IO::Async::OS(3pm) User Contributed Perl Documentation IO::Async::OS(3pm)
NAME
"IO::Async::OS" - operating system abstractions for "IO::Async"
DESCRIPTION
This module acts as a class to provide a number of utility methods
whose exact behaviour may depend on the type of OS it is running on. It
is provided as a class so that specific kinds of operating system can
override methods in it.
As well as these support functions it also provides a number of
constants, all with names beginning "HAVE_" which describe various
features that may or may not be available on the OS or perl build. Most
of these are either hard-coded per OS, or detected at runtime.
The following constants may be overridden by environment variables.
• HAVE_POSIX_FORK
True if the "fork()" call has full POSIX semantics (full process
separation). This is true on most OSes but false on MSWin32.
This may be overridden to be false by setting the environment
variable "IO_ASYNC_NO_FORK".
• HAVE_THREADS
True if "ithreads" are available, meaning that the "threads" module
can be used. This depends on whether perl was built with threading
support.
This may be overridable to be false by setting the environment
variable "IO_ASYNC_NO_THREADS".
getfamilybyname
$family = IO::Async::OS->getfamilybyname( $name )
Return a protocol family value based on the given name. If $name looks
like a number it will be returned as-is. The string values "inet",
"inet6" and "unix" will be converted to the appropriate "AF_*"
constant.
getsocktypebyname
$socktype = IO::Async::OS->getsocktypebyname( $name )
Return a socket type value based on the given name. If $name looks like
a number it will be returned as-is. The string values "stream", "dgram"
and "raw" will be converted to the appropriate "SOCK_*" constant.
socketpair
( $S1, $S2 ) = IO::Async::OS->socketpair( $family, $socktype, $proto )
An abstraction of the socketpair(2) syscall, where any argument may be
missing (or given as "undef").
If $family is not provided, a suitable value will be provided by the OS
(likely "AF_UNIX" on POSIX-based platforms). If $socktype is not
provided, then "SOCK_STREAM" will be used.
Additionally, this method supports building connected "SOCK_STREAM" or
"SOCK_DGRAM" pairs in the "AF_INET" family even if the underlying
platform's socketpair(2) does not, by connecting two normal sockets
together.
$family and $socktype may also be given symbolically as defined by
"getfamilybyname" and "getsocktypebyname".
pipepair
( $rd, $wr ) = IO::Async::OS->pipepair
An abstraction of the pipe(2) syscall, which returns the two new
handles.
pipequad
( $rdA, $wrA, $rdB, $wrB ) = IO::Async::OS->pipequad
This method is intended for creating two pairs of filehandles that are
linked together, suitable for passing as the STDIN/STDOUT pair to a
child process. After this function returns, $rdA and $wrA will be a
linked pair, as will $rdB and $wrB.
On platforms that support socketpair(2), this implementation will be
preferred, in which case $rdA and $wrB will actually be the same
filehandle, as will $rdB and $wrA. This saves a file descriptor in the
parent process.
When creating a IO::Async::Stream or subclass of it, the "read_handle"
and "write_handle" parameters should always be used.
my ( $childRd, $myWr, $myRd, $childWr ) = IO::Async::OS->pipequad;
$loop->open_process(
stdin => $childRd,
stdout => $childWr,
...
);
my $str = IO::Async::Stream->new(
read_handle => $myRd,
write_handle => $myWr,
...
);
$loop->add( $str );
signame2num
$signum = IO::Async::OS->signame2num( $signame )
This utility method converts a signal name (such as "TERM") into its
system- specific signal number. This may be useful to pass to
"POSIX::SigSet" or use in other places which use numbers instead of
symbolic names.
signum2name
$signame = IO::Async::OS->signum2name( $signum )
The inverse of signame2num; this method convers signal numbers into
readable names.
extract_addrinfo
( $family, $socktype, $protocol, $addr ) = IO::Async::OS->extract_addrinfo( $ai )
Given an ARRAY or HASH reference value containing an addrinfo, returns
a family, socktype and protocol argument suitable for a "socket" call
and an address suitable for "connect" or "bind".
If given an ARRAY it should be in the following form:
[ $family, $socktype, $protocol, $addr ]
If given a HASH it should contain the following keys:
family socktype protocol addr
Each field in the result will be initialised to 0 (or empty string for
the address) if not defined in the $ai value.
The family type may also be given as a symbolic string as defined by
"getfamilybyname".
The socktype may also be given as a symbolic string; "stream", "dgram"
or "raw"; this will be converted to the appropriate "SOCK_*" constant.
Note that the "addr" field, if provided, must be a packed socket
address, such as returned by "pack_sockaddr_in" or "pack_sockaddr_un".
If the HASH form is used, rather than passing a packed socket address
in the "addr" field, certain other hash keys may be used instead for
convenience on certain named families.
family => 'inet'
Will pack an IP address and port number from keys called "ip" and
"port". If "ip" is missing it will be set to "0.0.0.0". If "port"
is missing it will be set to 0.
family => 'inet6'
Will pack an IP address and port number from keys called "ip" and
"port". If "ip" is missing it will be set to "::". If "port" is
missing it will be set to 0. Optionally will also include values
from "scopeid" and "flowinfo" keys if provided.
This will only work if a "pack_sockaddr_in6" function can be found
in "Socket"
family => 'unix'
Will pack a UNIX socket path from a key called "path".
make_addr_for_peer
$connectaddr = IO::Async::OS->make_addr_for_peer( $family, $listenaddr )
Given the "sockdomain" and "sockname" of a listening socket. creates an
address suitable to "connect()" to it.
This method will handle specially any "AF_INET" address bound to
"INADDR_ANY" or any "AF_INET6" address bound to "IN6ADDR_ANY", as some
OSes do not allow connect(2)ing to those and would instead insist on
receiving "INADDR_LOOPBACK" or "IN6ADDR_LOOPBACK" respectively.
This method is used by the "->connect( peer => $sock )" parameter of
handle and loop connect methods.
LOOP IMPLEMENTATION METHODS
The following methods are provided on "IO::Async::OS" because they are
likely to require OS-specific implementations, but are used by
IO::Async::Loop to implement its functionality. It can use the HASH
reference "$loop->{os}" to store other data it requires.
loop_watch_signal
loop_unwatch_signal
IO::Async::OS->loop_watch_signal( $loop, $signal, $code )
IO::Async::OS->loop_unwatch_signal( $loop, $signal )
Used to implement the "watch_signal" / "unwatch_signal" Loop pair.
potentially_open_fds
@fds = IO::Async::OS->potentially_open_fds
Returns a list of filedescriptors which might need closing. By default
this will return "0 .. _SC_OPEN_MAX". OS-specific subclasses may have a
better guess.
AUTHOR
Paul Evans <leonerd@leonerd.org.uk>
perl v5.34.0 2022-08-19 IO::Async::OS(3pm)
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