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system/unicode: check for buffer overflows; refs #5284

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This commit is contained in:
Araq 2017-02-08 15:22:36 +01:00
commit 3caf108425
2 changed files with 78 additions and 43 deletions
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72
lib/pure/unicode.nim
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@ -49,6 +49,8 @@ proc runeLenAt*(s: string, i: Natural): int =
elif ord(s[i]) shr 1 == 0b1111110: result = 6
else: result = 1
const replRune = Rune(0xFFFD)
template fastRuneAt*(s: string, i: int, result: untyped, doInc = true) =
## Returns the Unicode character ``s[i]`` in ``result``. If ``doInc == true``
## ``i`` is incremented by the number of bytes that have been processed.
@ -58,49 +60,69 @@ template fastRuneAt*(s: string, i: int, result: untyped, doInc = true) =
when doInc: inc(i)
elif ord(s[i]) shr 5 == 0b110:
# assert(ord(s[i+1]) shr 6 == 0b10)
result = Rune((ord(s[i]) and (ones(5))) shl 6 or
(ord(s[i+1]) and ones(6)))
when doInc: inc(i, 2)
if i <= s.len - 2:
result = Rune((ord(s[i]) and (ones(5))) shl 6 or
(ord(s[i+1]) and ones(6)))
when doInc: inc(i, 2)
else:
result = replRune
when doInc: inc(i)
elif ord(s[i]) shr 4 == 0b1110:
# assert(ord(s[i+1]) shr 6 == 0b10)
# assert(ord(s[i+2]) shr 6 == 0b10)
result = Rune((ord(s[i]) and ones(4)) shl 12 or
(ord(s[i+1]) and ones(6)) shl 6 or
(ord(s[i+2]) and ones(6)))
when doInc: inc(i, 3)
if i <= s.len - 3:
result = Rune((ord(s[i]) and ones(4)) shl 12 or
(ord(s[i+1]) and ones(6)) shl 6 or
(ord(s[i+2]) and ones(6)))
when doInc: inc(i, 3)
else:
result = replRune
when doInc: inc(i)
elif ord(s[i]) shr 3 == 0b11110:
# assert(ord(s[i+1]) shr 6 == 0b10)
# assert(ord(s[i+2]) shr 6 == 0b10)
# assert(ord(s[i+3]) shr 6 == 0b10)
result = Rune((ord(s[i]) and ones(3)) shl 18 or
(ord(s[i+1]) and ones(6)) shl 12 or
(ord(s[i+2]) and ones(6)) shl 6 or
(ord(s[i+3]) and ones(6)))
when doInc: inc(i, 4)
if i <= s.len - 4:
result = Rune((ord(s[i]) and ones(3)) shl 18 or
(ord(s[i+1]) and ones(6)) shl 12 or
(ord(s[i+2]) and ones(6)) shl 6 or
(ord(s[i+3]) and ones(6)))
when doInc: inc(i, 4)
else:
result = replRune
when doInc: inc(i)
elif ord(s[i]) shr 2 == 0b111110:
# assert(ord(s[i+1]) shr 6 == 0b10)
# assert(ord(s[i+2]) shr 6 == 0b10)
# assert(ord(s[i+3]) shr 6 == 0b10)
# assert(ord(s[i+4]) shr 6 == 0b10)
result = Rune((ord(s[i]) and ones(2)) shl 24 or
(ord(s[i+1]) and ones(6)) shl 18 or
(ord(s[i+2]) and ones(6)) shl 12 or
(ord(s[i+3]) and ones(6)) shl 6 or
(ord(s[i+4]) and ones(6)))
when doInc: inc(i, 5)
if i <= s.len - 5:
result = Rune((ord(s[i]) and ones(2)) shl 24 or
(ord(s[i+1]) and ones(6)) shl 18 or
(ord(s[i+2]) and ones(6)) shl 12 or
(ord(s[i+3]) and ones(6)) shl 6 or
(ord(s[i+4]) and ones(6)))
when doInc: inc(i, 5)
else:
result = replRune
when doInc: inc(i)
elif ord(s[i]) shr 1 == 0b1111110:
# assert(ord(s[i+1]) shr 6 == 0b10)
# assert(ord(s[i+2]) shr 6 == 0b10)
# assert(ord(s[i+3]) shr 6 == 0b10)
# assert(ord(s[i+4]) shr 6 == 0b10)
# assert(ord(s[i+5]) shr 6 == 0b10)
result = Rune((ord(s[i]) and ones(1)) shl 30 or
(ord(s[i+1]) and ones(6)) shl 24 or
(ord(s[i+2]) and ones(6)) shl 18 or
(ord(s[i+3]) and ones(6)) shl 12 or
(ord(s[i+4]) and ones(6)) shl 6 or
(ord(s[i+5]) and ones(6)))
when doInc: inc(i, 6)
if i <= s.len - 6:
result = Rune((ord(s[i]) and ones(1)) shl 30 or
(ord(s[i+1]) and ones(6)) shl 24 or
(ord(s[i+2]) and ones(6)) shl 18 or
(ord(s[i+3]) and ones(6)) shl 12 or
(ord(s[i+4]) and ones(6)) shl 6 or
(ord(s[i+5]) and ones(6)))
when doInc: inc(i, 6)
else:
result = replRune
when doInc: inc(i)
else:
result = Rune(ord(s[i]))
when doInc: inc(i)