Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 96 insertions, 0 deletions

diff --git a/third_party/rust/scroll/src/pwrite.rs b/third_party/rust/scroll/src/pwrite.rs
new file mode 100644
index 0000000000..ab6d96157d
--- /dev/null
+++ b/third_party/rust/scroll/src/pwrite.rs
@@ -0,0 +1,96 @@
+use core::result;
+
+use crate::ctx::TryIntoCtx;
+use crate::error;
+
+/// A very generic, contextual pwrite interface in Rust.
+///
+/// Like [Pread](trait.Pread.html) — but for writing!
+///
+/// Implementing `Pwrite` on a data store allows you to then write almost arbitrarily complex types
+/// efficiently.
+///
+/// To this end the Pwrite trait works in conjuction with the [TryIntoCtx](ctx/trait.TryIntoCtx.html);
+/// The `TryIntoCtx` trait implemented on a type defines how to convert said type into data that
+/// an implementation of Pwrite can … well … write.
+///
+/// As with [Pread](trait.Pread.html) 'data' does not necessarily mean `&[u8]` but can be any
+/// indexable type. In fact much of the documentation of `Pread` applies to `Pwrite` as well just
+/// with 'read' switched for 'write' and 'From' switched with 'Into' so if you haven't yet you
+/// should read the documentation of `Pread` first.
+///
+/// Unless you need to implement your own data store — that is either can't convert to `&[u8]` or
+/// have a data that does not expose a `&mut [u8]` — you will probably want to implement
+/// [TryIntoCtx](ctx/trait.TryIntoCtx.html) on your Rust types to be written.
+///
+pub trait Pwrite<Ctx: Copy, E> {
+    #[inline]
+    fn pwrite<N: TryIntoCtx<Ctx, Self, Error = E>>(
+        &mut self,
+        n: N,
+        offset: usize,
+    ) -> result::Result<usize, E>
+    where
+        Ctx: Default,
+    {
+        self.pwrite_with(n, offset, Ctx::default())
+    }
+
+    /// Write `N` at offset `I` with context `Ctx`
+    /// # Example
+    /// ```
+    /// use scroll::{Pwrite, Pread, LE};
+    /// let mut bytes: [u8; 8] = [0, 0, 0, 0, 0, 0, 0, 0];
+    /// bytes.pwrite_with::<u32>(0xbeefbeef, 0, LE).unwrap();
+    /// assert_eq!(bytes.pread_with::<u32>(0, LE).unwrap(), 0xbeefbeef);
+    fn pwrite_with<N: TryIntoCtx<Ctx, Self, Error = E>>(
+        &mut self,
+        n: N,
+        offset: usize,
+        ctx: Ctx,
+    ) -> result::Result<usize, E>;
+
+    /// Write `n` into `self` at `offset`, with a default `Ctx`. Updates the offset.
+    #[inline]
+    fn gwrite<N: TryIntoCtx<Ctx, Self, Error = E>>(
+        &mut self,
+        n: N,
+        offset: &mut usize,
+    ) -> result::Result<usize, E>
+    where
+        Ctx: Default,
+    {
+        let ctx = Ctx::default();
+        self.gwrite_with(n, offset, ctx)
+    }
+
+    /// Write `n` into `self` at `offset`, with the `ctx`. Updates the offset.
+    #[inline]
+    fn gwrite_with<N: TryIntoCtx<Ctx, Self, Error = E>>(
+        &mut self,
+        n: N,
+        offset: &mut usize,
+        ctx: Ctx,
+    ) -> result::Result<usize, E> {
+        let o = *offset;
+        self.pwrite_with(n, o, ctx).map(|size| {
+            *offset += size;
+            size
+        })
+    }
+}
+
+impl<Ctx: Copy, E: From<error::Error>> Pwrite<Ctx, E> for [u8] {
+    fn pwrite_with<N: TryIntoCtx<Ctx, Self, Error = E>>(
+        &mut self,
+        n: N,
+        offset: usize,
+        ctx: Ctx,
+    ) -> result::Result<usize, E> {
+        if offset >= self.len() {
+            return Err(error::Error::BadOffset(offset).into());
+        }
+        let dst = &mut self[offset..];
+        n.try_into_ctx(dst, ctx)
+    }
+}