Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

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

1 files changed, 185 insertions, 0 deletions

diff --git a/vendor/object/src/read/read_cache.rs b/vendor/object/src/read/read_cache.rs
new file mode 100644
index 000000000..19a98a44d
--- /dev/null
+++ b/vendor/object/src/read/read_cache.rs
@@ -0,0 +1,185 @@
+use core::ops::Range;
+use std::boxed::Box;
+use std::cell::RefCell;
+use std::collections::hash_map::Entry;
+use std::collections::HashMap;
+use std::convert::TryInto;
+use std::io::{Read, Seek, SeekFrom};
+use std::mem;
+use std::vec::Vec;
+
+use crate::read::ReadRef;
+
+/// An implementation of `ReadRef` for data in a stream that implements
+/// `Read + Seek`.
+///
+/// Contains a cache of read-only blocks of data, allowing references to
+/// them to be returned. Entries in the cache are never removed.
+/// Entries are keyed on the offset and size of the read.
+/// Currently overlapping reads are considered separate reads.
+#[derive(Debug)]
+pub struct ReadCache<R: Read + Seek> {
+    cache: RefCell<ReadCacheInternal<R>>,
+}
+
+#[derive(Debug)]
+struct ReadCacheInternal<R: Read + Seek> {
+    read: R,
+    bufs: HashMap<(u64, u64), Box<[u8]>>,
+    strings: HashMap<(u64, u8), Box<[u8]>>,
+}
+
+impl<R: Read + Seek> ReadCache<R> {
+    /// Create an empty `ReadCache` for the given stream.
+    pub fn new(read: R) -> Self {
+        ReadCache {
+            cache: RefCell::new(ReadCacheInternal {
+                read,
+                bufs: HashMap::new(),
+                strings: HashMap::new(),
+            }),
+        }
+    }
+
+    /// Return an implementation of `ReadRef` that restricts reads
+    /// to the given range of the stream.
+    pub fn range(&self, offset: u64, size: u64) -> ReadCacheRange<'_, R> {
+        ReadCacheRange {
+            r: self,
+            offset,
+            size,
+        }
+    }
+
+    /// Free buffers used by the cache.
+    pub fn clear(&mut self) {
+        self.cache.borrow_mut().bufs.clear();
+    }
+
+    /// Unwrap this `ReadCache<R>`, returning the underlying reader.
+    pub fn into_inner(self) -> R {
+        self.cache.into_inner().read
+    }
+}
+
+impl<'a, R: Read + Seek> ReadRef<'a> for &'a ReadCache<R> {
+    fn len(self) -> Result<u64, ()> {
+        let cache = &mut *self.cache.borrow_mut();
+        cache.read.seek(SeekFrom::End(0)).map_err(|_| ())
+    }
+
+    fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8], ()> {
+        if size == 0 {
+            return Ok(&[]);
+        }
+        let cache = &mut *self.cache.borrow_mut();
+        let buf = match cache.bufs.entry((offset, size)) {
+            Entry::Occupied(entry) => entry.into_mut(),
+            Entry::Vacant(entry) => {
+                let size = size.try_into().map_err(|_| ())?;
+                cache
+                    .read
+                    .seek(SeekFrom::Start(offset as u64))
+                    .map_err(|_| ())?;
+                let mut bytes = vec![0; size].into_boxed_slice();
+                cache.read.read_exact(&mut bytes).map_err(|_| ())?;
+                entry.insert(bytes)
+            }
+        };
+        // Extend the lifetime to that of self.
+        // This is OK because we never mutate or remove entries.
+        Ok(unsafe { mem::transmute::<&[u8], &[u8]>(buf) })
+    }
+
+    fn read_bytes_at_until(self, range: Range<u64>, delimiter: u8) -> Result<&'a [u8], ()> {
+        let cache = &mut *self.cache.borrow_mut();
+        let buf = match cache.strings.entry((range.start, delimiter)) {
+            Entry::Occupied(entry) => entry.into_mut(),
+            Entry::Vacant(entry) => {
+                cache
+                    .read
+                    .seek(SeekFrom::Start(range.start))
+                    .map_err(|_| ())?;
+
+                let max_check: usize = (range.end - range.start).try_into().map_err(|_| ())?;
+                // Strings should be relatively small.
+                // TODO: make this configurable?
+                let max_check = max_check.min(4096);
+
+                let mut bytes = Vec::new();
+                let mut checked = 0;
+                loop {
+                    bytes.resize((checked + 256).min(max_check), 0);
+                    let read = cache.read.read(&mut bytes[checked..]).map_err(|_| ())?;
+                    if read == 0 {
+                        return Err(());
+                    }
+                    if let Some(len) = memchr::memchr(delimiter, &bytes[checked..][..read]) {
+                        bytes.truncate(checked + len);
+                        break entry.insert(bytes.into_boxed_slice());
+                    }
+                    checked += read;
+                    if checked >= max_check {
+                        return Err(());
+                    }
+                }
+            }
+        };
+        // Extend the lifetime to that of self.
+        // This is OK because we never mutate or remove entries.
+        Ok(unsafe { mem::transmute::<&[u8], &[u8]>(buf) })
+    }
+}
+
+/// An implementation of `ReadRef` for a range of data in a stream that
+/// implements `Read + Seek`.
+///
+/// Shares an underlying `ReadCache` with a lifetime of `'a`.
+#[derive(Debug)]
+pub struct ReadCacheRange<'a, R: Read + Seek> {
+    r: &'a ReadCache<R>,
+    offset: u64,
+    size: u64,
+}
+
+impl<'a, R: Read + Seek> Clone for ReadCacheRange<'a, R> {
+    fn clone(&self) -> Self {
+        Self {
+            r: self.r,
+            offset: self.offset,
+            size: self.size,
+        }
+    }
+}
+
+impl<'a, R: Read + Seek> Copy for ReadCacheRange<'a, R> {}
+
+impl<'a, R: Read + Seek> ReadRef<'a> for ReadCacheRange<'a, R> {
+    fn len(self) -> Result<u64, ()> {
+        Ok(self.size)
+    }
+
+    fn read_bytes_at(self, offset: u64, size: u64) -> Result<&'a [u8], ()> {
+        if size == 0 {
+            return Ok(&[]);
+        }
+        let end = offset.checked_add(size).ok_or(())?;
+        if end > self.size {
+            return Err(());
+        }
+        let r_offset = self.offset.checked_add(offset).ok_or(())?;
+        self.r.read_bytes_at(r_offset, size)
+    }
+
+    fn read_bytes_at_until(self, range: Range<u64>, delimiter: u8) -> Result<&'a [u8], ()> {
+        let r_start = self.offset.checked_add(range.start).ok_or(())?;
+        let r_end = self.offset.checked_add(range.end).ok_or(())?;
+        let bytes = self.r.read_bytes_at_until(r_start..r_end, delimiter)?;
+        let size = bytes.len().try_into().map_err(|_| ())?;
+        let end = range.start.checked_add(size).ok_or(())?;
+        if end > self.size {
+            return Err(());
+        }
+        Ok(bytes)
+    }
+}