Re: [bug] Crazy I/O. -cont.

Re: [bug] Crazy I/O. -cont.

[Michael V. Nikolaev]

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I took a look at implementation of FILE structure in newlib/libc/include/sys/reent.h (src distribution). It contains the field -offset:

struct __sFILE {
    ...
    int    _offset;    /* current lseek offset */
    ...
};

Struct FILE typedef'ed as __sFILE. So, there exist two file offset references: one for streams, another for block I/O. I think, block I/O is based on WinAPI file I/O. Stream I/O should be built, in general, on block I/O level. And when you use lseek() the resulting file offset is not sinchronized with the file offset field in the respective stream structure (*stdin, in your case) because block I/O knows nothing about stream I/O.

Regards,

Micahel

-----Original Message-----
From: Earnie Boyd <earnie_boyd@yahoo.com>
To: Michael V. Nikolaev <mvn@gu.kiev.ua>; cygwin users <cygwin@sourceware.cygnus.com>
Date: 8 áåðåçíÿ 1999 ð. 21:45
Subject: Re: [bug] Crazy I/O.


>---"Michael V. Nikolaev" <mvn@gu.kiev.ua> wrote:
>>
>> 
>> -----Original Message-----
>> From: Earnie Boyd <earnie_boyd@yahoo.com>
>> To: cygwin users <cygwin@sourceware.cygnus.com>
>> Date: 8 áåðåçíÿ 1999 ð. 18:46
>> Subject: [bug] Crazy I/O.
>> 
>> 
>> Hi!
>> 
>> You use stdin as a _stream_ when calling gets(). So, try to call
>fseek(stdin, 0L, SEEK_SET) after the second dup2(). It should work.
>> 
>
>Didn't help.  Besides, it shouldn't be needed.
>==
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Re: [bug] Crazy I/O. -cont.

[Michael V. Nikolaev]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
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I took a look at implementation of FILE structure in newlib/libc/include/sys/reent.h (src distribution). It contains the field -offset:

struct __sFILE {
    ...
    int    _offset;    /* current lseek offset */
    ...
};

Struct FILE typedef'ed as __sFILE. So, there exist two file offset references: one for streams, another for block I/O. I think, block I/O is based on WinAPI file I/O. Stream I/O should be built, in general, on block I/O level. And when you use lseek() the resulting file offset is not sinchronized with the file offset field in the respective stream structure (*stdin, in your case) because block I/O knows nothing about stream I/O.

Regards,

Micahel

-----Original Message-----
From: Earnie Boyd <earnie_boyd@yahoo.com>
To: Michael V. Nikolaev <mvn@gu.kiev.ua>; cygwin users <cygwin@sourceware.cygnus.com>
Date: 8 áåðåçíÿ 1999 ð. 21:45
Subject: Re: [bug] Crazy I/O.


>---"Michael V. Nikolaev" <mvn@gu.kiev.ua> wrote:
>>
>> 
>> -----Original Message-----
>> From: Earnie Boyd <earnie_boyd@yahoo.com>
>> To: cygwin users <cygwin@sourceware.cygnus.com>
>> Date: 8 áåðåçíÿ 1999 ð. 18:46
>> Subject: [bug] Crazy I/O.
>> 
>> 
>> Hi!
>> 
>> You use stdin as a _stream_ when calling gets(). So, try to call
>fseek(stdin, 0L, SEEK_SET) after the second dup2(). It should work.
>> 
>
>Didn't help.  Besides, it shouldn't be needed.
>==
>-                        \\||//
>-------------------o0O0--Earnie--0O0o-------------------
>--                earnie_boyd@yahoo.com               --
>-- http://www.freeyellow.com/members5/gw32/index.html --
>----------------------ooo0O--O0ooo----------------------
>
>PS: Newbie's, you should visit my page.
>_________________________________________________________
>DO YOU YAHOO!?
>Get your free @yahoo.com address at http://mail.yahoo.com
>
\vKCB•Ø[\b\x1d^[È\x1d[œÝXœØܚX™H\x19œ›ÛH\x1d\x1a\x1a\È^[\x1a\Ý\x0fÃB”Ù[™\b\x18H^[Y\ÜØYÙH\x1d^[È\x18ÞYÝÚ[‹][œÝXœØܚX™P\x1cÛÝ\˜Ù]Ø\™K˜ÞY۝\˘ÛÛCB