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author | Norbert Preining <norbert@preining.info> | 2019-09-02 13:46:59 +0900 |
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committer | Norbert Preining <norbert@preining.info> | 2019-09-02 13:46:59 +0900 |
commit | e0c6872cf40896c7be36b11dcc744620f10adf1d (patch) | |
tree | 60335e10d2f4354b0674ec22d7b53f0f8abee672 /systems/texlive/tlnet/tlpkg/tlperl/lib/SDBM_File.pm |
Initial commit
Diffstat (limited to 'systems/texlive/tlnet/tlpkg/tlperl/lib/SDBM_File.pm')
-rw-r--r-- | systems/texlive/tlnet/tlpkg/tlperl/lib/SDBM_File.pm | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/systems/texlive/tlnet/tlpkg/tlperl/lib/SDBM_File.pm b/systems/texlive/tlnet/tlpkg/tlperl/lib/SDBM_File.pm new file mode 100644 index 0000000000..5df9085760 --- /dev/null +++ b/systems/texlive/tlnet/tlpkg/tlperl/lib/SDBM_File.pm @@ -0,0 +1,131 @@ +package SDBM_File; + +use strict; +use warnings; + +require Tie::Hash; +require XSLoader; + +our @ISA = qw(Tie::Hash); +our $VERSION = "1.14"; + +our @EXPORT_OK = qw(PAGFEXT DIRFEXT PAIRMAX); +use Exporter "import"; + +XSLoader::load(); + +1; + +__END__ + +=head1 NAME + +SDBM_File - Tied access to sdbm files + +=head1 SYNOPSIS + + use Fcntl; # For O_RDWR, O_CREAT, etc. + use SDBM_File; + + tie(%h, 'SDBM_File', 'filename', O_RDWR|O_CREAT, 0666) + or die "Couldn't tie SDBM file 'filename': $!; aborting"; + + # Now read and change the hash + $h{newkey} = newvalue; + print $h{oldkey}; + ... + + untie %h; + +=head1 DESCRIPTION + +C<SDBM_File> establishes a connection between a Perl hash variable and +a file in SDBM_File format. You can manipulate the data in the file +just as if it were in a Perl hash, but when your program exits, the +data will remain in the file, to be used the next time your program +runs. + +=head2 Tie + +Use C<SDBM_File> with the Perl built-in C<tie> function to establish +the connection between the variable and the file. + + tie %hash, 'SDBM_File', $basename, $modeflags, $perms; + + tie %hash, 'SDBM_File', $dirfile, $modeflags, $perms, $pagfilename; + +C<$basename> is the base filename for the database. The database is two +files with ".dir" and ".pag" extensions appended to C<$basename>, + + $basename.dir (or .sdbm_dir on VMS, per DIRFEXT constant) + $basename.pag + +The two filenames can also be given separately in full as C<$dirfile> +and C<$pagfilename>. This suits for two files without ".dir" and ".pag" +extensions, perhaps for example two files from L<File::Temp>. + +C<$modeflags> can be the following constants from the C<Fcntl> module (in +the style of the L<open(2)> system call), + + O_RDONLY read-only access + O_WRONLY write-only access + O_RDWR read and write access + +If you want to create the file if it does not already exist then bitwise-OR +(C<|>) C<O_CREAT> too. If you omit C<O_CREAT> and the database does not +already exist then the C<tie> call will fail. + + O_CREAT create database if doesn't already exist + +C<$perms> is the file permissions bits to use if new database files are +created. This parameter is mandatory even when not creating a new database. +The permissions will be reduced by the user's umask so the usual value here +would be 0666, or if some very private data then 0600. (See +L<perlfunc/umask>.) + +=head1 EXPORTS + +SDBM_File optionally exports the following constants: + +=over + +=item * + +C<PAGFEXT> - the extension used for the page file, usually C<.pag>. + +=item * + +C<DIRFEXT> - the extension used for the directory file, C<.dir> +everywhere but VMS, where it is C<.sdbm_dir>. + +=item * + +C<PAIRMAX> - the maximum size of a stored hash entry, including the +length of both the key and value. + +=back + +These constants can also be used with fully qualified names, +eg. C<SDBM_File::PAGFEXT>. + +=head1 DIAGNOSTICS + +On failure, the C<tie> call returns an undefined value and probably +sets C<$!> to contain the reason the file could not be tied. + +=head2 C<sdbm store returned -1, errno 22, key "..." at ...> + +This warning is emitted when you try to store a key or a value that +is too long. It means that the change was not recorded in the +database. See BUGS AND WARNINGS below. + +=head1 BUGS AND WARNINGS + +There are a number of limits on the size of the data that you can +store in the SDBM file. The most important is that the length of a +key, plus the length of its associated value, may not exceed 1008 +bytes. + +See L<perlfunc/tie>, L<perldbmfilter>, L<Fcntl> + +=cut |