.\"-
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.Dd January 10, 2016
.Dt CRYB_PERCENT 3
.Os
.Sh NAME
.Nm cryb_percent_decode ,
.Nm cryb_percent_encode
.Nd RFC 3986 percent-encoding
.Sh SYNOPSIS
.In stddef.h
.In cryb/rfc3986.h
.Ft "int"
.Fn cryb_percent_decode "const char *in" "size_t ilen" "char *out" "size_t olen"
.Ft "int"
.Fn cryb_percent_encode "const char *in" "size_t ilen" "char *out" "size_t olen"
.Sh DESCRIPTION
The
.Fn cryb_percent_decode
and
.Fn cryb_percent_encode
functions decode and encode percent-encoded strings as described in
RFC 3986.
.Pp
In both cases, the
.Fa in
parameter points to the data to be decoded or encoded and the
.Fa ilen
parameter is its length.
Decoding or encoding stops after
.Fa ilen
characters or when a NUL character is encountered, whichever comes
first.
If the exact length of the input string is not known,
.Fa ilen
can be set to
.Dv SIZE_MAX
to decode or encode the entire string.
.Pp
The
.Fa out
parameter points to a buffer in which the decoded or encoded data is
to be stored.
The
.Fa olen
parameter points to a
.Vt size_t
containing the size of that buffer, and is updated upon return to
contain the actual size of the output, including the terminating NUL
character.
If the output buffer is too small to contain the output, the overflow
is discarded, but the variable pointed to by
.Fa olen
still reflects the amount of space that would have been required to
store it.
.Pp
The output is always NUL-terminated, regardless of how much or how
little output was produced, provided that the initial value of
.Fa olen
is non-zero.
.Pp
If
.Fa out
is
.Dv NULL
and no other error is encountered, no output is produced, but the
value pointed to by
.Fa olen
is still updated to reflect the amount of space required to hold the
encoded or decoded sequence.
.Sh RETURN VALUES
The
.Fn cryb_percent_decode
and
.Fn cryb_percent_encode
return 0 if successful.
.Pp
If the output would have overflowed the buffer provided by the caller,
they return -1 and set
.Va errno
to
.Er ENOSPC ,
and the output buffer contains as much decoded or encoded data as
would fit.
.Pp
If an invalid input sequence is encountered, the
.Fn cryb_percent_decode
function returns -1 and sets
.Va errno
to
.Er EINVAL ,
and the output buffer contains the result of decoding the input up to
the invalid sequence.
.Sh IMPLEMENTATION NOTES
The
.In cryb/rfc3986.h
header provides macros which allows these functions to be referred to
without their
.Dq Li cryb_
prefix.
.Sh SEE ALSO
.Xr cryb_base32 3 ,
.Xr cryb_base64 3
.Sh REFERENCES
.Rs
.%A "Berners-Lee, T."
.%A "Fielding, R."
.%A "Masinter, L."
.%D "January 2005"
.%R "Uniform Resource Identifier (URI): Generic Syntax"
.%O "RFC 3968"
.Re
.Sh AUTHORS
The
.Fn cryb_percent_decode
and
.Fn cryb_percent_encode
functions and this manual page were written by
.An Dag-Erling Sm\(/orgrav Aq Mt des@des.no .