From 6444bee8f3e188be014841ea8cd7cfb53eb03ed9 Mon Sep 17 00:00:00 2001
From: Igor Tolmachev <me@igorek.dev>
Date: Sat, 15 Jun 2024 13:09:12 +0900
Subject: Optimize file reading

---
 src/zip/driver.rs | 38 +++++++++++++-------------------------
 1 file changed, 13 insertions(+), 25 deletions(-)

(limited to 'src')

diff --git a/src/zip/driver.rs b/src/zip/driver.rs
index 733d44b..313bf8d 100644
--- a/src/zip/driver.rs
+++ b/src/zip/driver.rs
@@ -4,7 +4,7 @@ use crate::zip::structs::{EOCDR64Locator, CDR, EOCDR, EOCDR64};
 use crate::zip::ZipFile;
 use std::collections::HashMap as Map;
 use std::fs::File;
-use std::io::{Read, Seek, SeekFrom, Write};
+use std::io::{Cursor, Read, Seek, SeekFrom, Write};
 
 pub struct Zip<IO = File> {
     io: IO,
@@ -89,34 +89,22 @@ impl<IO: Read + Seek> ArchiveRead for Zip<IO> {
             io.read(&mut buf)?;
             buf
         };
-        let mut records = buf.as_slice();
 
+        let mut p: usize = 0;
         for _ in 0..cd_records {
-            let buf = {
-                let mut buf = [0; 46];
-                records.read(&mut buf)?;
-                buf
-            };
-
-            if u32::from_le_bytes(buf[0..4].try_into().unwrap()) != 0x02014b50 {
+            if u32::from_le_bytes(buf[p..p + 4].try_into().unwrap()) != 0x02014b50 {
                 return Err(ZipError::InvalidCDRSignature.into());
             }
-            let cdr: CDR = bincode::deserialize(&buf[4..]).map_err(|_| ZipError::InvalidCDR)?;
-            let name = {
-                let mut buf = vec![0; cdr.name_len as usize];
-                records.read(&mut buf)?;
-                String::from_utf8(buf).map_err(|_| ZipError::InvalidFileName)?
-            };
-            let extra_fields = {
-                let mut buf = vec![0; cdr.extra_field_len as usize];
-                records.read(&mut buf)?;
-                buf
-            };
-            let comment = {
-                let mut buf = vec![0; cdr.comment_len as usize];
-                records.read(&mut buf)?;
-                String::from_utf8(buf).map_err(|_| ZipError::InvalidFileComment)?
-            };
+            p += 4;
+            let cdr: CDR =
+                bincode::deserialize(&buf[p..p + 42]).map_err(|_| ZipError::InvalidCDR)?;
+            p += 42;
+            let name = String::from_utf8(buf[p..p + cdr.name_len as usize].into()).unwrap();
+            p += cdr.name_len as usize;
+            let extra_fields: Vec<u8> = buf[p..p + cdr.extra_field_len as usize].into();
+            p += cdr.extra_field_len as usize;
+            let comment = String::from_utf8(buf[p..p + cdr.comment_len as usize].into()).unwrap();
+            p += cdr.comment_len as usize;
 
             files.insert(
                 name.clone(),
-- 
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