
+
+#if defined(_WIN32)
+/*
+  Set console mode for the whole duration of the client session.
+
+  We need for input
+    - line input (i.e read lines from console)
+    - echo typed characters
+    - "cooked" mode, i.e we do not want to handle all keystrokes,
+      like DEL etc ourselves, yet. We might want handle keystrokes
+      in the future, to implement tab completion, and better
+      (multiline) history.
+
+ Disable VT escapes for the output.We do not know what kind of escapes SELECT would return.
+*/
+struct Console_mode
+{
+  HANDLE in= GetStdHandle(STD_INPUT_HANDLE);
+  HANDLE out= GetStdHandle(STD_OUTPUT_HANDLE);
+  DWORD mode_in=0;
+  DWORD mode_out=0;
+
+  enum {STDIN_CHANGED = 1, STDOUT_CHANGED = 2};
+  int changes=0;
+
+  Console_mode()
+  {
+    if (in && in != INVALID_HANDLE_VALUE && GetConsoleMode(in, &mode_in))
+    {
+      SetConsoleMode(in, ENABLE_ECHO_INPUT|ENABLE_LINE_INPUT|ENABLE_PROCESSED_INPUT);
+      changes |= STDIN_CHANGED;
+    }
+
+    if (out && out != INVALID_HANDLE_VALUE && GetConsoleMode(out, &mode_out))
+    {
+#ifdef ENABLE_VIRTUAL_TERMINAL_INPUT
+      SetConsoleMode(out, mode_out & ~ENABLE_VIRTUAL_TERMINAL_INPUT);
+      changes |= STDOUT_CHANGED;
+#endif
+    }
+  }
+
+  ~Console_mode()
+  {
+    if (changes & STDIN_CHANGED)
+      SetConsoleMode(in, mode_in);
+
+    if(changes & STDOUT_CHANGED)
+      SetConsoleMode(out, mode_out);
+  }
+};
+
+static Console_mode my_conmode;
+
+#define MAX_CGETS_LINE_LEN 65535
+/** Read line from console, chomp EOL*/
+static char *win_readline()
+{
+  static wchar_t wstrbuf[MAX_CGETS_LINE_LEN];
+  static char strbuf[MAX_CGETS_LINE_LEN * 4];
+
+  DWORD nchars= 0;
+  uint len= 0;
+  SetLastError(0);
+  if (!ReadConsoleW(GetStdHandle(STD_INPUT_HANDLE), wstrbuf, MAX_CGETS_LINE_LEN-1,
+                    &nchars, NULL))
+    goto err;
+  if (nchars == 0 && GetLastError() == ERROR_OPERATION_ABORTED)
+    goto err;
+
+  for (;nchars > 0; nchars--)
+  {
+    if (wstrbuf[nchars - 1] != '\n' && wstrbuf[nchars - 1] != '\r')
+      break;
+  }
+
+  if (nchars > 0)
+  {
+    uint errors;
+    len= my_convert(strbuf, sizeof(strbuf), charset_info,
+                    (const char *) wstrbuf, nchars * sizeof(wchar_t),
+                    &my_charset_utf16le_bin, &errors);
+  }
+  strbuf[len]= 0;
+  return strbuf;
+err:
+  return NULL;
+}
+#endif
+
+
 #ifdef HAVE_VIDATTR
 static int have_curses= 0;
 static void my_vidattr(chtype attrs)
@@ -208,7 +298,6 @@ unsigned short terminal_width= 80;
 
 static uint opt_protocol=0;
 static const char *opt_protocol_type= "";
-static CHARSET_INFO *charset_info= &my_charset_latin1;
 
 static uint protocol_to_force= MYSQL_PROTOCOL_DEFAULT;
 
@@ -2033,11 +2122,6 @@ static int get_options(int argc, char **argv)
 
 static int read_and_execute(bool interactive)
 {
-#if defined(_WIN32)
-  String tmpbuf;
-  String buffer;
-#endif
-
   char	*line= NULL;
   char	in_string=0;
   ulong line_number=0;
@@ -2115,26 +2199,7 @@ static int read_and_execute(bool interactive)
 
 #if defined(_WIN32)
       tee_fputs(prompt, stdout);
-      if (!tmpbuf.is_alloced())
-        tmpbuf.alloc(65535);
-      tmpbuf.length(0);
-      buffer.length(0);
-      size_t clen;
-      do
-      {
-	line= my_cgets((char*)tmpbuf.ptr(), tmpbuf.alloced_length()-1, &clen);
-        buffer.append(line, clen);
-        /* 
-           if we got buffer fully filled than there is a chance that
-           something else is still in console input buffer
-        */
-      } while (tmpbuf.alloced_length() <= clen);
-      /* 
-        An empty line is returned from my_cgets when there's error reading :
-        Ctrl-c for example
-      */
-      if (line)
-        line= buffer.c_ptr();
+      line= win_readline();
 #else
       if (opt_outfile)
 	fputs(prompt, OUTFILE);
@@ -2201,10 +2266,7 @@ static int read_and_execute(bool interactive)
     }
   }
 
-#if defined(_WIN32)
-  buffer.free();
-  tmpbuf.free();
-#else
+#if !defined(_WIN32)
   if (interactive)
     /*
       free the last entered line.