aboutsummaryrefslogtreecommitdiff
path: root/src/streams.h
blob: a6e781b95ba96686a72c4e2bc5c8100a83a11bd9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2019 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_STREAMS_H
#define BITCOIN_STREAMS_H

#include <serialize.h>
#include <span.h>
#include <support/allocators/zeroafterfree.h>

#include <algorithm>
#include <assert.h>
#include <ios>
#include <limits>
#include <optional>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <string>
#include <utility>
#include <vector>

template<typename Stream>
class OverrideStream
{
    Stream* stream;

    const int nType;
    const int nVersion;

public:
    OverrideStream(Stream* stream_, int nType_, int nVersion_) : stream(stream_), nType(nType_), nVersion(nVersion_) {}

    template<typename T>
    OverrideStream<Stream>& operator<<(const T& obj)
    {
        // Serialize to this stream
        ::Serialize(*this, obj);
        return (*this);
    }

    template<typename T>
    OverrideStream<Stream>& operator>>(T&& obj)
    {
        // Unserialize from this stream
        ::Unserialize(*this, obj);
        return (*this);
    }

    void write(const char* pch, size_t nSize)
    {
        stream->write(pch, nSize);
    }

    void read(char* pch, size_t nSize)
    {
        stream->read(pch, nSize);
    }

    int GetVersion() const { return nVersion; }
    int GetType() const { return nType; }
    size_t size() const { return stream->size(); }
    void ignore(size_t size) { return stream->ignore(size); }
};

/* Minimal stream for overwriting and/or appending to an existing byte vector
 *
 * The referenced vector will grow as necessary
 */
class CVectorWriter
{
 public:

/*
 * @param[in]  nTypeIn Serialization Type
 * @param[in]  nVersionIn Serialization Version (including any flags)
 * @param[in]  vchDataIn  Referenced byte vector to overwrite/append
 * @param[in]  nPosIn Starting position. Vector index where writes should start. The vector will initially
 *                    grow as necessary to max(nPosIn, vec.size()). So to append, use vec.size().
*/
    CVectorWriter(int nTypeIn, int nVersionIn, std::vector<unsigned char>& vchDataIn, size_t nPosIn) : nType(nTypeIn), nVersion(nVersionIn), vchData(vchDataIn), nPos(nPosIn)
    {
        if(nPos > vchData.size())
            vchData.resize(nPos);
    }
/*
 * (other params same as above)
 * @param[in]  args  A list of items to serialize starting at nPosIn.
*/
    template <typename... Args>
    CVectorWriter(int nTypeIn, int nVersionIn, std::vector<unsigned char>& vchDataIn, size_t nPosIn, Args&&... args) : CVectorWriter(nTypeIn, nVersionIn, vchDataIn, nPosIn)
    {
        ::SerializeMany(*this, std::forward<Args>(args)...);
    }
    void write(const char* pch, size_t nSize)
    {
        assert(nPos <= vchData.size());
        size_t nOverwrite = std::min(nSize, vchData.size() - nPos);
        if (nOverwrite) {
            memcpy(vchData.data() + nPos, reinterpret_cast<const unsigned char*>(pch), nOverwrite);
        }
        if (nOverwrite < nSize) {
            vchData.insert(vchData.end(), reinterpret_cast<const unsigned char*>(pch) + nOverwrite, reinterpret_cast<const unsigned char*>(pch) + nSize);
        }
        nPos += nSize;
    }
    template<typename T>
    CVectorWriter& operator<<(const T& obj)
    {
        // Serialize to this stream
        ::Serialize(*this, obj);
        return (*this);
    }
    int GetVersion() const
    {
        return nVersion;
    }
    int GetType() const
    {
        return nType;
    }
private:
    const int nType;
    const int nVersion;
    std::vector<unsigned char>& vchData;
    size_t nPos;
};

/** Minimal stream for reading from an existing vector by reference
 */
class VectorReader
{
private:
    const int m_type;
    const int m_version;
    const std::vector<unsigned char>& m_data;
    size_t m_pos = 0;

public:

    /**
     * @param[in]  type Serialization Type
     * @param[in]  version Serialization Version (including any flags)
     * @param[in]  data Referenced byte vector to overwrite/append
     * @param[in]  pos Starting position. Vector index where reads should start.
     */
    VectorReader(int type, int version, const std::vector<unsigned char>& data, size_t pos)
        : m_type(type), m_version(version), m_data(data), m_pos(pos)
    {
        if (m_pos > m_data.size()) {
            throw std::ios_base::failure("VectorReader(...): end of data (m_pos > m_data.size())");
        }
    }

    /**
     * (other params same as above)
     * @param[in]  args  A list of items to deserialize starting at pos.
     */
    template <typename... Args>
    VectorReader(int type, int version, const std::vector<unsigned char>& data, size_t pos,
                  Args&&... args)
        : VectorReader(type, version, data, pos)
    {
        ::UnserializeMany(*this, std::forward<Args>(args)...);
    }

    template<typename T>
    VectorReader& operator>>(T& obj)
    {
        // Unserialize from this stream
        ::Unserialize(*this, obj);
        return (*this);
    }

    int GetVersion() const { return m_version; }
    int GetType() const { return m_type; }

    size_t size() const { return m_data.size() - m_pos; }
    bool empty() const { return m_data.size() == m_pos; }

    void read(char* dst, size_t n)
    {
        if (n == 0) {
            return;
        }

        // Read from the beginning of the buffer
        size_t pos_next = m_pos + n;
        if (pos_next > m_data.size()) {
            throw std::ios_base::failure("VectorReader::read(): end of data");
        }
        memcpy(dst, m_data.data() + m_pos, n);
        m_pos = pos_next;
    }
};

/** Double ended buffer combining vector and stream-like interfaces.
 *
 * >> and << read and write unformatted data using the above serialization templates.
 * Fills with data in linear time; some stringstream implementations take N^2 time.
 */
class CDataStream
{
protected:
    using vector_type = SerializeData;
    vector_type vch;
    unsigned int nReadPos{0};

    int nType;
    int nVersion;

public:
    typedef vector_type::allocator_type   allocator_type;
    typedef vector_type::size_type        size_type;
    typedef vector_type::difference_type  difference_type;
    typedef vector_type::reference        reference;
    typedef vector_type::const_reference  const_reference;
    typedef vector_type::value_type       value_type;
    typedef vector_type::iterator         iterator;
    typedef vector_type::const_iterator   const_iterator;
    typedef vector_type::reverse_iterator reverse_iterator;

    explicit CDataStream(int nTypeIn, int nVersionIn)
        : nType{nTypeIn},
          nVersion{nVersionIn} {}

    explicit CDataStream(Span<const uint8_t> sp, int nTypeIn, int nVersionIn)
        : vch(sp.data(), sp.data() + sp.size()),
          nType{nTypeIn},
          nVersion{nVersionIn} {}

    template <typename... Args>
    CDataStream(int nTypeIn, int nVersionIn, Args&&... args)
        : nType{nTypeIn},
          nVersion{nVersionIn}
    {
        ::SerializeMany(*this, std::forward<Args>(args)...);
    }

    std::string str() const
    {
        return (std::string(begin(), end()));
    }


    //
    // Vector subset
    //
    const_iterator begin() const                     { return vch.begin() + nReadPos; }
    iterator begin()                                 { return vch.begin() + nReadPos; }
    const_iterator end() const                       { return vch.end(); }
    iterator end()                                   { return vch.end(); }
    size_type size() const                           { return vch.size() - nReadPos; }
    bool empty() const                               { return vch.size() == nReadPos; }
    void resize(size_type n, value_type c=0)         { vch.resize(n + nReadPos, c); }
    void reserve(size_type n)                        { vch.reserve(n + nReadPos); }
    const_reference operator[](size_type pos) const  { return vch[pos + nReadPos]; }
    reference operator[](size_type pos)              { return vch[pos + nReadPos]; }
    void clear()                                     { vch.clear(); nReadPos = 0; }
    iterator insert(iterator it, const uint8_t x) { return vch.insert(it, x); }
    void insert(iterator it, size_type n, const uint8_t x) { vch.insert(it, n, x); }
    value_type* data()                               { return vch.data() + nReadPos; }
    const value_type* data() const                   { return vch.data() + nReadPos; }

    void insert(iterator it, std::vector<uint8_t>::const_iterator first, std::vector<uint8_t>::const_iterator last)
    {
        if (last == first) return;
        assert(last - first > 0);
        if (it == vch.begin() + nReadPos && (unsigned int)(last - first) <= nReadPos)
        {
            // special case for inserting at the front when there's room
            nReadPos -= (last - first);
            memcpy(&vch[nReadPos], &first[0], last - first);
        }
        else
            vch.insert(it, first, last);
    }

    void insert(iterator it, const char* first, const char* last)
    {
        if (last == first) return;
        assert(last - first > 0);
        if (it == vch.begin() + nReadPos && (unsigned int)(last - first) <= nReadPos)
        {
            // special case for inserting at the front when there's room
            nReadPos -= (last - first);
            memcpy(&vch[nReadPos], &first[0], last - first);
        }
        else
            vch.insert(it, first, last);
    }

    iterator erase(iterator it)
    {
        if (it == vch.begin() + nReadPos)
        {
            // special case for erasing from the front
            if (++nReadPos >= vch.size())
            {
                // whenever we reach the end, we take the opportunity to clear the buffer
                nReadPos = 0;
                return vch.erase(vch.begin(), vch.end());
            }
            return vch.begin() + nReadPos;
        }
        else
            return vch.erase(it);
    }

    iterator erase(iterator first, iterator last)
    {
        if (first == vch.begin() + nReadPos)
        {
            // special case for erasing from the front
            if (last == vch.end())
            {
                nReadPos = 0;
                return vch.erase(vch.begin(), vch.end());
            }
            else
            {
                nReadPos = (last - vch.begin());
                return last;
            }
        }
        else
            return vch.erase(first, last);
    }

    inline void Compact()
    {
        vch.erase(vch.begin(), vch.begin() + nReadPos);
        nReadPos = 0;
    }

    bool Rewind(std::optional<size_type> n = std::nullopt)
    {
        // Total rewind if no size is passed
        if (!n) {
            nReadPos = 0;
            return true;
        }
        // Rewind by n characters if the buffer hasn't been compacted yet
        if (*n > nReadPos)
            return false;
        nReadPos -= *n;
        return true;
    }


    //
    // Stream subset
    //
    bool eof() const             { return size() == 0; }
    CDataStream* rdbuf()         { return this; }
    int in_avail() const         { return size(); }

    void SetType(int n)          { nType = n; }
    int GetType() const          { return nType; }
    void SetVersion(int n)       { nVersion = n; }
    int GetVersion() const       { return nVersion; }

    void read(char* pch, size_t nSize)
    {
        if (nSize == 0) return;

        // Read from the beginning of the buffer
        unsigned int nReadPosNext = nReadPos + nSize;
        if (nReadPosNext > vch.size()) {
            throw std::ios_base::failure("CDataStream::read(): end of data");
        }
        memcpy(pch, &vch[nReadPos], nSize);
        if (nReadPosNext == vch.size())
        {
            nReadPos = 0;
            vch.clear();
            return;
        }
        nReadPos = nReadPosNext;
    }

    void ignore(int nSize)
    {
        // Ignore from the beginning of the buffer
        if (nSize < 0) {
            throw std::ios_base::failure("CDataStream::ignore(): nSize negative");
        }
        unsigned int nReadPosNext = nReadPos + nSize;
        if (nReadPosNext >= vch.size())
        {
            if (nReadPosNext > vch.size())
                throw std::ios_base::failure("CDataStream::ignore(): end of data");
            nReadPos = 0;
            vch.clear();
            return;
        }
        nReadPos = nReadPosNext;
    }

    void write(const char* pch, size_t nSize)
    {
        // Write to the end of the buffer
        vch.insert(vch.end(), pch, pch + nSize);
    }

    template<typename Stream>
    void Serialize(Stream& s) const
    {
        // Special case: stream << stream concatenates like stream += stream
        if (!vch.empty())
            s.write((char*)vch.data(), vch.size() * sizeof(value_type));
    }

    template<typename T>
    CDataStream& operator<<(const T& obj)
    {
        // Serialize to this stream
        ::Serialize(*this, obj);
        return (*this);
    }

    template<typename T>
    CDataStream& operator>>(T&& obj)
    {
        // Unserialize from this stream
        ::Unserialize(*this, obj);
        return (*this);
    }

    /**
     * XOR the contents of this stream with a certain key.
     *
     * @param[in] key    The key used to XOR the data in this stream.
     */
    void Xor(const std::vector<unsigned char>& key)
    {
        if (key.size() == 0) {
            return;
        }

        for (size_type i = 0, j = 0; i != size(); i++) {
            vch[i] ^= key[j++];

            // This potentially acts on very many bytes of data, so it's
            // important that we calculate `j`, i.e. the `key` index in this
            // way instead of doing a %, which would effectively be a division
            // for each byte Xor'd -- much slower than need be.
            if (j == key.size())
                j = 0;
        }
    }
};

template <typename IStream>
class BitStreamReader
{
private:
    IStream& m_istream;

    /// Buffered byte read in from the input stream. A new byte is read into the
    /// buffer when m_offset reaches 8.
    uint8_t m_buffer{0};

    /// Number of high order bits in m_buffer already returned by previous
    /// Read() calls. The next bit to be returned is at this offset from the
    /// most significant bit position.
    int m_offset{8};

public:
    explicit BitStreamReader(IStream& istream) : m_istream(istream) {}

    /** Read the specified number of bits from the stream. The data is returned
     * in the nbits least significant bits of a 64-bit uint.
     */
    uint64_t Read(int nbits) {
        if (nbits < 0 || nbits > 64) {
            throw std::out_of_range("nbits must be between 0 and 64");
        }

        uint64_t data = 0;
        while (nbits > 0) {
            if (m_offset == 8) {
                m_istream >> m_buffer;
                m_offset = 0;
            }

            int bits = std::min(8 - m_offset, nbits);
            data <<= bits;
            data |= static_cast<uint8_t>(m_buffer << m_offset) >> (8 - bits);
            m_offset += bits;
            nbits -= bits;
        }
        return data;
    }
};

template <typename OStream>
class BitStreamWriter
{
private:
    OStream& m_ostream;

    /// Buffered byte waiting to be written to the output stream. The byte is
    /// written buffer when m_offset reaches 8 or Flush() is called.
    uint8_t m_buffer{0};

    /// Number of high order bits in m_buffer already written by previous
    /// Write() calls and not yet flushed to the stream. The next bit to be
    /// written to is at this offset from the most significant bit position.
    int m_offset{0};

public:
    explicit BitStreamWriter(OStream& ostream) : m_ostream(ostream) {}

    ~BitStreamWriter()
    {
        Flush();
    }

    /** Write the nbits least significant bits of a 64-bit int to the output
     * stream. Data is buffered until it completes an octet.
     */
    void Write(uint64_t data, int nbits) {
        if (nbits < 0 || nbits > 64) {
            throw std::out_of_range("nbits must be between 0 and 64");
        }

        while (nbits > 0) {
            int bits = std::min(8 - m_offset, nbits);
            m_buffer |= (data << (64 - nbits)) >> (64 - 8 + m_offset);
            m_offset += bits;
            nbits -= bits;

            if (m_offset == 8) {
                Flush();
            }
        }
    }

    /** Flush any unwritten bits to the output stream, padding with 0's to the
     * next byte boundary.
     */
    void Flush() {
        if (m_offset == 0) {
            return;
        }

        m_ostream << m_buffer;
        m_buffer = 0;
        m_offset = 0;
    }
};



/** Non-refcounted RAII wrapper for FILE*
 *
 * Will automatically close the file when it goes out of scope if not null.
 * If you're returning the file pointer, return file.release().
 * If you need to close the file early, use file.fclose() instead of fclose(file).
 */
class CAutoFile
{
private:
    const int nType;
    const int nVersion;

    FILE* file;

public:
    CAutoFile(FILE* filenew, int nTypeIn, int nVersionIn) : nType(nTypeIn), nVersion(nVersionIn)
    {
        file = filenew;
    }

    ~CAutoFile()
    {
        fclose();
    }

    // Disallow copies
    CAutoFile(const CAutoFile&) = delete;
    CAutoFile& operator=(const CAutoFile&) = delete;

    void fclose()
    {
        if (file) {
            ::fclose(file);
            file = nullptr;
        }
    }

    /** Get wrapped FILE* with transfer of ownership.
     * @note This will invalidate the CAutoFile object, and makes it the responsibility of the caller
     * of this function to clean up the returned FILE*.
     */
    FILE* release()             { FILE* ret = file; file = nullptr; return ret; }

    /** Get wrapped FILE* without transfer of ownership.
     * @note Ownership of the FILE* will remain with this class. Use this only if the scope of the
     * CAutoFile outlives use of the passed pointer.
     */
    FILE* Get() const           { return file; }

    /** Return true if the wrapped FILE* is nullptr, false otherwise.
     */
    bool IsNull() const         { return (file == nullptr); }

    //
    // Stream subset
    //
    int GetType() const          { return nType; }
    int GetVersion() const       { return nVersion; }

    void read(char* pch, size_t nSize)
    {
        if (!file)
            throw std::ios_base::failure("CAutoFile::read: file handle is nullptr");
        if (fread(pch, 1, nSize, file) != nSize)
            throw std::ios_base::failure(feof(file) ? "CAutoFile::read: end of file" : "CAutoFile::read: fread failed");
    }

    void ignore(size_t nSize)
    {
        if (!file)
            throw std::ios_base::failure("CAutoFile::ignore: file handle is nullptr");
        unsigned char data[4096];
        while (nSize > 0) {
            size_t nNow = std::min<size_t>(nSize, sizeof(data));
            if (fread(data, 1, nNow, file) != nNow)
                throw std::ios_base::failure(feof(file) ? "CAutoFile::ignore: end of file" : "CAutoFile::read: fread failed");
            nSize -= nNow;
        }
    }

    void write(const char* pch, size_t nSize)
    {
        if (!file)
            throw std::ios_base::failure("CAutoFile::write: file handle is nullptr");
        if (fwrite(pch, 1, nSize, file) != nSize)
            throw std::ios_base::failure("CAutoFile::write: write failed");
    }

    template<typename T>
    CAutoFile& operator<<(const T& obj)
    {
        // Serialize to this stream
        if (!file)
            throw std::ios_base::failure("CAutoFile::operator<<: file handle is nullptr");
        ::Serialize(*this, obj);
        return (*this);
    }

    template<typename T>
    CAutoFile& operator>>(T&& obj)
    {
        // Unserialize from this stream
        if (!file)
            throw std::ios_base::failure("CAutoFile::operator>>: file handle is nullptr");
        ::Unserialize(*this, obj);
        return (*this);
    }
};

/** Non-refcounted RAII wrapper around a FILE* that implements a ring buffer to
 *  deserialize from. It guarantees the ability to rewind a given number of bytes.
 *
 *  Will automatically close the file when it goes out of scope if not null.
 *  If you need to close the file early, use file.fclose() instead of fclose(file).
 */
class CBufferedFile
{
private:
    const int nType;
    const int nVersion;

    FILE *src;            //!< source file
    uint64_t nSrcPos;     //!< how many bytes have been read from source
    uint64_t nReadPos;    //!< how many bytes have been read from this
    uint64_t nReadLimit;  //!< up to which position we're allowed to read
    uint64_t nRewind;     //!< how many bytes we guarantee to rewind
    std::vector<char> vchBuf; //!< the buffer

protected:
    //! read data from the source to fill the buffer
    bool Fill() {
        unsigned int pos = nSrcPos % vchBuf.size();
        unsigned int readNow = vchBuf.size() - pos;
        unsigned int nAvail = vchBuf.size() - (nSrcPos - nReadPos) - nRewind;
        if (nAvail < readNow)
            readNow = nAvail;
        if (readNow == 0)
            return false;
        size_t nBytes = fread((void*)&vchBuf[pos], 1, readNow, src);
        if (nBytes == 0) {
            throw std::ios_base::failure(feof(src) ? "CBufferedFile::Fill: end of file" : "CBufferedFile::Fill: fread failed");
        }
        nSrcPos += nBytes;
        return true;
    }

public:
    CBufferedFile(FILE *fileIn, uint64_t nBufSize, uint64_t nRewindIn, int nTypeIn, int nVersionIn) :
        nType(nTypeIn), nVersion(nVersionIn), nSrcPos(0), nReadPos(0), nReadLimit(std::numeric_limits<uint64_t>::max()), nRewind(nRewindIn), vchBuf(nBufSize, 0)
    {
        if (nRewindIn >= nBufSize)
            throw std::ios_base::failure("Rewind limit must be less than buffer size");
        src = fileIn;
    }

    ~CBufferedFile()
    {
        fclose();
    }

    // Disallow copies
    CBufferedFile(const CBufferedFile&) = delete;
    CBufferedFile& operator=(const CBufferedFile&) = delete;

    int GetVersion() const { return nVersion; }
    int GetType() const { return nType; }

    void fclose()
    {
        if (src) {
            ::fclose(src);
            src = nullptr;
        }
    }

    //! check whether we're at the end of the source file
    bool eof() const {
        return nReadPos == nSrcPos && feof(src);
    }

    //! read a number of bytes
    void read(char *pch, size_t nSize) {
        if (nSize + nReadPos > nReadLimit)
            throw std::ios_base::failure("Read attempted past buffer limit");
        while (nSize > 0) {
            if (nReadPos == nSrcPos)
                Fill();
            unsigned int pos = nReadPos % vchBuf.size();
            size_t nNow = nSize;
            if (nNow + pos > vchBuf.size())
                nNow = vchBuf.size() - pos;
            if (nNow + nReadPos > nSrcPos)
                nNow = nSrcPos - nReadPos;
            memcpy(pch, &vchBuf[pos], nNow);
            nReadPos += nNow;
            pch += nNow;
            nSize -= nNow;
        }
    }

    //! return the current reading position
    uint64_t GetPos() const {
        return nReadPos;
    }

    //! rewind to a given reading position
    bool SetPos(uint64_t nPos) {
        size_t bufsize = vchBuf.size();
        if (nPos + bufsize < nSrcPos) {
            // rewinding too far, rewind as far as possible
            nReadPos = nSrcPos - bufsize;
            return false;
        }
        if (nPos > nSrcPos) {
            // can't go this far forward, go as far as possible
            nReadPos = nSrcPos;
            return false;
        }
        nReadPos = nPos;
        return true;
    }

    //! prevent reading beyond a certain position
    //! no argument removes the limit
    bool SetLimit(uint64_t nPos = std::numeric_limits<uint64_t>::max()) {
        if (nPos < nReadPos)
            return false;
        nReadLimit = nPos;
        return true;
    }

    template<typename T>
    CBufferedFile& operator>>(T&& obj) {
        // Unserialize from this stream
        ::Unserialize(*this, obj);
        return (*this);
    }

    //! search for a given byte in the stream, and remain positioned on it
    void FindByte(char ch) {
        while (true) {
            if (nReadPos == nSrcPos)
                Fill();
            if (vchBuf[nReadPos % vchBuf.size()] == ch)
                break;
            nReadPos++;
        }
    }
};

#endif // BITCOIN_STREAMS_H