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fix(BytesOp::Find): fix slice index overflow #82

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Merged
dr-orlovsky merged 6 commits into from
Jun 26, 2023
Merged

fix(BytesOp::Find): fix slice index overflow #82

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34bc087
fix(BytesOp::Find): fix slice index overflow
6293 Jun 21, 2023
66bd8dd
fix(BytesOp::Find): it never overflows destination register because t…
6293 Jun 21, 2023
b45b2c1
use window function
6293 Jun 21, 2023
9c5bb40
fix(BytesOp::Rev): do not set None to RegA on failure
6293 Jun 24, 2023
3a44520
fix(DigestOp::Ripemd): reverse byte array because RIPEMD-160 is big-e…
6293 Jun 24, 2023
34b518a
fix(BytesOp::Rev): set dest to None on failure
6293 Jun 26, 2023
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23 changes: 9 additions & 14 deletions src/isa/exec.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -669,17 +669,8 @@ impl InstructionSet for BytesOp {
let (s1, s2) = regs.get_both_s(*reg1, *reg2)?;
let r1 = s1.as_ref();
let r2 = s2.as_ref();
let len = r2.len();
let mut count = 0usize;
for i in 0..r1.len() {
if r1[i..len] == r2[..len] {
count += 1;
}
}
if count > u16::MAX as usize {
regs.st0 = false;
count -= 1;
}
let count = r1.windows(r2.len()).filter(|r1| *r1 == r2).count();
assert!(count <= u16::MAX as usize);
regs.set(RegA::A16, Reg32::Reg0, count as u16);
Some(())
};
Expand All @@ -698,7 +689,7 @@ impl InstructionSet for BytesOp {
};
f().unwrap_or_else(|| {
regs.st0 = false;
regs.set(RegA::A16, Reg32::Reg0, MaybeNumber::none());
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@dr-orlovsky dr-orlovsky Jun 26, 2023

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Why are we removing this if the spec below says

If the first or the second string is `None`, sets `st0` to `false` and `a16[0]` to `None`.

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@6293 6293 Jun 26, 2023 •
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this is the spec for Find. The code here is for Rev. I thought this was accidentally copy-pasted from Find above

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@dr-orlovsky dr-orlovsky Jun 26, 2023

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Yet still the Rev must reset the destination to the uninitialized state:

/// If the source string register is uninitialized, resets destination to the uninitialized

So I assume the above line should stay and be changed to

Suggested change
regs.set(RegA::A16, Reg32::Reg0, MaybeNumber::none());
regs.s16[reg2.as_usize()] = None;

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@6293 6293 Jun 26, 2023

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true

regs.s16[reg2.as_usize()] = None;
})
}
BytesOp::Con(reg1, reg2, n, offset_dst, len_dst) => {
Expand Down Expand Up @@ -822,8 +813,12 @@ impl InstructionSet for DigestOp {
DigestOp::Ripemd(src, dst) => {
let s = regs.get_s(*src);
none = s.is_none();
let hash: Option<[u8; 20]> =
s.map(|s| ripemd::Ripemd160::digest(s.as_ref()).into());
let hash = s.map(|s| {
let mut hash: [u8; 20] = ripemd::Ripemd160::digest(s.as_ref()).into();
// RIPEMD-160 is big-endian
hash.reverse();
hash
});
regs.set(RegR::R160, dst, hash);
}
DigestOp::Sha256(src, dst) => {
Expand Down
9 changes: 3 additions & 6 deletions src/isa/instr.rs
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Expand Up @@ -677,13 +677,10 @@ pub enum BytesOp {
/** `a16` register index to save the length of the conjoint fragment */ Reg32,
),

/// Count number of occurrences of one string within another putting result to `a16[1]`,
/// Count number of occurrences of one string within another putting result to `a16[0]`,
///
/// If the first or the second string is `None`, sets `st0` to `false` and `a16[1]` to `None`.
///
/// If the number of occurrences is `u16::MAX + 1`, sets `a16[1]` to `u16::MAX` and `st0` to
/// `false`.
#[display("find {0},{1},a16[1]")]
/// If the first or the second string is `None`, sets `st0` to `false` and `a16[0]` to `None`.
#[display("find a16[0],{0},{1}")]
Find(/** `s` register with string */ RegS, /** `s` register with matching fragment */ RegS),

/// Extract byte string slice into general `r` register. The length of the extracted string is
Expand Down