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fix #14655 setLen(seq) now zeros memory (#14656)

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* simplify sysstr.nim

* fix #14655
This commit is contained in:
Timothee Cour
2020-06-14 02:11:26 -07:00
committed by GitHub
parent d3b25a2948
commit 0fc5d3f13b
2 changed files with 23 additions and 15 deletions
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29
lib/system/sysstr.nim
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@@ -15,6 +15,13 @@
# we don't use refcounts because that's a behaviour
# the programmer may not want
proc dataPointer(a: PGenericSeq, elemAlign: int): pointer =
cast[pointer](cast[ByteAddress](a) +% align(GenericSeqSize, elemAlign))
proc dataPointer(a: PGenericSeq, elemAlign, elemSize, index: int): pointer =
cast[pointer](cast[ByteAddress](a) +% align(GenericSeqSize, elemAlign) +% (index*%elemSize))
proc resize(old: int): int {.inline.} =
if old <= 0: result = 4
elif old < 65536: result = old * 2
@@ -267,9 +274,6 @@ proc incrSeqV2(seq: PGenericSeq, elemSize, elemAlign: int): PGenericSeq {.compil
result = cast[PGenericSeq](growObj(result, align(GenericSeqSize, elemAlign) + elemSize * r))
result.reserved = r
template `+!`(p: pointer, s: int): pointer =
cast[pointer](cast[int](p) +% s)
proc incrSeqV3(s: PGenericSeq, typ: PNimType): PGenericSeq {.compilerproc.} =
if s == nil:
result = cast[PGenericSeq](newSeq(typ, 1))
@@ -281,7 +285,7 @@ proc incrSeqV3(s: PGenericSeq, typ: PNimType): PGenericSeq {.compilerproc.} =
when defined(nimIncrSeqV3):
result = cast[PGenericSeq](newSeq(typ, r))
result.len = s.len
copyMem(result +! align(GenericSeqSize, typ.base.align), s +! align(GenericSeqSize, typ.base.align), s.len * typ.base.size)
copyMem(dataPointer(result, typ.base.align), dataPointer(s, typ.base.align), s.len * typ.base.size)
# since we steal the content from 's', it's crucial to set s's len to 0.
s.len = 0
else:
@@ -303,7 +307,7 @@ proc setLengthSeq(seq: PGenericSeq, elemSize, elemAlign, newLen: int): PGenericS
when false: # compileOption("gc", "v2"):
for i in newLen..result.len-1:
let len0 = gch.tempStack.len
forAllChildrenAux(cast[pointer](cast[ByteAddress](result) +% align(GenericSeqSize, elemAlign) +% (i*%elemSize)),
forAllChildrenAux(dataPointer(result, elemAlign, elemSize, i),
extGetCellType(result).base, waPush)
let len1 = gch.tempStack.len
for i in len0 ..< len1:
@@ -312,8 +316,7 @@ proc setLengthSeq(seq: PGenericSeq, elemSize, elemAlign, newLen: int): PGenericS
else:
if ntfNoRefs notin extGetCellType(result).base.flags:
for i in newLen..result.len-1:
forAllChildrenAux(cast[pointer](cast[ByteAddress](result) +%
align(GenericSeqSize, elemAlign) +% (i*%elemSize)),
forAllChildrenAux(dataPointer(result, elemAlign, elemSize, i),
extGetCellType(result).base, waZctDecRef)
# XXX: zeroing out the memory can still result in crashes if a wiped-out
@@ -322,8 +325,7 @@ proc setLengthSeq(seq: PGenericSeq, elemSize, elemAlign, newLen: int): PGenericS
# presence of user defined destructors, the user will expect the cell to be
# "destroyed" thus creating the same problem. We can destroy the cell in the
# finalizer of the sequence, but this makes destruction non-deterministic.
zeroMem(cast[pointer](cast[ByteAddress](result) +% align(GenericSeqSize, elemAlign) +%
(newLen*%elemSize)), (result.len-%newLen) *% elemSize)
zeroMem(dataPointer(result, elemAlign, elemSize, newLen), (result.len-%newLen) *% elemSize)
result.len = newLen
proc setLengthSeqV2(s: PGenericSeq, typ: PNimType, newLen: int): PGenericSeq {.
@@ -338,7 +340,7 @@ proc setLengthSeqV2(s: PGenericSeq, typ: PNimType, newLen: int): PGenericSeq {.
if s.space < newLen:
let r = max(resize(s.space), newLen)
result = cast[PGenericSeq](newSeq(typ, r))
copyMem(result +! align(GenericSeqSize, elemAlign), s +! align(GenericSeqSize, elemAlign), s.len * elemSize)
copyMem(dataPointer(result, elemAlign), dataPointer(s, elemAlign), s.len * elemSize)
# since we steal the content from 's', it's crucial to set s's len to 0.
s.len = 0
elif newLen < s.len:
@@ -349,8 +351,7 @@ proc setLengthSeqV2(s: PGenericSeq, typ: PNimType, newLen: int): PGenericSeq {.
not defined(gcRegions):
if ntfNoRefs notin typ.base.flags:
for i in newLen..result.len-1:
forAllChildrenAux(cast[pointer](cast[ByteAddress](result) +%
align(GenericSeqSize, elemAlign) +% (i*%elemSize)),
forAllChildrenAux(dataPointer(result, elemAlign, elemSize, i),
extGetCellType(result).base, waZctDecRef)
# XXX: zeroing out the memory can still result in crashes if a wiped-out
@@ -359,10 +360,10 @@ proc setLengthSeqV2(s: PGenericSeq, typ: PNimType, newLen: int): PGenericSeq {.
# presence of user defined destructors, the user will expect the cell to be
# "destroyed" thus creating the same problem. We can destroy the cell in the
# finalizer of the sequence, but this makes destruction non-deterministic.
zeroMem(cast[pointer](cast[ByteAddress](result) +% align(GenericSeqSize, elemAlign) +%
(newLen*%elemSize)), (result.len-%newLen) *% elemSize)
zeroMem(dataPointer(result, elemAlign, elemSize, newLen), (result.len-%newLen) *% elemSize)
else:
result = s
zeroMem(dataPointer(result, elemAlign, elemSize, result.len), (newLen-%result.len) *% elemSize)
result.len = newLen
else:
result = setLengthSeq(s, typ.base.size, newLen)

9
tests/collections/tseq.nim
View File

@@ -206,4 +206,11 @@ block ttoseq:
stdout.write("\n")
block tseqmapitchain:
doAssert @[101, 102] == [1, 2].mapIt(func (x: int): int = it + x).mapIt(it(100))
doAssert @[101, 102] == [1, 2].mapIt(func (x: int): int = it + x).mapIt(it(100))
for i in 0..100:
# fix #14655
var test = newSeqOfCap[uint32](1)
test.setLen(1)
doAssert test[0] == 0, $(test[0], i)