satrs/src/cfdp/filestore.rs

@@ -133,6 +133,20 @@ pub trait VirtualFilestore {
 
     fn file_size(&self, path: &str) -> Result<u64, FilestoreError>;
 
+    /// This special function is the CFDP specific abstraction to calculate the checksum of a file.
+    /// This allows to keep OS specific details like reading the whole file in the most efficient
+    /// manner inside the file system abstraction.
+    ///
+    /// The passed verification buffer argument will be used by the specific implementation as
+    /// a buffer to read the file into. It is recommended to use common buffer sizes like
+    /// 4096 or 8192 bytes.
+    fn calculate_checksum(
+        &self,
+        file_path: &str,
+        checksum_type: ChecksumType,
+        verification_buf: &mut [u8],
+    ) -> Result<u32, FilestoreError>;
+
     /// This special function is the CFDP specific abstraction to verify the checksum of a file.
     /// This allows to keep OS specific details like reading the whole file in the most efficient
     /// manner inside the file system abstraction.
@@ -146,11 +160,17 @@ pub trait VirtualFilestore {
         checksum_type: ChecksumType,
         expected_checksum: u32,
         verification_buf: &mut [u8],
-    ) -> Result<bool, FilestoreError>;
+    ) -> Result<bool, FilestoreError> {
+        Ok(
+            self.calculate_checksum(file_path, checksum_type, verification_buf)?
+                == expected_checksum,
+        )
+    }
 }
 
 #[cfg(feature = "std")]
 pub mod std_mod {
+
     use super::*;
     use std::{
         fs::{self, File, OpenOptions},
@@ -280,20 +300,14 @@ pub mod std_mod {
             Ok(path.metadata()?.len())
         }
 
-        fn checksum_verify(
+        fn calculate_checksum(
             &self,
             file_path: &str,
             checksum_type: ChecksumType,
-            expected_checksum: u32,
             verification_buf: &mut [u8],
-        ) -> Result<bool, FilestoreError> {
+        ) -> Result<u32, FilestoreError> {
             match checksum_type {
-                ChecksumType::Modular => {
-                    if self.calc_modular_checksum(file_path)? == expected_checksum {
-                        return Ok(true);
-                    }
-                    Ok(false)
-                }
+                ChecksumType::Modular => self.calc_modular_checksum(file_path),
                 ChecksumType::Crc32 => {
                     let mut digest = CRC_32.digest();
                     let file_to_check = File::open(file_path)?;
@@ -305,12 +319,9 @@ pub mod std_mod {
                         }
                         digest.update(&verification_buf[0..bytes_read]);
                     }
-                    if digest.finalize() == expected_checksum {
-                        return Ok(true);
+                    Ok(digest.finalize())
                 }
-                    Ok(false)
-                }
-                ChecksumType::NullChecksum => Ok(true),
+                ChecksumType::NullChecksum => Ok(0),
                 _ => Err(FilestoreError::ChecksumTypeNotImplemented(checksum_type)),
             }
         }