File manager

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=encoding utf8 =head1 NAME POSIX::1003::Fcntl - POSIX function fcntl =head1 SYNOPSIS use POSIX::1003::Fcntl; =head1 DESCRIPTION One function, which hides many tricks with file-descriptors. This module tries to provide functions which separates the various uses. =head1 FUNCTIONS =head2 Standard POSIX =over 4 =item B<fcntl>($fd, $function, SCALAR) See C<perlfunc fcntl>. This raw call to C<fcntl()> is only in some cases simple, but often isn't. =item B<flockfd>($fd, $flags) Not standard POSIX, but available on many POSIX platforms. Often implemented as L<fcntl()\|POSIX::1003::Fcntl/"Standard POSIX">, which is more complex to use. On other platforms implemented as separate OS feature. Perl core provides a C<flock> which may hide plaform differences. This C<flockfd> is the pure version. Try to use L<setfd_lock()\|POSIX::1003::Fcntl/"Additional">, which is more portable and flexible. example: use POSIX::1003::Fcntl ':flock'; if(flockfd $fd, LOCK_EX\|LOCK_NB) ... flockfd $fd, LOCK_UN; =item B<lockf>($fd, $flag, $length) Not standard POSIX, but available on many POSIX platforms. Often implemented via L<fcntl()\|POSIX::1003::Fcntl/"Standard POSIX">, which is more complex to use. example: use POSIX::1003::Fcntl ':lockfd'; if(lockf $fd, F_LOCK) ... lockf $fd, F_ULOCK; =back =head2 Additional =over 4 =item B<fcntl_dup>($fd\|$fh, %options) Commands F_DUPFD and F_DUPFD_CLOEXEC: dupplicate a file-descriptor to the lowest free fd number. -Option --Default close_on_exec <false> =over 2 =item close_on_exec => BOOLEAN =back example: my $dup_fd = fcntl_dup \STDOUT; my $dup_fd = fcntl_dup 2, close_on_exec => 1; =item B<getfd_control>($fd\|$fh) Control the file descriptor flags, command F_GETFD. =item B<getfd_flags>($fd\|$fh) Get the file status flags and access modes, command F_GETFL. example: my $flags = getfd_flags(fd); if ((flags & O_ACCMODE) == O_RDWR) =item B<getfd_islocked>($fd\|$fh, %options) Command F_GETLCK. Returns the first lock which would prevent getting the lock. The %options are the same as for L<setfd_lock()\|POSIX::1003::Fcntl/"Additional">. example: if(my $lock = getfd_islocked \IN) ... =item B<getfd_lease>($fd\|$fh) Command F_GETLEASE. example: my $lease = getfd_lease(\STDIN) or die $!; if($lease != F_RDLCK) ... =item B<getfd_owner>($fd\|$fh, %options) Commands F_GETOWN and F_GETOWN_EX. example: my ($type, $pid) = getfd_owner($fd); defined $type or die $!; if($type==F_OWNER_PGRP) ... my $pid = getfd_owner($fd) or die $!; =item B<getfd_pipe_size>($fd\|$fh) Command F_GETPIPE_SZ. example: my $size = getfd_pipe_size($pipe) or die $!; =item B<getfd_signal>($fd\|$fh) Command F_GETSIG. example: my $signal = getfd_signal(\STDOUT) or die $!; =item B<setfd_control>($fd\|$fh, $flags) Change the file descriptor flags, command F_SETFD. =item B<setfd_flags>($fd\|$fh, $flags) Change the file status flags and access modes, command F_SETFL. =item B<setfd_lease>($fd\|$fh, $flags) Command F_SETLEASE. example: setfd_lease(\STDOUT, F_WRLCK) or die $!; =item B<setfd_lock>($fd\|$fh, %options) Commands F_SETLKP and F_SETLKWP. Request a lock for (a section of) a file. -Option --Default len <until end of file> private <false> start 0 type F_RDLCK wait <false> whence SEEK_SET =over 2 =item len => BLOCK_LENGTH =item private => BOOLEAN Linux kernel >= 3.15 provides "open file description locks", also known as "file-private POSIX locks". Use them when available. =item start => FILEPOS =item type => F_RDLCK\|F_WRLCK\|F_UNLCK =item wait => BOOLEAN =item whence => SEEK_SET\|SEEK_CUR\|SEEK_END =back example: setfd_lock \IN, type => F_WRLCK, wait => 1 or die "cannot lock IN: $!\n"; =item B<setfd_notify>($fd\|$fh, $flags) Command F_NOTIFY. example: my $d = openfd('/etc', O_RDONLY\|O_DIRECTORY) or die $!; setfd_notify($d, DN_ACCESS\|DN_CREATE\|DN_MULTISHOT) or die $!; =item B<setfd_owner>($fd\|$fh, $pid, %options) Commands F_GETOWN and F_GETOWN_EX. The _EX version is attempted if provided. -Option--Default type <looks at sign> =over 2 =item type => F_OWNER_TID\|F_OWNER_PID\|F_OWNER_PGRP =back example: setfd_owner($fh, $pid) or die $!; setfd_owner($fh, $pid, type => F_OWNER_TID) or die $!; setfd_owner($fh, -9); # $pid=9, type=F_OWNER_PGRP =item B<setfd_pipe_size>($fd\|$fh, $size) Command F_SETPIPE_SZ. example: setfd_pipe_size($pipe, 16384) or die $!; =item B<setfd_signal>($fd\|$fh, $signal) Command F_SETSIG. example: setfd_signal(\*STDOUT, SIGINT) or die $!; =back =head1 CONSTANTS The following constants are exported, shown here with the values discovered during installation of this module. =for comment #TABLE_FCNTL_START The constant names for this fcntl module are inserted here during installation. =for comment #TABLE_FCNTL_END =head1 SEE ALSO This module is part of POSIX-1003 distribution version 1.02, built on November 10, 2020. Website: F<http://perl.overmeer.net/CPAN>. The code is based on L<POSIX>, which is released with Perl itself. See also L<POSIX::Util> for additional functionality. =head1 COPYRIGHTS Copyrights 2011-2020 on the perl code and the related documentation by [Mark Overmeer]. For other contributors see ChangeLog. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See F<http://dev.perl.org/licenses/>

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