diff options
| -rw-r--r-- | absl/strings/internal/escaping.cc | 22 |
1 files changed, 12 insertions, 10 deletions
diff --git a/absl/strings/internal/escaping.cc b/absl/strings/internal/escaping.cc index cfea0961..8bd0890d 100644 --- a/absl/strings/internal/escaping.cc +++ b/absl/strings/internal/escaping.cc @@ -28,19 +28,11 @@ size_t CalculateBase64EscapedLenInternal(size_t input_len, bool do_padding) { // Base64 encodes three bytes of input at a time. If the input is not // divisible by three, we pad as appropriate. // - // (from https://tools.ietf.org/html/rfc3548) - // Special processing is performed if fewer than 24 bits are available - // at the end of the data being encoded. A full encoding quantum is - // always completed at the end of a quantity. When fewer than 24 input - // bits are available in an input group, zero bits are added (on the - // right) to form an integral number of 6-bit groups. Padding at the - // end of the data is performed using the '=' character. Since all base - // 64 input is an integral number of octets, only the following cases - // can arise: - // Base64 encodes each three bytes of input into four bytes of output. size_t len = (input_len / 3) * 4; + // Since all base 64 input is an integral number of octets, only the following + // cases can arise: if (input_len % 3 == 0) { // (from https://tools.ietf.org/html/rfc3548) // (1) the final quantum of encoding input is an integral multiple of 24 @@ -83,6 +75,16 @@ size_t Base64EscapeInternal(const unsigned char* src, size_t szsrc, char* dest, char* const limit_dest = dest + szdest; const unsigned char* const limit_src = src + szsrc; + // (from https://tools.ietf.org/html/rfc3548) + // Special processing is performed if fewer than 24 bits are available + // at the end of the data being encoded. A full encoding quantum is + // always completed at the end of a quantity. When fewer than 24 input + // bits are available in an input group, zero bits are added (on the + // right) to form an integral number of 6-bit groups. + // + // If do_padding is true, padding at the end of the data is performed. This + // output padding uses the '=' character. + // Three bytes of data encodes to four characters of cyphertext. // So we can pump through three-byte chunks atomically. if (szsrc >= 3) { // "limit_src - 3" is UB if szsrc < 3. |