Adding upstream version 115.8.0esr.upstream/115.8.0esr

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

1 files changed, 193 insertions, 0 deletions

diff --git a/third_party/rust/scroll/README.md b/third_party/rust/scroll/README.md
new file mode 100644
index 0000000000..717fe6a234
--- /dev/null
+++ b/third_party/rust/scroll/README.md
@@ -0,0 +1,193 @@
+ [![Build Status](https://travis-ci.org/m4b/scroll.svg?branch=master)](https://travis-ci.org/m4b/scroll)
+## Scroll - cast some magic
+
+```text
+         _______________
+    ()==(              (@==()
+         '______________'|
+           |             |
+           |   ἀρετή     |
+         __)_____________|
+    ()==(               (@==()
+         '--------------'
+
+```
+
+### Documentation
+
+https://docs.rs/scroll
+
+### Usage
+
+Add to your `Cargo.toml`
+
+```toml, no_test
+[dependencies]
+scroll = "0.10"
+```
+
+### Overview
+
+Scroll implements several traits for read/writing generic containers (byte buffers are currently implemented by default). Most familiar will likely be the `Pread` trait, which at its basic takes an immutable reference to self, an immutable offset to read at, (and a parsing context, more on that later), and then returns the deserialized value.
+
+Because self is immutable, _**all** reads can be performed in parallel_ and hence are trivially parallelizable.
+
+A simple example demonstrates its flexibility:
+
+```rust
+use scroll::{ctx, Pread, LE};
+
+fn main() -> Result<(), scroll::Error> {
+    let bytes: [u8; 4] = [0xde, 0xad, 0xbe, 0xef];
+
+    // reads a u32 out of `b` with the endianness of the host machine, at offset 0, turbofish-style
+    let number: u32 = bytes.pread::<u32>(0)?;
+    // ...or a byte, with type ascription on the binding.
+    let byte: u8 = bytes.pread(0)?;
+
+    //If the type is known another way by the compiler, say reading into a struct field, we can omit the turbofish, and type ascription altogether!
+
+    // If we want, we can explicitly add a endianness to read with by calling `pread_with`.
+    // The following reads a u32 out of `b` with Big Endian byte order, at offset 0
+    let be_number: u32 = bytes.pread_with(0, scroll::BE)?;
+    // or a u16 - specify the type either on the variable or with the beloved turbofish
+    let be_number2 = bytes.pread_with::<u16>(2, scroll::BE)?;
+
+    // Scroll has core friendly errors (no allocation). This will have the type `scroll::Error::BadOffset` because it tried to read beyond the bound
+    let byte: scroll::Result<i64> = bytes.pread(0);
+
+    // Scroll is extensible: as long as the type implements `TryWithCtx`, then you can read your type out of the byte array!
+
+    // We can parse out custom datatypes, or types with lifetimes
+    // if they implement the conversion trait `TryFromCtx`; here we parse a C-style \0 delimited &str (safely)
+    let hello: &[u8] = b"hello_world\0more words";
+    let hello_world: &str = hello.pread(0)?;
+    assert_eq!("hello_world", hello_world);
+
+    // ... and this parses the string if its space separated!
+    use scroll::ctx::*;
+    let spaces: &[u8] = b"hello world some junk";
+    let world: &str = spaces.pread_with(6, StrCtx::Delimiter(SPACE))?;
+    assert_eq!("world", world);
+    Ok(())
+}
+```
+
+### Deriving `Pread` and `Pwrite`
+
+Scroll implements a custom derive that can provide `Pread` and `Pwrite` implementations for your structs.
+
+```rust
+use scroll::{Pread, Pwrite, BE};
+
+#[derive(Pread, Pwrite)]
+struct Data {
+    one: u32,
+    two: u16,
+    three: u8,
+}
+
+fn main() -> Result<(), scroll::Error> {
+    let bytes: [u8; 7] = [0xde, 0xad, 0xbe, 0xef, 0xfa, 0xce, 0xff];
+    // Read a single `Data` at offset zero in big-endian byte order.
+    let data: Data = bytes.pread_with(0, BE)?;
+    assert_eq!(data.one, 0xdeadbeef);
+    assert_eq!(data.two, 0xface);
+    assert_eq!(data.three, 0xff);
+
+    // Write it back to a buffer
+    let mut out: [u8; 7] = [0; 7];
+    out.pwrite_with(data, 0, BE)?;
+    assert_eq!(bytes, out);
+    Ok(())
+}
+```
+
+This feature is **not** enabled by default, you must enable the `derive` feature in Cargo.toml to use it:
+
+```toml, no_test
+[dependencies]
+scroll = { version = "0.10", features = ["derive"] }
+```
+
+# `std::io` API
+
+Scroll can also read/write simple types from a `std::io::Read` or `std::io::Write` implementor. The  built-in numeric types are taken care of for you.  If you want to read a custom type, you need to implement the `FromCtx` (_how_ to parse) and `SizeWith` (_how_ big the parsed thing will be) traits.  You must compile with default features. For example:
+
+```rust
+use std::io::Cursor;
+use scroll::IOread;
+
+fn main() -> Result<(), scroll::Error> {
+    let bytes_ = [0x01,0x00,0x00,0x00,0x00,0x00,0x00,0x00, 0xef,0xbe,0x00,0x00,];
+    let mut bytes = Cursor::new(bytes_);
+
+    // this will bump the cursor's Seek
+    let foo = bytes.ioread::<usize>()?;
+    // ..ditto
+    let bar = bytes.ioread::<u32>()?;
+    Ok(())
+}
+```
+
+Similarly, we can write to anything that implements `std::io::Write` quite naturally:
+
+```rust
+use scroll::{IOwrite, LE, BE};
+use std::io::{Write, Cursor};
+
+fn main() -> Result<(), scroll::Error> {
+    let mut bytes = [0x0u8; 10];
+    let mut cursor = Cursor::new(&mut bytes[..]);
+    cursor.write_all(b"hello")?;
+    cursor.iowrite_with(0xdeadbeef as u32, BE)?;
+    assert_eq!(cursor.into_inner(), [0x68, 0x65, 0x6c, 0x6c, 0x6f, 0xde, 0xad, 0xbe, 0xef, 0x0]);
+    Ok(())
+}
+```
+
+# Advanced Uses
+
+Scroll is designed to be highly configurable - it allows you to implement various context (`Ctx`) sensitive traits, which then grants the implementor _automatic_ uses of the `Pread` and/or `Pwrite` traits.
+
+For example, suppose we have a datatype and we want to specify how to parse or serialize this datatype out of some arbitrary
+byte buffer. In order to do this, we need to provide a [TryFromCtx](trait.TryFromCtx.html) impl for our datatype.
+
+In particular, if we do this for the `[u8]` target, using the convention `(usize, YourCtx)`, you will automatically get access to
+calling `pread_with::<YourDatatype>` on arrays of bytes.
+
+```rust
+use scroll::{ctx, Pread, BE, Endian};
+
+struct Data<'a> {
+  name: &'a str,
+  id: u32,
+}
+
+// note the lifetime specified here
+impl<'a> ctx::TryFromCtx<'a, Endian> for Data<'a> {
+  type Error = scroll::Error;
+  // and the lifetime annotation on `&'a [u8]` here
+  fn try_from_ctx (src: &'a [u8], endian: Endian)
+    -> Result<(Self, usize), Self::Error> {
+    let offset = &mut 0;
+    let name = src.gread::<&str>(offset)?;
+    let id = src.gread_with(offset, endian)?;
+    Ok((Data { name: name, id: id }, *offset))
+  }
+}
+
+fn main() -> Result<(), scroll::Error> {
+    let bytes = b"UserName\x00\x01\x02\x03\x04";
+    let data = bytes.pread_with::<Data>(0, BE)?;
+    assert_eq!(data.id, 0x01020304);
+    assert_eq!(data.name.to_string(), "UserName".to_string());
+    Ok(())
+}
+```
+
+Please see the official documentation, or a simple [example](examples/data_ctx.rs) for more.
+
+# Contributing
+
+Any ideas, thoughts, or contributions are welcome!