Re: PSPP on windows: backtraces.

[John Darrington]

On Wed, Feb 21, 2007 at 07:38:27AM -0800, Ben Pfaff wrote:
     John Darrington <address@hidden> writes:
     
     > So it looks as if there may be a problem with dfm_put_record.
     > Examining that function, I'm suspicious, because:
     >
     >  switch (fh_get_mode (w->fh))
     >     {
     >     case FH_MODE_TEXT:
     >       fwrite (rec, len, 1, w->file);
     >       putc ('\n', w->file);
     >       break;
     >
     >     case FH_MODE_BINARY:
     >       {
     >         size_t record_width = fh_get_record_width (w->fh);
     >         size_t write_bytes = MIN (len, record_width);
     >         size_t pad_bytes = record_width - write_bytes;
     >         fwrite (rec, write_bytes, 1, w->file);
     >
     > ... the tests for record_width are not performed in the first case.
     > And this case I suspect never arises except under windows.  I suggest
     > that we start by putting some assertions in the first case of this
     > switch  and see what happens.
     
     This is probably a red herring.  The record width here is the
     desired width of the *output* record.  Most of the time, the file
     handle is set for "text" mode, in which the output takes the form
     of lines of text terminating by new-line characters.  (This has
     little to do with whether the FILE * is opened in text or binary
     mode.)  In this mode, there's no fixed record width, so the
     record width isn't checked.

You're right.  

Looking at the code again, I think the line
        fwrite (rec, len, 1, w->file);

is not strictly correct.  It ought to read

       fwrite (rec, sizeof (*rec), len, w->file);

I'm also wondering if, on mingw32, putc ('\n', w->file) ought not to
be followed by putc ('\r', w->file).


I rather doubt that these changes will fix these crashes, but who
knows ....?

J'


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