- serport = CreateFile(cfg->serline, GENERIC_READ | GENERIC_WRITE, 0, NULL,
- OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
+ {
+ /*
+ * Munge the string supplied by the user into a Windows filename.
+ *
+ * Windows supports opening a few "legacy" devices (including
+ * COM1-9) by specifying their names verbatim as a filename to
+ * open. (Thus, no files can ever have these names. See
+ * <http://msdn2.microsoft.com/en-us/library/aa365247.aspx>
+ * ("Naming a File") for the complete list of reserved names.)
+ *
+ * However, this doesn't let you get at devices COM10 and above.
+ * For that, you need to specify a filename like "\\.\COM10".
+ * This is also necessary for special serial and serial-like
+ * devices such as \\.\WCEUSBSH001. It also works for the "legacy"
+ * names, so you can do \\.\COM1 (verified as far back as Win95).
+ * See <http://msdn2.microsoft.com/en-us/library/aa363858.aspx>
+ * (CreateFile() docs).
+ *
+ * So, we believe that prepending "\\.\" should always be the
+ * Right Thing. However, just in case someone finds something to
+ * talk to that doesn't exist under there, if the serial line
+ * contains a backslash, we use it verbatim. (This also lets
+ * existing configurations using \\.\ continue working.)
+ */
+ char *serfilename =
+ dupprintf("%s%s", strchr(serline, '\\') ? "" : "\\\\.\\", serline);
+ serport = CreateFile(serfilename, GENERIC_READ | GENERIC_WRITE, 0, NULL,
+ OPEN_EXISTING, FILE_FLAG_OVERLAPPED, NULL);
+ sfree(serfilename);
+ }
+