From 31dc6d87d7b401742531bc4acf084a9cbf355131 Mon Sep 17 00:00:00 2001
From: Bryan Newbold <bnewbold@robocracy.org>
Date: Mon, 30 Oct 2017 19:18:32 -0700
Subject: replace (most) seek() code with read_at/write_at

---
 src/sleep_file.rs     | 16 +++++++++-------
 src/sleep_register.rs |  7 +++++--
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/src/sleep_file.rs b/src/sleep_file.rs
index 71e95ba..90e08c4 100644
--- a/src/sleep_file.rs
+++ b/src/sleep_file.rs
@@ -1,6 +1,6 @@
 
 use std::io::prelude::*;
-use std::io::SeekFrom;
+use std::os::unix::fs::FileExt;
 use std::path::Path;
 use std::fs::File;
 use integer_encoding::FixedInt;
@@ -139,9 +139,10 @@ impl SleepStorage for SleepFile {
             bail!("Tried to read beyond end of SLEEP file");
         }
         let mut entry = vec![0; entry_size];
-        self.file
-            .seek(SeekFrom::Start(32 + (entry_size as u64) * index))?;
-        self.file.read_exact(&mut entry)?;
+        let got = self.file.read_at(&mut entry, 32 + (entry_size as u64) * index)?;
+        if got != entry.len() {
+            bail!("Short file read");
+        }
         Ok(entry)
     }
 
@@ -150,9 +151,10 @@ impl SleepStorage for SleepFile {
         if data.len() != self.entry_size as usize {
             bail!("Tried to write mis-sized data");
         }
-        self.file
-            .seek(SeekFrom::Start(32 + (self.entry_size as u64) * index))?;
-        self.file.write_all(&data)?;
+        let put = self.file.write_at(&data, 32 + (self.entry_size as u64) * index)?;
+        if put != data.len() {
+            bail!("Short file write");
+        }
         Ok(())
     }
 
diff --git a/src/sleep_register.rs b/src/sleep_register.rs
index 3e1c48e..276e4c9 100644
--- a/src/sleep_register.rs
+++ b/src/sleep_register.rs
@@ -3,6 +3,7 @@ use std::io::prelude::*;
 use std::fs::File;
 use std::path::{Path, PathBuf};
 use std::io::SeekFrom;
+use std::os::unix::fs::FileExt;
 use integer_encoding::FixedInt;
 use std::fs::OpenOptions;
 use crypto::blake2b::Blake2b;
@@ -412,8 +413,10 @@ impl HyperRegister for SleepDirRegister {
 
         // Read chunk
         let mut data = vec![0; data_len as usize];
-        data_file.seek(SeekFrom::Start(offset))?;
-        data_file.read_exact(&mut data)?;
+        let got = data_file.read_at(&mut data, offset)?;
+        if got != data.len() {
+            bail!("Short file read");
+        }
 
         // TODO: check the hash? separate function?
         Ok(data)
-- 
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