Data::Buffer - Read/write buffer class
my $buffer = Data::Buffer->new;
## Add a 32-bit integer.
## Get it back.
my $int = $buffer->get_int32;
Data::Buffer implements a low-level binary buffer in which you can get
and put integers, strings, and other data. Internally the implementa-
tion is based on "pack" and "unpack", such that Data::Buffer is really
a layer on top of those built-in functions.
All of the get_* and put_* methods respect the internal offset state in
the buffer object. This means that you should read data out of the
buffer in the same order that you put it in. For example:
$buf->get_int16; # 24
$buf->get_int32; # 1233455
$buf->get_int16; # 99
Of course, this assumes that you know the order of the data items in
the buffer. If your setup is such that your sending and receiving pro-
cesses won't necessarily know what's inside the buffers they receive,
take a look at the TEMPLATE USAGE section.
Creates a new buffer object and returns it. The buffer is initially
This method takes no arguments.
Creates a new buffer object and appends to it each of the octet strings
Returns the new buffer object.
Returns the next 8-bit integer from the buffer (which is really just
the ASCII code for the next character/byte in the buffer).
Appends an 8-bit integer to the buffer (which is really just the char-
acter corresponding to that integer, in ASCII).
Returns the next 16-bit integer from the buffer.
Appends a 16-bit integer to the buffer.
Returns the next 32-bit integer from the buffer.
Appends a 32-bit integer to the buffer.
More appropriately called get_byte, perhaps, this returns the next byte
from the buffer.
Appends a byte (or a sequence of bytes) to the buffer. There is no
restriction on the length of the byte string $bytes; if it makes you
uncomfortable to call put_char to put multiple bytes, you can instead
call this method as put_chars. It's the same thing.
Grabs $n bytes from the buffer, where $n is a positive integer. Incre-
ments the internal offset state by $n.
$buffer->put_bytes($bytes [, $n ])
Appends a sequence of bytes to the buffer; if $n is unspecified,
appends the entire length of $bytes. Otherwise appends only the first
$n bytes of $bytes.
Returns the next "string" from the buffer. A string here is represented
as the length of the string (a 32-bit integer) followed by the string
Appends a string (32-bit integer length and the string itself) to the
Extracts the next $n bytes from the buffer $buffer, increments the off-
set state in $buffer, and returns a new buffer object containing the
Generally when you use Data::Buffer it's to communicate with another
process (perhaps a C program) that bundles up its data into binary
buffers. In those cases, it's very likely that the data will be in some
well-known order in the buffer: in other words, it might be documented
that a certain C program creates a buffer containing:
* an int8
* a string
* an int32
In this case, you would presumably know about the order of the data in
the buffer, and you could extract it accordingly:
In other cases, however, there may not be a well-defined order of data
items in the buffer. This might be the case if you're inventing your
own protocol, and you want your binary buffers to "know" about their
contents. In this case, you'll want to use the templating features of
When you use the put_ methods to place data in a buffer, Data::Buffer
keeps track of the types of data that you're inserting in a template
description of the buffer. This template contains all of the informa-
tion necessary for a process to receive a buffer and extract the data
in the buffer without knowledge of the order of the items.
To use this feature, simply use the insert_template method after you've
filled your buffer to completion. For example:
my $buffer = Data::Buffer->new;
## Ship off the buffer to another process.
The receiving process should then invoke the get_all method on the
buffer to extract all of the data:
my $buffer = Data::Buffer->new;
$buffer->append( $received_buffer_data );
my @data = $buffer->get_all;
@data will now contain two elements: "foo" and 9999.
Appends raw data $bytes to the end of the in-memory buffer. Generally
you don't need to use this method unless you're initializing an empty
buffer, because when you need to add data to a buffer you should gener-
ally use one of the put_* methods.
Empties out the buffer object.
$buffer->bytes([ $offset [, $length [, $replacement ]]])
Behaves exactly like the substr built-in function, except on the buffer
$buffer. Given no arguments, bytes returns the entire buffer; given one
argument $offset, returns everything from that position to the end of
the string; given $offset and $length, returns the segment of the
buffer starting at $offset and consisting of $length bytes; and given
all three arguments, replaces that segment with $replacement.
This is a very low-level method, and you generally won't need to use
Also be warned that you should not intermix use of this method with use
of the get_* and put_* methods; the latter classes of methods maintain
internal state of the buffer offset where arguments will be gotten from
and put, respectively. The bytes method gives no thought to this inter-
nal offset state.
Returns the length of the buffer object.
Returns the internal offset state.
If you insist on intermixing calls to bytes with calls to the get_* and
put_* methods, you'll probably want to use this method to get some sta-
tus on that internal offset.
Sets the internal offset state to $offset.
Sets the internal offset state to 0.
Returns a hex dump of the buffer. The dump is of the entire buffer
$buffer; in other words, dump doesn't respect the internal offset
@args is passed directly through to the bytes method, which means that
you can supply arguments to emulate support of the internal offset:
my $dump = $buffer->dump($buffer->offset);
A helper method: pads out the buffer so that the length of the trans-
ferred packet will be evenly divisible by 8, which is a requirement of
the SSH protocol.
AUTHOR & COPYRIGHTS
Benjamin Trott, firstname.lastname@example.org
Except where otherwise noted, Data::Buffer is Copyright 2001 Benjamin
Trott. All rights reserved. Data::Buffer is free software; you may
redistribute it and/or modify it under the same terms as Perl itself.
perl v5.8.8 2001-07-28 Buffer(3)
See also Data::Dumper(3)
See also Data::Grove(3)
See also Data::Grove::Parent(3)
See also Data::Grove::Visitor(3)
See also Data::Random(3)
See also Data::Random::WordList(3)
See also SOAP::Data(3)
Man(1) output converted with