Fix "tinc start" on Windows when the path contains spaces.

When invoking "tinc start" with spaces in the path, the following
happens:

    > "c:\Program Files (x86)\tinc\tinc.exe" start
    c:\Program: unrecognized argument 'Files'
    Try `c:\Program --help' for more information.

This is caused by inconsistent handling of command line strings between
execvp() and the spawned process' CRT, as documented on MSDN:
http://msdn.microsoft.com/library/431x4c1w.aspx

diff --git a/src/tincctl.c b/src/tincctl.c
index 6227750..12cffeb 100644 (file)
--- a/src/tincctl.c
+++ b/src/tincctl.c
@@ -810,7 +810,19 @@ static int cmd_start(int argc, char *argv[]) {
        int nargc = 0;
        char **nargv = xzalloc((optind + argc) * sizeof *nargv);
 
-       nargv[nargc++] = c;
+       char *arg0 = c;
+#ifdef HAVE_MINGW
+       /*
+          Windows has no real concept of an "argv array". A command line is just one string.
+          The CRT of the new process will decode the command line string to generate argv before calling main(), and (by convention)
+          it uses quotes to handle spaces in arguments.
+          Therefore we need to quote all arguments that might contain spaces. No, execvp() won't do that for us (see MSDN).
+          If we don't do that, then execvp() will run fine but any spaces in the filename contained in arg0 will bleed
+          into the next arguments when the spawned process' CRT parses its command line, resulting in chaos.
+       */
+       xasprintf(&arg0, "\"%s\"", arg0);
+#endif
+       nargv[nargc++] = arg0;
        for(int i = 1; i < optind; i++)
                nargv[nargc++] = orig_argv[i];
        for(int i = 1; i < argc; i++)