Source file src/internal/poll/sendfile_solaris.go

     1	// Copyright 2015 The Go Authors. All rights reserved.
     2	// Use of this source code is governed by a BSD-style
     3	// license that can be found in the LICENSE file.
     4	
     5	package poll
     6	
     7	import "syscall"
     8	
     9	// Not strictly needed, but very helpful for debugging, see issue #10221.
    10	//go:cgo_import_dynamic _ _ "libsendfile.so"
    11	//go:cgo_import_dynamic _ _ "libsocket.so"
    12	
    13	// maxSendfileSize is the largest chunk size we ask the kernel to copy
    14	// at a time.
    15	const maxSendfileSize int = 4 << 20
    16	
    17	// SendFile wraps the sendfile system call.
    18	func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
    19		if err := dstFD.writeLock(); err != nil {
    20			return 0, err
    21		}
    22		defer dstFD.writeUnlock()
    23	
    24		dst := int(dstFD.Sysfd)
    25		var written int64
    26		var err error
    27		for remain > 0 {
    28			n := maxSendfileSize
    29			if int64(n) > remain {
    30				n = int(remain)
    31			}
    32			pos1 := pos
    33			n, err1 := syscall.Sendfile(dst, src, &pos1, n)
    34			if err1 == syscall.EAGAIN || err1 == syscall.EINTR {
    35				// partial write may have occurred
    36				n = int(pos1 - pos)
    37			}
    38			if n > 0 {
    39				pos += int64(n)
    40				written += int64(n)
    41				remain -= int64(n)
    42			} else if n == 0 && err1 == nil {
    43				break
    44			}
    45			if err1 == syscall.EAGAIN {
    46				if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil {
    47					continue
    48				}
    49			}
    50			if err1 == syscall.EINTR {
    51				continue
    52			}
    53			if err1 != nil {
    54				// This includes syscall.ENOSYS (no kernel
    55				// support) and syscall.EINVAL (fd types which
    56				// don't implement sendfile)
    57				err = err1
    58				break
    59			}
    60		}
    61		return written, err
    62	}
    63	

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