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file_descriptor.cr
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file_descriptor.cr
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require "c/fcntl"
# An IO over a file descriptor.
class IO::FileDescriptor
include Buffered
@read_timeout : Float64?
@write_timeout : Float64?
@read_event : Event::Event?
@write_event : Event::Event?
# :nodoc:
property read_timed_out : Bool
property write_timed_out : Bool
def initialize(@fd : Int32, blocking = false, edge_triggerable = false)
@edge_triggerable = !!edge_triggerable
@closed = false
@read_timed_out = false
@write_timed_out = false
@fd = fd
unless blocking
self.blocking = false
if @edge_triggerable
@read_event = Scheduler.create_fd_read_event(self, @edge_triggerable)
@write_event = Scheduler.create_fd_write_event(self, @edge_triggerable)
end
end
end
# Set the number of seconds to wait when reading before raising an `IO::Timeout`.
def read_timeout=(read_timeout : Number)
@read_timeout = read_timeout.to_f
end
# ditto
def read_timeout=(read_timeout : Time::Span)
self.read_timeout = read_timeout.total_seconds
end
# Sets no timeout on read operations, so an `IO::Timeout` will never be raised.
def read_timeout=(read_timeout : Nil)
@read_timeout = nil
end
# Set the number of seconds to wait when writing before raising an `IO::Timeout`.
def write_timeout=(write_timeout : Number)
@write_timeout = write_timeout.to_f
end
# ditto
def write_timeout=(write_timeout : Time::Span)
self.write_timeout = write_timeout.total_seconds
end
# Sets no timeout on write operations, so an `IO::Timeout` will never be raised.
def write_timeout=(write_timeout : Nil)
@write_timeout = nil
end
def blocking
fcntl(LibC::F_GETFL) & LibC::O_NONBLOCK == 0
end
def blocking=(value)
flags = fcntl(LibC::F_GETFL)
if value
flags &= ~LibC::O_NONBLOCK
else
flags |= LibC::O_NONBLOCK
end
fcntl(LibC::F_SETFL, flags)
end
def close_on_exec?
flags = fcntl(LibC::F_GETFD)
(flags & LibC::FD_CLOEXEC) == LibC::FD_CLOEXEC
end
def close_on_exec=(arg : Bool)
fcntl(LibC::F_SETFD, arg ? LibC::FD_CLOEXEC : 0)
arg
end
def self.fcntl(fd, cmd, arg = 0)
r = LibC.fcntl fd, cmd, arg
raise Errno.new("fcntl() failed") if r == -1
r
end
def fcntl(cmd, arg = 0)
self.class.fcntl @fd, cmd, arg
end
# :nodoc:
def resume_read
if reader = @readers.try &.shift?
reader.resume
end
end
# :nodoc:
def resume_write
if writer = @writers.try &.shift?
writer.resume
end
end
def stat
if LibC.fstat(@fd, out stat) != 0
raise Errno.new("Unable to get stat")
end
File::Stat.new(stat)
end
# Seeks to a given *offset* (in bytes) according to the *whence* argument.
# Returns `self`.
#
# ```
# 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)
check_open
flush
seek_value = LibC.lseek(@fd, offset, whence)
if seek_value == -1
raise Errno.new "Unable to seek"
end
@in_buffer_rem = Slice.new(Pointer(UInt8).null, 0)
self
end
# Same as `pos`.
def tell
pos
end
# Returns the current position (in bytes) in this IO.
#
# ```
# io = MemoryIO.new "hello"
# io.pos # => 0
# io.gets(2) # => "he"
# io.pos # => 2
# ```
def pos
check_open
seek_value = LibC.lseek(@fd, 0, Seek::Current)
raise Errno.new "Unable to tell" if seek_value == -1
seek_value - @in_buffer_rem.size
end
# Sets the current position (in bytes) in this IO.
#
# ```
# io = MemoryIO.new "hello"
# io.pos = 3
# io.gets_to_end # => "lo"
# ```
def pos=(value)
seek value
value
end
def fd
@fd
end
def finalize
return if closed?
close rescue nil
end
def closed?
@closed
end
def tty?
LibC.isatty(fd) == 1
end
def reopen(other : IO::FileDescriptor)
if LibC.dup2(other.fd, self.fd) == -1
raise Errno.new("Could not reopen file descriptor")
end
# flag is lost after dup
self.close_on_exec = true
other
end
def to_fd_io
self
end
private def unbuffered_read(slice : Slice(UInt8))
count = slice.size
loop do
bytes_read = LibC.read(@fd, slice.pointer(count).as(Void*), count)
if bytes_read != -1
return bytes_read
end
if Errno.value == Errno::EAGAIN
wait_readable
else
raise Errno.new "Error reading file"
end
end
ensure
if (readers = @readers) && !readers.empty?
add_read_event
end
end
private def unbuffered_write(slice : Slice(UInt8))
count = slice.size
total = count
loop do
bytes_written = LibC.write(@fd, slice.pointer(count).as(Void*), count)
if bytes_written != -1
count -= bytes_written
return total if count == 0
slice += bytes_written
else
if Errno.value == Errno::EAGAIN
wait_writable
next
elsif Errno.value == Errno::EBADF
raise IO::Error.new "File not open for writing"
else
raise Errno.new "Error writing file"
end
end
end
ensure
if (writers = @writers) && !writers.empty?
add_write_event
end
end
private def wait_readable
wait_readable { |err| raise err }
end
private def wait_readable
readers = (@readers ||= Deque(Fiber).new)
readers << Fiber.current
add_read_event
Scheduler.reschedule
if @read_timed_out
@read_timed_out = false
yield Timeout.new("read timed out")
end
nil
end
private def add_read_event
return if @edge_triggerable
event = @read_event ||= Scheduler.create_fd_read_event(self)
event.add @read_timeout
nil
end
private def wait_writable(timeout = @write_timeout)
wait_writable(timeout: timeout) { |err| raise err }
end
# msg/timeout are overridden in nonblock_connect
private def wait_writable(msg = "write timed out", timeout = @write_timeout)
writers = (@writers ||= Deque(Fiber).new)
writers << Fiber.current
add_write_event timeout
Scheduler.reschedule
if @write_timed_out
@write_timed_out = false
yield Timeout.new(msg)
end
nil
end
private def add_write_event(timeout = @write_timeout)
return if @edge_triggerable
event = @write_event ||= Scheduler.create_fd_write_event(self)
event.add timeout
nil
end
private def unbuffered_rewind
seek(0, IO::Seek::Set)
self
end
private def unbuffered_close
return if @closed
err = nil
if LibC.close(@fd) != 0
case Errno.value
when Errno::EINTR, Errno::EINPROGRESS
# ignore
else
err = Errno.new("Error closing file")
end
end
@closed = true
@read_event.try &.free
@read_event = nil
@write_event.try &.free
@write_event = nil
if readers = @readers
Scheduler.enqueue readers
readers.clear
end
if writers = @writers
Scheduler.enqueue writers
writers.clear
end
raise err if err
end
private def unbuffered_flush
# Nothing
end
end