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file.go
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file.go
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// Copyright 2017 The go-hep Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package rootio
import (
"fmt"
"io"
"os"
)
type Reader interface {
io.Reader
io.ReaderAt
io.Seeker
io.Closer
}
type Writer interface {
io.Writer
io.WriterAt
io.Seeker
io.Closer
}
// A ROOT file is a suite of consecutive data records (TKey's) with
// the following format (see also the TKey class). If the key is
// located past the 32 bit file limit (> 2 GB) then some fields will
// be 8 instead of 4 bytes:
// 1->4 Nbytes = Length of compressed object (in bytes)
// 5->6 Version = TKey version identifier
// 7->10 ObjLen = Length of uncompressed object
// 11->14 Datime = Date and time when object was written to file
// 15->16 KeyLen = Length of the key structure (in bytes)
// 17->18 Cycle = Cycle of key
// 19->22 [19->26] SeekKey = Pointer to record itself (consistency check)
// 23->26 [27->34] SeekPdir = Pointer to directory header
// 27->27 [35->35] lname = Number of bytes in the class name
// 28->.. [36->..] ClassName = Object Class Name
// ..->.. lname = Number of bytes in the object name
// ..->.. Name = lName bytes with the name of the object
// ..->.. lTitle = Number of bytes in the object title
// ..->.. Title = Title of the object
// -----> DATA = Data bytes associated to the object
//
// The first data record starts at byte fBEGIN (currently set to kBEGIN).
// Bytes 1->kBEGIN contain the file description, when fVersion >= 1000000
// it is a large file (> 2 GB) and the offsets will be 8 bytes long and
// fUnits will be set to 8:
// 1->4 "root" = Root file identifier
// 5->8 fVersion = File format version
// 9->12 fBEGIN = Pointer to first data record
// 13->16 [13->20] fEND = Pointer to first free word at the EOF
// 17->20 [21->28] fSeekFree = Pointer to FREE data record
// 21->24 [29->32] fNbytesFree = Number of bytes in FREE data record
// 25->28 [33->36] nfree = Number of free data records
// 29->32 [37->40] fNbytesName = Number of bytes in TNamed at creation time
// 33->33 [41->41] fUnits = Number of bytes for file pointers
// 34->37 [42->45] fCompress = Compression level and algorithm
// 38->41 [46->53] fSeekInfo = Pointer to TStreamerInfo record
// 42->45 [54->57] fNbytesInfo = Number of bytes in TStreamerInfo record
// 46->63 [58->75] fUUID = Universal Unique ID
type File struct {
r Reader
w Writer
seeker io.Seeker
closer io.Closer
id string //non-root, identifies filename, etc.
version int32
begin int64
// Remainder of record is variable length, 4 or 8 bytes per pointer
end int64
seekfree int64 // first available record
nbytesfree int32 // total bytes available
nfree int32 // total free bytes
nbytesname int32 // number of bytes in TNamed at creation time
units byte
compression int32
seekinfo int64 // pointer to TStreamerInfo
nbytesinfo int32 // sizeof(TStreamerInfo)
uuid [18]byte
dir tdirectory // root directory of this file
siKey Key
sinfos []StreamerInfo
}
// Open opens the named ROOT file for reading. If successful, methods on the
// returned file can be used for reading; the associated file descriptor
// has mode os.O_RDONLY.
func Open(path string) (*File, error) {
fd, err := os.Open(path)
if err != nil {
return nil, fmt.Errorf("rootio: unable to open %q (%q)", path, err.Error())
}
f := &File{
r: fd,
seeker: fd,
closer: fd,
id: path,
}
f.dir = tdirectory{file: f}
err = f.readHeader()
if err != nil {
return nil, fmt.Errorf("rootio: failed to read header %q: %v", path, err)
}
return f, nil
}
// NewReader creates a new ROOT file reader.
func NewReader(r Reader, name string) (*File, error) {
f := &File{
r: r,
seeker: r,
closer: r,
id: name,
}
f.dir = tdirectory{file: f}
err := f.readHeader()
if err != nil {
return nil, fmt.Errorf("rootio: failed to read header: %v", err)
}
return f, nil
}
// Read implements io.Reader
func (f *File) Read(p []byte) (int, error) {
return f.r.Read(p)
}
// ReadAt implements io.ReaderAt
func (f *File) ReadAt(p []byte, off int64) (int, error) {
return f.r.ReadAt(p, off)
}
// Seek implements io.Seeker
func (f *File) Seek(offset int64, whence int) (int64, error) {
return f.seeker.Seek(offset, whence)
}
// Version returns the ROOT version this file was created with.
func (f *File) Version() int {
return int(f.version)
}
func (f *File) readHeader() error {
buf := make([]byte, 64)
if _, err := f.ReadAt(buf, 0); err != nil {
return err
}
r := NewRBuffer(buf, nil, 0)
// Header
var magic [4]byte
if _, err := io.ReadFull(r.r, magic[:]); err != nil || string(magic[:]) != "root" {
if err != nil {
return fmt.Errorf("rootio: failed to read ROOT file magic header: %v", err)
}
return fmt.Errorf("rootio: %q is not a root file", f.id)
}
r.ReadI32(&f.version)
var i32 int32
r.ReadI32(&i32)
f.begin = int64(i32)
if f.version < 1000000 { // small file
r.ReadI32(&i32)
f.end = int64(i32)
r.ReadI32(&i32)
f.seekfree = int64(i32)
r.ReadI32(&f.nbytesfree)
r.ReadI32(&f.nfree)
r.ReadI32(&f.nbytesname)
r.ReadU8(&f.units)
r.ReadI32(&f.compression)
r.ReadI32(&i32)
f.seekinfo = int64(i32)
r.ReadI32(&f.nbytesinfo)
} else { // large files
r.ReadI64(&f.end)
r.ReadI64(&f.seekfree)
r.ReadI32(&f.nbytesfree)
r.ReadI32(&f.nfree)
r.ReadI32(&f.nbytesname)
r.ReadU8(&f.units)
r.ReadI32(&f.compression)
r.ReadI64(&f.seekinfo)
r.ReadI32(&f.nbytesinfo)
}
f.version %= 1000000
if _, err := io.ReadFull(r.r, f.uuid[:]); err != nil || r.Err() != nil {
if err != nil {
return fmt.Errorf("rootio: failed to read ROOT's UUID file: %v", err)
}
return r.Err()
}
var err error
err = f.dir.readDirInfo()
if err != nil {
return fmt.Errorf("rootio: failed to read ROOT directory infos: %v", err)
}
err = f.readStreamerInfo()
if err != nil {
return fmt.Errorf("rootio: failed to read ROOT streamer infos: %v", err)
}
err = f.dir.readKeys()
if err != nil {
return fmt.Errorf("rootio: failed to read ROOT file keys: %v", err)
}
return nil
}
func (f *File) Map() {
for _, k := range f.dir.keys {
if k.class == "TBasket" {
//b := k.AsBasket()
fmt.Printf("%8s %60s %6v %6v %f\n", k.class, k.name, k.bytes-k.keylen, k.objlen, float64(k.objlen)/float64(k.bytes-k.keylen))
} else {
//println(k.classname, k.name, k.title)
fmt.Printf("%8s %60s %6v %6v %f\n", k.class, k.name, k.bytes-k.keylen, k.objlen, float64(k.objlen)/float64(k.bytes-k.keylen))
}
}
}
func (f *File) Tell() int64 {
where, err := f.Seek(0, ioSeekCurrent)
if err != nil {
panic(err)
}
return where
}
// Close closes the File, rendering it unusable for I/O.
// It returns an error, if any.
func (f *File) Close() error {
for _, k := range f.dir.keys {
k.f = nil
}
f.dir.keys = nil
f.dir.file = nil
return f.closer.Close()
}
// Keys returns the list of keys this File contains
func (f *File) Keys() []Key {
return f.dir.keys
}
func (f *File) Name() string {
return f.dir.Name()
}
func (f *File) Title() string {
return f.dir.Title()
}
func (f *File) Class() string {
return "TFile"
}
// readStreamerInfo reads the list of StreamerInfo from this file
func (f *File) readStreamerInfo() error {
if f.seekinfo <= 0 || f.seekinfo >= f.end {
return fmt.Errorf("rootio: invalid pointer to StreamerInfo (pos=%v end=%v)", f.seekinfo, f.end)
}
buf := make([]byte, int(f.nbytesinfo))
nbytes, err := f.ReadAt(buf, f.seekinfo)
if err != nil {
return err
}
if nbytes != int(f.nbytesinfo) {
return fmt.Errorf("rootio: requested [%v] bytes. read [%v] bytes from file", f.nbytesinfo, nbytes)
}
err = f.siKey.UnmarshalROOT(NewRBuffer(buf, nil, 0))
f.siKey.f = f
if err != nil {
return err
}
objs := f.siKey.Value().(List)
f.sinfos = make([]StreamerInfo, 0, objs.Len())
for i := 0; i < objs.Len(); i++ {
obj, ok := objs.At(i).(StreamerInfo)
if !ok {
continue
}
f.sinfos = append(f.sinfos, obj)
streamers.add(obj)
}
return nil
}
// StreamerInfo returns the list of StreamerInfos of this file.
func (f *File) StreamerInfo() []StreamerInfo {
return f.sinfos
}
// Get returns the object identified by namecycle
// namecycle has the format name;cycle
// name = * is illegal, cycle = * is illegal
// cycle = "" or cycle = 9999 ==> apply to a memory object
//
// examples:
// foo : get object named foo in memory
// if object is not in memory, try with highest cycle from file
// foo;1 : get cycle 1 of foo on file
func (f *File) Get(namecycle string) (Object, error) {
return f.dir.Get(namecycle)
}
var _ Object = (*File)(nil)
var _ Named = (*File)(nil)
var _ Directory = (*File)(nil)