ash: add title built-in

Implement a 'title' built-in for ash.  It's very simple-minded,
performs almost no error checking and is completely non-portable.

- With no arguments it prints the current console title.

- If arguments are provided the *first only* is set as the console
  title.

Costs 88-116 bytes.

(GitHub issue #401)

3 files changed, 28 insertions, 2 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 4abdcf459..41d4cd940 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -158,6 +158,7 @@ BOOL conToCharA(LPSTR d);
 BOOL readConsoleInput_utf8(HANDLE h, INPUT_RECORD *r, DWORD len, DWORD *got);
 
 void set_title(const char *str);
+int get_title(char *buf, int len);
 void move_cursor_row(int n);
 void reset_screen(void);
 int winansi_putchar(int c);
diff --git a/shell/ash.c b/shell/ash.c
index d312cb8cd..df27e9c8d 100644
--- a/shell/ash.c
+++ b/shell/ash.c
@@ -11253,6 +11253,9 @@ static int readcmd(int, char **) FAST_FUNC;
 static int setcmd(int, char **) FAST_FUNC;
 static int shiftcmd(int, char **) FAST_FUNC;
 static int timescmd(int, char **) FAST_FUNC;
+#if ENABLE_PLATFORM_MINGW32
+static int titlecmd(int, char **) FAST_FUNC;
+#endif
 static int trapcmd(int, char **) FAST_FUNC;
 static int umaskcmd(int, char **) FAST_FUNC;
 static int unsetcmd(int, char **) FAST_FUNC;
@@ -11352,6 +11355,9 @@ static const struct builtincmd builtintab[] = {
         { BUILTIN_REGULAR       "test"    , testcmd    },
 #endif
         { BUILTIN_SPEC_REG      "times"   , timescmd   },
+#if ENABLE_PLATFORM_MINGW32
+        { BUILTIN_REGULAR       "title"   , titlecmd   },
+#endif
         { BUILTIN_SPEC_REG      "trap"    , trapcmd    },
         { BUILTIN_REGULAR       "true"    , truecmd    },
         { BUILTIN_REGULAR       "type"    , typecmd    },
@@ -15549,6 +15555,21 @@ timescmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
         return 0;
 }
 
+#if ENABLE_PLATFORM_MINGW32
+static int FAST_FUNC
+titlecmd(int argc UNUSED_PARAM, char **argv UNUSED_PARAM)
+{
+        if (*argptr == NULL) {
+                char buffer[256];
+                if (get_title(buffer, sizeof(buffer)))
+                        puts(buffer);
+        } else {
+                set_title(*argptr);
+        }
+        return 0;
+}
+#endif
+
 #if ENABLE_FEATURE_SH_MATH
 /*
  * The let builtin. Partially stolen from GNU Bash, the Bourne Again SHell.
diff --git a/win32/winansi.c b/win32/winansi.c
index 0dd2e17f2..3b7744b39 100644
--- a/win32/winansi.c
+++ b/win32/winansi.c
@@ -179,8 +179,12 @@ int terminal_mode(int reset)
 
 void set_title(const char *str)
 {
-        if (is_console(STDOUT_FILENO))
-                SetConsoleTitle(str);
+        SetConsoleTitle(str);
+}
+
+int get_title(char *buf, int len)
+{
+        return GetConsoleTitle(buf, len);
 }
 
 static HANDLE dup_handle(HANDLE h)