diff options
Diffstat (limited to 'libgo/go/math/big/nat.go')
| -rw-r--r-- | libgo/go/math/big/nat.go | 15 |
1 files changed, 11 insertions, 4 deletions
diff --git a/libgo/go/math/big/nat.go b/libgo/go/math/big/nat.go index c31ec5156b8..6a3989bf9d8 100644 --- a/libgo/go/math/big/nat.go +++ b/libgo/go/math/big/nat.go @@ -1476,19 +1476,26 @@ func (z nat) expNNMontgomery(x, y, m nat) nat { } // bytes writes the value of z into buf using big-endian encoding. -// len(buf) must be >= len(z)*_S. The value of z is encoded in the -// slice buf[i:]. The number i of unused bytes at the beginning of -// buf is returned as result. +// The value of z is encoded in the slice buf[i:]. If the value of z +// cannot be represented in buf, bytes panics. The number i of unused +// bytes at the beginning of buf is returned as result. func (z nat) bytes(buf []byte) (i int) { i = len(buf) for _, d := range z { for j := 0; j < _S; j++ { i-- - buf[i] = byte(d) + if i >= 0 { + buf[i] = byte(d) + } else if byte(d) != 0 { + panic("math/big: buffer too small to fit value") + } d >>= 8 } } + if i < 0 { + i = 0 + } for i < len(buf) && buf[i] == 0 { i++ } |