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Revert "internal/poll: drop redundant ENOSYS and EXDEV error checks in CopyFileRange()"

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This reverts https://go.dev/cl/425881.

Reason for revert: broke make.bash on linux/amd64 with Linux 5.19.6.

	[...]
	Building Go toolchain2 using go_bootstrap and Go toolchain1.
	go install internal/unsafeheader: copying /tmp/go-build4206185186/b007/_pkg_.a to /home/mvdan/tip/pkg/linux_amd64/internal/unsafeheader.a: write /home/mvdan/tip/pkg/linux_amd64/internal/unsafeheader.a: copy_file_range: invalid cross-device link
	go install internal/goarch: copying /tmp/go-build4206185186/b006/_pkg_.a to /home/mvdan/tip/pkg/linux_amd64/internal/goarch.a: write /home/mvdan/tip/pkg/linux_amd64/internal/goarch.a: copy_file_range: invalid cross-device link
	[...]

Change-Id: I793856935d4315a870c2d31da46be00cc342b5f8
Reviewed-on: https://go-review.googlesource.com/c/go/+/428396
Reviewed-by: Wayne Zuo <wdvxdr@golangcn.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: hopehook <hopehook@golangcn.org>
Reviewed-by: Andy Pan <panjf2000@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
This commit is contained in:
Daniel Martí 2022-09-05 08:37:48 +00:00 committed by Gopher Robot
parent 4c1ca42aa2
commit 1c50484335
1 changed files with 23 additions and 8 deletions
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31
src/internal/poll/copy_file_range_linux.go
View File

@ -41,9 +41,25 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
}
n, err := copyFileRange(dst, src, int(max))
switch err {
case syscall.EINVAL, syscall.EIO, syscall.EOPNOTSUPP, syscall.EPERM:
// EINVAL is what we see if, for example,
// dst or src refers to a pipe rather than a regular
case syscall.ENOSYS:
// copy_file_range(2) was introduced in Linux 4.5.
// Go supports Linux >= 2.6.33, so the system call
// may not be present.
//
// If we see ENOSYS, we have certainly not transferred
// any data, so we can tell the caller that we
// couldn't handle the transfer and let them fall
// back to more generic code.
return 0, false, nil
case syscall.EXDEV, syscall.EINVAL, syscall.EIO, syscall.EOPNOTSUPP, syscall.EPERM:
// Prior to Linux 5.3, it was not possible to
// copy_file_range across file systems. Similarly to
// the ENOSYS case above, if we see EXDEV, we have
// not transferred any data, and we can let the caller
// fall back to generic code.
//
// As for EINVAL, that is what we see if, for example,
// dst or src refer to a pipe rather than a regular
// file. This is another case where no data has been
// transferred, so we consider it unhandled.
//
@ -54,10 +70,9 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
// See issue #40731.
//
// If the process is running inside a Docker container,
// we might see EPERM instead of ENOSYS. See issue #40893.
// Since EPERM might also be a legitimate error: operation not permitted,
// we should still keep this error even if we have the previous kernel version 5.3 check
// and don't mark copy_file_range(2) as unsupported.
// we might see EPERM instead of ENOSYS. See issue
// #40893. Since EPERM might also be a legitimate error,
// don't mark copy_file_range(2) as unsupported.
return 0, false, nil
case nil:
if n == 0 {
@ -68,7 +83,7 @@ func CopyFileRange(dst, src *FD, remain int64) (written int64, handled bool, err
if written == 0 {
return 0, false, nil
}
// Otherwise, src is at EOF, which means
// Otherwise src is at EOF, which means
// we are done.
return written, true, nil
}