[Bug 8346] New: cmd crashes on malformed statement

[Wine Bugs]

http://bugs.winehq.org/show_bug.cgi?id=8346

Summary: cmd crashes on malformed statement
           Product: Wine
           Version: CVS
          Platform: Other
        OS/Version: other
            Status: NEW
          Keywords: download
          Severity: normal
          Priority: P2
         Component: wine-programs
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

The command
  cmd /c foo.cmd
where foo.cmd contains
  if not defined %x echo yes
crashes.  (It's not valid cmd syntax, but I did observe this in
the wild.)  Turns out cmd's WCMD_if is trying to strdup a null string.

=>1 0xf7de42a3 (0x00341048)
  2 0x7e58efcd WCMD_if+0xfc(p=0x16c6db) [.../programs/cmd/builtins.c:808] in cmd
(0x00341188)
  3 0x7e5946f8 WCMD_process_command+0x162d(command=...)
[...programs/cmd/wcmdmain.c:641] in cmd (0x00345278)

Wine-dbg>frame 1
808         command = strdup (command);