67 lines
1.4 KiB
Go
67 lines
1.4 KiB
Go
// iomisc.go -- misc i/o functions
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//
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// (c) 2016 Sudhi Herle <sudhi@herle.net>
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//
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// Licensing Terms: GPLv2
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//
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// If you need a commercial license for this work, please contact
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// the author.
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//
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// This software does not come with any express or implied
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// warranty; it is provided "as is". No claim is made to its
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// suitability for any purpose.
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package sign
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import (
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"encoding/binary"
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"fmt"
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"github.com/opencoff/go-mmap"
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"github.com/opencoff/go-utils"
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"hash"
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"os"
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)
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// Simple function to reliably write data to a file.
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// Does MORE than ioutil.WriteFile() - in that it doesn't trash the
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// existing file with an incomplete write.
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func writeFile(fn string, b []byte, ovwrite bool, mode uint32) error {
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var opts uint32
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if ovwrite {
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opts |= utils.OPT_OVERWRITE
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}
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sf, err := utils.NewSafeFile(fn, opts, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, os.FileMode(mode))
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if err != nil {
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return err
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}
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defer sf.Abort()
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if _, err = sf.Write(b); err != nil {
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return err
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}
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return sf.Close()
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}
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// Generate file checksum out of hash function h
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func fileCksum(fn string, h hash.Hash) ([]byte, error) {
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fd, err := os.Open(fn)
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if err != nil {
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return nil, fmt.Errorf("can't open %s: %s", fn, err)
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}
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defer fd.Close()
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sz, err := mmap.Reader(fd, func(b []byte) error {
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h.Write(b)
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return nil
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})
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if err != nil {
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return nil, err
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}
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var b [8]byte
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binary.BigEndian.PutUint64(b[:], uint64(sz))
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h.Write(b[:])
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return h.Sum(nil)[:], nil
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}
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