✏ 编辑: BIO_f_base64.3

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.IX Title "BIO_f_base64 3"
.TH BIO_f_base64 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_f_base64 \- base64 BIO filter
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\& #include <openssl/bio.h>
\& #include <openssl/evp.h>
\&
\& BIO_METHOD *   BIO_f_base64(void);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIBIO_f_base64()\fR returns the base64 \s-1BIO\s0 method. This is a filter
\&\s-1BIO\s0 that base64 encodes any data written through it and decodes
any data read through it.
.PP
Base64 BIOs do not support \fIBIO_gets()\fR or \fIBIO_puts()\fR.
.PP
\&\fIBIO_flush()\fR on a base64 \s-1BIO\s0 that is being written through is
used to signal that no more data is to be encoded: this is used
to flush the final block through the \s-1BIO.\s0
.PP
The flag \s-1BIO_FLAGS_BASE64_NO_NL\s0 can be set with \fIBIO_set_flags()\fR
to encode the data all on one line or expect the data to be all
on one line.
.SH "NOTES"
.IX Header "NOTES"
Because of the format of base64 encoding the end of the encoded
block cannot always be reliably determined.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIBIO_f_base64()\fR returns the base64 \s-1BIO\s0 method.
.SH "EXAMPLES"
.IX Header "EXAMPLES"
Base64 encode the string \*(L"Hello World\en\*(R" and write the result
to standard output:
.PP
.Vb 2
\& BIO *bio, *b64;
\& char message[] = "Hello World \en";
\&
\& b64 = BIO_new(BIO_f_base64());
\& bio = BIO_new_fp(stdout, BIO_NOCLOSE);
\& BIO_push(b64, bio);
\& BIO_write(b64, message, strlen(message));
\& BIO_flush(b64);
\&
\& BIO_free_all(b64);
.Ve
.PP
Read Base64 encoded data from standard input and write the decoded
data to standard output:
.PP
.Vb 3
\& BIO *bio, *b64, *bio_out;
\& char inbuf[512];
\& int inlen;
\&
\& b64 = BIO_new(BIO_f_base64());
\& bio = BIO_new_fp(stdin, BIO_NOCLOSE);
\& bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
\& BIO_push(b64, bio);
\& while((inlen = BIO_read(b64, inbuf, 512)) > 0) 
\&        BIO_write(bio_out, inbuf, inlen);
\&
\& BIO_flush(bio_out);
\& BIO_free_all(b64);
.Ve
.SH "BUGS"
.IX Header "BUGS"
The ambiguity of \s-1EOF\s0 in base64 encoded data can cause additional
data following the base64 encoded block to be misinterpreted.
.PP
There should be some way of specifying a test that the \s-1BIO\s0 can perform
to reliably determine \s-1EOF \s0(for example a \s-1MIME\s0 boundary).
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1TBA\s0

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