✏ 编辑: BIO_vfree.3

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.\" ========================================================================
.\"
.IX Title "BIO_new 3"
.TH BIO_new 3 "2019-12-20" "1.0.2u" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
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.nh
.SH "NAME"
BIO_new, BIO_set, BIO_free, BIO_vfree, BIO_free_all \- BIO allocation and freeing functions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/bio.h>
\&
\& BIO *  BIO_new(BIO_METHOD *type);
\& int    BIO_set(BIO *a,BIO_METHOD *type);
\& int    BIO_free(BIO *a);
\& void   BIO_vfree(BIO *a);
\& void   BIO_free_all(BIO *a);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
The \fIBIO_new()\fR function returns a new \s-1BIO\s0 using method \fBtype\fR.
.PP
\&\fIBIO_set()\fR sets the method of an already existing \s-1BIO.\s0
.PP
\&\fIBIO_free()\fR frees up a single \s-1BIO,\s0 \fIBIO_vfree()\fR also frees up a single \s-1BIO\s0
but it does not return a value. Calling \fIBIO_free()\fR may also have some effect
on the underlying I/O structure, for example it may close the file being
referred to under certain circumstances. For more details see the individual
\&\s-1BIO_METHOD\s0 descriptions.
.PP
\&\fIBIO_free_all()\fR frees up an entire \s-1BIO\s0 chain, it does not halt if an error
occurs freeing up an individual \s-1BIO\s0 in the chain.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIBIO_new()\fR returns a newly created \s-1BIO\s0 or \s-1NULL\s0 if the call fails.
.PP
\&\fIBIO_set()\fR, \fIBIO_free()\fR return 1 for success and 0 for failure.
.PP
\&\fIBIO_free_all()\fR and \fIBIO_vfree()\fR do not return values.
.SH "NOTES"
.IX Header "NOTES"
Some BIOs (such as memory BIOs) can be used immediately after calling
\&\fIBIO_new()\fR. Others (such as file BIOs) need some additional initialization,
and frequently a utility function exists to create and initialize such BIOs.
.PP
If \fIBIO_free()\fR is called on a \s-1BIO\s0 chain it will only free one \s-1BIO\s0 resulting
in a memory leak.
.PP
Calling \fIBIO_free_all()\fR a single \s-1BIO\s0 has the same effect as calling \fIBIO_free()\fR
on it other than the discarded return value.
.PP
Normally the \fBtype\fR argument is supplied by a function which returns a
pointer to a \s-1BIO_METHOD.\s0 There is a naming convention for such functions:
a source/sink \s-1BIO\s0 is normally called BIO_s_*() and a filter \s-1BIO\s0
BIO_f_*();
.SH "EXAMPLE"
.IX Header "EXAMPLE"
Create a memory \s-1BIO:\s0
.PP
.Vb 1
\& BIO *mem = BIO_new(BIO_s_mem());
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1TBA\s0

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