Switch from OpenSSL 0.9.7d to 0.9.7e.
[dragonfly.git] / secure / lib / libcrypto / man / BIO_read.3
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2''' $RCSfile$$Revision$$Date$
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4''' $Log$
5'''
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34'''
35'''
36''' Set up \*(-- to give an unbreakable dash;
37''' string Tr holds user defined translation string.
38''' Bell System Logo is used as a dummy character.
39'''
984263bc 40.tr \(*W-|\(bv\*(Tr
984263bc 41.ie n \{\
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42.ds -- \(*W-
43.ds PI pi
44.if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch
45.if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch
46.ds L" ""
47.ds R" ""
48''' \*(M", \*(S", \*(N" and \*(T" are the equivalent of
49''' \*(L" and \*(R", except that they are used on ".xx" lines,
50''' such as .IP and .SH, which do another additional levels of
51''' double-quote interpretation
52.ds M" """
53.ds S" """
54.ds N" """""
55.ds T" """""
56.ds L' '
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62'br\}
63.el\{\
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64.ds -- \(em\|
65.tr \*(Tr
66.ds L" ``
67.ds R" ''
68.ds M" ``
69.ds S" ''
70.ds N" ``
71.ds T" ''
72.ds L' `
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77.ds T' '
78.ds PI \(*p
984263bc 79'br\}
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80.\" If the F register is turned on, we'll generate
81.\" index entries out stderr for the following things:
82.\" TH Title
83.\" SH Header
84.\" Sh Subsection
85.\" Ip Item
86.\" X<> Xref (embedded
87.\" Of course, you have to process the output yourself
88.\" in some meaninful fashion.
89.if \nF \{
90.de IX
91.tm Index:\\$1\t\\n%\t"\\$2"
984263bc 92..
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93.nr % 0
94.rr F
984263bc 95.\}
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96.TH BIO_read 3 "0.9.7d" "2/Sep/2004" "OpenSSL"
97.UC
98.if n .hy 0
984263bc 99.if n .na
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100.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
101.de CQ \" put $1 in typewriter font
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103'if n "\c
104'if t \\&\\$1\c
105'if n \\&\\$1\c
106'if n \&"
107\\&\\$2 \\$3 \\$4 \\$5 \\$6 \\$7
108'.ft R
109..
110.\" @(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2
111. \" AM - accent mark definitions
984263bc 112.bd B 3
74dab6c2 113. \" fudge factors for nroff and troff
984263bc 114.if n \{\
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115. ds #H 0
116. ds #V .8m
117. ds #F .3m
118. ds #[ \f1
119. ds #] \fP
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120.\}
121.if t \{\
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122. ds #H ((1u-(\\\\n(.fu%2u))*.13m)
123. ds #V .6m
124. ds #F 0
125. ds #[ \&
126. ds #] \&
984263bc 127.\}
74dab6c2 128. \" simple accents for nroff and troff
984263bc 129.if n \{\
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130. ds ' \&
131. ds ` \&
132. ds ^ \&
133. ds , \&
134. ds ~ ~
135. ds ? ?
136. ds ! !
137. ds /
138. ds q
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139.\}
140.if t \{\
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141. ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u"
142. ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u'
143. ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u'
144. ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u'
145. ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u'
146. ds ? \s-2c\h'-\w'c'u*7/10'\u\h'\*(#H'\zi\d\s+2\h'\w'c'u*8/10'
147. ds ! \s-2\(or\s+2\h'-\w'\(or'u'\v'-.8m'.\v'.8m'
148. ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u'
149. ds q o\h'-\w'o'u*8/10'\s-4\v'.4m'\z\(*i\v'-.4m'\s+4\h'\w'o'u*8/10'
984263bc 150.\}
74dab6c2 151. \" troff and (daisy-wheel) nroff accents
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156.ds . \\k:\h'-(\\n(.wu*8/10)'\v'\*(#V*4/10'\z.\v'-\*(#V*4/10'\h'|\\n:u'
157.ds 3 \*(#[\v'.2m'\s-2\&3\s0\v'-.2m'\*(#]
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159.ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H'
160.ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u'
161.ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#]
162.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
163.ds ae a\h'-(\w'a'u*4/10)'e
164.ds Ae A\h'-(\w'A'u*4/10)'E
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167. \" corrections for vroff
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168.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
169.if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u'
74dab6c2 170. \" for low resolution devices (crt and lpr)
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171.if \n(.H>23 .if \n(.V>19 \
172\{\
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173. ds : e
174. ds 8 ss
175. ds v \h'-1'\o'\(aa\(ga'
176. ds _ \h'-1'^
177. ds . \h'-1'.
178. ds 3 3
179. ds o a
180. ds d- d\h'-1'\(ga
181. ds D- D\h'-1'\(hy
182. ds th \o'bp'
183. ds Th \o'LP'
184. ds ae ae
185. ds Ae AE
186. ds oe oe
187. ds Oe OE
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188.\}
189.rm #[ #] #H #V #F C
984263bc 190.SH "NAME"
74dab6c2 191BIO_read, BIO_write, BIO_gets, BIO_puts \- BIO I/O functions
984263bc 192.SH "SYNOPSIS"
74dab6c2 193.PP
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194.Vb 1
195\& #include <openssl/bio.h>
196.Ve
197.Vb 4
198\& int BIO_read(BIO *b, void *buf, int len);
199\& int BIO_gets(BIO *b,char *buf, int size);
200\& int BIO_write(BIO *b, const void *buf, int len);
201\& int BIO_puts(BIO *b,const char *buf);
202.Ve
203.SH "DESCRIPTION"
74dab6c2 204\fIBIO_read()\fR attempts to read \fBlen\fR bytes from BIO \fBb\fR and places
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205the data in \fBbuf\fR.
206.PP
74dab6c2 207\fIBIO_gets()\fR performs the BIOs \*(L"gets\*(R" operation and places the data
984263bc 208in \fBbuf\fR. Usually this operation will attempt to read a line of data
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209from the BIO of maximum length \fBlen\fR. There are exceptions to this
210however, for example \fIBIO_gets()\fR on a digest BIO will calculate and
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211return the digest and other BIOs may not support \fIBIO_gets()\fR at all.
212.PP
74dab6c2 213\fIBIO_write()\fR attempts to write \fBlen\fR bytes from \fBbuf\fR to BIO \fBb\fR.
984263bc 214.PP
74dab6c2 215\fIBIO_puts()\fR attempts to write a null terminated string \fBbuf\fR to BIO \fBb\fR
984263bc 216.SH "RETURN VALUES"
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217All these functions return either the amount of data successfully read or
218written (if the return value is positive) or that no data was successfully
219read or written if the result is 0 or \-1. If the return value is \-2 then
74dab6c2 220the operation is not implemented in the specific BIO type.
984263bc 221.SH "NOTES"
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222A 0 or \-1 return is not necessarily an indication of an error. In
223particular when the source/sink is non-blocking or of a certain type
224it may merely be an indication that no data is currently available and that
225the application should retry the operation later.
226.PP
227One technique sometimes used with blocking sockets is to use a system call
228(such as \fIselect()\fR, \fIpoll()\fR or equivalent) to determine when data is available
229and then call \fIread()\fR to read the data. The equivalent with BIOs (that is call
74dab6c2 230\fIselect()\fR on the underlying I/O structure and then call \fIBIO_read()\fR to
984263bc 231read the data) should \fBnot\fR be used because a single call to \fIBIO_read()\fR
74dab6c2 232can cause several reads (and writes in the case of SSL BIOs) on the underlying
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233I/O structure and may block as a result. Instead \fIselect()\fR (or equivalent)
234should be combined with non blocking I/O so successive reads will request
235a retry instead of blocking.
236.PP
237See BIO_should_retry(3) for details of how to
238determine the cause of a retry and other I/O issues.
239.PP
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240If the \fIBIO_gets()\fR function is not supported by a BIO then it possible to
241work around this by adding a buffering BIO BIO_f_buffer(3)
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242to the chain.
243.SH "SEE ALSO"
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244BIO_should_retry(3)
245.PP
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246TBA
247
248.rn }` ''
249.IX Title "BIO_read 3"
250.IX Name "BIO_read, BIO_write, BIO_gets, BIO_puts - BIO I/O functions"
251
252.IX Header "NAME"
253
254.IX Header "SYNOPSIS"
255
256.IX Header "DESCRIPTION"
257
258.IX Header "RETURN VALUES"
259
260.IX Header "NOTES"
261
262.IX Header "SEE ALSO"
263