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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 | 248 |
1 files changed, 248 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..fc3aead --- /dev/null +++ b/secure/lib/libcrypto/man/BIO_should_retry.3 @@ -0,0 +1,248 @@ +.\" Automatically generated by Pod::Man 2.28 (Pod::Simple 3.28) +.\" +.\" Standard preamble: +.\" ======================================================================== +.de Sp \" Vertical space (when we can't use .PP) +.if t .sp .5v +.if n .sp +.. +.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. \*(C+ will +.\" give a nicer C++. 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Always turn off hyphenation; it makes +.\" way too many mistakes in technical documents. +.if n .ad l +.nh +.SH "NAME" +BIO_should_retry, BIO_should_read, BIO_should_write, +BIO_should_io_special, BIO_retry_type, BIO_should_retry, +BIO_get_retry_BIO, BIO_get_retry_reason \- BIO retry functions +.SH "SYNOPSIS" +.IX Header "SYNOPSIS" +.Vb 1 +\& #include <openssl/bio.h> +\& +\& #define BIO_should_read(a) ((a)\->flags & BIO_FLAGS_READ) +\& #define BIO_should_write(a) ((a)\->flags & BIO_FLAGS_WRITE) +\& #define BIO_should_io_special(a) ((a)\->flags & BIO_FLAGS_IO_SPECIAL) +\& #define BIO_retry_type(a) ((a)\->flags & BIO_FLAGS_RWS) +\& #define BIO_should_retry(a) ((a)\->flags & BIO_FLAGS_SHOULD_RETRY) +\& +\& #define BIO_FLAGS_READ 0x01 +\& #define BIO_FLAGS_WRITE 0x02 +\& #define BIO_FLAGS_IO_SPECIAL 0x04 +\& #define BIO_FLAGS_RWS (BIO_FLAGS_READ|BIO_FLAGS_WRITE|BIO_FLAGS_IO_SPECIAL) +\& #define BIO_FLAGS_SHOULD_RETRY 0x08 +\& +\& BIO * BIO_get_retry_BIO(BIO *bio, int *reason); +\& int BIO_get_retry_reason(BIO *bio); +.Ve +.SH "DESCRIPTION" +.IX Header "DESCRIPTION" +These functions determine why a \s-1BIO\s0 is not able to read or write data. +They will typically be called after a failed \fIBIO_read()\fR or \fIBIO_write()\fR +call. +.PP +\&\fIBIO_should_retry()\fR is true if the call that produced this condition +should then be retried at a later time. +.PP +If \fIBIO_should_retry()\fR is false then the cause is an error condition. +.PP +\&\fIBIO_should_read()\fR is true if the cause of the condition is that a \s-1BIO\s0 +needs to read data. +.PP +\&\fIBIO_should_write()\fR is true if the cause of the condition is that a \s-1BIO\s0 +needs to read data. +.PP +\&\fIBIO_should_io_special()\fR is true if some \*(L"special\*(R" condition, that is a +reason other than reading or writing is the cause of the condition. +.PP +\&\fIBIO_retry_type()\fR returns a mask of the cause of a retry condition +consisting of the values \fB\s-1BIO_FLAGS_READ\s0\fR, \fB\s-1BIO_FLAGS_WRITE\s0\fR, +\&\fB\s-1BIO_FLAGS_IO_SPECIAL\s0\fR though current \s-1BIO\s0 types will only set one of +these. +.PP +\&\fIBIO_get_retry_BIO()\fR determines the precise reason for the special +condition, it returns the \s-1BIO\s0 that caused this condition and if +\&\fBreason\fR is not \s-1NULL\s0 it contains the reason code. 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 I/O\s0 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 |
