mirror of
https://github.com/seaweedfs/seaweedfs.git
synced 2024-12-15 11:09:06 +08:00
76 lines
2.0 KiB
Go
76 lines
2.0 KiB
Go
package mount
|
|
|
|
import (
|
|
"github.com/seaweedfs/seaweedfs/weed/util"
|
|
"syscall"
|
|
|
|
"github.com/hanwen/go-fuse/v2/fuse"
|
|
|
|
"github.com/seaweedfs/seaweedfs/weed/filer"
|
|
"github.com/seaweedfs/seaweedfs/weed/glog"
|
|
)
|
|
|
|
// These are non-POSIX extensions
|
|
const (
|
|
SEEK_DATA uint32 = 3 // seek to next data after the offset
|
|
SEEK_HOLE uint32 = 4 // seek to next hole after the offset
|
|
ENXIO = fuse.Status(syscall.ENXIO)
|
|
)
|
|
|
|
// Lseek finds next data or hole segments after the specified offset
|
|
// See https://man7.org/linux/man-pages/man2/lseek.2.html
|
|
func (wfs *WFS) Lseek(cancel <-chan struct{}, in *fuse.LseekIn, out *fuse.LseekOut) fuse.Status {
|
|
// not a documented feature
|
|
if in.Padding != 0 {
|
|
return fuse.EINVAL
|
|
}
|
|
|
|
if in.Whence != SEEK_DATA && in.Whence != SEEK_HOLE {
|
|
return fuse.EINVAL
|
|
}
|
|
|
|
// file must exist
|
|
fh := wfs.GetHandle(FileHandleId(in.Fh))
|
|
if fh == nil {
|
|
return fuse.EBADF
|
|
}
|
|
|
|
// lock the file until the proper offset was calculated
|
|
fhActiveLock := fh.wfs.fhLockTable.AcquireLock("Lseek", fh.fh, util.SharedLock)
|
|
defer fh.wfs.fhLockTable.ReleaseLock(fh.fh, fhActiveLock)
|
|
fh.entryLock.RLock()
|
|
defer fh.entryLock.RUnlock()
|
|
|
|
fileSize := int64(filer.FileSize(fh.GetEntry()))
|
|
offset := max(int64(in.Offset), 0)
|
|
|
|
glog.V(4).Infof(
|
|
"Lseek %s fh %d in [%d,%d], whence %d",
|
|
fh.FullPath(), fh.fh, offset, fileSize, in.Whence,
|
|
)
|
|
|
|
// can neither seek beyond file nor seek to a hole at the end of the file with SEEK_DATA
|
|
if offset > fileSize {
|
|
return ENXIO
|
|
} else if in.Whence == SEEK_DATA && offset == fileSize {
|
|
return ENXIO
|
|
}
|
|
|
|
// search chunks for the offset
|
|
found, offset := fh.entryChunkGroup.SearchChunks(offset, fileSize, in.Whence)
|
|
if found {
|
|
out.Offset = uint64(offset)
|
|
return fuse.OK
|
|
}
|
|
|
|
// in case we found no exact matches, we return the recommended fallbacks, that is:
|
|
// original offset for SEEK_DATA or end of file for an implicit hole
|
|
if in.Whence == SEEK_DATA {
|
|
out.Offset = in.Offset
|
|
} else {
|
|
out.Offset = uint64(fileSize)
|
|
}
|
|
|
|
return fuse.OK
|
|
}
|