Adding upstream version 86.0.1.upstream/86.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 282 insertions, 0 deletions

diff --git a/third_party/rust/base64/src/read/decoder.rs b/third_party/rust/base64/src/read/decoder.rs
new file mode 100644
index 0000000000..7a9c4cd292
--- /dev/null
+++ b/third_party/rust/base64/src/read/decoder.rs
@@ -0,0 +1,282 @@
+use crate::{decode_config_slice, Config, DecodeError};
+use std::io::Read;
+use std::{cmp, fmt, io};
+
+// This should be large, but it has to fit on the stack.
+pub(crate) const BUF_SIZE: usize = 1024;
+
+// 4 bytes of base64 data encode 3 bytes of raw data (modulo padding).
+const BASE64_CHUNK_SIZE: usize = 4;
+const DECODED_CHUNK_SIZE: usize = 3;
+
+/// A `Read` implementation that decodes base64 data read from an underlying reader.
+///
+/// # Examples
+///
+/// ```
+/// use std::io::Read;
+/// use std::io::Cursor;
+///
+/// // use a cursor as the simplest possible `Read` -- in real code this is probably a file, etc.
+/// let mut wrapped_reader = Cursor::new(b"YXNkZg==");
+/// let mut decoder = base64::read::DecoderReader::new(
+///     &mut wrapped_reader, base64::STANDARD);
+///
+/// // handle errors as you normally would
+/// let mut result = Vec::new();
+/// decoder.read_to_end(&mut result).unwrap();
+///
+/// assert_eq!(b"asdf", &result[..]);
+///
+/// ```
+pub struct DecoderReader<'a, R: 'a + io::Read> {
+    config: Config,
+    /// Where b64 data is read from
+    r: &'a mut R,
+
+    // Holds b64 data read from the delegate reader.
+    b64_buffer: [u8; BUF_SIZE],
+    // The start of the pending buffered data in b64_buffer.
+    b64_offset: usize,
+    // The amount of buffered b64 data.
+    b64_len: usize,
+    // Since the caller may provide us with a buffer of size 1 or 2 that's too small to copy a
+    // decoded chunk in to, we have to be able to hang on to a few decoded bytes.
+    // 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],
+    // 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,
+}
+
+impl<'a, R: io::Read> fmt::Debug for DecoderReader<'a, R> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("DecoderReader")
+            .field("config", &self.config)
+            .field("b64_offset", &self.b64_offset)
+            .field("b64_len", &self.b64_len)
+            .field("decoded_buffer", &self.decoded_buffer)
+            .field("decoded_offset", &self.decoded_offset)
+            .field("decoded_len", &self.decoded_len)
+            .field("total_b64_decoded", &self.total_b64_decoded)
+            .finish()
+    }
+}
+
+impl<'a, R: io::Read> DecoderReader<'a, R> {
+    /// Create a new decoder that will read from the provided reader `r`.
+    pub fn new(r: &'a mut R, config: Config) -> Self {
+        DecoderReader {
+            config,
+            r,
+            b64_buffer: [0; BUF_SIZE],
+            b64_offset: 0,
+            b64_len: 0,
+            decoded_buffer: [0; DECODED_CHUNK_SIZE],
+            decoded_offset: 0,
+            decoded_len: 0,
+            total_b64_decoded: 0,
+        }
+    }
+
+    /// Write as much as possible of the decoded buffer into the target buffer.
+    /// Must only be called when there is something to write and space to write into.
+    /// Returns a Result with the number of (decoded) bytes copied.
+    fn flush_decoded_buf(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        debug_assert!(self.decoded_len > 0);
+        debug_assert!(buf.len() > 0);
+
+        let copy_len = cmp::min(self.decoded_len, buf.len());
+        debug_assert!(copy_len > 0);
+        debug_assert!(copy_len <= self.decoded_len);
+
+        buf[..copy_len].copy_from_slice(
+            &self.decoded_buffer[self.decoded_offset..self.decoded_offset + copy_len],
+        );
+
+        self.decoded_offset += copy_len;
+        self.decoded_len -= copy_len;
+
+        debug_assert!(self.decoded_len < DECODED_CHUNK_SIZE);
+
+        Ok(copy_len)
+    }
+
+    /// Read into the remaining space in the buffer after the current contents.
+    /// Must only be called when there is space to read into in the buffer.
+    /// Returns the number of bytes read.
+    fn read_from_delegate(&mut self) -> io::Result<usize> {
+        debug_assert!(self.b64_offset + self.b64_len < BUF_SIZE);
+
+        let read = self
+            .r
+            .read(&mut self.b64_buffer[self.b64_offset + self.b64_len..])?;
+        self.b64_len += read;
+
+        debug_assert!(self.b64_offset + self.b64_len <= BUF_SIZE);
+
+        return Ok(read);
+    }
+
+    /// Decode the requested number of bytes from the b64 buffer into the provided buffer. It's the
+    /// 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);
+        debug_assert!(self.b64_offset + self.b64_len <= BUF_SIZE);
+        debug_assert!(buf.len() > 0);
+
+        let decoded = decode_config_slice(
+            &self.b64_buffer[self.b64_offset..self.b64_offset + num_bytes],
+            self.config,
+            &mut buf[..],
+        )
+        .map_err(|e| match e {
+            DecodeError::InvalidByte(offset, byte) => {
+                DecodeError::InvalidByte(self.total_b64_decoded + offset, byte)
+            }
+            DecodeError::InvalidLength => DecodeError::InvalidLength,
+            DecodeError::InvalidLastSymbol(offset, byte) => {
+                DecodeError::InvalidLastSymbol(self.total_b64_decoded + offset, byte)
+            }
+        })
+        .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;
+
+        debug_assert!(self.b64_offset + self.b64_len <= BUF_SIZE);
+
+        Ok(decoded)
+    }
+}
+
+impl<'a, R: Read> Read for DecoderReader<'a, R> {
+    /// Decode input from the wrapped reader.
+    ///
+    /// Under non-error circumstances, this returns `Ok` with the value being the number of bytes
+    /// written in `buf`.
+    ///
+    /// Where possible, this function buffers base64 to minimize the number of read() calls to the
+    /// delegate reader.
+    ///
+    /// # Errors
+    ///
+    /// Any errors emitted by the delegate reader are returned. Decoding errors due to invalid
+    /// base64 are also possible, and will have `io::ErrorKind::InvalidData`.
+    fn read(&mut self, buf: &mut [u8]) -> io::Result<usize> {
+        if buf.len() == 0 {
+            return Ok(0);
+        }
+
+        // offset == BUF_SIZE when we copied it all last time
+        debug_assert!(self.b64_offset <= BUF_SIZE);
+        debug_assert!(self.b64_offset + self.b64_len <= BUF_SIZE);
+        debug_assert!(if self.b64_offset == BUF_SIZE {
+            self.b64_len == 0
+        } else {
+            self.b64_len <= BUF_SIZE
+        });
+
+        debug_assert!(if self.decoded_len == 0 {
+            // can be = when we were able to copy the complete chunk
+            self.decoded_offset <= DECODED_CHUNK_SIZE
+        } else {
+            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.
+        debug_assert!(self.decoded_len < DECODED_CHUNK_SIZE);
+        debug_assert!(self.decoded_len + self.decoded_offset <= DECODED_CHUNK_SIZE);
+
+        if self.decoded_len > 0 {
+            // we have a few leftover decoded bytes; flush that rather than pull in more b64
+            self.flush_decoded_buf(buf)
+        } 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_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
+                    at_eof = true;
+                    break;
+                }
+            }
+
+            if self.b64_len == 0 {
+                debug_assert!(at_eof);
+                // we must be at EOF, and we have no data left to decode
+                return Ok(0);
+            };
+
+            debug_assert!(if at_eof {
+                // if we are at eof, we may not have a complete chunk
+                self.b64_len > 0
+            } else {
+                // otherwise, we must have at least one chunk
+                self.b64_len >= BASE64_CHUNK_SIZE
+            });
+
+            debug_assert_eq!(0, self.decoded_len);
+
+            if buf.len() < DECODED_CHUNK_SIZE {
+                // caller requested an annoyingly short read
+                // have to write to a tmp buf first to avoid double mutable borrow
+                let mut decoded_chunk = [0_u8; DECODED_CHUNK_SIZE];
+                // if we are at eof, could have less than BASE64_CHUNK_SIZE, in which case we have
+                // to assume that these last few tokens are, in fact, valid (i.e. must be 2-4 b64
+                // tokens, not 1, since 1 token can't decode to 1 byte).
+                let to_decode = cmp::min(self.b64_len, BASE64_CHUNK_SIZE);
+
+                let decoded = self.decode_to_buf(to_decode, &mut decoded_chunk[..])?;
+                self.decoded_buffer[..decoded].copy_from_slice(&decoded_chunk[..decoded]);
+
+                self.decoded_offset = 0;
+                self.decoded_len = decoded;
+
+                // can be less than 3 on last block due to padding
+                debug_assert!(decoded <= 3);
+
+                self.flush_decoded_buf(buf)
+            } else {
+                let b64_bytes_that_can_decode_into_buf = (buf.len() / DECODED_CHUNK_SIZE)
+                    .checked_mul(BASE64_CHUNK_SIZE)
+                    .expect("too many chunks");
+                debug_assert!(b64_bytes_that_can_decode_into_buf >= BASE64_CHUNK_SIZE);
+
+                let b64_bytes_available_to_decode = if at_eof {
+                    self.b64_len
+                } else {
+                    // only use complete chunks
+                    self.b64_len - self.b64_len % 4
+                };
+
+                let actual_decode_len = cmp::min(
+                    b64_bytes_that_can_decode_into_buf,
+                    b64_bytes_available_to_decode,
+                );
+                self.decode_to_buf(actual_decode_len, buf)
+            }
+        }
+    }
+}