- UUID LIBRARY
- COPYRIGHT AND LICENSE
- SEE ALSO
UUID - DCE compatible Universally Unique Identifier library for Perl
use UUID ':all'; generate($uuid); # generate binary UUID, prefer random generate_random($uuid); # generate binary UUID, using random generate_time($uuid); # generate binary UUID, using time $string = uuid(); # generate stringified UUID unparse($uuid, $string); # change $uuid string unparse_lower($uuid, $string); # change $uuid to lowercase string unparse_upper($uuid, $string); # change $uuid to uppercase string $rc = parse($string, $uuid); # map string to UUID, return -1 on error copy($dst, $src); # copy binary UUID from $src to $dst compare($uuid1, $uuid2); # compare binary UUIDs clear( $uuid ); # set binary UUID to NULL is_null( $uuid); # compare binary UUID to NULL
The UUID library is used to generate unique identifiers for objects that may be accessible beyond the local system. For instance, they could be used to generate unique HTTP cookies across multiple web servers without communication between the servers, and without fear of a name clash.
The generated UUIDs can be reasonably expected to be unique within a system, and unique across all systems, and are compatible with those created by the Open Software Foundation (OSF) Distributed Computing Environment (DCE) utility uuidgen.
Most of the UUID functions expose the underlying libuuid C interface rather directly. That is, many return their values in their parameters and nothing else.
Not very Perlish, is it? It's been like that for a long time though, so not very likely to change any time soon.
All take or return UUIDs in either binary or string format. The string format resembles the following:
Or, in terms of printf(3) format:
The binary format is simply a packed 16 byte binary value.
generate( $uuid )
Generates a new binary UUID based on high quality randomness from /dev/urandom, if available.
Alternately, the current time, the local ethernet MAC address (if available), and random data generated using a pseudo-random generator are used.
The previous content of $uuid, if any, is lost.
generate_random( $uuid )
Generates a new binary UUID but forces the use of the all-random algorithm, even if a high-quality random number generator (i.e., /dev/urandom) is not available, in which case a pseudo-random generator is used.
Note that the use of a pseudo-random generator may compromise the uniqueness of UUIDs generated in this fashion.
generate_time( $uuid )
Generates a new binary UUID but forces the use of the alternative algorithm which uses the current time and the local ethernet MAC address (if available).
This algorithm used to be the default one used to generate UUIDs, but because of the use of the ethernet MAC address, it can leak information about when and where the UUID was generated.
This can cause privacy problems in some applications, so the generate() function only uses this algorithm if a high-quality source of randomness is not available.
unparse( $uuid, $string )
Converts the binary UUID in $uuid to string format and returns in $string. The previous content of $string, if any, is lost.
The case of the hex digits returned may be upper or lower case, and is dependent on the system-dependent local default.
unparse_lower( $uuid, $string )
Same as unparse() but $string is forced to lower case.
unparse_upper( $uuid, $string )
Same as unparse() but $string is forced to upper case.
$rc = parse( $string, $uuid )
Converts the string format UUID in $string to binary and returns in $uuid. The previous content of $uuid, if any, is lost.
Returns 0 on success and -1 on failure. Additionally on failure, the content of $uuid is unchanged.
clear( $uuid )
Sets $uuid equal to the value of the NULL UUID.
is_null( $uuid )
Compares the value of $uuid to the NULL UUID.
Returns 1 if NULL, and 0 otherwise.
copy( $dst, $src )
Copies the binary $src UUID to $dst.
If $src isn't a UUID, $dst is set to the NULL UUID.
compare( $uuid1, $uuid2 )
Compares two binary UUIDs.
Returns an integer less than, equal to, or greater than zero if $uuid1 is less than, equal to, or greater than $uuid2.
However, if either operand is not a UUID, falls back to a simple string comparison returning similar values.
$string = uuid()
Creates a new string format UUID and returns it in a more Perlish way.
Functionally the equivalent of calling generate() and then unparse(), but throwing away the intermediate binary UUID.
Note that on some systems external packages will need to be installed first. Notably, uuid-dev or uuid-devel on Debian and RedHat Linux, respectively, and their derivatives.
All functions may be imported in the usual manner, either individually or all at once using the ":all" tag.
Need more tests and sanity checks.
COPYRIGHT AND LICENSE
This software is Copyright (c) 2014-2016 by Rick Myers.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
Details of this license can be found within the 'License' text file.
Rick Myers <email@example.com>.
Authors and/or previous maintainers:
Lukas Zapletal <firstname.lastname@example.org> Joseph N. Hall <email@example.com> Colin Faber <firstname.lastname@example.org> Peter J. Braam <email@example.com>
David E. Wheeler
uuid(3), uuid_clear(3), uuid_compare(3), uuid_copy(3), uuid_generate(3), uuid_is_null(3), uuid_parse(3), uuid_unparse(3), perl(1).