Implement `NtfsString::read_from_fs` to simplify several functions.

4 files changed, 29 insertions, 38 deletions

diff --git a/src/attribute.rs b/src/attribute.rs
index 3af1d01..6536e39 100644
--- a/src/attribute.rs
+++ b/src/attribute.rs
@@ -214,19 +214,8 @@ impl NtfsAttribute {
     where
         T: Read + Seek,
     {
-        let name_length = self.name_length();
-        if buf.len() < name_length {
-            return Err(NtfsError::BufferTooSmall {
-                expected: name_length,
-                actual: buf.len(),
-            });
-        }
-
         let name_position = self.position + self.header.name_offset as u64;
-        fs.seek(SeekFrom::Start(name_position))?;
-        fs.read_exact(&mut buf[..name_length])?;
-
-        Ok(NtfsString(&buf[..name_length]))
+        NtfsString::read_from_fs(fs, name_position, self.name_length(), buf)
     }
 
     pub fn structured_value<T>(&self, fs: &mut T) -> Result<NtfsStructuredValue>
diff --git a/src/string.rs b/src/string.rs
index 18acc4d..1b226c8 100644
--- a/src/string.rs
+++ b/src/string.rs
@@ -1,7 +1,9 @@
 // Copyright 2021 Colin Finck <colin@reactos.org>
 // SPDX-License-Identifier: GPL-2.0-or-later
 
+use crate::error::{NtfsError, Result};
 use alloc::string::String;
+use binread::io::{Read, Seek, SeekFrom};
 use core::char;
 use core::cmp::Ordering;
 use core::convert::TryInto;
@@ -65,6 +67,28 @@ impl<'a> NtfsString<'a> {
         self.0.len()
     }
 
+    pub(crate) fn read_from_fs<T>(
+        fs: &mut T,
+        position: u64,
+        length: usize,
+        buf: &'a mut [u8],
+    ) -> Result<Self>
+    where
+        T: Read + Seek,
+    {
+        if buf.len() < length {
+            return Err(NtfsError::BufferTooSmall {
+                expected: length,
+                actual: buf.len(),
+            });
+        }
+
+        fs.seek(SeekFrom::Start(position))?;
+        fs.read_exact(&mut buf[..length])?;
+
+        Ok(Self(&buf[..length]))
+    }
+
     /// Attempts to convert `self` to an owned `String`.
     /// Returns `Some(String)` if all characters could be converted successfully or `None` if a decoding error occurred.
     pub fn to_string_checked(&self) -> Option<String> {
diff --git a/src/structured_values/file_name.rs b/src/structured_values/file_name.rs
index 7a2edf6..71b0fd8 100644
--- a/src/structured_values/file_name.rs
+++ b/src/structured_values/file_name.rs
@@ -7,7 +7,7 @@ use crate::error::{NtfsError, Result};
 use crate::string::NtfsString;
 use crate::structured_values::NtfsFileAttributeFlags;
 use crate::time::NtfsTime;
-use binread::io::{Read, Seek, SeekFrom};
+use binread::io::{Read, Seek};
 use binread::{BinRead, BinReaderExt};
 use core::mem;
 use enumn::N;
@@ -126,18 +126,7 @@ impl NtfsFileName {
     where
         T: Read + Seek,
     {
-        let name_length = self.name_length();
-        if buf.len() < name_length {
-            return Err(NtfsError::BufferTooSmall {
-                expected: name_length,
-                actual: buf.len(),
-            });
-        }
-
-        fs.seek(SeekFrom::Start(self.name_position))?;
-        fs.read_exact(&mut buf[..name_length])?;
-
-        Ok(NtfsString(&buf[..name_length]))
+        NtfsString::read_from_fs(fs, self.name_position, self.name_length(), buf)
     }
 }
 
diff --git a/src/structured_values/volume_name.rs b/src/structured_values/volume_name.rs
index 72bd3bc..2f70ea7 100644
--- a/src/structured_values/volume_name.rs
+++ b/src/structured_values/volume_name.rs
@@ -5,7 +5,7 @@ use crate::attribute::NtfsAttributeType;
 use crate::attribute_value::NtfsAttributeValueAttached;
 use crate::error::{NtfsError, Result};
 use crate::string::NtfsString;
-use binread::io::{Read, Seek, SeekFrom};
+use binread::io::{Read, Seek};
 use core::mem;
 
 /// The smallest VolumeName attribute has a name containing just a single character.
@@ -67,17 +67,6 @@ impl NtfsVolumeName {
     where
         T: Read + Seek,
     {
-        let name_length = self.name_length();
-        if buf.len() < name_length {
-            return Err(NtfsError::BufferTooSmall {
-                expected: name_length,
-                actual: buf.len(),
-            });
-        }
-
-        fs.seek(SeekFrom::Start(self.name_position))?;
-        fs.read_exact(&mut buf[..name_length])?;
-
-        Ok(NtfsString(&buf[..name_length]))
+        NtfsString::read_from_fs(fs, self.name_position, self.name_length(), buf)
     }
 }