diff options
Diffstat (limited to 'vendor/github.com/golang/snappy/decode_other.go')
| -rw-r--r-- | vendor/github.com/golang/snappy/decode_other.go | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/vendor/github.com/golang/snappy/decode_other.go b/vendor/github.com/golang/snappy/decode_other.go index 8c9f204..b88318e 100644 --- a/vendor/github.com/golang/snappy/decode_other.go +++ b/vendor/github.com/golang/snappy/decode_other.go @@ -85,14 +85,28 @@ func decode(dst, src []byte) int { if offset <= 0 || d < offset || length > len(dst)-d { return decodeErrCodeCorrupt } - // Copy from an earlier sub-slice of dst to a later sub-slice. Unlike - // the built-in copy function, this byte-by-byte copy always runs + // Copy from an earlier sub-slice of dst to a later sub-slice. + // If no overlap, use the built-in copy: + if offset >= length { + copy(dst[d:d+length], dst[d-offset:]) + d += length + continue + } + + // Unlike the built-in copy function, this byte-by-byte copy always runs // forwards, even if the slices overlap. Conceptually, this is: // // d += forwardCopy(dst[d:d+length], dst[d-offset:]) - for end := d + length; d != end; d++ { - dst[d] = dst[d-offset] + // + // We align the slices into a and b and show the compiler they are the same size. + // This allows the loop to run without bounds checks. + a := dst[d : d+length] + b := dst[d-offset:] + b = b[:len(a)] + for i := range a { + a[i] = b[i] } + d += length } if d != len(dst) { return decodeErrCodeCorrupt |