From d2f423521ec76406944ad83098ec33afe20c692b Mon Sep 17 00:00:00 2001
From: Kim Altintop <kim@eagain.io>
Date: Mon, 9 Jan 2023 13:18:33 +0100
Subject: This is it

Squashed commit of all the exploration history. Development starts here.

Signed-off-by: Kim Altintop <kim@eagain.io>
---
 src/io.rs | 146 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 146 insertions(+)
 create mode 100644 src/io.rs

(limited to 'src/io.rs')

diff --git a/src/io.rs b/src/io.rs
new file mode 100644
index 0000000..86f91c6
--- /dev/null
+++ b/src/io.rs
@@ -0,0 +1,146 @@
+// Copyright © 2022 Kim Altintop <kim@eagain.io>
+// SPDX-License-Identifier: GPL-2.0-only WITH openvpn-openssl-exception
+
+use sha2::{
+    digest::generic_array::GenericArray,
+    Digest,
+};
+
+/// Created by [`Lines::until_blank`], stops iteration at the first blank line.
+pub struct UntilBlank<B> {
+    inner: Lines<B>,
+}
+
+impl<B: std::io::BufRead> Iterator for UntilBlank<B> {
+    type Item = std::io::Result<String>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next().and_then(|res| match res {
+            Ok(line) => {
+                if line.is_empty() {
+                    None
+                } else {
+                    Some(Ok(line))
+                }
+            },
+            Err(e) => Some(Err(e)),
+        })
+    }
+}
+
+impl<B: std::io::Seek> std::io::Seek for UntilBlank<B> {
+    fn seek(&mut self, pos: std::io::SeekFrom) -> std::io::Result<u64> {
+        self.inner.seek(pos)
+    }
+}
+
+/// Like [`std::io::Lines`], but allows to retain ownership of the underlying
+/// [`std::io::BufRead`].
+pub struct Lines<B> {
+    buf: B,
+}
+
+impl<B: std::io::BufRead> Lines<B> {
+    pub fn new(buf: B) -> Self {
+        Self { buf }
+    }
+
+    pub fn until_blank(self) -> UntilBlank<B> {
+        UntilBlank { inner: self }
+    }
+}
+
+impl<B: std::io::BufRead> Iterator for Lines<B> {
+    type Item = std::io::Result<String>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let mut buf = String::new();
+        match self.buf.read_line(&mut buf) {
+            Ok(0) => None,
+            Ok(_) => {
+                if buf.ends_with('\n') {
+                    buf.pop();
+                    if buf.ends_with('\r') {
+                        buf.pop();
+                    }
+                }
+                Some(Ok(buf))
+            },
+            Err(e) => Some(Err(e)),
+        }
+    }
+}
+
+impl<B: std::io::Seek> std::io::Seek for Lines<B> {
+    fn seek(&mut self, pos: std::io::SeekFrom) -> std::io::Result<u64> {
+        self.buf.seek(pos)
+    }
+}
+
+/// A [`std::io::Write`] which also computes a hash digest from the bytes
+/// written to it.
+pub struct HashWriter<D, W> {
+    hasher: D,
+    writer: W,
+}
+
+impl<D, W> HashWriter<D, W> {
+    pub fn new(hasher: D, writer: W) -> Self {
+        Self { hasher, writer }
+    }
+}
+
+impl<D, W> HashWriter<D, W>
+where
+    D: Digest,
+{
+    pub fn hash(self) -> GenericArray<u8, D::OutputSize> {
+        self.hasher.finalize()
+    }
+}
+
+impl<D, W> std::io::Write for HashWriter<D, W>
+where
+    D: Digest,
+    W: std::io::Write,
+{
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        self.hasher.update(buf);
+        self.writer.write(buf)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        self.writer.flush()
+    }
+}
+
+/// A [`std::io::Write`] which keeps track of the number of bytes written to it
+pub struct LenWriter<W> {
+    written: u64,
+    writer: W,
+}
+
+impl<W> LenWriter<W> {
+    pub fn new(writer: W) -> Self {
+        Self { written: 0, writer }
+    }
+
+    pub fn bytes_written(&self) -> u64 {
+        self.written
+    }
+}
+
+impl<W> std::io::Write for LenWriter<W>
+where
+    W: std::io::Write,
+{
+    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
+        let n = self.writer.write(buf)?;
+        self.written += n as u64;
+        Ok(n)
+    }
+
+    fn flush(&mut self) -> std::io::Result<()> {
+        self.writer.flush()
+    }
+}
-- 
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