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From: "lh_mouse at 126 dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/64064] basic_filebuf seekoff return value is unusable
 for files opened in text mode on Windows
Date: Fri, 19 Jan 2024 08:18:19 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D64064

--- Comment #2 from LIU Hao <lh_mouse at 126 dot com> ---
It looks that MS STL calls `_fseeki64(fp, ...)` [1], while libstdc++ calls
`lseek(_fileno(fp), ...)` [2].

The seek operation shall take the buffering of `FILE` struct into account,
hence I think the libstdc++ implementation is incorrect.


[1]
https://github.com/microsoft/STL/blob/442029c6fa37f1b6f9203357de09672d57040=
77c/stl/inc/__msvc_filebuf.hpp#L624
[2]
https://github.com/gcc-mirror/gcc/blob/9693459e030977d6e906ea7eb587ed09ee4f=
ddbd/libstdc%2B%2B-v3/config/io/basic_file_stdio.cc#L425=