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From Evgeny Kotkov <evgeny.kot...@visualsvn.com>
Subject Re: [PATCH] Don't seek to the end when opening files with APR_FOPEN_APPEND
Date Fri, 15 Sep 2017 13:32:19 GMT
Evgeny Kotkov <evgeny.kotkov@visualsvn.com> writes:

> Currently, the Windows implementation of APR_FOPEN_APPEND flag performs
> a seek to the file's end when opening it.
>
> Apparently, this is a leftover from the very first version of handling file
> appends (https://svn.apache.org/r59449) that performed a single seek to
> the file's end when opening it and did not support proper atomic appends
> with multiple process or threads writing to the same file.
>
> Since then, such atomic appends have been implemented, but the seek
> was not removed.  It can cause unexpected behavior when reading from
> a file opened with APR_FOPEN_APPEND, assuming no writes happened
> to the file.  In this case, as there have been no writes, the file offset
> should not be repositioned and reading should start from the beginning of
> the file.  However, due to the unwanted seek during open, the actual reading
> would instead start from the file's end and cause an unexpected EOF.
>
> The attached patch fixes the issue and adds a test for it.  The log message
> is included in the beginning of the patch file.

Committed in https://svn.apache.org/r1808456


Regards,
Evgeny Kotkov

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