1 files changed, 43 insertions, 22 deletions

diff --git a/vendor/base64/src/read/decoder.rs b/vendor/base64/src/read/decoder.rs
index 4888c9c4e..b656ae3d2 100644
--- a/vendor/base64/src/read/decoder.rs
+++ b/vendor/base64/src/read/decoder.rs
@@ -1,4 +1,4 @@
-use crate::{engine::Engine, DecodeError};
+use crate::{engine::Engine, DecodeError, PAD_BYTE};
 use std::{cmp, fmt, io};
 
 // This should be large, but it has to fit on the stack.
@@ -46,13 +46,15 @@ pub struct DecoderReader<'e, E: Engine, R: io::Read> {
     // Technically we only need to hold 2 bytes but then we'd need a separate temporary buffer to
     // decode 3 bytes into and then juggle copying one byte into the provided read buf and the rest
     // into here, which seems like a lot of complexity for 1 extra byte of storage.
-    decoded_buffer: [u8; 3],
+    decoded_buffer: [u8; DECODED_CHUNK_SIZE],
     // index of start of decoded data
     decoded_offset: usize,
     // length of decoded data
     decoded_len: usize,
     // used to provide accurate offsets in errors
     total_b64_decoded: usize,
+    // offset of previously seen padding, if any
+    padding_offset: Option<usize>,
 }
 
 impl<'e, E: Engine, R: io::Read> fmt::Debug for DecoderReader<'e, E, R> {
@@ -64,6 +66,7 @@ impl<'e, E: Engine, R: io::Read> fmt::Debug for DecoderReader<'e, E, R> {
             .field("decoded_offset", &self.decoded_offset)
             .field("decoded_len", &self.decoded_len)
             .field("total_b64_decoded", &self.total_b64_decoded)
+            .field("padding_offset", &self.padding_offset)
             .finish()
     }
 }
@@ -81,6 +84,7 @@ impl<'e, E: Engine, R: io::Read> DecoderReader<'e, E, R> {
             decoded_offset: 0,
             decoded_len: 0,
             total_b64_decoded: 0,
+            padding_offset: None,
         }
     }
 
@@ -127,20 +131,28 @@ impl<'e, E: Engine, R: io::Read> DecoderReader<'e, E, R> {
     /// caller's responsibility to choose the number of b64 bytes to decode correctly.
     ///
     /// Returns a Result with the number of decoded bytes written to `buf`.
-    fn decode_to_buf(&mut self, num_bytes: usize, buf: &mut [u8]) -> io::Result<usize> {
-        debug_assert!(self.b64_len >= num_bytes);
+    fn decode_to_buf(&mut self, b64_len_to_decode: usize, buf: &mut [u8]) -> io::Result<usize> {
+        debug_assert!(self.b64_len >= b64_len_to_decode);
         debug_assert!(self.b64_offset + self.b64_len <= BUF_SIZE);
         debug_assert!(!buf.is_empty());
 
-        let decoded = self
+        let b64_to_decode = &self.b64_buffer[self.b64_offset..self.b64_offset + b64_len_to_decode];
+        let decode_metadata = self
             .engine
             .internal_decode(
-                &self.b64_buffer[self.b64_offset..self.b64_offset + num_bytes],
+                b64_to_decode,
                 buf,
-                self.engine.internal_decoded_len_estimate(num_bytes),
+                self.engine.internal_decoded_len_estimate(b64_len_to_decode),
             )
             .map_err(|e| match e {
                 DecodeError::InvalidByte(offset, byte) => {
+                    // This can be incorrect, but not in a way that probably matters to anyone:
+                    // if there was padding handled in a previous decode, and we are now getting
+                    // InvalidByte due to more padding, we should arguably report InvalidByte with
+                    // PAD_BYTE at the original padding position (`self.padding_offset`), but we
+                    // don't have a good way to tie those two cases together, so instead we
+                    // just report the invalid byte as if the previous padding, and its possibly
+                    // related downgrade to a now invalid byte, didn't happen.
                     DecodeError::InvalidByte(self.total_b64_decoded + offset, byte)
                 }
                 DecodeError::InvalidLength => DecodeError::InvalidLength,
@@ -151,13 +163,27 @@ impl<'e, E: Engine, R: io::Read> DecoderReader<'e, E, R> {
             })
             .map_err(|e| io::Error::new(io::ErrorKind::InvalidData, e))?;
 
-        self.total_b64_decoded += num_bytes;
-        self.b64_offset += num_bytes;
-        self.b64_len -= num_bytes;
+        if let Some(offset) = self.padding_offset {
+            // we've already seen padding
+            if decode_metadata.decoded_len > 0 {
+                // we read more after already finding padding; report error at first padding byte
+                return Err(io::Error::new(
+                    io::ErrorKind::InvalidData,
+                    DecodeError::InvalidByte(offset, PAD_BYTE),
+                ));
+            }
+        }
+
+        self.padding_offset = self.padding_offset.or(decode_metadata
+            .padding_offset
+            .map(|offset| self.total_b64_decoded + offset));
+        self.total_b64_decoded += b64_len_to_decode;
+        self.b64_offset += b64_len_to_decode;
+        self.b64_len -= b64_len_to_decode;
 
         debug_assert!(self.b64_offset + self.b64_len <= BUF_SIZE);
 
-        Ok(decoded)
+        Ok(decode_metadata.decoded_len)
     }
 
     /// Unwraps this `DecoderReader`, returning the base reader which it reads base64 encoded
@@ -205,9 +231,9 @@ impl<'e, E: Engine, R: io::Read> io::Read for DecoderReader<'e, E, R> {
             self.decoded_offset < DECODED_CHUNK_SIZE
         });
 
-        // We shouldn't ever decode into here when we can't immediately write at least one byte into
-        // the provided buf, so the effective length should only be 3 momentarily between when we
-        // decode and when we copy into the target buffer.
+        // We shouldn't ever decode into decoded_buffer when we can't immediately write at least one
+        // byte into the provided buf, so the effective length should only be 3 momentarily between
+        // when we decode and when we copy into the target buffer.
         debug_assert!(self.decoded_len < DECODED_CHUNK_SIZE);
         debug_assert!(self.decoded_len + self.decoded_offset <= DECODED_CHUNK_SIZE);
 
@@ -217,20 +243,15 @@ impl<'e, E: Engine, R: io::Read> io::Read for DecoderReader<'e, E, R> {
         } else {
             let mut at_eof = false;
             while self.b64_len < BASE64_CHUNK_SIZE {
-                // Work around lack of copy_within, which is only present in 1.37
                 // Copy any bytes we have to the start of the buffer.
-                // We know we have < 1 chunk, so we can use a tiny tmp buffer.
-                let mut memmove_buf = [0_u8; BASE64_CHUNK_SIZE];
-                memmove_buf[..self.b64_len].copy_from_slice(
-                    &self.b64_buffer[self.b64_offset..self.b64_offset + self.b64_len],
-                );
-                self.b64_buffer[0..self.b64_len].copy_from_slice(&memmove_buf[..self.b64_len]);
+                self.b64_buffer
+                    .copy_within(self.b64_offset..self.b64_offset + self.b64_len, 0);
                 self.b64_offset = 0;
 
                 // then fill in more data
                 let read = self.read_from_delegate()?;
                 if read == 0 {
-                    // we never pass in an empty buf, so 0 => we've hit EOF
+                    // we never read into an empty buf, so 0 => we've hit EOF
                     at_eof = true;
                     break;
                 }