8000 gh-96735: Fix undefined behaviour in struct unpacking functions by mdickinson · Pull Request #96739 · python/cpython · GitHub
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gh-96735: Fix undefined behaviour in struct unpacking functions #96739

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Merged
merged 10 commits into from
Sep 25, 2022
Merged

gh-96735: Fix undefined behaviour in struct unpacking functions #96739

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22fdce6
Fix undefined behaviour in bu_ulonglong
mdickinson Sep 10, 2022
e12943b
Add regression test
mdickinson Sep 10, 2022
8efefd8
Also apply the fix to lu_longlong
mdickinson Sep 10, 2022
cba4b8b
Merge branch 'main' into fix-struct-unpack-undefined-behaviour
mdickinson Sep 10, 2022
0d49e73
Fix similar undefined behaviour issues in bu_int and lu_int
mdickinson Sep 10, 2022
bfd714f
Merge remote-tracking branch 'mdickinson/fix-struct-unpack-undefined-…
mdickinson Sep 10, 2022
5aeef09
Remove redundant test
mdickinson Sep 10, 2022
204e924
Fix accumulator type
mdickinson Sep 10, 2022
994703e
Branch-free sign-extension
mdickinson Sep 13, 2022
1294440
Fix unconventional spacing
mdickinson Sep 13, 2022
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Fix unconventional spacing
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@mdickinson
mdickinson committed Sep 13, 2022
commit 1294440b5c04c807f36911ab7d8721f87045ca90
12 changes: 6 additions & 6 deletions Modules/_struct.c
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Original file line number Diff line number Diff line change
Expand Up @@ -819,7 +819,7 @@ bu_short(_structmodulestate *state, const char *p, const formatdef *f)
} while (--i > 0);
/* Extend sign, avoiding implementation-defined or undefined behaviour. */
x = (x ^ 0x8000U) - 0x8000U;
return PyLong_FromLong(x & 0x8000U ? -1 - (long)(~x): (long)x);
return PyLong_FromLong(x & 0x8000U ? -1 - (long)(~x) : (long)x);
}

static PyObject *
Expand All @@ -836,7 +836,7 @@ bu_int(_structmodulestate *state, const char *p, const formatdef *f)
} while (--i > 0);
/* Extend sign, avoiding implementation-defined or undefined behaviour. */
x = (x ^ 0x80000000U) - 0x80000000U;
return PyLong_FromLong(x & 0x80000000U ? -1 - (long)(~x): (long)x);
return PyLong_FromLong(x & 0x80000000U ? -1 - (long)(~x) : (long)x);
}

static PyObject *
Expand Down Expand Up @@ -866,7 +866,7 @@ bu_longlong(_structmodulestate *state, const char *p, const formatdef *f)
/* Extend sign, avoiding implementation-defined or undefined behaviour. */
x = (x ^ 0x8000000000000000U) - 0x8000000000000000U;
return PyLong_FromLongLong(
x & 0x8000000000000000U ? -1 - (long long)(~x): (long long)x);
x & 0x8000000000000000U ? -1 - (long long)(~x) : (long long)x);
}

static PyObject *
Expand Down Expand Up @@ -1062,7 +1062,7 @@ lu_short(_structmodulestate *state, const char *p, const formatdef *f)
} while (i > 0);
/* Extend sign, avoiding implementation-defined or undefined behaviour. */
x = (x ^ 0x8000U) - 0x8000U;
return PyLong_FromLong(x & 0x8000U ? -1 - (long)(~x): (long)x);
return PyLong_FromLong(x & 0x8000U ? -1 - (long)(~x) : (long)x);
}

static PyObject *
Expand All @@ -1079,7 +1079,7 @@ lu_int(_structmodulestate *state, const char *p, const formatdef *f)
} while (i > 0);
/* Extend sign, avoiding implementation-defined or undefined behaviour. */
x = (x ^ 0x80000000U) - 0x80000000U;
return PyLong_FromLong(x & 0x80000000U ? -1 - (long)(~x): (long)x);
return PyLong_FromLong(x & 0x80000000U ? -1 - (long)(~x) : (long)x);
}

static PyObject *
Expand Down Expand Up @@ -1109,7 +1109,7 @@ lu_longlong(_structmodulestate *state, const char *p, const formatdef *f)
/* Extend sign, avoiding implementation-defined or undefined behaviour. */
x = (x ^ 0x8000000000000000U) - 0x8000000000000000U;
return PyLong_FromLongLong(
x & 0x8000000000000000U ? -1 - (long long)(~x): (long long)x);
x & 0x8000000000000000U ? -1 - (long long)(~x) : (long long)x);
}

static PyObject *
Expand Down
0