Replace hard-coded 512 with BLOCK_SIZE (#394)

Co-authored-by: ncihnegn <[email protected]>

src/archive.rs

@@ -9,6 +9,7 @@ use std::path::Path;
 
 use crate::entry::{EntryFields, EntryIo};
 use crate::error::TarError;
+use crate::header::BLOCK_SIZE;
 use crate::other;
 use crate::pax::*;
 use crate::{Entry, GnuExtSparseHeader, GnuSparseHeader, Header};
@@ -302,14 +303,14 @@ impl<'a> EntriesFields<'a> {
             // Otherwise, check if we are ignoring zeros and continue, or break as if this is the
             // end of the archive.
             if !header.as_bytes().iter().all(|i| *i == 0) {
-                self.next += 512;
+                self.next += BLOCK_SIZE;
                 break;
             }
 
             if !self.archive.inner.ignore_zeros {
                 return Ok(None);
             }
-            self.next += 512;
+            self.next += BLOCK_SIZE;
             header_pos = self.next;
         }
 
@@ -364,11 +365,11 @@ impl<'a> EntriesFields<'a> {
         // Store where the next entry is, rounding up by 512 bytes (the size of
         // a header);
         let size = size
-            .checked_add(511)
+            .checked_add(BLOCK_SIZE - 1)
             .ok_or_else(|| other("size overflow"))?;
         self.next = self
             .next
-            .checked_add(size & !(512 - 1))
+            .checked_add(size & !(BLOCK_SIZE - 1))
             .ok_or_else(|| other("size overflow"))?;
 
         Ok(Some(ret.into_entry()))
@@ -483,7 +484,7 @@ impl<'a> EntriesFields<'a> {
                 }
                 let off = block.offset()?;
                 let len = block.length()?;
-                if len != 0 && (size - remaining) % 512 != 0 {
+                if len != 0 && (size - remaining) % BLOCK_SIZE != 0 {
                     return Err(other(
                         "previous block in sparse file was not \
                          aligned to 512-byte boundary",
@@ -520,7 +521,7 @@ impl<'a> EntriesFields<'a> {
                         return Err(other("failed to read extension"));
                     }
 
-                    self.next += 512;
+                    self.next += BLOCK_SIZE;
                     for block in ext.sparse.iter() {
                         add_block(block)?;
                     }

src/builder.rs

@@ -4,6 +4,7 @@ use std::io::prelude::*;
 use std::path::Path;
 use std::str;
 
+use crate::header::BLOCK_SIZE;
 use crate::header::GNU_SPARSE_HEADERS_COUNT;
 use crate::header::{path2bytes, HeaderMode};
 use crate::GnuExtSparseHeader;
@@ -518,7 +519,7 @@ impl EntryWriter<'_> {
         prepare_header_path(obj.as_write(), header, path)?;
 
         // Reserve space for header, will be overwritten once data is written.
-        obj.write_all([0u8; 512].as_ref())?;
+        obj.write_all([0u8; BLOCK_SIZE as usize].as_ref())?;
 
         Ok(EntryWriter {
             obj,
@@ -544,13 +545,14 @@ impl EntryWriter<'_> {
 
     fn do_finish(&mut self) -> io::Result<()> {
         // Pad with zeros if necessary.
-        let buf = [0u8; 512];
-        let remaining = u64::wrapping_sub(512, self.written) % 512;
+        let buf = [0u8; BLOCK_SIZE as usize];
+        let remaining = BLOCK_SIZE.wrapping_sub(self.written) % BLOCK_SIZE;
         self.obj.write_all(&buf[..remaining as usize])?;
         let written = (self.written + remaining) as i64;
 
         // Seek back to the header position.
-        self.obj.seek(io::SeekFrom::Current(-written - 512))?;
+        self.obj
+            .seek(io::SeekFrom::Current(-written - BLOCK_SIZE as i64))?;
 
         self.header.set_size(self.written);
         self.header.set_cksum();
@@ -589,9 +591,9 @@ fn append(mut dst: &mut dyn Write, header: &Header, mut data: &mut dyn Read) ->
 }
 
 fn pad_zeroes(dst: &mut dyn Write, len: u64) -> io::Result<()> {
-    let buf = [0; 512];
-    let remaining = 512 - (len % 512);
-    if remaining < 512 {
+    let buf = [0; BLOCK_SIZE as usize];
+    let remaining = BLOCK_SIZE - (len % BLOCK_SIZE);
+    if remaining < BLOCK_SIZE {
         dst.write_all(&buf[..remaining as usize])?;
     }
     Ok(())

src/header.rs

@@ -24,6 +24,8 @@ use crate::EntryType;
 #[cfg(any(unix, windows))]
 const DETERMINISTIC_TIMESTAMP: u64 = 1153704088;
 
+pub(crate) const BLOCK_SIZE: u64 = 512;
+
 pub(crate) const GNU_SPARSE_HEADERS_COUNT: usize = 4;
 
 pub(crate) const GNU_EXT_SPARSE_HEADERS_COUNT: usize = 21;
@@ -32,7 +34,7 @@ pub(crate) const GNU_EXT_SPARSE_HEADERS_COUNT: usize = 21;
 #[repr(C)]
 #[allow(missing_docs)]
 pub struct Header {
-    bytes: [u8; 512],
+    bytes: [u8; BLOCK_SIZE as usize],
 }
 
 /// Declares the information that should be included when filling a Header
@@ -151,7 +153,9 @@ impl Header {
     /// extensions such as long path names, long link names, and setting the
     /// atime/ctime metadata attributes of files.
     pub fn new_gnu() -> Header {
-        let mut header = Header { bytes: [0; 512] };
+        let mut header = Header {
+            bytes: [0; BLOCK_SIZE as usize],
+        };
         unsafe {
             let gnu = cast_mut::<_, GnuHeader>(&mut header);
             gnu.magic = *b"ustar ";
@@ -169,7 +173,9 @@ impl Header {
     ///
     /// UStar is also the basis used for pax archives.
     pub fn new_ustar() -> Header {
-        let mut header = Header { bytes: [0; 512] };
+        let mut header = Header {
+            bytes: [0; BLOCK_SIZE as usize],
+        };
         unsafe {
             let gnu = cast_mut::<_, UstarHeader>(&mut header);
             gnu.magic = *b"ustar\0";
@@ -186,7 +192,9 @@ impl Header {
     /// format limits the path name limit and isn't able to contain extra
     /// metadata like atime/ctime.
     pub fn new_old() -> Header {
-        let mut header = Header { bytes: [0; 512] };
+        let mut header = Header {
+            bytes: [0; BLOCK_SIZE as usize],
+        };
         header.set_mtime(0);
         header
     }
@@ -276,12 +284,12 @@ impl Header {
     }
 
     /// Returns a view into this header as a byte array.
-    pub fn as_bytes(&self) -> &[u8; 512] {
+    pub fn as_bytes(&self) -> &[u8; BLOCK_SIZE as usize] {
         &self.bytes
     }
 
     /// Returns a view into this header as a byte array.
-    pub fn as_mut_bytes(&mut self) -> &mut [u8; 512] {
+    pub fn as_mut_bytes(&mut self) -> &mut [u8; BLOCK_SIZE as usize] {
         &mut self.bytes
     }
 
@@ -1406,14 +1414,14 @@ impl GnuExtSparseHeader {
     }
 
     /// Returns a view into this header as a byte array.
-    pub fn as_bytes(&self) -> &[u8; 512] {
-        debug_assert_eq!(mem::size_of_val(self), 512);
+    pub fn as_bytes(&self) -> &[u8; BLOCK_SIZE as usize] {
+        debug_assert_eq!(mem::size_of_val(self), BLOCK_SIZE as usize);
         unsafe { mem::transmute(self) }
     }
 
     /// Returns a view into this header as a byte array.
-    pub fn as_mut_bytes(&mut self) -> &mut [u8; 512] {
-        debug_assert_eq!(mem::size_of_val(self), 512);
+    pub fn as_mut_bytes(&mut self) -> &mut [u8; BLOCK_SIZE as usize] {
+        debug_assert_eq!(mem::size_of_val(self), BLOCK_SIZE as usize);
         unsafe { mem::transmute(self) }
     }