Bugfix in bn2vch: avoid excessive padding #18374

pull sipa wants to merge 1 commits into bitcoin:master from sipa:202003_fix_bn2vch changing 1 files +2 −2

sipa commented at 5:46 AM on March 18, 2020: member

It seems #17319 introduced an (unobserved) bug in the test framework in bn2vch: a zero padding byte was added for every nonzero number, even when the top byte was <= 0x7F. Fix this.
sipa commented at 5:46 AM on March 18, 2020: member

I'm happy to add a quick test case for this, but I don't see any obvious place to put a test of the test framework itself. Any suggestions?
fanquake added the label Tests on Mar 18, 2020

in test/functional/test_framework/script.py:36 in 812340c395 outdated

  32 | @@ -33,6 +33,7 @@ def bn2vch(v):
  33 |      ext = bytearray()
  34 |      if v.bit_length() > 0:
  35 |          have_ext = (v.bit_length() & 0x07) == 0
  36 | +    if have_ext:

kallewoof commented at 6:00 AM on March 18, 2020:

Alternative

if v.bit_length() > 0 and (v.bit_length() & 0x07) == 0:
    have_ext = True
    ext.append(0)

sipa commented at 7:20 AM on March 18, 2020:

Thanks, much better indeed.

Bugfix in bn2vch: avoid excessive padding f65868baa9
sipa force-pushed on Mar 18, 2020
DrahtBot commented at 7:44 AM on March 18, 2020: member


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Conflicts

Reviewers, this pull request conflicts with the following ones:
- #17977 ([WIP] Implement BIP 340-342 validation (Schnorr/taproot/tapscript) by sipa)
If you consider this pull request important, please also help to review the conflicting pull requests. Ideally, start with the one that should be merged first.

in test/functional/test_framework/script.py:34 in f65868baa9

  30 | @@ -31,8 +31,8 @@ def bn2vch(v):
  31 |      # isn't a spare bit in the bit length, add an extension byte.
  32 |      have_ext = False
  33 |      ext = bytearray()
  34 | -    if v.bit_length() > 0:
  35 | -        have_ext = (v.bit_length() & 0x07) == 0
  36 | +    if v.bit_length() > 0 && (v.bit_length() & 0x07) == 0:

MarcoFalke commented at 1:47 PM on March 18, 2020:

    if v.bit_length() > 0 and (v.bit_length() & 0x07) == 0:

sipa commented at 5:23 PM on March 18, 2020: member

Closing in favor of #18378.
sipa closed this on Mar 18, 2020
laanwj referenced this in commit 67de1ee8bc on Mar 19, 2020
DrahtBot locked this on Feb 15, 2022

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#17319 Tests: remove bignum module #18378 Bugfix & simplify bn2vch using int.to_bytes

Bugfix in bn2vch: avoid excessive padding #18374

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