Re: [Mingw-users] Grep 2.5 for MinGW [Was: Problem with Grep]

[Earnie Boyd]

CC: make-w32 because this has direct effect on implementation.

Wu Yongwei wrote:
> Check the following simple program:
>
> ********************************************************************
> #include <io.h>
> #include <stdio.h>
> #include <errno.h>
>
> int main()
> {
>     char buf[30705];
>     int n;
>     //setvbuf(stdin, NULL, _IONBF, 0);
>     n = read(0, buf, sizeof buf);
>     printf("%d\n", n);
>     if (n < 0)
>         printf("%d\n", errno);
>     return 0;
> }
> ********************************************************************
>
> This program will output -1 and 12 when running on my Windows 2000 box. 
> Changing 30705 to 30704 will make it work. Uncommenting the line setvbuf 
> has no effects. Building with MSVC 6 has the identical ouput.

Interesting error, "Not enough space"!  The maximum limit for NT4 
cmd.exe is 30698.  As Luke pointed out, this doesn't happen with the 
MSYS console.  I was asking about setvbuf because it sets the iostream 
to nonbuffered.  Ironic though, the Run-Time Library Reference manual 
uses 60000 in the _read() example.

> Since I had MSVC and the CRT source, I tried tracing into read(), and 
> found the failure occurred at the following line:
>
>   if ( !ReadFile( (HANDLE)_osfhnd(fh), buffer, cnt, (LPDWORD)&os_read,
>                   NULL ) )
>
> So the problem seems to be in the OS level? I cannot dig more since I do 
> not have the source of ReadFile().

Seems more to be a problem with cmd.exe.

Earnie.