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Diffstat (limited to 'secure/lib/libcrypto/man/BIO_read.3')
| -rw-r--r-- | secure/lib/libcrypto/man/BIO_read.3 | 203 |
1 files changed, 203 insertions, 0 deletions
diff --git a/secure/lib/libcrypto/man/BIO_read.3 b/secure/lib/libcrypto/man/BIO_read.3 new file mode 100644 index 0000000..9b0b5ba --- /dev/null +++ b/secure/lib/libcrypto/man/BIO_read.3 @@ -0,0 +1,203 @@ +.\" Automatically generated by Pod::Man version 1.15 +.\" Thu May 9 13:15:48 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. Always turn off hyphenation; it +.\" makes way too many mistakes in technical documents. +.hy 0 +.if n .na +.\" +.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). +.\" Fear. Run. Save yourself. 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Usually this operation will attempt to read a line of data +from the \s-1BIO\s0 of maximum length \fBlen\fR. There are exceptions to this +however, for example \fIBIO_gets()\fR on a digest \s-1BIO\s0 will calculate and +return the digest and other BIOs may not support \fIBIO_gets()\fR at all. +.PP +\&\fIBIO_write()\fR attempts to write \fBlen\fR bytes from \fBbuf\fR to \s-1BIO\s0 \fBb\fR. +.PP +\&\fIBIO_puts()\fR attempts to write a null terminated string \fBbuf\fR to \s-1BIO\s0 \fBb\fR +.SH "RETURN VALUES" +.IX Header "RETURN VALUES" +All these functions return either the amount of data successfully read or +written (if the return value is positive) or that no data was successfully +read or written if the result is 0 or \-1. If the return value is \-2 then +the operation is not implemented in the specific \s-1BIO\s0 type. +.SH "NOTES" +.IX Header "NOTES" +A 0 or \-1 return is not necessarily an indication of an error. In +particular when the source/sink is non-blocking or of a certain type +it may merely be an indication that no data is currently available and that +the application should retry the operation later. +.PP +One technique sometimes used with blocking sockets is to use a system call +(such as \fIselect()\fR, \fIpoll()\fR or equivalent) to determine when data is available +and then call \fIread()\fR to read the data. The equivalent with BIOs (that is call +\&\fIselect()\fR on the underlying I/O structure and then call \fIBIO_read()\fR to +read the data) should \fBnot\fR be used because a single call to \fIBIO_read()\fR +can cause several reads (and writes in the case of \s-1SSL\s0 BIOs) on the underlying +I/O structure and may block as a result. Instead \fIselect()\fR (or equivalent) +should be combined with non blocking I/O so successive reads will request +a retry instead of blocking. +.PP +See BIO_should_retry(3) for details of how to +determine the cause of a retry and other I/O issues. +.PP +If the \fIBIO_gets()\fR function is not supported by a \s-1BIO\s0 then it possible to +work around this by adding a buffering \s-1BIO\s0 BIO_f_buffer(3) +to the chain. +.SH "SEE ALSO" +.IX Header "SEE ALSO" +BIO_should_retry(3) +.PP +\&\s-1TBA\s0 |
