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Workaround a go bug to avoid seek offsets whose lower 32 bits are -1

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This commit is contained in:
Gilbert Chen
2017-09-01 15:05:14 -04:00
parent 93cfbf27cb
commit 197d20f0e0
1 changed files with 15 additions and 6 deletions
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21
src/duplicacy_backupmanager.go
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@@ -17,6 +17,7 @@ import (
"sync/atomic"
"strings"
"strconv"
"runtime"
"encoding/hex"
"path/filepath"
)
@@ -1152,21 +1153,29 @@ func (manager *BackupManager) RestoreFile(chunkDownloader *ChunkDownloader, chun
existingFile, err = os.Open(fullPath)
if err != nil {
if os.IsNotExist(err) {
if inPlace && entry.Size > 100 * 1024 * 1024 {
// macOS has no sparse file support
if inPlace && entry.Size > 100 * 1024 * 1024 && runtime.GOOS != "darwin" {
// Create an empty sparse file
existingFile, err = os.OpenFile(fullPath, os.O_WRONLY | os.O_CREATE | os.O_TRUNC, 0600)
if err != nil {
LOG_ERROR("DOWNLOAD_CREATE", "Failed to create the file %s for in-place writing", fullPath)
LOG_ERROR("DOWNLOAD_CREATE", "Failed to create the file %s for in-place writing: %v", fullPath, err)
return false
}
_, err = existingFile.Seek(entry.Size - 1, 0)
n := int64(1)
// There is a go bug on Windows (https://github.com/golang/go/issues/21681) that causes Seek to fail
// if the lower 32 bit of the offset argument is 0xffffffff. Therefore we need to avoid that value by increasing n.
if uint32(entry.Size) == 0 && (entry.Size >> 32) > 0 {
n = int64(2)
}
_, err = existingFile.Seek(entry.Size - n, 0)
if err != nil {
LOG_ERROR("DOWNLOAD_CREATE", "Failed to resize the initial file %s for in-place writing", fullPath)
LOG_ERROR("DOWNLOAD_CREATE", "Failed to resize the initial file %s for in-place writing: %v", fullPath, err)
return false
}
_, err = existingFile.Write([]byte("\x00"))
_, err = existingFile.Write([]byte("\x00\x00")[:n])
if err != nil {
LOG_ERROR("DOWNLOAD_CREATE", "Failed to initialize the sparse file %s for in-place writing", fullPath)
LOG_ERROR("DOWNLOAD_CREATE", "Failed to initialize the sparse file %s for in-place writing: %v", fullPath, err)
return false
}
existingFile.Close()