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set cap more carefully on unsafe slices

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Treating a pointer as a pointer to a large array of bytes,
or converting back the other way, isn't totally insane, but
it does create slices with an extremely large cap. This bit
me while I was trying to build the 16-byte packed Container
structure, but it's probably actually worth fixing in general.
This commit is contained in:
Seebs 2019-03-19 23:09:26 -05:00
parent 8041785ea4
commit 8475b97d87
1 changed files with 11 additions and 11 deletions
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22
roaring/roaring.go
View file

@ -1068,13 +1068,13 @@ func (b *Bitmap) unmarshalPilosaRoaring(data []byte) error {
switch c.typ {
case containerRun:
runCount := binary.LittleEndian.Uint16(data[offset : offset+runCountHeaderSize])
c.setRuns((*[0xFFFFFFF]interval16)(unsafe.Pointer(&data[offset+runCountHeaderSize]))[:runCount])
c.setRuns((*[0xFFFFFFF]interval16)(unsafe.Pointer(&data[offset+runCountHeaderSize]))[:runCount:runCount])
opsOffset = int(offset) + runCountHeaderSize + len(c.runs())*interval16Size
case containerArray:
c.setArray((*[0xFFFFFFF]uint16)(unsafe.Pointer(&data[offset]))[:c.n])
c.setArray((*[0xFFFFFFF]uint16)(unsafe.Pointer(&data[offset]))[:c.n:c.n])
opsOffset = int(offset) + len(c.array())*2 // sizeof(uint32)
case containerBitmap:
c.setBitmap((*[0xFFFFFFF]uint64)(unsafe.Pointer(&data[offset]))[:bitmapN])
c.setBitmap((*[0xFFFFFFF]uint64)(unsafe.Pointer(&data[offset]))[:bitmapN:bitmapN])
opsOffset = int(offset) + len(c.bitmap())*8 // sizeof(uint64)
}
}
@ -2144,7 +2144,7 @@ func (c *Container) arrayWriteTo(w io.Writer) (n int64, err error) {
//}
// Write sizeof(uint16) * cardinality bytes.
nn, err := w.Write((*[0xFFFFFFF]byte)(unsafe.Pointer(&array[0]))[:2*c.n])
nn, err := w.Write((*[0xFFFFFFF]byte)(unsafe.Pointer(&array[0]))[: 2*c.n : 2*c.n])
return int64(nn), err
}
@ -2152,7 +2152,7 @@ func (c *Container) bitmapWriteTo(w io.Writer) (n int64, err error) {
statsHit("Container/bitmapWriteTo")
bitmap := c.bitmap()
// Write sizeof(uint64) * bitmapN bytes.
nn, err := w.Write((*[0xFFFFFFF]byte)(unsafe.Pointer(&bitmap[0]))[:(8 * bitmapN)])
nn, err := w.Write((*[0xFFFFFFF]byte)(unsafe.Pointer(&bitmap[0]))[:(8 * bitmapN):(8 * bitmapN)])
return int64(nn), err
}
@ -2168,7 +2168,7 @@ func (c *Container) runWriteTo(w io.Writer) (n int64, err error) {
if err != nil {
return 0, err
}
nn, err := w.Write((*[0xFFFFFFF]byte)(unsafe.Pointer(&runs[0]))[:interval16Size*len(runs)])
nn, err := w.Write((*[0xFFFFFFF]byte)(unsafe.Pointer(&runs[0]))[: interval16Size*len(runs) : interval16Size*len(runs)])
return int64(runCountHeaderSize + nn), err
}
@ -4284,9 +4284,9 @@ func readOffsets(b *Bitmap, data []byte, pos int, keyN uint32) error {
_, c := citer.Value()
switch c.typ {
case containerArray:
c.setArray((*[0xFFFFFFF]uint16)(unsafe.Pointer(&data[offset]))[:c.n])
c.setArray((*[0xFFFFFFF]uint16)(unsafe.Pointer(&data[offset]))[:c.n:c.n])
case containerBitmap:
c.setBitmap((*[0xFFFFFFF]uint64)(unsafe.Pointer(&data[offset]))[:bitmapN])
c.setBitmap((*[0xFFFFFFF]uint64)(unsafe.Pointer(&data[offset]))[:bitmapN:bitmapN])
default:
return fmt.Errorf("unsupported container type %d", c.typ)
}
@ -4302,7 +4302,7 @@ func readWithRuns(b *Bitmap, data []byte, pos int, keyN uint32) {
switch c.typ {
case containerRun:
runCount := binary.LittleEndian.Uint16(data[pos : pos+runCountHeaderSize])
c.setRuns((*[0xFFFFFFF]interval16)(unsafe.Pointer(&data[pos+runCountHeaderSize]))[:runCount])
c.setRuns((*[0xFFFFFFF]interval16)(unsafe.Pointer(&data[pos+runCountHeaderSize]))[:runCount:runCount])
runs := c.runs()
for o := range runs { // must convert from start:length to start:end :(
@ -4310,10 +4310,10 @@ func readWithRuns(b *Bitmap, data []byte, pos int, keyN uint32) {
}
pos += int((runCount * interval16Size) + runCountHeaderSize)
case containerArray:
c.setArray((*[0xFFFFFFF]uint16)(unsafe.Pointer(&data[pos]))[:c.n])
c.setArray((*[0xFFFFFFF]uint16)(unsafe.Pointer(&data[pos]))[:c.n:c.n])
pos += int(c.n * 2)
case containerBitmap:
c.setBitmap((*[0xFFFFFFF]uint64)(unsafe.Pointer(&data[pos]))[:bitmapN])
c.setBitmap((*[0xFFFFFFF]uint64)(unsafe.Pointer(&data[pos]))[:bitmapN:bitmapN])
pos += bitmapN * 8
}
}