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76 lines
2.0 KiB
Go
76 lines
2.0 KiB
Go
package mount
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import (
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"github.com/seaweedfs/seaweedfs/weed/util"
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"syscall"
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"github.com/hanwen/go-fuse/v2/fuse"
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"github.com/seaweedfs/seaweedfs/weed/filer"
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"github.com/seaweedfs/seaweedfs/weed/glog"
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)
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// These are non-POSIX extensions
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const (
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SEEK_DATA uint32 = 3 // seek to next data after the offset
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SEEK_HOLE uint32 = 4 // seek to next hole after the offset
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ENXIO = fuse.Status(syscall.ENXIO)
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)
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// Lseek finds next data or hole segments after the specified offset
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// See https://man7.org/linux/man-pages/man2/lseek.2.html
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func (wfs *WFS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekOut) fuse.Status {
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// not a documented feature
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if in.Padding != 0 {
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return fuse.EINVAL
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}
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if in.Whence != SEEK_DATA && in.Whence != SEEK_HOLE {
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return fuse.EINVAL
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}
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// file must exist
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fh := wfs.GetHandle(FileHandleId(in.Fh))
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if fh == nil {
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return fuse.EBADF
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}
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// lock the file until the proper offset was calculated
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fhActiveLock := fh.wfs.fhLockTable.AcquireLock("Lseek", fh.fh, util.SharedLock)
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defer fh.wfs.fhLockTable.ReleaseLock(fh.fh, fhActiveLock)
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fh.entryLock.RLock()
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defer fh.entryLock.RUnlock()
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fileSize := int64(filer.FileSize(fh.GetEntry()))
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offset := max(int64(in.Offset), 0)
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glog.V(4).Infof(
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"Lseek %s fh %d in [%d,%d], whence %d",
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fh.FullPath(), fh.fh, offset, fileSize, in.Whence,
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)
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// can neither seek beyond file nor seek to a hole at the end of the file with SEEK_DATA
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if offset > fileSize {
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return ENXIO
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} else if in.Whence == SEEK_DATA && offset == fileSize {
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return ENXIO
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}
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// search chunks for the offset
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found, offset := fh.entryChunkGroup.SearchChunks(offset, fileSize, in.Whence)
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if found {
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out.Offset = uint64(offset)
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return fuse.OK
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}
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// in case we found no exact matches, we return the recommended fallbacks, that is:
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// original offset for SEEK_DATA or end of file for an implicit hole
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if in.Whence == SEEK_DATA {
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out.Offset = in.Offset
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} else {
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out.Offset = uint64(fileSize)
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}
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return fuse.OK
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}
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