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
// Copyright (c) 2013-2015 Sandstorm Development Group, Inc. and contributors
// Licensed under the MIT License:
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

//! Reading and writing of messages using the
//! [packed stream encoding](https://capnproto.org/encoding.html#packing).

use std::{io, mem, ptr, slice};
use std::io::{Read, BufRead, Write};

use crate::serialize;
use crate::Result;
use crate::message;

struct PackedRead<R> where R: BufRead {
    inner: R,
}

impl <R> PackedRead<R> where R: BufRead {

    fn get_read_buffer(&mut self) -> io::Result<(*const u8, *const u8)> {
        let buf = self.inner.fill_buf()?;
        Ok((buf.as_ptr(), buf.as_ptr().wrapping_offset(buf.len() as isize)))
    }
}

#[inline]
fn ptr_sub<T>(p1: *const T, p2: *const T) -> usize {
    (p1 as usize - p2 as usize) / mem::size_of::<T>()
}

macro_rules! refresh_buffer(
    ($this:expr, $size:ident, $in_ptr:ident, $in_end:ident, $out:ident,
     $outBuf:ident, $buffer_begin:ident) => (
        {
            $this.inner.consume($size);
            let (b, e) = $this.get_read_buffer()?;
            $in_ptr = b;
            $in_end = e;
            $size = ptr_sub($in_end, $in_ptr);
            $buffer_begin = b;
            if $size == 0 {
                return Err(io::Error::new(io::ErrorKind::Other,
                                          "Premature end of packed input."));
            }
        }
        );
    );

impl <R> Read for PackedRead<R> where R: BufRead {

    fn read(&mut self, out_buf: &mut [u8]) -> io::Result<usize> {
        let len = out_buf.len();

        if len == 0 { return Ok(0); }

        assert!(len % 8 == 0, "PackedRead reads must be word-aligned.");

        unsafe {
            let mut out = out_buf.as_mut_ptr();
            let out_end: *mut u8 = out_buf.as_mut_ptr().wrapping_offset(len as isize);

            let (mut in_ptr, mut in_end) = self.get_read_buffer()?;
            let mut buffer_begin = in_ptr;
            let mut size = ptr_sub(in_end, in_ptr);
            if size == 0 {
                return Ok(0);
            }

            loop {

                let tag: u8;

                assert_eq!(ptr_sub(out, out_buf.as_mut_ptr()) % 8, 0,
                           "Output pointer should always be aligned here.");

                if ptr_sub(in_end, in_ptr) < 10 {
                    if out >= out_end {
                        self.inner.consume(ptr_sub(in_ptr, buffer_begin));
                        return Ok(ptr_sub(out, out_buf.as_mut_ptr()));
                    }

                    if ptr_sub(in_end, in_ptr) == 0 {
                        refresh_buffer!(self, size, in_ptr, in_end, out, out_buf, buffer_begin);
                        continue;
                    }

                    //# We have at least 1, but not 10, bytes available. We need to read
                    //# slowly, doing a bounds check on each byte.

                    tag = *in_ptr;
                    in_ptr = in_ptr.offset(1);

                    for i in 0..8 {
                        if (tag & (1u8 << i)) != 0 {
                            if ptr_sub(in_end, in_ptr) == 0 {
                                refresh_buffer!(self, size, in_ptr, in_end,
                                                out, out_buf, buffer_begin);
                            }
                            *out = *in_ptr;
                            out = out.offset(1);
                            in_ptr = in_ptr.offset(1);
                        } else {
                            *out = 0;
                            out = out.offset(1);
                        }
                    }

                    if ptr_sub(in_end, in_ptr) == 0 && (tag == 0 || tag == 0xff) {
                        refresh_buffer!(self, size, in_ptr, in_end,
                                        out, out_buf, buffer_begin);
                    }
                } else {
                    tag = *in_ptr;
                    in_ptr = in_ptr.offset(1);

                    for n in 0..8 {
                        let is_nonzero = (tag & (1u8 << n)) != 0;
                        *out = (*in_ptr) & ((-(is_nonzero as i8)) as u8);
                        out = out.offset(1);
                        in_ptr = in_ptr.offset(is_nonzero as isize);
                    }
                }
                if tag == 0 {
                    assert!(ptr_sub(in_end, in_ptr) > 0,
                            "Should always have non-empty buffer here.");

                    let run_length : usize = (*in_ptr) as usize * 8;
                    in_ptr = in_ptr.offset(1);

                    if run_length > ptr_sub(out_end, out) {
                        return Err(io::Error::new(io::ErrorKind::Other,
                                                  "Packed input did not end cleanly on a segment boundary."));
                    }

                    ptr::write_bytes(out, 0, run_length);
                    out = out.offset(run_length as isize);

                } else if tag == 0xff {
                    assert!(ptr_sub(in_end, in_ptr) > 0,
                            "Should always have non-empty buffer here");

                    let mut run_length : usize = (*in_ptr) as usize * 8;
                    in_ptr = in_ptr.offset(1);

                    if run_length > ptr_sub(out_end, out) {
                        return Err(io::Error::new(io::ErrorKind::Other,
                                                  "Packed input did not end cleanly on a segment boundary."));
                    }

                    let in_remaining = ptr_sub(in_end, in_ptr);
                    if in_remaining >= run_length {
                        //# Fast path.
                        ptr::copy_nonoverlapping(in_ptr, out, run_length);
                        out = out.offset(run_length as isize);
                        in_ptr = in_ptr.offset(run_length as isize);
                    } else {
                        //# Copy over the first buffer, then do one big read for the rest.
                        ptr::copy_nonoverlapping(in_ptr, out, in_remaining);
                        out = out.offset(in_remaining as isize);
                        run_length -= in_remaining;

                        self.inner.consume(size);
                        {
                            let buf = slice::from_raw_parts_mut::<u8>(out, run_length);
                            self.inner.read_exact(buf)?;
                        }

                        out = out.offset(run_length as isize);

                        if out == out_end {
                            return Ok(len);
                        } else {
                            let (b, e) = self.get_read_buffer()?;
                            in_ptr = b;
                            in_end = e;
                            size = ptr_sub(e, b);
                            buffer_begin = in_ptr;
                            continue;
                        }
                    }
                }

                if out == out_end {
                    self.inner.consume(ptr_sub(in_ptr, buffer_begin));
                    return Ok(len);
                }
            }
        }
    }
}

/// Reads a packed message from a stream using the provided options.
pub fn read_message<R>(read: &mut R,
                       options: message::ReaderOptions)
                       -> Result<crate::message::Reader<serialize::OwnedSegments>>
    where R: BufRead
{
    let mut packed_read = PackedRead { inner: read };
    serialize::read_message(&mut packed_read, options)
}

struct PackedWrite<W> where W: Write {
    inner: W,
}

impl <W> Write for PackedWrite<W> where W: Write {
    fn write(&mut self, in_buf: &[u8]) -> io::Result<usize> {
        unsafe {
            let mut buf_idx: usize = 0;
            let mut buf: [u8; 64] = [0; 64];

            let mut in_ptr: *const u8 = in_buf.as_ptr();
            let in_end: *const u8 = in_buf.as_ptr().wrapping_offset(in_buf.len() as isize);

            while in_ptr < in_end {

                if buf_idx + 10 > buf.len() {
                    //# Oops, we're out of space. We need at least 10
                    //# bytes for the fast path, since we don't
                    //# bounds-check on every byte.
                    self.inner.write_all(&buf[..buf_idx])?;
                    buf_idx = 0;
                }

                let tag_pos = buf_idx;
                buf_idx += 1;

                let bit0 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit0 as usize;
                in_ptr = in_ptr.offset(1);

                let bit1 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit1 as usize;
                in_ptr = in_ptr.offset(1);

                let bit2 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit2 as usize;
                in_ptr = in_ptr.offset(1);

                let bit3 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit3 as usize;
                in_ptr = in_ptr.offset(1);

                let bit4 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit4 as usize;
                in_ptr = in_ptr.offset(1);

                let bit5 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit5 as usize;
                in_ptr = in_ptr.offset(1);

                let bit6 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit6 as usize;
                in_ptr = in_ptr.offset(1);

                let bit7 = (*in_ptr != 0) as u8;
                *buf.get_unchecked_mut(buf_idx) = *in_ptr;
                buf_idx += bit7 as usize;
                in_ptr = in_ptr.offset(1);

                let tag: u8 = (bit0 << 0) | (bit1 << 1) | (bit2 << 2) | (bit3 << 3)
                            | (bit4 << 4) | (bit5 << 5) | (bit6 << 6) | (bit7 << 7);


                *buf.get_unchecked_mut(tag_pos) = tag;

                if tag == 0 {
                    //# An all-zero word is followed by a count of
                    //# consecutive zero words (not including the first
                    //# one).

                    let mut in_word : *const [u8; 8] = in_ptr as *const [u8; 8];
                    let mut limit : *const [u8; 8] = in_end as *const [u8; 8];
                    if ptr_sub(limit, in_word) > 255 {
                        limit = in_word.offset(255);
                    }
                    while in_word < limit && *in_word == [0;8] {
                        in_word = in_word.offset(1);
                    }

                    *buf.get_unchecked_mut(buf_idx) = ptr_sub(in_word, in_ptr as *const [u8; 8]) as u8;
                    buf_idx += 1;
                    in_ptr = in_word as *const u8;
                } else if tag == 0xff {
                    //# An all-nonzero word is followed by a count of
                    //# consecutive uncompressed words, followed by the
                    //# uncompressed words themselves.

                    //# Count the number of consecutive words in the input
                    //# which have no more than a single zero-byte. We look
                    //# for at least two zeros because that's the point
                    //# where our compression scheme becomes a net win.
                    let run_start = in_ptr;
                    let mut limit = in_end;
                    if ptr_sub(limit, in_ptr) > 255 * 8 {
                        limit = in_ptr.offset(255 * 8);
                    }

                    while in_ptr < limit {
                        let mut c = 0;

                        for _ in 0..8 {
                            c += (*in_ptr == 0) as u8;
                            in_ptr = in_ptr.offset(1);
                        }

                        if c >= 2 {
                            //# Un-read the word with multiple zeros, since
                            //# we'll want to compress that one.
                            in_ptr = in_ptr.offset(-8);
                            break;
                        }
                    }

                    let count: usize = ptr_sub(in_ptr, run_start);
                    *buf.get_unchecked_mut(buf_idx) = (count / 8) as u8;
                    buf_idx += 1;

                    self.inner.write_all(&buf[..buf_idx])?;
                    buf_idx = 0;
                    self.inner.write_all(slice::from_raw_parts::<u8>(run_start, count))?;
                }
            }

            self.inner.write_all(&buf[..buf_idx])?;
            Ok(in_buf.len())
        }
    }

   fn flush(&mut self) -> io::Result<()> { self.inner.flush() }
}

/// Writes a packed message to a stream.
pub fn write_message<W, A>(write: &mut W, message: &crate::message::Builder<A>) -> io::Result<()>
    where W: Write, A: crate::message::Allocator
{
    let mut packed_write = PackedWrite { inner: write };
    serialize::write_message(&mut packed_write, message)
}

#[cfg(test)]
mod tests {
    use std::io::{Write, Read};

    use std::io::Cursor;
    use quickcheck::{quickcheck, TestResult};

    use crate::message::{ReaderOptions};
    use crate::serialize::test::write_message_segments;
    use crate::serialize_packed::{PackedRead, PackedWrite};
    use super::read_message;

    pub fn check_unpacks_to(packed: &[u8], unpacked: &[u8]) {
        let mut packed_read = PackedRead { inner: packed };

        let mut bytes: Vec<u8> = vec![0; unpacked.len()];
        packed_read.read_exact(&mut bytes[..]).unwrap();

        let mut buf = [0; 8];
        assert_eq!(packed_read.read(&mut buf).unwrap(), 0); // EOF
        assert_eq!(bytes, unpacked);
    }

    pub fn check_packing(unpacked: &[u8], packed: &[u8]) {
        // --------
        // write

        let mut bytes: Vec<u8> = vec![0; packed.len()];
        {
            let mut packed_write = PackedWrite { inner: &mut bytes[..] };
            packed_write.write(unpacked).unwrap();
        }

        assert_eq!(bytes, packed);

        // --------
        // read
        check_unpacks_to(packed, unpacked);
    }

    #[test]
    pub fn simple_packing() {
        check_packing(&[], &[]);
        check_packing(&[0; 8], &[0,0]);
        check_packing(&[0,0,12,0,0,34,0,0], &[0x24,12,34]);
        check_packing(&[1,3,2,4,5,7,6,8], &[0xff,1,3,2,4,5,7,6,8,0]);
        check_packing(&[0,0,0,0,0,0,0,0,1,3,2,4,5,7,6,8], &[0,0,0xff,1,3,2,4,5,7,6,8,0]);
        check_packing(&[0,0,12,0,0,34,0,0,1,3,2,4,5,7,6,8], &[0x24,12,34,0xff,1,3,2,4,5,7,6,8,0]);
        check_packing(&[1,3,2,4,5,7,6,8,8,6,7,4,5,2,3,1], &[0xff,1,3,2,4,5,7,6,8,1,8,6,7,4,5,2,3,1]);

        check_packing(
            &[1,2,3,4,5,6,7,8, 1,2,3,4,5,6,7,8, 1,2,3,4,5,6,7,8, 1,2,3,4,5,6,7,8, 0,2,4,0,9,0,5,1],
            &[0xff,1,2,3,4,5,6,7,8, 3, 1,2,3,4,5,6,7,8, 1,2,3,4,5,6,7,8, 1,2,3,4,5,6,7,8,
              0xd6,2,4,9,5,1]);
        check_packing(
            &[1,2,3,4,5,6,7,8, 1,2,3,4,5,6,7,8, 6,2,4,3,9,0,5,1, 1,2,3,4,5,6,7,8, 0,2,4,0,9,0,5,1],
            &[0xff,1,2,3,4,5,6,7,8, 3, 1,2,3,4,5,6,7,8, 6,2,4,3,9,0,5,1, 1,2,3,4,5,6,7,8,
              0xd6,2,4,9,5,1]);

        check_packing(
            &[8,0,100,6,0,1,1,2, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,1,0,2,0,3,1],
            &[0xed,8,100,6,1,1,2, 0,2, 0xd4,1,2,3,1]);

        check_packing(&[0; 16], &[0,1]);
        check_packing(&[0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0], &[0,2]);
    }

    fn word_segments_to_byte_segments(word_segments: Vec<Vec<u64>>) -> Vec<Vec<u8>> {
        let mut result = Vec::new();
        for s in word_segments {
            let mut byte_seg = Vec::new();
            for w in s {
                for b in &w.to_le_bytes() {
                    byte_seg.push(*b)
                }
            }
            result.push(byte_seg);
        }
        result
    }

    #[test]
    #[cfg_attr(miri, ignore)] // miri takes a long time with quickcheck
    fn check_round_trip() {
        fn round_trip(word_segments: Vec<Vec<u64>>) -> TestResult {
            use crate::message::ReaderSegments;
            if word_segments.len() == 0 { return TestResult::discard(); }
            let segments = word_segments_to_byte_segments(word_segments);
            let mut cursor = Cursor::new(Vec::new());

            write_message_segments(&mut PackedWrite { inner: &mut cursor }, &segments);
            cursor.set_position(0);
            let message = read_message(&mut cursor, ReaderOptions::new()).unwrap();
            let result_segments = message.into_segments();

            TestResult::from_bool(segments.iter().enumerate().all(|(i, segment)| {
                &segment[..] == result_segments.get_segment(i as u32).unwrap()
            }))
        }

        quickcheck(round_trip as fn(Vec<Vec<u64>>) -> TestResult);
    }

    #[test]
    #[cfg_attr(miri, ignore)] // miri takes a long time with quickcheck
    fn fuzz_unpack() {
        fn unpack(packed: Vec<u8>) -> TestResult {

            let len = packed.len();
            let mut packed_read = PackedRead { inner: &packed[..] };

            let mut out_buffer: Vec<u8> = vec![0; len * 8];

            let _ = packed_read.read_exact(&mut out_buffer);
            TestResult::from_bool(true)
        }

        quickcheck(unpack as fn(Vec<u8>) -> TestResult);
    }

    #[test]
    fn did_not_end_cleanly_on_a_segment_boundary() {
        let packed = &[0xff, 1, 2, 3, 4, 5, 6, 7, 8, 37, 1, 2];
        let mut packed_read = PackedRead {inner: &packed[..]};

        let mut bytes: Vec<u8> = vec![0; 200];
        match packed_read.read_exact(&mut bytes[..]) {
            Ok(_) => panic!("should have been an error"),
            Err(e) => {
                assert_eq!(e.to_string(),
                           "Packed input did not end cleanly on a segment boundary.");
            }
        }
    }

    #[test]
    fn premature_end_of_packed_input() {
        fn helper(packed: &[u8]) {
            let mut packed_read = PackedRead {inner: packed};

            let mut bytes: Vec<u8> = vec![0; 200];
            match packed_read.read_exact(&mut bytes[..]) {
                Ok(_) => panic!("should have been an error"),
                Err(e) => {
                    assert_eq!(e.to_string(), "Premature end of packed input.");
                }
            }
        }

        helper(&[0xf0, 1, 2]);
        helper(&[0]);
        helper(&[0xff, 1, 2, 3, 4, 5, 6, 7, 8]);

        // In this case, the error is only due to the fact that the unpacked data does not
        // fill up the given output buffer.
        helper(&[1, 1]);
    }

    #[test]
    fn packed_segment_table() {
        let packed_buf = &[0x11, 4, 1, 0, 1, 0, 0];

        check_unpacks_to(
            packed_buf,
            &[4, 0, 0, 0, 1, 0, 0, 0,
              0, 0, 0, 0, 0, 0, 0, 0,
              0, 0, 0, 0, 0, 0, 0, 0,
              0, 0, 0, 0, 0, 0, 0, 0]);

        let mut cursor = Cursor::new(packed_buf);

        // At one point, this failed due to serialize::read_message()
        // reading the segment table only one word at a time.
        read_message(&mut cursor, Default::default()).unwrap();
    }
}