nim-chronos/asyncdispatch2/sendfile.nim

87 lines
3.6 KiB
Nim

#
# Asyncdispatch2 SendFile
# (c) Copyright 2018
# Status Research & Development GmbH
#
# Licensed under either of
# Apache License, version 2.0, (LICENSE-APACHEv2)
# MIT license (LICENSE-MIT)
## This module provides cross-platform wrapper for ``sendfile()`` syscall.
when defined(nimdoc):
proc sendfile*(outfd, infd: int, offset: int, count: int): int =
## Copies data between file descriptor ``infd`` and ``outfd``. Because this
## copying is done within the kernel, ``sendfile()`` is more efficient than
## the combination of ``read(2)`` and ``write(2)``, which would require
## transferring data to and from user space.
##
## ``infd`` should be a file descriptor opened for reading and
## ``outfd`` should be a descriptor opened for writing.
##
## The ``infd`` argument must correspond to a file which supports
## ``mmap(2)``-like operations (i.e., it cannot be a socket).
##
## ``offset`` the file offset from which ``sendfile()`` will start reading
## data from ``infd``.
##
## ``count`` is the number of bytes to copy between the file descriptors.
##
## If the transfer was successful, the number of bytes written to ``outfd``
## is returned. Note that a successful call to ``sendfile()`` may write
## fewer bytes than requested; the caller should be prepared to retry the
## call if there were unsent bytes.
##
## On error, ``-1`` is returned.
when defined(linux) or defined(android):
proc osSendFile*(outfd, infd: cint, offset: ptr int, count: int): int
{.importc: "sendfile", header: "<sys/sendfile.h>".}
proc sendfile*(outfd, infd: int, offset: int, count: int): int =
var o = offset
result = osSendFile(cint(outfd), cint(infd), addr offset, count)
elif defined(freebsd) or defined(openbsd) or defined(netbsd) or
defined(dragonflybsd):
type
sendfileHeader* = object {.importc: "sf_hdtr",
header: """#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>""",
pure, final.}
proc osSendFile*(outfd, infd: cint, offset: int, size: int,
hdtr: ptr sendfileHeader, sbytes: ptr int,
flags: int): int {.importc: "sendfile",
header: """#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>""".}
proc sendfile*(outfd, infd: int, offset: int, count: int): int =
var o = 0
result = osSendFile(cint(outfd), cint(infd), offset, count, nil,
addr o, 0)
elif defined(macosx):
type
sendfileHeader* = object {.importc: "sf_hdtr",
header: """#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>""",
pure, final.}
proc osSendFile*(fd, s: cint, offset: int, size: ptr int,
hdtr: ptr sendfileHeader,
flags: int): int {.importc: "sendfile",
header: """#include <sys/types.h>
#include <sys/socket.h>
#include <sys/uio.h>""".}
proc sendfile*(outfd, infd: int, offset: int, count: int): int =
var o = 0
result = osSendFile(cint(fd), cint(s), offset, addr o, nil, 0)