'\" t
.\"     Title: kcapi_cipher_stream_update
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets vsnapshot <http://docbook.sf.net/>
.\"      Date: April 2024
.\"    Manual: Programming Interface
.\"    Source: libkcapi Manual 1.4.0
.\"  Language: English
.\"
.TH "KCAPI_CIPHER_STREAM_" "3" "April 2024" "libkcapi Manual 1\&.4\&.0" "Programming Interface"
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.SH "NAME"
kcapi_cipher_stream_update \- send more data for processing (stream)
.SH "SYNOPSIS"
.HP \w'ssize_t\ kcapi_cipher_stream_update('u
.BI "ssize_t kcapi_cipher_stream_update(struct\ kcapi_handle\ *\ " "handle" ", struct\ iovec\ *\ " "iov" ", size_t\ " "iovlen" ");"
.SH "ARGUMENTS"
.PP
\fIhandle\fR
.RS 4
[in] cipher handle
.RE
.PP
\fIiov\fR
.RS 4
[in] scatter/gather list with data to be processed by the cipher operation\&.
.RE
.PP
\fIiovlen\fR
.RS 4
[in] number of scatter/gather list elements\&.
.RE
.SH "DESCRIPTION"
.PP
Using this function call, more plaintext for encryption or ciphertext for decryption can be submitted to the kernel\&.
.PP
This function may cause the caller to sleep if the kernel buffer holding the data is getting full\&. The process will be woken up once more buffer space becomes available by calling
\fBkcapi_cipher_stream_op\fR\&.
.SH "NOTE"
.PP
with the separate API calls of
\fBkcapi_cipher_stream_update\fR
and
\fBkcapi_cipher_stream_op\fR
a multi\-threaded application can be implemented where one thread sends data to be processed and one thread picks up data processed by the cipher operation\&.
.SH "IMPORTANT NOTE"
.PP
The kernel will only process sysconf(_SC_PAGESIZE) * ALG_MAX_PAGES at one time\&. If your input data is larger than this threshold, you MUST segment it into chunks of at most sysconf(_SC_PAGESIZE) * ALG_MAX_PAGES and invoke the
\fBkcapi_cipher_stream_update\fR
on that segment followed by
\fBkcapi_cipher_stream_op\fR
before the next chunk is processed\&. If this rule is not obeyed, the thread invoking
\fBkcapi_cipher_stream_update\fR
will be put to sleep until another thread invokes
\fBkcapi_cipher_stream_op\fR\&.
.SH "WARNING"
.PP
The memory referenced by
\fIiov\fR
is not accessed by the kernel during this call\&. The memory is first accessed when
\fBkcapi_cipher_stream_op\fR
is called\&. Thus, you MUST make sure that the referenced memory is still present at the time
\fBkcapi_cipher_stream_op\fR
is called\&.
.PP
\fIreturn\fR
number of bytes sent to the kernel upon success; a negative errno\-style error code if an error occurred
.SH "AUTHOR"
.PP
\fBStephan Mueller\fR <\&smueller@chronox.de\&>
.RS 4
Author.
.RE
.SH "COPYRIGHT"
.br