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| author | Dr. Matthias St. Pierre <matthias.st.pierre@ncp-e.com> | 2021-09-28 16:12:32 +0200 |
|---|---|---|
| committer | Dr. Matthias St. Pierre <matthias.st.pierre@ncp-e.com> | 2021-09-30 14:09:59 +0200 |
| commit | c23abef43ef482e129f440d40c98eb6d3a094e2b (patch) | |
| tree | c817572ba1a2a5c991bc64dcc7831d2a2b02bac2 /doc | |
| parent | b9b45aa45873c63b8207eb527249f430288c17a0 (diff) | |
doc/man3/SSL_set_fd.pod: add note about Windows compiler warning
According to an old stackoverflow thread [1], citing an even older comment by
Andy Polyakov (1875e6db29, Pull up Win64 support from 0.9.8., 2005-07-05),
a cast of 'SOCKET' (UINT_PTR) to 'int' does not create a problem, because although
the documentation [2] claims that the upper limit is INVALID_SOCKET-1 (2^64 - 2),
in practice the socket() implementation on Windows returns an index into the kernel
handle table, the size of which is limited to 2^24 [3].
Add this note to the manual page to avoid unnecessary roundtrips to StackOverflow.
[1] https://stackoverflow.com/questions/1953639/is-it-safe-to-cast-socket-to-int-under-win64
[2] https://docs.microsoft.com/en-us/windows/win32/winsock/socket-data-type-2
[3] https://docs.microsoft.com/en-us/windows/win32/sysinfo/kernel-objects
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/16699)
(cherry picked from commit f8dd5869bca047a23599ac925aace70efcf487ad)
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/man3/SSL_set_fd.pod | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/doc/man3/SSL_set_fd.pod b/doc/man3/SSL_set_fd.pod index 6780d515f9..1e1496cfee 100644 --- a/doc/man3/SSL_set_fd.pod +++ b/doc/man3/SSL_set_fd.pod @@ -45,6 +45,17 @@ The operation succeeded. =back +=head1 NOTES + +On Windows, a socket handle is a 64-bit data type (UINT_PTR), which leads to a +compiler warning (conversion from 'SOCKET' to 'int', possible loss of data) when +passing the socket handle to SSL_set_*fd(). For the time being, this warning can +safely be ignored, because although the Microsoft documentation claims that the +upper limit is INVALID_SOCKET-1 (2^64 - 2), in practice the current socket() +implementation returns an index into the kernel handle table, the size of which +is limited to 2^24. + + =head1 SEE ALSO L<SSL_get_fd(3)>, L<SSL_set_bio(3)>, |