From 51f2737ca7af016e3dd3ad03673f48a754a1642e Mon Sep 17 00:00:00 2001
From: igorechek06 <me@igorek.dev>
Date: Sat, 10 Aug 2024 15:11:42 +0900
Subject: Replace Vec with Iterator

---
 src/zip/driver.rs  | 41 ++++++++++++++++++++++++-----------------
 src/zip/structs.rs |  2 +-
 tests/zip.rs       | 14 +++++++-------
 3 files changed, 32 insertions(+), 25 deletions(-)

diff --git a/src/zip/driver.rs b/src/zip/driver.rs
index 8dc902f..b4217c8 100644
--- a/src/zip/driver.rs
+++ b/src/zip/driver.rs
@@ -15,21 +15,30 @@ use std::collections::HashMap as Map;
 use std::fs::File;
 use std::io::{BufReader, Read, Seek, SeekFrom, Write};
 
-#[inline]
-fn split_fields(bytes: &[u8]) -> Option<Vec<(u16, &[u8])>> {
-    let mut fields = Vec::new();
-
-    let mut p = 0;
-    while p < bytes.len() {
-        let header: ExtraHeader = deserialize(bytes.get(p..p + 4)?).unwrap();
-        p += 4;
-        let data = bytes.get(p..p + header.size as usize)?;
-        p += header.size as usize;
+struct Fields<'b> {
+    pointer: usize,
+    bytes: &'b [u8],
+}
 
-        fields.push((header.id, data));
+impl<'b> Fields<'b> {
+    pub fn new(bytes: &'b [u8]) -> Self {
+        Self { pointer: 0, bytes }
     }
+}
 
-    Some(fields)
+impl<'b> Iterator for Fields<'b> {
+    type Item = (u16, &'b [u8]);
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let header: ExtraHeader =
+            deserialize(self.bytes.get(self.pointer..self.pointer + 4)?).unwrap();
+        self.pointer += 4;
+        let data = self
+            .bytes
+            .get(self.pointer..self.pointer + header.size as usize)?;
+        self.pointer += header.size as usize;
+        Some((header.id, data))
+    }
 }
 
 #[inline]
@@ -159,7 +168,7 @@ impl<Io: Read + Seek> ArchiveRead for Zip<Io> {
             let mut ctime = None;
 
             // Parse extensible data fields
-            for (id, mut data) in split_fields(&extra_fields).ok_or(ZipError::InvalidExtraFields)? {
+            for (id, mut data) in Fields::new(&extra_fields) {
                 match id {
                     // Zip64
                     0x0001 => {
@@ -175,9 +184,7 @@ impl<Io: Read + Seek> ArchiveRead for Zip<Io> {
                     }
                     // NTFS
                     0x000a => {
-                        for (id, mut data) in
-                            split_fields(&data).ok_or(ZipError::InvalidExtraFields)?
-                        {
+                        for (id, mut data) in Fields::new(&data[4..]) {
                             match id {
                                 0x0001 => {
                                     mtime = ntfs_to_local(u64::from_le_bytes(data.read_arr()?))
@@ -198,7 +205,7 @@ impl<Io: Read + Seek> ArchiveRead for Zip<Io> {
                     // AES
                     0x9901 => {
                         let aes: AesField = deserialize(&data.read_arr::<7>()?).unwrap();
-                        if aes.id != 0x4541 {
+                        if aes.id != [0x41, 0x45] {
                             return Err(ZipError::InvalidExtraFields);
                         }
                         encryption_method = match aes.strength {
diff --git a/src/zip/structs.rs b/src/zip/structs.rs
index 8b25400..4b4524f 100644
--- a/src/zip/structs.rs
+++ b/src/zip/structs.rs
@@ -67,7 +67,7 @@ pub struct ExtraHeader {
 #[derive(Serialize, Deserialize)]
 pub struct AesField {
     pub version: u16,
-    pub id: u16,
+    pub id: [u8; 2],
     pub strength: u8,
     pub compression_method: u16,
 }
diff --git a/tests/zip.rs b/tests/zip.rs
index 9283df3..e44098c 100644
--- a/tests/zip.rs
+++ b/tests/zip.rs
@@ -92,6 +92,13 @@ fn test_zip_weak() {
 
 #[test]
 fn test_zip() {
+    assert_eq!(
+        Archive::<Zip>::read_from_file("tests/files/empty.zip")
+            .unwrap()
+            .len(),
+        0
+    );
+
     let mut archive = Archive::<Zip>::read_from_file("tests/files/archive.zip").unwrap();
 
     assert_eq!(archive.comment(), "archive comment");
@@ -158,11 +165,4 @@ fn test_zip() {
 fn test_bad_zip() {
     assert!(Archive::<Zip>::read_from_file("tests/files/blank")
         .is_err_and(|e| e == ZipError::EocdrNotFound));
-
-    assert_eq!(
-        Archive::<Zip>::read_from_file("tests/files/empty.zip")
-            .unwrap()
-            .len(),
-        0
-    );
 }
-- 
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