bam/async/io/reader: Read magic number with header

noodles-bam/src/async/io/reader.rs

@@ -12,13 +12,8 @@ use noodles_csi::BinningIndex;
 use noodles_sam::{self as sam, alignment::RecordBuf};
 use tokio::io::{self, AsyncRead, AsyncSeek};
 
-use self::{
-    header::{magic_number::read_magic_number, read_header},
-    query::query,
-    record::read_record,
-    record_buf::read_record_buf,
-};
-use crate::{io::reader::resolve_region, Record, MAGIC_NUMBER};
+use self::{header::read_header, query::query, record::read_record, record_buf::read_record_buf};
+use crate::{io::reader::resolve_region, Record};
 
 /// An async BAM reader.
 ///
@@ -120,7 +115,6 @@ where
     /// # }
     /// ```
     pub async fn read_header(&mut self) -> io::Result<sam::Header> {
-        read_magic(&mut self.inner).await?;
         read_header(&mut self.inner).await
     }
 
@@ -427,45 +421,3 @@ impl<R> From<R> for Reader<R> {
         }
     }
 }
-
-async fn read_magic<R>(reader: &mut R) -> io::Result<()>
-where
-    R: AsyncRead + Unpin,
-{
-    let magic = read_magic_number(reader).await?;
-
-    if magic == MAGIC_NUMBER {
-        Ok(())
-    } else {
-        Err(io::Error::new(
-            io::ErrorKind::InvalidData,
-            "invalid BAM header",
-        ))
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[tokio::test]
-    async fn test_read_magic() {
-        let data = b"BAM\x01";
-        let mut reader = &data[..];
-        assert!(read_magic(&mut reader).await.is_ok());
-
-        let data = [];
-        let mut reader = &data[..];
-        assert!(matches!(
-            read_magic(&mut reader).await,
-            Err(ref e) if e.kind() == io::ErrorKind::UnexpectedEof
-        ));
-
-        let data = b"MThd";
-        let mut reader = &data[..];
-        assert!(matches!(
-            read_magic(&mut reader).await,
-            Err(ref e) if e.kind() == io::ErrorKind::InvalidData
-        ));
-    }
-}

noodles-bam/src/async/io/reader/header.rs

@@ -1,16 +1,22 @@
-pub(super) mod magic_number;
+mod magic_number;
 mod reference_sequences;
 
 use noodles_sam as sam;
 use tokio::io::{self, AsyncBufRead, AsyncBufReadExt, AsyncRead, AsyncReadExt, BufReader};
 
-use self::reference_sequences::read_reference_sequences;
+use self::{magic_number::read_magic_number, reference_sequences::read_reference_sequences};
 use crate::io::reader::header::reference_sequences_eq;
 
 pub(super) async fn read_header<R>(reader: &mut R) -> io::Result<sam::Header>
 where
     R: AsyncRead + Unpin,
 {
+    use crate::io::reader::header::magic_number;
+
+    read_magic_number(reader)
+        .await
+        .and_then(magic_number::validate)?;
+
     let mut header = read_header_inner(reader).await?;
     let reference_sequences = read_reference_sequences(reader).await?;
 
@@ -106,6 +112,7 @@ mod tests {
     };
 
     use super::*;
+    use crate::MAGIC_NUMBER;
 
     const SQ0_LN: NonZeroUsize = match NonZeroUsize::new(8) {
         Some(length) => length,
@@ -119,6 +126,7 @@ mod tests {
     #[tokio::test]
     async fn test_read_header() -> io::Result<()> {
         let mut src = Vec::new();
+        src.extend(MAGIC_NUMBER);
         put_u32_le(&mut src, 27); // l_text
         src.extend(b"@HD\tVN:1.6\n@SQ\tSN:sq0\tLN:8\n"); // text
         put_u32_le(&mut src, 1); // n_ref

noodles-bam/src/async/io/reader/header/magic_number.rs

@@ -2,7 +2,7 @@ use tokio::io::{self, AsyncRead, AsyncReadExt};
 
 use crate::MAGIC_NUMBER;
 
-pub(crate) async fn read_magic_number<R>(reader: &mut R) -> io::Result<[u8; MAGIC_NUMBER.len()]>
+pub(super) async fn read_magic_number<R>(reader: &mut R) -> io::Result<[u8; MAGIC_NUMBER.len()]>
 where
     R: AsyncRead + Unpin,
 {

noodles-bam/src/io/reader/header.rs

@@ -1,4 +1,4 @@
-mod magic_number;
+pub(crate) mod magic_number;
 mod reference_sequences;
 mod sam_header;
 

noodles-bam/src/io/reader/header/magic_number.rs

@@ -13,7 +13,7 @@ where
     Ok(buf)
 }
 
-pub(super) fn validate(buf: Buf) -> io::Result<()> {
+pub(crate) fn validate(buf: Buf) -> io::Result<()> {
     if is_valid(buf) {
         Ok(())
     } else {