b64_encoder_create
,
b64_decoder_create
—
base-64 encoder and decoder
PDEL Library (libpdel, -lpdel)
#include <pdel/io/filter.h>
#include <pdel/io/base64.h>
struct filter *
b64_encoder_create
(const
char *charset);
struct filter *
b64_decoder_create
(const
char *charset, int
strict);
extern const char b64_rfc2045_charset[];
These routines create filter objects (see
filter(3))
that encode and decode binary data using base-64 encoding.
Both functions take a charset argument. If
equal to NULL
, then the default (RFC 2045) character
set is used. Otherwise, charset must point to a string
with 65 unique characters. The first 64 are used to encode the data, while
the last character is used as a pad character when the data length is not a
multiple of three.
b64_encoder_create
() returns a new
encoding filter. For every three bytes input to the filter, four bytes from
the chosen character set will be output. If the input length is not a
multiple of three, then one or two pad characters will be added at the end
of the output, so that the output length of the filter is always a multiple
of four.
b64_decoder_create
() returns a new
decoding filter. Every four bytes input to the filter are decoded into up to
three bytes of output. If strict is non-zero, then any
malformed input causes an internal error to be generated in the filter, with
errno set to EINVAL.
Malformed
input is any input character not from the chosen character set. In any case,
the pad character is always ignored. If strict is
zero, then any unrecognized characters are simply ignored, rather than
causing an error.
b64_encoder_create
() always generates
strings that are accepted by b64_decoder_create
() in
strict mode, when created with the same character set.
The RFC 2045 character set is avilable in
b64_rfc2045_charset.
If there was a system error, b64_encoder_create
() and
b64_encoder_create
() return
NULL
with errno set to the
appropriate value. If an invalid charset is passed,
errno will be set to EINVAL.
filter(3),
libpdel(3)
N. Freed and
N. Borenstein, Multipurpose
Internet Mail Extensions (MIME) Part One: Format of Internet Message
Bodies, RFC 2045.
The PDEL library was developed at Packet Design, LLC.
http://www.packetdesign.com/
Archie Cobbs ⟨archie@freebsd.org⟩