      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

    // Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.

    use std;
    use std::{io, mem};
    use std::ptr;

    use buffer::{ReadBuffer, WriteBuffer, BufferResult};
    use buffer::BufferResult::{BufferUnderflow, BufferOverflow};
    use symmetriccipher::{SynchronousStreamCipher, SymmetricCipherError};

    /// Write a u64 into a vector, which must be 8 bytes long. The value is written in big-endian
    /// format.
    pub fn write_u64_be(dst: &mut[u8], mut input: u64) {
        assert!(dst.len() == 8);
        input = input.to_be();
        unsafe {
            let tmp = &input as *const _ as *const u8;
            ptr::copy_nonoverlapping(tmp, dst.get_unchecked_mut(0), 8);
        }
    }

    /// Write a u64 into a vector, which must be 8 bytes long. The value is written in little-endian
    /// format.
    pub fn write_u64_le(dst: &mut[u8], mut input: u64) {
        assert!(dst.len() == 8);
        input = input.to_le();
        unsafe {
            let tmp = &input as *const _ as *const u8;
            ptr::copy_nonoverlapping(tmp, dst.get_unchecked_mut(0), 8);
        }
    }

    /// Write a vector of u64s into a vector of bytes. The values are written in little-endian format.
    pub fn write_u64v_le(dst: &mut[u8], input: &[u64]) {
        assert!(dst.len() == 8 * input.len());
        unsafe {
            let mut x: *mut u8 = dst.get_unchecked_mut(0);
            let mut y: *const u64 = input.get_unchecked(0);
            for _ in 0..input.len() {
                let tmp = (*y).to_le();
                ptr::copy_nonoverlapping(&tmp as *const _ as *const u8, x, 8);
                x = x.offset(8);
                y = y.offset(1);
            }
        }
    }

    /// Write a u32 into a vector, which must be 4 bytes long. The value is written in big-endian
    /// format.
    pub fn write_u32_be(dst: &mut [u8], mut input: u32) {
        assert!(dst.len() == 4);
        input = input.to_be();
        unsafe {
            let tmp = &input as *const _ as *const u8;
            ptr::copy_nonoverlapping(tmp, dst.get_unchecked_mut(0), 4);
        }
    }

    /// Write a u32 into a vector, which must be 4 bytes long. The value is written in little-endian
    /// format.
    pub fn write_u32_le(dst: &mut[u8], mut input: u32) {
        assert!(dst.len() == 4);
        input = input.to_le();
        unsafe {
            let tmp = &input as *const _ as *const u8;
            ptr::copy_nonoverlapping(tmp, dst.get_unchecked_mut(0), 4);
        }
    }

    /// Write a vector of u32s into a vector of bytes. The values are written in little-endian format.
    pub fn write_u32v_le (dst: &mut[u8], input: &[u32]) {
        assert!(dst.len() == 4 * input.len());
        unsafe {
            let mut x: *mut u8 = dst.get_unchecked_mut(0);
            let mut y: *const u32 = input.get_unchecked(0);
            for _ in 0..input.len() {
                let tmp = (*y).to_le();
                ptr::copy_nonoverlapping(&tmp as *const _ as *const u8, x, 4);
                x = x.offset(4);
                y = y.offset(1);
            }
        }
    }

    /// Read a vector of bytes into a vector of u64s. The values are read in big-endian format.
    pub fn read_u64v_be(dst: &mut[u64], input: &[u8]) {
        assert!(dst.len() * 8 == input.len());
        unsafe {
            let mut x: *mut u64 = dst.get_unchecked_mut(0);
            let mut y: *const u8 = input.get_unchecked(0);
            for _ in 0..dst.len() {
                let mut tmp: u64 = mem::uninitialized();
                ptr::copy_nonoverlapping(y, &mut tmp as *mut _ as *mut u8, 8);
                *x = u64::from_be(tmp);
                x = x.offset(1);
                y = y.offset(8);
            }
        }
    }

    /// Read a vector of bytes into a vector of u64s. The values are read in little-endian format.
    pub fn read_u64v_le(dst: &mut[u64], input: &[u8]) {
        assert!(dst.len() * 8 == input.len());
        unsafe {
            let mut x: *mut u64 = dst.get_unchecked_mut(0);
            let mut y: *const u8 = input.get_unchecked(0);
            for _ in 0..dst.len() {
                let mut tmp: u64 = mem::uninitialized();
                ptr::copy_nonoverlapping(y, &mut tmp as *mut _ as *mut u8, 8);
                *x = u64::from_le(tmp);
                x = x.offset(1);
                y = y.offset(8);
            }
        }
    }

    /// Read a vector of bytes into a vector of u32s. The values are read in big-endian format.
    pub fn read_u32v_be(dst: &mut[u32], input: &[u8]) {
        assert!(dst.len() * 4 == input.len());
        unsafe {
            let mut x: *mut u32 = dst.get_unchecked_mut(0);
            let mut y: *const u8 = input.get_unchecked(0);
            for _ in 0..dst.len() {
                let mut tmp: u32 = mem::uninitialized();
                ptr::copy_nonoverlapping(y, &mut tmp as *mut _ as *mut u8, 4);
                *x = u32::from_be(tmp);
                x = x.offset(1);
                y = y.offset(4);
            }
        }
    }

    /// Read a vector of bytes into a vector of u32s. The values are read in little-endian format.
    pub fn read_u32v_le(dst: &mut[u32], input: &[u8]) {
        assert!(dst.len() * 4 == input.len());
        unsafe {
            let mut x: *mut u32 = dst.get_unchecked_mut(0);
            let mut y: *const u8 = input.get_unchecked(0);
            for _ in 0..dst.len() {
                let mut tmp: u32 = mem::uninitialized();
                ptr::copy_nonoverlapping(y, &mut tmp as *mut _ as *mut u8, 4);
                *x = u32::from_le(tmp);
                x = x.offset(1);
                y = y.offset(4);
            }
        }
    }

    /// Read the value of a vector of bytes as a u32 value in little-endian format.
    pub fn read_u32_le(input: &[u8]) -> u32 {
        assert!(input.len() == 4);
        unsafe {
            let mut tmp: u32 = mem::uninitialized();
            ptr::copy_nonoverlapping(input.get_unchecked(0), &mut tmp as *mut _ as *mut u8, 4);
            u32::from_le(tmp)
        }
    }

    /// Read the value of a vector of bytes as a u32 value in big-endian format.
    pub fn read_u32_be(input: &[u8]) -> u32 {
        assert!(input.len() == 4);
        unsafe {
            let mut tmp: u32 = mem::uninitialized();
            ptr::copy_nonoverlapping(input.get_unchecked(0), &mut tmp as *mut _ as *mut u8, 4);
            u32::from_be(tmp)
        }
    }

    /// XOR plaintext and keystream, storing the result in dst.
    pub fn xor_keystream(dst: &mut[u8], plaintext: &[u8], keystream: &[u8]) {
        assert!(dst.len() == plaintext.len());
        assert!(plaintext.len() <= keystream.len());

        // Do one byte at a time, using unsafe to skip bounds checking.
        let p = plaintext.as_ptr();
        let k = keystream.as_ptr();
        let d = dst.as_mut_ptr();
        for i in 0isize..plaintext.len() as isize {
            unsafe{ *d.offset(i) = *p.offset(i) ^ *k.offset(i) };
        }
    }

    /// Copy bytes from src to dest
    #[inline]
    pub fn copy_memory(src: &[u8], dst: &mut [u8]) {
        assert!(dst.len() >= src.len());
        unsafe {
            let srcp = src.as_ptr();
            let dstp = dst.as_mut_ptr();
            ptr::copy_nonoverlapping(srcp, dstp, src.len());
        }
    }

    /// Zero all bytes in dst
    #[inline]
    pub fn zero(dst: &mut [u8]) {
        unsafe {
            ptr::write_bytes(dst.as_mut_ptr(), 0, dst.len());
        }
    }

    /// An extension trait to implement a few useful serialization
    /// methods on types that implement Write
    pub trait WriteExt {
        fn write_u8(&mut self, val: u8) -> io::Result<()>;
        fn write_u32_le(&mut self, val: u32) -> io::Result<()>;
        fn write_u32_be(&mut self, val: u32) -> io::Result<()>;
        fn write_u64_le(&mut self, val: u64) -> io::Result<()>;
        fn write_u64_be(&mut self, val: u64) -> io::Result<()>;
    }

    impl <T> WriteExt for T where T: io::Write {
        fn write_u8(&mut self, val: u8) -> io::Result<()> {
            let buff = [val];
            self.write_all(&buff)
        }
        fn write_u32_le(&mut self, val: u32) -> io::Result<()> {
            let mut buff = [0u8; 4];
            write_u32_le(&mut buff, val);
            self.write_all(&buff)
        }
        fn write_u32_be(&mut self, val: u32) -> io::Result<()> {
            let mut buff = [0u8; 4];
            write_u32_be(&mut buff, val);
            self.write_all(&buff)
        }
        fn write_u64_le(&mut self, val: u64) -> io::Result<()> {
            let mut buff = [0u8; 8];
            write_u64_le(&mut buff, val);
            self.write_all(&buff)
        }
        fn write_u64_be(&mut self, val: u64) -> io::Result<()> {
            let mut buff = [0u8; 8];
            write_u64_be(&mut buff, val);
            self.write_all(&buff)
        }
    }

    /// symm_enc_or_dec() implements the necessary functionality to turn a SynchronousStreamCipher into
    /// an Encryptor or Decryptor
    pub fn symm_enc_or_dec<S: SynchronousStreamCipher, R: ReadBuffer, W: WriteBuffer>(
            c: &mut S,
            input: &mut R,
            output: &mut W) ->
            Result<BufferResult, SymmetricCipherError> {
        let count = std::cmp::min(input.remaining(), output.remaining());
        c.process(input.take_next(count), output.take_next(count));
        if input.is_empty() {
            Ok(BufferUnderflow)
        } else {
            Ok(BufferOverflow)
        }
    }

    /// Convert the value in bytes to the number of bits, a tuple where the 1st item is the
    /// high-order value and the 2nd item is the low order value.
    fn to_bits(x: u64) -> (u64, u64) {
        (x >> 61, x << 3)
    }

    /// Adds the specified number of bytes to the bit count. panic!() if this would cause numeric
    /// overflow.
    pub fn add_bytes_to_bits(bits: u64, bytes: u64) -> u64 {
        let (new_high_bits, new_low_bits) = to_bits(bytes);

        if new_high_bits > 0 {
            panic!("Numeric overflow occured.")
        }

        bits.checked_add(new_low_bits).expect("Numeric overflow occured.")
    }

    /// Adds the specified number of bytes to the bit count, which is a tuple where the first element is
    /// the high order value. panic!() if this would cause numeric overflow.
    pub fn add_bytes_to_bits_tuple
            (bits: (u64, u64), bytes: u64) -> (u64, u64) {
        let (new_high_bits, new_low_bits) = to_bits(bytes);
        let (hi, low) = bits;

        // Add the low order value - if there is no overflow, then add the high order values
        // If the addition of the low order values causes overflow, add one to the high order values
        // before adding them.
        match low.checked_add(new_low_bits) {
            Some(x) => {
                if new_high_bits == 0 {
                    // This is the fast path - every other alternative will rarely occur in practice
                    // considering how large an input would need to be for those paths to be used.
                    return (hi, x);
                } else {
                    match hi.checked_add(new_high_bits) {
                        Some(y) => return (y, x),
                        None => panic!("Numeric overflow occured.")
                    }
                }
            },
            None => {
                let z = match new_high_bits.checked_add(1) {
                    Some(w) => w,
                    None => panic!("Numeric overflow occured.")
                };
                match hi.checked_add(z) {
                    // This re-executes the addition that was already performed earlier when overflow
                    // occured, this time allowing the overflow to happen. Technically, this could be
                    // avoided by using the checked add intrinsic directly, but that involves using
                    // unsafe code and is not really worthwhile considering how infrequently code will
                    // run in practice. This is the reason that this function requires that the type T
                    // be UnsignedInt - overflow is not defined for Signed types. This function could
                    // be implemented for signed types as well if that were needed.
                    Some(y) => return (y, low.wrapping_add(new_low_bits)),
                    None => panic!("Numeric overflow occured.")
                }
            }
        }
    }

    /// A FixedBuffer, likes its name implies, is a fixed size buffer. When the buffer becomes full, it
    /// must be processed. The input() method takes care of processing and then clearing the buffer
    /// automatically. However, other methods do not and require the caller to process the buffer. Any
    /// method that modifies the buffer directory or provides the caller with bytes that can be modifies
    /// results in those bytes being marked as used by the buffer.
    pub trait FixedBuffer {
        /// Input a vector of bytes. If the buffer becomes full, process it with the provided
        /// function and then clear the buffer.
        fn input<F: FnMut(&[u8])>(&mut self, input: &[u8], func: F);

        /// Reset the buffer.
        fn reset(&mut self);

        /// Zero the buffer up until the specified index. The buffer position currently must not be
        /// greater than that index.
        fn zero_until(&mut self, idx: usize);

        /// Get a slice of the buffer of the specified size. There must be at least that many bytes
        /// remaining in the buffer.
        fn next<'s>(&'s mut self, len: usize) -> &'s mut [u8];

        /// Get the current buffer. The buffer must already be full. This clears the buffer as well.
        fn full_buffer<'s>(&'s mut self) -> &'s [u8];

         /// Get the current buffer.
        fn current_buffer<'s>(&'s mut self) -> &'s [u8];

        /// Get the current position of the buffer.
        fn position(&self) -> usize;

        /// Get the number of bytes remaining in the buffer until it is full.
        fn remaining(&self) -> usize;

        /// Get the size of the buffer
        fn size(&self) -> usize;
    }

    macro_rules! impl_fixed_buffer( ($name:ident, $size:expr) => (
        impl FixedBuffer for $name {
            fn input<F: FnMut(&[u8])>(&mut self, input: &[u8], mut func: F) {
                let mut i = 0;

                // FIXME: #6304 - This local variable shouldn't be necessary.
                let size = $size;

                // If there is already data in the buffer, copy as much as we can into it and process
                // the data if the buffer becomes full.
                if self.buffer_idx != 0 {
                    let buffer_remaining = size - self.buffer_idx;
                    if input.len() >= buffer_remaining {
                            copy_memory(
                                &input[..buffer_remaining],
                                &mut self.buffer[self.buffer_idx..size]);
                        self.buffer_idx = 0;
                        func(&self.buffer);
                        i += buffer_remaining;
                    } else {
                        copy_memory(
                            input,
                            &mut self.buffer[self.buffer_idx..self.buffer_idx + input.len()]);
                        self.buffer_idx += input.len();
                        return;
                    }
                }

                // While we have at least a full buffer size chunks's worth of data, process that data
                // without copying it into the buffer
                while input.len() - i >= size {
                    func(&input[i..i + size]);
                    i += size;
                }

                // Copy any input data into the buffer. At this point in the method, the ammount of
                // data left in the input vector will be less than the buffer size and the buffer will
                // be empty.
                let input_remaining = input.len() - i;
                copy_memory(
                    &input[i..],
                    &mut self.buffer[0..input_remaining]);
                self.buffer_idx += input_remaining;
            }

            fn reset(&mut self) {
                self.buffer_idx = 0;
            }

            fn zero_until(&mut self, idx: usize) {
                assert!(idx >= self.buffer_idx);
                zero(&mut self.buffer[self.buffer_idx..idx]);
                self.buffer_idx = idx;
            }

            fn next<'s>(&'s mut self, len: usize) -> &'s mut [u8] {
                self.buffer_idx += len;
                &mut self.buffer[self.buffer_idx - len..self.buffer_idx]
            }

            fn full_buffer<'s>(&'s mut self) -> &'s [u8] {
                assert!(self.buffer_idx == $size);
                self.buffer_idx = 0;
                &self.buffer[..$size]
            }

            fn current_buffer<'s>(&'s mut self) -> &'s [u8] {
                let tmp = self.buffer_idx;
                self.buffer_idx = 0;
                &self.buffer[..tmp]
            }

            fn position(&self) -> usize { self.buffer_idx }

            fn remaining(&self) -> usize { $size - self.buffer_idx }

            fn size(&self) -> usize { $size }
        }
    ));

    /// A fixed size buffer of 64 bytes useful for cryptographic operations.
    #[derive(Copy)]
    pub struct FixedBuffer64 {
        buffer: [u8; 64],
        buffer_idx: usize,
    }

    impl Clone for FixedBuffer64 { fn clone(&self) -> FixedBuffer64 { *self } }

    impl FixedBuffer64 {
        /// Create a new buffer
        pub fn new() -> FixedBuffer64 {
            FixedBuffer64 {
                buffer: [0u8; 64],
                buffer_idx: 0
            }
        }
    }

    impl_fixed_buffer!(FixedBuffer64, 64);

    /// A fixed size buffer of 128 bytes useful for cryptographic operations.
    #[derive(Copy)]
    pub struct FixedBuffer128 {
        buffer: [u8; 128],
        buffer_idx: usize,
    }

    impl Clone for FixedBuffer128 { fn clone(&self) -> FixedBuffer128 { *self } }

    impl FixedBuffer128 {
        /// Create a new buffer
        pub fn new() -> FixedBuffer128 {
            FixedBuffer128 {
                buffer: [0u8; 128],
                buffer_idx: 0
            }
        }
    }

    impl_fixed_buffer!(FixedBuffer128, 128);

    /// The StandardPadding trait adds a method useful for various hash algorithms to a FixedBuffer
    /// struct.
    pub trait StandardPadding {
        /// Add standard padding to the buffer. The buffer must not be full when this method is called
        /// and is guaranteed to have exactly rem remaining bytes when it returns. If there are not at
        /// least rem bytes available, the buffer will be zero padded, processed, cleared, and then
        /// filled with zeros again until only rem bytes are remaining.
        fn standard_padding<F: FnMut(&[u8])>(&mut self, rem: usize, func: F);
    }

    impl <T: FixedBuffer> StandardPadding for T {
        fn standard_padding<F: FnMut(&[u8])>(&mut self, rem: usize, mut func: F) {
            let size = self.size();

            self.next(1)[0] = 128;

            if self.remaining() < rem {
                self.zero_until(size);
                func(self.full_buffer());
            }

            self.zero_until(size - rem);
        }
    }

    #[cfg(test)]
    pub mod test {
        use std;
        use std::iter::repeat;

        use rand::IsaacRng;
        use rand::distributions::{IndependentSample, Range};

        use cryptoutil::{add_bytes_to_bits, add_bytes_to_bits_tuple};
        use digest::Digest;

        /// Feed 1,000,000 'a's into the digest with varying input sizes and check that the result is
        /// correct.
        pub fn test_digest_1million_random<D: Digest>(digest: &mut D, blocksize: usize, expected: &str) {
            let total_size = 1000000;
            let buffer: Vec<u8> = repeat('a' as u8).take(blocksize * 2).collect();
            let mut rng = IsaacRng::new_unseeded();
            let range = Range::new(0, 2 * blocksize + 1);
            let mut count = 0;

            digest.reset();

            while count < total_size {
                let next = range.ind_sample(&mut rng);
                let remaining = total_size - count;
                let size = if next > remaining { remaining } else { next };
                digest.input(&buffer[..size]);
                count += size;
            }

            let result_str = digest.result_str();

            assert!(expected == &result_str[..]);
        }

        // A normal addition - no overflow occurs
        #[test]
        fn test_add_bytes_to_bits_ok() {
            assert!(add_bytes_to_bits(100, 10) == 180);
        }

        // A simple failure case - adding 1 to the max value
        #[test]
        #[should_panic]
        fn test_add_bytes_to_bits_overflow() {
            add_bytes_to_bits(std::u64::MAX, 1);
        }

        // A normal addition - no overflow occurs (fast path)
        #[test]
        fn test_add_bytes_to_bits_tuple_ok() {
            assert!(add_bytes_to_bits_tuple((5, 100), 10) == (5, 180));
        }

        // The low order value overflows into the high order value
        #[test]
        fn test_add_bytes_to_bits_tuple_ok2() {
            assert!(add_bytes_to_bits_tuple((5, std::u64::MAX), 1) == (6, 7));
        }

        // The value to add is too large to be converted into bits without overflowing its type
        #[test]
        fn test_add_bytes_to_bits_tuple_ok3() {
            assert!(add_bytes_to_bits_tuple((5, 0), 0x4000000000000001) == (7, 8));
        }

        // A simple failure case - adding 1 to the max value
        #[test]
        #[should_panic]
        fn test_add_bytes_to_bits_tuple_overflow() {
            add_bytes_to_bits_tuple((std::u64::MAX, std::u64::MAX), 1);
        }

        // The value to add is too large to convert to bytes without overflowing its type, but the high
        // order value from this conversion overflows when added to the existing high order value
        #[test]
        #[should_panic]
        fn test_add_bytes_to_bits_tuple_overflow2() {
            let value: u64 = std::u64::MAX;
            add_bytes_to_bits_tuple((value - 1, 0), 0x8000000000000000);
        }
    }

# Help

## Keyboard Shortcuts

?
  Show this help dialog
S
  Focus the search field
⇤
  Move up in search results
⇥
  Move down in search results
⏎
  Go to active search result
+
  Collapse/expand all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g. `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g. `vec -> usize` or `* -> vec`)