[Bug 1759] New: getc returns 0x000000FF instead of 0xFFFFFFFF (-1) for EOF

[Wine Bugs]

http://bugs.winehq.com/show_bug.cgi?id=1759

Summary: getc returns 0x000000FF instead of 0xFFFFFFFF (-1) for
                    EOF
           Product: Wine
           Version: 20030911
          Platform: PC
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: wine-files
        AssignedTo: [e-mail]
        ReportedBy: [e-mail]

A program I'm working on calls getc (which I assume maps to MSVCRT_getc).  It
has been having problems detecting the EOF condition.  It seems that the first
EOF indication comes as a 0x000000ff (255) instead of 0xffffffff (-1).  This
causes the character 0xff to be processed as a real character.  Strangely
enough, another call to getc_unlocked causes the proper value of 0xffffffff to
be returned, and the EOF is handled.  Unfortunately this extra bogus character
breaks this program which is simply checking against EOF (-1).

while (1) {
  int c;
  c = getc_unlocked(myfile);
  if (c == EOF)
    break;
  else
    // process character
}

This behavior goes away when using the native Win98 msvcrt.dll.  I've looked in
dlls/msvcrt/file.c for anything that could cause this, but everything in there
looked good.  My hunch is that somewhere a character value of 0xff is getting
promoted to int without sign-extension, but I haven't seen this where I have looked.