From ea2c3354689c9c977e2d58d872df507ba22e00c8 Mon Sep 17 00:00:00 2001
From: Antonio Scandurra <as-cii@github.com>
Date: Tue, 15 May 2018 14:02:29 +0200
Subject: [PATCH] Truncate existing file on save

---
 xray_core/src/buffer.rs |  3 ++-
 xray_server/src/fs.rs   | 34 ++++++++++++++++++++--------------
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/xray_core/src/buffer.rs b/xray_core/src/buffer.rs
index ca9a9d9a..7bc101e2 100644
--- a/xray_core/src/buffer.rs
+++ b/xray_core/src/buffer.rs
@@ -1661,7 +1661,8 @@ impl BufferSnapshot {
     pub fn iter<'a>(&'a self) -> impl 'a + Iterator<Item = &'a [u16]> {
         self.fragments.iter().filter_map(|fragment| {
             if fragment.is_visible() {
-                Some(fragment.insertion.text.code_units.as_ref())
+                let range = fragment.start_offset..fragment.end_offset;
+                Some(&fragment.insertion.text.code_units[range])
             } else {
                 None
             }
diff --git a/xray_server/src/fs.rs b/xray_server/src/fs.rs
index 5bb4c59b..345faf91 100644
--- a/xray_server/src/fs.rs
+++ b/xray_server/src/fs.rs
@@ -4,7 +4,7 @@ use parking_lot::Mutex;
 use std::char::decode_utf16;
 use std::ffi::OsString;
 use std::fs;
-use std::io::{self, Read, Write};
+use std::io::{self, Read, Seek, SeekFrom, Write};
 use std::os::unix::fs::MetadataExt;
 use std::path::PathBuf;
 use std::sync::Arc;
@@ -196,21 +196,27 @@ impl xray_fs::File for File {
         let file = self.file.clone();
         thread::spawn(move || {
             fn write(file: &mut fs::File, snapshot: BufferSnapshot) -> Result<(), io::Error> {
-                let mut buf_writer = io::BufWriter::new(file);
-                let mut encode_buf = [0_u8; 4];
-                for character in snapshot
-                    .iter()
-                    .flat_map(|c| decode_utf16(c.iter().cloned()))
+                let mut size = 0_u64;
                 {
-                    let character = character.map_err(|_| {
-                        io::Error::new(
-                            io::ErrorKind::InvalidData,
-                            "buffer did not contain valid UTF-8",
-                        )
-                    })?;
-                    let encoded_char = character.encode_utf8(&mut encode_buf);
-                    buf_writer.write(encoded_char.as_bytes())?;
+                    let mut buf_writer = io::BufWriter::new(&mut *file);
+                    buf_writer.seek(SeekFrom::Start(0))?;
+                    for character in snapshot
+                        .iter()
+                        .flat_map(|c| decode_utf16(c.iter().cloned()))
+                    {
+                        let character = character.map_err(|_| {
+                            io::Error::new(
+                                io::ErrorKind::InvalidData,
+                                "buffer did not contain valid UTF-8",
+                            )
+                        })?;
+                        let mut encode_buf = [0_u8; 4];
+                        let encoded_char = character.encode_utf8(&mut encode_buf);
+                        buf_writer.write(encoded_char.as_bytes())?;
+                        size += encoded_char.len() as u64;
+                    }
                 }
+                file.set_len(size)?;
                 Ok(())
             }