cram/io/reader/header/magic_number: Split read and validation

zaeleus · Jan 5, 2025 · 8fef33a · 8fef33a
1 parent 123198f
commit 8fef33a
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Showing 5 changed files with 48 additions and 51 deletions.
diff --git a/noodles-cram/src/async/io/reader.rs b/noodles-cram/src/async/io/reader.rs
@@ -111,7 +111,11 @@ where
     /// # }
     /// ```
     pub async fn read_file_definition(&mut self) -> io::Result<FileDefinition> {
-        header::read_magic_number(&mut self.inner).await?;
+        use crate::io::reader::header::magic_number;
+
+        header::read_magic_number(&mut self.inner)
+            .await
+            .and_then(magic_number::validate)?;
 
         let format = read_format(&mut self.inner).await?;
         let file_id = read_file_id(&mut self.inner).await?;

diff --git a/noodles-cram/src/async/io/reader/header/magic_number.rs b/noodles-cram/src/async/io/reader/header/magic_number.rs
@@ -1,46 +1,32 @@
 use tokio::io::{self, AsyncRead, AsyncReadExt};
 
-pub(crate) async fn read_magic_number<R>(reader: &mut R) -> io::Result<()>
+use crate::MAGIC_NUMBER;
+
+pub(crate) async fn read_magic_number<R>(reader: &mut R) -> io::Result<[u8; MAGIC_NUMBER.len()]>
 where
     R: AsyncRead + Unpin,
 {
-    use crate::MAGIC_NUMBER;
-
-    let mut magic = [0; 4];
-    reader.read_exact(&mut magic).await?;
-
-    if magic == MAGIC_NUMBER {
-        Ok(())
-    } else {
-        Err(io::Error::new(
-            io::ErrorKind::InvalidData,
-            "invalid CRAM header",
-        ))
-    }
+    let mut buf = [0; MAGIC_NUMBER.len()];
+    reader.read_exact(&mut buf).await?;
+    Ok(buf)
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[tokio::test]
-    async fn test_read_magic_number() {
-        let data = b"CRAM";
-        let mut reader = &data[..];
-        assert!(read_magic_number(&mut reader).await.is_ok());
+    async fn test_read_magic_number() -> io::Result<()> {
+        let src = b"CRAM";
+        let mut reader = &src[..];
+        assert_eq!(read_magic_number(&mut reader).await?, *b"CRAM");
 
-        let data = [];
-        let mut reader = &data[..];
+        let mut src = &[][..];
         assert!(matches!(
-            read_magic_number(&mut reader).await,
-            Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof
+            read_magic_number(&mut src).await,
+            Err(e) if e.kind() == io::ErrorKind::UnexpectedEof
         ));
 
-        let data = b"BAM\x01";
-        let mut reader = &data[..];
-        assert!(matches!(
-            read_magic_number(&mut reader).await,
-            Err(ref e) if e.kind() == io::ErrorKind::InvalidData
-        ));
+        Ok(())
     }
 }
diff --git a/noodles-cram/src/io/reader.rs b/noodles-cram/src/io/reader.rs
@@ -3,7 +3,7 @@
 mod builder;
 pub(crate) mod container;
 pub(crate) mod data_container;
-mod header;
+pub(crate) mod header;
 pub(crate) mod header_container;
 pub(crate) mod num;
 mod query;
@@ -128,7 +128,7 @@ where
     /// # Ok::<(), io::Error>(())
     /// ```
     pub fn read_file_definition(&mut self) -> io::Result<FileDefinition> {
-        header::read_magic_number(&mut self.inner)?;
+        header::read_magic_number(&mut self.inner).and_then(header::magic_number::validate)?;
 
         let format = read_format(&mut self.inner)?;
         let file_id = read_file_id(&mut self.inner)?;

diff --git a/noodles-cram/src/io/reader/header.rs b/noodles-cram/src/io/reader/header.rs
@@ -1,3 +1,3 @@
-mod magic_number;
+pub(crate) mod magic_number;
 
 pub(super) use self::magic_number::read_magic_number;
diff --git a/noodles-cram/src/io/reader/header/magic_number.rs b/noodles-cram/src/io/reader/header/magic_number.rs
@@ -2,14 +2,19 @@ use std::io::{self, Read};
 
 use crate::MAGIC_NUMBER;
 
-pub(crate) fn read_magic_number<R>(reader: &mut R) -> io::Result<()>
+type Buf = [u8; MAGIC_NUMBER.len()];
+
+pub(crate) fn read_magic_number<R>(reader: &mut R) -> io::Result<Buf>
 where
     R: Read,
 {
-    let mut buf = [0; 4];
+    let mut buf = [0; MAGIC_NUMBER.len()];
     reader.read_exact(&mut buf)?;
+    Ok(buf)
+}
 
-    if buf == MAGIC_NUMBER {
+pub(crate) fn validate(buf: Buf) -> io::Result<()> {
+    if is_valid(buf) {
         Ok(())
     } else {
         Err(io::Error::new(
@@ -19,31 +24,33 @@ where
     }
 }
 
+fn is_valid(buf: Buf) -> bool {
+    buf == MAGIC_NUMBER
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
     #[test]
-    fn test_read_magic_number() {
-        let data = b"CRAM";
-        let mut reader = &data[..];
-        assert!(read_magic_number(&mut reader).is_ok());
-    }
+    fn test_read_magic_number() -> io::Result<()> {
+        let src = b"CRAM";
+        let mut reader = &src[..];
+        assert_eq!(read_magic_number(&mut reader)?, *b"CRAM");
 
-    #[test]
-    fn test_read_magic_number_with_invalid_input() {
-        let data = [];
-        let mut reader = &data[..];
+        let src = [];
+        let mut reader = &src[..];
         assert!(matches!(
             read_magic_number(&mut reader),
-            Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof,
+            Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof
         ));
 
-        let data = b"BAM\x01";
-        let mut reader = &data[..];
-        assert!(matches!(
-            read_magic_number(&mut reader),
-            Err(ref e) if e.kind() == io::ErrorKind::InvalidData,
-        ));
+        Ok(())
+    }
+
+    #[test]
+    fn test_is_valid() {
+        assert!(is_valid(*b"CRAM"));
+        assert!(!is_valid([0x00, 0x00, 0x00, 0x00]));
     }
 }