Make PackageSrc::read_at always read buf.len bytes

pkgar-core/src/package.rs

@@ -8,11 +8,11 @@ use crate::{Entry, Error, HEADER_SIZE, Header};
 
 pub trait PackageSrc {
     type Err: From<Error>;
-    
+
     fn read_at(&mut self, offset: u64, buf: &mut [u8]) -> Result<usize, Self::Err>;
-    
+
     fn header(&self) -> Header;
-    
+
     /// Users of implementors of `PackageSrc` should use `header` instead of `read_header` for
     /// cheap header access.
     /// Implementors of `PackageSrc` should call this function during initialization and store
@@ -23,7 +23,7 @@ pub trait PackageSrc {
         let header = Header::new(&header_data, &public_key)?;
         Ok(header.clone())
     }
-    
+
     fn read_entries(&mut self) -> Result<Vec<Entry>, Self::Err> {
         let header = self.header();
         let entries_size = header.entries_size()
@@ -35,25 +35,25 @@ pub trait PackageSrc {
         let entries = header.entries(&entries_data)?;
         Ok(entries.to_vec())
     }
-    
+
     /// Read from this src at a given entry's data with a given offset within that entry
     fn read_entry(&mut self, entry: Entry, offset: usize, buf: &mut [u8]) -> Result<usize, Self::Err> {
         if offset as u64 > entry.size {
             return Ok(0);
         }
-        
+
         let mut end = usize::try_from(entry.size - offset as u64)
             .map_err(Error::TryFromInt)?;
-        
+
         if end > buf.len() {
             end = buf.len();
         }
-        
+
         let offset =
             HEADER_SIZE as u64 +
             self.header().entries_size()? +
             entry.offset + offset as u64;
-        
+
         self.read_at(offset as u64, &mut buf[..end])
     }
 }
@@ -78,11 +78,11 @@ impl<'a> PackageBuf<'a> {
 
 impl PackageSrc for PackageBuf<'_> {
     type Err = Error;
-    
+
     fn header(&self) -> Header {
         self.header
     }
-    
+
     fn read_at(&mut self, offset: u64, buf: &mut [u8]) -> Result<usize, Error> {
         let start = usize::try_from(offset)
             .map_err(Error::TryFromInt)?;
@@ -96,7 +96,6 @@ impl PackageSrc for PackageBuf<'_> {
             end = len;
         }
         buf.copy_from_slice(&self.src[start..end]);
-        Ok(end.checked_sub(start).unwrap())
+        Ok(buf.len())
     }
 }
-

pkgar/src/package.rs

@@ -51,7 +51,8 @@ impl PackageSrc for PackageFile {
 
     fn read_at(&mut self, offset: u64, buf: &mut [u8]) -> Result<usize, Self::Err> {
         self.src.seek(SeekFrom::Start(offset))?;
-        Ok(self.src.read(buf)?)
+        self.src.read_exact(buf)?;
+        Ok(buf.len())
     }
 }