1a2f01efa6
Update the Go library to the 1.10beta1 release.
Requires a few changes to the compiler for modifications to the map
runtime code, and to handle some nowritebarrier cases in the runtime.
Reviewed-on: https://go-review.googlesource.com/86455
gotools/:
* Makefile.am (go_cmd_vet_files): New variable.
(go_cmd_buildid_files, go_cmd_test2json_files): New variables.
(s-zdefaultcc): Change from constants to functions.
(noinst_PROGRAMS): Add vet, buildid, and test2json.
(cgo$(EXEEXT)): Link against $(LIBGOTOOL).
(vet$(EXEEXT)): New target.
(buildid$(EXEEXT)): New target.
(test2json$(EXEEXT)): New target.
(install-exec-local): Install all $(noinst_PROGRAMS).
(uninstall-local): Uninstasll all $(noinst_PROGRAMS).
(check-go-tool): Depend on $(noinst_PROGRAMS). Copy down
objabi.go.
(check-runtime): Depend on $(noinst_PROGRAMS).
(check-cgo-test, check-carchive-test): Likewise.
(check-vet): New target.
(check): Depend on check-vet. Look at cmd_vet-testlog.
(.PHONY): Add check-vet.
* Makefile.in: Rebuild.
From-SVN: r256365
92 lines
2.8 KiB
Go
92 lines
2.8 KiB
Go
// Copyright 2017 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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package buildid
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import (
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"bytes"
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"crypto/sha256"
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"fmt"
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"io"
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)
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// FindAndHash reads all of r and returns the offsets of occurrences of id.
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// While reading, findAndHash also computes and returns
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// a hash of the content of r, but with occurrences of id replaced by zeros.
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// FindAndHash reads bufSize bytes from r at a time.
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// If bufSize == 0, FindAndHash uses a reasonable default.
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func FindAndHash(r io.Reader, id string, bufSize int) (matches []int64, hash [32]byte, err error) {
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if bufSize == 0 {
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bufSize = 31 * 1024 // bufSize+little will likely fit in 32 kB
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}
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if len(id) > bufSize {
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return nil, [32]byte{}, fmt.Errorf("buildid.FindAndHash: buffer too small")
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}
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zeros := make([]byte, len(id))
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idBytes := []byte(id)
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// The strategy is to read the file through buf, looking for id,
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// but we need to worry about what happens if id is broken up
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// and returned in parts by two different reads.
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// We allocate a tiny buffer (at least len(id)) and a big buffer (bufSize bytes)
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// next to each other in memory and then copy the tail of
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// one read into the tiny buffer before reading new data into the big buffer.
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// The search for id is over the entire tiny+big buffer.
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tiny := (len(id) + 127) &^ 127 // round up to 128-aligned
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buf := make([]byte, tiny+bufSize)
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h := sha256.New()
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start := tiny
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for offset := int64(0); ; {
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// The file offset maintained by the loop corresponds to &buf[tiny].
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// buf[start:tiny] is left over from previous iteration.
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// After reading n bytes into buf[tiny:], we process buf[start:tiny+n].
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n, err := io.ReadFull(r, buf[tiny:])
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if err != io.ErrUnexpectedEOF && err != io.EOF && err != nil {
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return nil, [32]byte{}, err
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}
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// Process any matches.
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for {
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i := bytes.Index(buf[start:tiny+n], idBytes)
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if i < 0 {
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break
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}
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matches = append(matches, offset+int64(start+i-tiny))
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h.Write(buf[start : start+i])
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h.Write(zeros)
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start += i + len(id)
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}
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if n < bufSize {
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// Did not fill buffer, must be at end of file.
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h.Write(buf[start : tiny+n])
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break
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}
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// Process all but final tiny bytes of buf (bufSize = len(buf)-tiny).
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// Note that start > len(buf)-tiny is possible, if the search above
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// found an id ending in the final tiny fringe. That's OK.
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if start < len(buf)-tiny {
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h.Write(buf[start : len(buf)-tiny])
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start = len(buf) - tiny
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}
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// Slide ending tiny-sized fringe to beginning of buffer.
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copy(buf[0:], buf[bufSize:])
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start -= bufSize
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offset += int64(bufSize)
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}
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h.Sum(hash[:0])
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return matches, hash, nil
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}
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func Rewrite(w io.WriterAt, pos []int64, id string) error {
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b := []byte(id)
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for _, p := range pos {
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if _, err := w.WriteAt(b, p); err != nil {
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return err
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}
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}
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return nil
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}
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