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The minimum bootstrap version for Go ≥ 1.20 is Go 1.17. That version supports the new style //go:build lines. Thus the old style //+build lines can be dropped in this part of the tree as well. Leave the //+build lines in cmd/dist which will ensure the minimum Go version during bootstrap. As suggested by Cherry during review of CL 430496 For #44505 Change-Id: If53c0b02cacbfb055a33e73cfd38578dfd3aa340 Reviewed-on: https://go-review.googlesource.com/c/go/+/436915 TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Cherry Mui <cherryyz@google.com> Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> Auto-Submit: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Than McIntosh <thanm@google.com>
45 lines
1.1 KiB
Go
45 lines
1.1 KiB
Go
// Copyright 2018 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || (solaris && go1.20)
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package base
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import (
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"internal/unsafeheader"
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"os"
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"runtime"
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"syscall"
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"unsafe"
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)
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// TODO(mdempsky): Is there a higher-level abstraction that still
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// works well for iimport?
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// mapFile returns length bytes from the file starting at the
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// specified offset as a string.
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func MapFile(f *os.File, offset, length int64) (string, error) {
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// POSIX mmap: "The implementation may require that off is a
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// multiple of the page size."
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x := offset & int64(os.Getpagesize()-1)
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offset -= x
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length += x
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buf, err := syscall.Mmap(int(f.Fd()), offset, int(length), syscall.PROT_READ, syscall.MAP_SHARED)
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runtime.KeepAlive(f)
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if err != nil {
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return "", err
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}
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buf = buf[x:]
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pSlice := (*unsafeheader.Slice)(unsafe.Pointer(&buf))
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var res string
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pString := (*unsafeheader.String)(unsafe.Pointer(&res))
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pString.Data = pSlice.Data
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pString.Len = pSlice.Len
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return res, nil
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}
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