diff options
| author | Andy Pan <i@andypan.me> | 2024-10-24 13:10:54 +0800 |
|---|---|---|
| committer | Damien Neil <dneil@google.com> | 2024-10-25 19:05:35 +0000 |
| commit | 3320ce94b669c083e7a94a36dd5d5bceb6c0df0e (patch) | |
| tree | 8aacee66978c299f85d6dc66e3f0da305aac5c74 /src | |
| parent | 22664f33b7389f1b3df409a831c83213cfbbe6d3 (diff) | |
| download | go-3320ce94b669c083e7a94a36dd5d5bceb6c0df0e.tar.xz | |
internal/poll: handle the special case of sendfile(2) sending the full chunk
CL 622235 would fix #70000 while resulting in one extra sendfile(2) system
call when sendfile(2) returns (>0, EAGAIN).
That's also why I left sendfile_bsd.go behind, and didn't make it line up
with other two implementations: sendfile_linux.go and sendfile_solaris.go.
Unlike sendfile(2)'s on Linux and Solaris that always return (0, EAGAIN),
sendfile(2)'s on *BSD and macOS may return (>0, EAGAIN) when using a socket
marked for non-blocking I/O. In that case, the current code will try to re-call
sendfile(2) immediately, which will most likely get us a (0, EAGAIN).
After that, it goes to `dstFD.pd.waitWrite(dstFD.isFile)` below,
which should have been done in the first place.
Thus, the real problem that leads to #70000 is that the old code doesn't handle
the special case of sendfile(2) sending the exact number of bytes the caller requested.
Fixes #70000
Change-Id: I6073d6b9feb58b3d7e114ec21e4e80d9727bca66
Reviewed-on: https://go-review.googlesource.com/c/go/+/622255
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Run-TryBot: Andy Pan <panjf2000@gmail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/internal/poll/sendfile_bsd.go | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/src/internal/poll/sendfile_bsd.go b/src/internal/poll/sendfile_bsd.go index bc665978c3..7f28f0db80 100644 --- a/src/internal/poll/sendfile_bsd.go +++ b/src/internal/poll/sendfile_bsd.go @@ -35,13 +35,28 @@ func SendFile(dstFD *FD, src int, pos, remain int64) (written int64, err error, if int64(n) > remain { n = int(remain) } + m := n pos1 := pos n, err = syscall.Sendfile(dst, src, &pos1, n) if n > 0 { pos += int64(n) written += int64(n) remain -= int64(n) - continue + // (n, nil) indicates that sendfile(2) has transferred + // the exact number of bytes we requested, or some unretryable + // error have occurred with partial bytes sent. Either way, we + // don't need to go through the following logic to check EINTR + // or fell into dstFD.pd.waitWrite, just continue to send the + // next chunk or break the loop. + if n == m { + continue + } else if err != syscall.EAGAIN && + err != syscall.EINTR && + err != syscall.EBUSY { + // Particularly, EPIPE. Errors like that would normally lead + // the subsequent sendfile(2) call to (-1, EBADF). + break + } } else if err != syscall.EAGAIN && err != syscall.EINTR { // This includes syscall.ENOSYS (no kernel // support) and syscall.EINVAL (fd types which |