class IO::FileDescriptor

Overview

An IO over a file descriptor.

Included Modules

Direct Known Subclasses

Defined in:

io/console.cr
io/file_descriptor.cr

Constructors

Class Method Summary

Macro Summary

Instance Method Summary

Instance methods inherited from module IO::Buffered

buffer_size : Int32 buffer_size, buffer_size=(value) buffer_size=, close : Nil close, flush flush, flush_on_newline=(flush_on_newline) flush_on_newline=, flush_on_newline? : Bool flush_on_newline?, peek : Bytes peek, pos : Int64 pos, read(slice : Bytes) : Int32 read, read_buffering=(read_buffering) read_buffering=, read_buffering? : Bool read_buffering?, rewind rewind, sync=(sync) sync=, sync? : Bool sync?, unbuffered_close unbuffered_close, unbuffered_flush unbuffered_flush, unbuffered_read(slice : Bytes) unbuffered_read, unbuffered_rewind unbuffered_rewind, unbuffered_write(slice : Bytes) unbuffered_write, write(slice : Bytes) : Nil write

Instance methods inherited from module Crystal::System::FileDescriptor

file_descriptor_close(&) : Nil
file_descriptor_close
file_descriptor_close

Class methods inherited from module Crystal::System::FileDescriptor

cfmakeraw(termios) cfmakeraw, fcntl(fd, cmd, arg = 0) fcntl, from_stdio(fd) from_stdio, pipe(read_blocking, write_blocking) pipe, pread(file, buffer, offset) pread, system_info(fd) system_info, system_pipe : StaticArray(LibC::Int, 2) system_pipe, tcgetattr(fd) tcgetattr, tcsetattr(fd, optional_actions, termios_p) tcsetattr, write_fully(fd : LibC::Int, pointer : Pointer, size : Int32 = 1) : Nil
write_fully(fd : LibC::Int, slice : Slice(UInt8)) : Nil
write_fully

Instance methods inherited from module IO::Evented

evented_close : Nil evented_close

Instance methods inherited from class IO

<<(obj) : self <<, close close, closed? : Bool closed?, each_byte(&) : Nil
each_byte
each_byte
, each_char(&) : Nil
each_char
each_char
, each_line(*args, **options, &block : String -> ) : Nil
each_line(*args, **options)
each_line
, encoding : String encoding, flush flush, getb_to_end : Bytes getb_to_end, gets(limit : Int, chomp = false) : String | Nil
gets(delimiter : Char, limit : Int, chomp = false) : String | Nil
gets(delimiter : Char, chomp = false) : String | Nil
gets(delimiter : String, chomp = false) : String | Nil
gets(chomp = true) : String | Nil
gets
, gets_to_end : String gets_to_end, peek : Bytes | Nil peek, pos pos, pos=(value) pos=, print(obj : _) : Nil
print(*objects : _) : Nil
print
, printf(format_string, args : Array | Tuple) : Nil
printf(format_string, *args) : Nil
printf
, puts(string : String) : Nil
puts(obj : _) : Nil
puts : Nil
puts(*objects : _) : Nil
puts
, read(slice : Bytes) read, read_at(offset, bytesize, & : IO -> ) read_at, read_byte : UInt8 | Nil read_byte, read_bytes(type, format : IO::ByteFormat = IO::ByteFormat::SystemEndian) read_bytes, read_char : Char | Nil read_char, read_fully(slice : Bytes) : Int32 read_fully, read_fully?(slice : Bytes) : Int32 | Nil read_fully?, read_line(*args, **options) : String read_line, read_string(bytesize : Int) : String read_string, read_utf8(slice : Bytes) read_utf8, read_utf8_byte : UInt8 | Nil read_utf8_byte, rewind rewind, seek(offset, whence : Seek = Seek::Set) seek, set_encoding(encoding : String, invalid : Symbol | Nil = nil) : Nil set_encoding, skip(bytes_count : Int) : Nil skip, skip_to_end : Nil skip_to_end, tell tell, tty? : Bool tty?, write(slice : Bytes) : Nil write, write_byte(byte : UInt8) : Nil write_byte, write_bytes(object, format : IO::ByteFormat = IO::ByteFormat::SystemEndian) : Nil write_bytes, write_string(slice : Bytes) : Nil write_string, write_utf8(slice : Bytes) : Nil write_utf8

Class methods inherited from class IO

copy(src, dst, limit : Int) : Int64
copy(src, dst) : Int64
copy
, pipe(read_blocking = false, write_blocking = false) : Tuple(IO::FileDescriptor, IO::FileDescriptor)
pipe(read_blocking = false, write_blocking = false, &)
pipe
, same_content?(stream1 : IO, stream2 : IO) : Bool same_content?

Instance methods inherited from class Reference

==(other : self)
==(other : JSON::Any)
==(other : YAML::Any)
==(other)
==
, dup dup, hash(hasher) hash, initialize initialize, inspect(io : IO) : Nil inspect, object_id : UInt64 object_id, pretty_print(pp) : Nil pretty_print, same?(other : Reference) : Bool
same?(other : Nil)
same?
, to_s(io : IO) : Nil to_s

Constructor methods inherited from class Reference

new new, unsafe_construct(address : Pointer, *args, **opts) : self unsafe_construct

Class methods inherited from class Reference

pre_initialize(address : Pointer) pre_initialize

Instance methods inherited from class Object

! : Bool !, !=(other) !=, !~(other) !~, ==(other) ==, ===(other : JSON::Any)
===(other : YAML::Any)
===(other)
===
, =~(other) =~, as(type : Class) as, as?(type : Class) as?, class class, dup dup, hash(hasher)
hash
hash
, in?(collection : Object) : Bool
in?(*values : Object) : Bool
in?
, inspect(io : IO) : Nil
inspect : String
inspect
, is_a?(type : Class) : Bool is_a?, itself itself, nil? : Bool nil?, not_nil!(message)
not_nil!
not_nil!
, pretty_inspect(width = 79, newline = "\n", indent = 0) : String pretty_inspect, pretty_print(pp : PrettyPrint) : Nil pretty_print, responds_to?(name : Symbol) : Bool responds_to?, tap(&) tap, to_json(io : IO) : Nil
to_json : String
to_json
, to_pretty_json(indent : String = " ") : String
to_pretty_json(io : IO, indent : String = " ") : Nil
to_pretty_json
, to_s(io : IO) : Nil
to_s : String
to_s
, to_yaml(io : IO) : Nil
to_yaml : String
to_yaml
, try(&) try, unsafe_as(type : T.class) forall T unsafe_as

Class methods inherited from class Object

from_json(string_or_io, root : String)
from_json(string_or_io)
from_json
, from_yaml(string_or_io : String | IO) from_yaml

Macros inherited from class Object

class_getter(*names, &block) class_getter, class_getter!(*names) class_getter!, class_getter?(*names, &block) class_getter?, class_property(*names, &block) class_property, class_property!(*names) class_property!, class_property?(*names, &block) class_property?, class_setter(*names) class_setter, def_clone def_clone, def_equals(*fields) def_equals, def_equals_and_hash(*fields) def_equals_and_hash, def_hash(*fields) def_hash, delegate(*methods, to object) delegate, forward_missing_to(delegate) forward_missing_to, getter(*names, &block) getter, getter!(*names) getter!, getter?(*names, &block) getter?, property(*names, &block) property, property!(*names) property!, property?(*names, &block) property?, setter(*names) setter

Constructor Detail

def self.new(fd : Handle, blocking = nil, *, close_on_finalize : Bool = true) #

Class Method Detail

def self.fcntl(fd, cmd, arg = 0) #

Macro Detail

macro cooked_from_tc_mode! #

DEPRECATED


macro noecho_from_tc_mode! #

DEPRECATED


macro raw_from_tc_mode! #

DEPRECATED


Instance Method Detail

def blocking #

Returns whether I/O operations on this file descriptor block the current thread. If false, operations might opt to suspend the current fiber instead.

This might be different from the internal file descriptor. For example, when STDIN is a terminal on Windows, this returns false since the underlying blocking reads are done on a completely separate thread.


def blocking=(value) #

def close_on_exec=(value : Bool) #

def close_on_exec? : Bool #

def close_on_finalize=(close_on_finalize : Bool) #

Whether or not to close the file descriptor when this object is finalized. Disabling this is useful in order to create an IO wrapper over a file descriptor returned from a C API that keeps ownership of the descriptor. Do note that, if the fd is closed by its owner at any point, any IO operations will then fail.


def close_on_finalize? : Bool #

Whether or not to close the file descriptor when this object is finalized. Disabling this is useful in order to create an IO wrapper over a file descriptor returned from a C API that keeps ownership of the descriptor. Do note that, if the fd is closed by its owner at any point, any IO operations will then fail.


def closed? : Bool #
Description copied from class IO

Returns true if this IO is closed.

IO defines returns false, but including types may override.


def cooked(& : self -> _) #

Yields self to the given block, enables character processing for the duration of the block, and returns the block's value.

The so called cooked mode is the standard behavior of a terminal, doing line wise editing by the terminal and only sending the input to the program on a newline.

Raises IO::Error if this IO is not a terminal device.


def cooked! : Nil #

Enables character processing on this IO.

The so called cooked mode is the standard behavior of a terminal, doing line wise editing by the terminal and only sending the input to the program on a newline.

Raises IO::Error if this IO is not a terminal device.


def echo(& : self -> _) #

Yields self to the given block, enables character echoing for the duration of the block, and returns the block's value.

This causes user input to be displayed as they are entered on the terminal.

Raises IO::Error if this IO is not a terminal device.


def echo! : Nil #

Enables character echoing on this IO.

This causes user input to be displayed as they are entered on the terminal.

Raises IO::Error if this IO is not a terminal device.


def fcntl(cmd, arg = 0) #

def fd : Handle #

Returns the raw file-descriptor handle. Its type is platform-specific.


def finalize #

Finalizes the file descriptor resource.

This involves releasing the handle to the operating system, i.e. closing it. It does not implicitly call #flush, so data waiting in the buffer may be lost. It's recommended to always close the file descriptor explicitly via #close (or implicitly using the .open constructor).

Resource release can be disabled with close_on_finalize = false.

This method is a no-op if the file descriptor has already been closed.


def flock_exclusive(blocking = true, &) #

def flock_exclusive(blocking = true) : Nil #

Places an exclusive advisory lock. Only one process may hold an exclusive lock for a given file descriptor at a given time. IO::Error is raised if blocking is set to false and any existing lock is set.


def flock_shared(blocking = true, &) #

def flock_shared(blocking = true) : Nil #

Places a shared advisory lock. More than one process may hold a shared lock for a given file descriptor at a given time. IO::Error is raised if blocking is set to false and an existing exclusive lock is set.


def flock_unlock : Nil #

Removes an existing advisory lock held by this process.


def fsync(flush_metadata = true) : Nil #

Flushes all data written to this File Descriptor to the disk device so that all changed information can be retrieved even if the system crashes or is rebooted. The call blocks until the device reports that the transfer has completed. To reduce disk activity the flush_metadata parameter can be set to false, then the syscall fdatasync will be used and only data required for subsequent data retrieval is flushed. Metadata such as modified time and access time is not written.

NOTE Metadata is flushed even when flush_metadata is false on Windows and DragonFly BSD.


def info : File::Info #

Returns a File::Info object for this file descriptor, or raises IO::Error in case of an error.

Certain fields like the file size may not be updated until an explicit flush.

File.write("testfile", "abc")

file = File.new("testfile", "a")
file.info.size # => 3
file << "defgh"
file.info.size # => 3
file.flush
file.info.size # => 8

Use File.info if the file is not open and a path to the file is available.


def inspect(io : IO) : Nil #
Description copied from class Reference

Appends a String representation of this object which includes its class name, its object address and the values of all instance variables.

class Person
  def initialize(@name : String, @age : Int32)
  end
end

Person.new("John", 32).inspect # => #<Person:0x10fd31f20 @name="John", @age=32>

def noecho(& : self -> _) #

Yields self to the given block, disables character echoing for the duration of the block, and returns the block's value.

This will prevent displaying back to the user what they enter on the terminal.

Raises IO::Error if this IO is not a terminal device.

print "Enter password: "
password = STDIN.noecho &.gets.try &.chomp
puts

def noecho! : Nil #

Disables character echoing on this IO.

This will prevent displaying back to the user what they enter on the terminal.

Raises IO::Error if this IO is not a terminal device.


def pos=(value) #

Sets the current position (in bytes) in this IO.

File.write("testfile", "hello")

file = File.new("testfile")
file.pos = 3
file.gets_to_end # => "lo"

def pretty_print(pp) #

def raw(& : self -> _) #

Yields self to the given block, enables raw mode for the duration of the block, and returns the block's value.

In raw mode every keypress is directly sent to the program, no interpretation is done by the terminal. On Windows, this also enables ANSI input escape sequences.

Raises IO::Error if this IO is not a terminal device.


def raw! : Nil #

Enables raw mode on this IO.

In raw mode every keypress is directly sent to the program, no interpretation is done by the terminal. On Windows, this also enables ANSI input escape sequences.

Raises IO::Error if this IO is not a terminal device.


def read_timeout : Time::Span | Nil #

The time to wait when reading before raising an IO::TimeoutError.


def read_timeout=(read_timeout : Number) : Number #

Sets the number of seconds to wait when reading before raising an IO::TimeoutError.

DEPRECATED Use #read_timeout=(Time::Span?) instead.


def read_timeout=(read_timeout : Time::Span | Nil) #

The time to wait when reading before raising an IO::TimeoutError.


def reopen(other : IO::FileDescriptor) #

def seek(offset, whence : Seek = Seek::Set) #

Seeks to a given offset (in bytes) according to the whence argument. Returns self.

File.write("testfile", "abc")

file = File.new("testfile")
file.gets(3) # => "abc"
file.seek(1, IO::Seek::Set)
file.gets(2) # => "bc"
file.seek(-1, IO::Seek::Current)
file.gets(1) # => "c"

def seek(offset, whence : Seek = Seek::Set, &) #

Same as #seek but yields to the block after seeking and eventually seeks back to the original position when the block returns.


def tty? : Bool #
Description copied from class IO

Returns true if this IO is associated with a terminal device (tty), false otherwise.

IO returns false, but including types may override.

STDIN.tty?          # => true
IO::Memory.new.tty? # => false

def write_timeout : Time::Span | Nil #

Sets the time to wait when writing before raising an IO::TimeoutError.


def write_timeout=(write_timeout : Number) : Number #

Sets the number of seconds to wait when writing before raising an IO::TimeoutError.

DEPRECATED Use #write_timeout=(Time::Span?) instead.


def write_timeout=(write_timeout : Time::Span | Nil) #

Sets the time to wait when writing before raising an IO::TimeoutError.