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Re: [PATCH] Duplicate close of file handle on WIN32

From: Patrick Mayweg <mayweg_at_qint.de>
Date: 2003-02-01 07:28:10 CET

Hi Ryan,
rbb@rkbloom.net wrote:

>Why is SVN registering a cleanup in this code at all? The comment says
>that we have to close the file when the apr_file_t goes away, but the
>apr_file_t already has a cleanup in it. This means that the cleanup
>registered by svn is superfluous. Just remove that line and this problem
>should go away.
>
If we do not close the file descriptor, we will run out of file
descriptors in the c-library. There 512 of those max. If you have a gui
client, this number will be reached soon.

>
>Also, there is a FIXME in that code that talks about getting a pool from
>an APR type. While that line should just go away for the reasons given
>above, any other lines like that should be changed to apr_foo_pool_get().
>
This is a different kind of problem, which I did not wanted to fix right
now.

>
>Ryan
>
>
Patrick

>On Fri, 31 Jan 2003, Patrick Mayweg wrote:
>
>
>
>>Hi,
>>when a file descriptor is needed for neon the function
>>svn_io_fd_from_file is called. On WIN32 it creates a file descriptor
>>from the Win32-Handle. It also registers a cleanup function to close the
>>
>>file descriptor. This also closes the Win32-Handle, which is also closed
>>
>>for the apr-file. This is one closeing too many. Only if you run svn in
>>a debugger, this problem shows up. The right thing to do is to duplicate
>>
>>the handle. I have written a patch for that and it fixes my problem.
>>
>>* ./subversion/libsvn_subr/io.c
>>
>> (svn_io_fd_from_file) Added call to DuplicateHandle
>>
>>Index: subversion/libsvn_subr/io.c
>>===================================================================
>>--- subversion/libsvn_subr/io.c (revision 4685)
>>+++ subversion/libsvn_subr/io.c (working copy)
>>@@ -1674,7 +1674,15 @@
>> #ifndef SVN_WIN32
>> *fd_p = fd;
>> #else
>>- *fd_p = _open_osfhandle ((long) fd, _O_RDWR);
>>+ apr_os_file_t fd2 = 0;
>>+ if (DuplicateHandle (GetCurrentProcess(), fd, GetCurrentProcess(),
>>+ (LPHANDLE)&fd2, 0, FALSE,
>>+ DUPLICATE_SAME_ACCESS) == FALSE)
>>+ {
>>+ status = APR_EBADF;
>>+ return status;
>>+ }
>>+ *fd_p = _open_osfhandle ((long) fd2, _O_RDWR);
>>
>> /* We must close the file descriptor when the apr_file_t is
>> closed, otherwise we'll run out of them. What happens if the
>>
>>
>>Regards,
>>Patrick Mayweg
>>
>>
>>
>>
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>>
>>
>
>
>

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Received on Sat Feb 1 07:29:00 2003

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