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Diffstat (limited to 'secure/lib/libcrypto/man/BIO_should_retry.3')
| -rw-r--r-- | secure/lib/libcrypto/man/BIO_should_retry.3 | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/secure/lib/libcrypto/man/BIO_should_retry.3 b/secure/lib/libcrypto/man/BIO_should_retry.3 new file mode 100644 index 0000000..44ddb01 --- /dev/null +++ b/secure/lib/libcrypto/man/BIO_should_retry.3 @@ -0,0 +1,253 @@ +.\" Automatically generated by Pod::Man version 1.15 +.\" Thu May 9 13:16:11 2002 +.\" +.\" Standard preamble: +.\" ====================================================================== +.de Sh \" Subsection heading +.br +.if t .Sp +.ne 5 +.PP +\fB\\$1\fR +.PP +.. +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.de Ip \" List item +.br +.ie \\n(.$>=3 .ne \\$3 +.el .ne 3 +.IP "\\$1" \\$2 +.. +.de Vb \" Begin verbatim text +.ft CW +.nf +.ne \\$1 +.. +.de Ve \" End verbatim text +.ft R + +.fi +.. +.\" Set up some character translations and predefined strings. \*(-- will +.\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left +.\" double quote, and \*(R" will give a right double quote. | will give a +.\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used +.\" to do unbreakable dashes and therefore won't be available. \*(C` and +.\" \*(C' expand to `' in nroff, nothing in troff, for use with C<> +.tr \(*W-|\(bv\*(Tr +.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' +.ie n \{\ +. ds -- \(*W- +. ds PI pi +. if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch +. if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch +. ds L" "" +. ds R" "" +. ds C` "" +. ds C' "" +'br\} +.el\{\ +. ds -- \|\(em\| +. ds PI \(*p +. ds L" `` +. ds R" '' +'br\} +.\" +.\" If the F register is turned on, we'll generate index entries on stderr +.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and +.\" index entries marked with X<> in POD. Of course, you'll have to process +.\" the output yourself in some meaningful fashion. +.if \nF \{\ +. de IX +. tm Index:\\$1\t\\n%\t"\\$2" +.. +. nr % 0 +. rr F +.\} +.\" +.\" For nroff, turn off justification. 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The meaning of +the reason code and the action that should be taken depends on +the type of \s-1BIO\s0 that resulted in this condition. +.PP +\&\fIBIO_get_retry_reason()\fR returns the reason for a special condition if +passed the relevant \s-1BIO\s0, for example as returned by \fIBIO_get_retry_BIO()\fR. +.SH "NOTES" +.IX Header "NOTES" +If \fIBIO_should_retry()\fR returns false then the precise \*(L"error condition\*(R" +depends on the \s-1BIO\s0 type that caused it and the return code of the \s-1BIO\s0 +operation. For example if a call to \fIBIO_read()\fR on a socket \s-1BIO\s0 returns +0 and \fIBIO_should_retry()\fR is false then the cause will be that the +connection closed. A similar condition on a file \s-1BIO\s0 will mean that it +has reached \s-1EOF\s0. Some \s-1BIO\s0 types may place additional information on +the error queue. For more details see the individual \s-1BIO\s0 type manual +pages. +.PP +If the underlying I/O structure is in a blocking mode almost all current +\&\s-1BIO\s0 types will not request a retry, because the underlying I/O +calls will not. If the application knows that the \s-1BIO\s0 type will never +signal a retry then it need not call \fIBIO_should_retry()\fR after a failed +\&\s-1BIO\s0 I/O call. This is typically done with file BIOs. +.PP +\&\s-1SSL\s0 BIOs are the only current exception to this rule: they can request a +retry even if the underlying I/O structure is blocking, if a handshake +occurs during a call to \fIBIO_read()\fR. An application can retry the failed +call immediately or avoid this situation by setting \s-1SSL_MODE_AUTO_RETRY\s0 +on the underlying \s-1SSL\s0 structure. +.PP +While an application may retry a failed non blocking call immediately +this is likely to be very inefficient because the call will fail +repeatedly until data can be processed or is available. An application +will normally wait until the necessary condition is satisfied. How +this is done depends on the underlying I/O structure. +.PP +For example if the cause is ultimately a socket and \fIBIO_should_read()\fR +is true then a call to \fIselect()\fR may be made to wait until data is +available and then retry the \s-1BIO\s0 operation. By combining the retry +conditions of several non blocking BIOs in a single \fIselect()\fR call +it is possible to service several BIOs in a single thread, though +the performance may be poor if \s-1SSL\s0 BIOs are present because long delays +can occur during the initial handshake process. +.PP +It is possible for a \s-1BIO\s0 to block indefinitely if the underlying I/O +structure cannot process or return any data. This depends on the behaviour of +the platforms I/O functions. This is often not desirable: one solution +is to use non blocking I/O and use a timeout on the \fIselect()\fR (or +equivalent) call. +.SH "BUGS" +.IX Header "BUGS" +The OpenSSL \s-1ASN1\s0 functions cannot gracefully deal with non blocking I/O: +that is they cannot retry after a partial read or write. This is usually +worked around by only passing the relevant data to \s-1ASN1\s0 functions when +the entire structure can be read or written. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +\&\s-1TBA\s0 |
