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unicode: avoid divide by zero in is16/is32 for zero-stride ranges #80129

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fereidani wants to merge 1 commit into from
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unicode: avoid divide by zero in is16/is32 for zero-stride ranges #80129

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8 changes: 4 additions & 4 deletions src/unicode/letter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,7 @@ func is16(ranges []Range16, r uint16) bool {
return false
}
if r <= range_.Hi {
return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
return range_.Stride <= 1 || (r-range_.Lo)%range_.Stride == 0
}
}
return false
Expand All @@ -109,7 +109,7 @@ func is16(ranges []Range16, r uint16) bool {
m := int(uint(lo+hi) >> 1)
range_ := &ranges[m]
if range_.Lo <= r && r <= range_.Hi {
return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
return range_.Stride <= 1 || (r-range_.Lo)%range_.Stride == 0
}
if r < range_.Lo {
hi = m
Expand All @@ -129,7 +129,7 @@ func is32(ranges []Range32, r uint32) bool {
return false
}
if r <= range_.Hi {
return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
return range_.Stride <= 1 || (r-range_.Lo)%range_.Stride == 0
}
}
return false
Expand All @@ -142,7 +142,7 @@ func is32(ranges []Range32, r uint32) bool {
m := int(uint(lo+hi) >> 1)
range_ := ranges[m]
if range_.Lo <= r && r <= range_.Hi {
return range_.Stride == 1 || (r-range_.Lo)%range_.Stride == 0
return range_.Stride <= 1 || (r-range_.Lo)%range_.Stride == 0
}
if r < range_.Lo {
hi = m
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8 changes: 8 additions & 0 deletions src/unicode/letter_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,14 @@ func TestIsUpper(t *testing.T) {
}
}

func TestIsZeroStride(t *testing.T) {
// A RangeTable range with Stride == 0 must not cause Is to divide by zero.
tab := &RangeTable{R16: []Range16{{Lo: 'A', Hi: 'A', Stride: 0}}}
if !Is(tab, 'A') {
t.Errorf("Is(tab, 'A') = false, want true")
}
}

func caseString(c int) string {
switch c {
case UpperCase:
Expand Down