bufio: fix overflow calculation in Scan
I was being too clever, as usual. Write the obvious code to make sure
that when we grow the buffer we don't overflow.
Change-Id: I1641831177b0bb8a89ab6e9bcabccf6c2fcfe1d2
Reviewed-on: https://go-review.googlesource.com/14781
Reviewed-by: Minux Ma <minux@golang.org>
diff --git a/src/bufio/scan.go b/src/bufio/scan.go
index 4f06f97..0ec584b 100644
--- a/src/bufio/scan.go
+++ b/src/bufio/scan.go
@@ -162,11 +162,13 @@
}
// Is the buffer full? If so, resize.
if s.end == len(s.buf) {
- if len(s.buf) >= s.maxTokenSize {
+ // Guarantee no overflow in the multiplication below.
+ const maxInt = int(^uint(0) >> 1)
+ if len(s.buf) >= s.maxTokenSize || len(s.buf) > maxInt/2 {
s.setErr(ErrTooLong)
return false
}
- newSize := len(s.buf) * 2 // See protection against overflow in Buffer.
+ newSize := len(s.buf) * 2
if newSize == 0 {
newSize = startBufSize
}
@@ -238,12 +240,6 @@
panic("Buffer called after Scan")
}
s.buf = buf[0:cap(buf)]
- // Guarantee no overflow: we multiply len(s.buf) by two in Scan,
- // but only if it exceeds maxTokenSize.
- const maxInt = int(^uint(0) >> 1)
- if max > maxInt {
- max = maxInt
- }
s.maxTokenSize = max
}
