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8 package poll
9
10 import "syscall"
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13
14 const maxSendfileSize int = 4 << 20
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16
17 func SendFile(dstFD *FD, src int, pos, remain int64) (int64, error) {
18 if err := dstFD.writeLock(); err != nil {
19 return 0, err
20 }
21 defer dstFD.writeUnlock()
22 if err := dstFD.pd.prepareWrite(dstFD.isFile); err != nil {
23 return 0, err
24 }
25
26 dst := dstFD.Sysfd
27 var written int64
28 var err error
29 for remain > 0 {
30 n := maxSendfileSize
31 if int64(n) > remain {
32 n = int(remain)
33 }
34 pos1 := pos
35 n, err1 := syscall.Sendfile(dst, src, &pos1, n)
36 if n > 0 {
37 pos += int64(n)
38 written += int64(n)
39 remain -= int64(n)
40 } else if n == 0 && err1 == nil {
41 break
42 }
43 if err1 == syscall.EINTR {
44 continue
45 }
46 if err1 == syscall.EAGAIN {
47 if err1 = dstFD.pd.waitWrite(dstFD.isFile); err1 == nil {
48 continue
49 }
50 }
51 if err1 != nil {
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54
55 err = err1
56 break
57 }
58 }
59 return written, err
60 }
61
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