From d0ba754dc2c9b4346be78f1f261d8b09d5012bb3 Mon Sep 17 00:00:00 2001
From: 5ec1cff <56485584+5ec1cff@users.noreply.github.com>
Date: Sat, 22 Mar 2025 20:54:26 +0800
Subject: [PATCH] patterns/zip: Handling padded extra fields (#369)

* Handling unresolved extra fields

* Update zip.hexpat

* Update zip.hexpat

* Update zip.hexpat
---
 patterns/zip.hexpat | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/patterns/zip.hexpat b/patterns/zip.hexpat
index 492e7ad..1d69a7b 100644
--- a/patterns/zip.hexpat
+++ b/patterns/zip.hexpat
@@ -75,19 +75,26 @@ namespace extra {
     struct ExtraField {
         u16 tag;
         u16 TSize;
-        if (tag == 0x5455){
+        if (tag == 0x5455) {
             extra::X5455_ExtendedTimestamp x5455_ExtendedTimestamp;
-        }else if (tag == 0x000a){
+        } else if (tag == 0x000a) {
             extra::X000A_NTFS x000A_NTFS;
-        }else if (tag == 0x7875){
+        } else if (tag == 0x7875) {
             extra::X7875_NewUnix x7875_NewUnix;
-        }else if (tag == 0x5855){
+        } else if (tag == 0x5855) {
             extra::X5855_InfoZipUnix x5855_InfoZipUnix;
-        }else{
+        } else {
             std::print("Unsupported tag 0x{:02X}", tag);
             padding[TSize];
         }
     };
+    
+    fn has_extra_field(u32 extraEnd) {
+        if ($ + 4 > extraEnd) return false;
+        u16 tag = std::mem::read_unsigned($, 2, std::mem::Endian::Little);
+        u16 len = std::mem::read_unsigned($ + 2, 2, std::mem::Endian::Little);
+        return !(tag == 0 || len == 0) && $ + 4 + len <= extraEnd;
+    };
 }
 
 fn find_eocd() {
@@ -184,7 +191,8 @@ struct LocalFileHeader {
     u16 extraFieldLength [[ comment("Extra field length (m)") ]];
     char fileName[fileNameLength] [[ comment("File Name") ]];
     u64 extraEnd = $ + extraFieldLength;
-    extra::ExtraField extraFields[while ($ < extraEnd)] [[comment("Extra Fields")]];
+    extra::ExtraField extraFields[while (extra::has_extra_field(extraEnd))] [[comment("Extra Fields")]];
+    padding[extraEnd - $];
     u8 data[compressedSize] [[name("File Data")]];
 };
 
@@ -213,8 +221,9 @@ struct CentralDirectoryFileHeader {
     File file;
     char fileName[fileNameLength];
     u64 extraEnd = $ + extraFieldLength;
-    extra::ExtraField extraFields[while ($ < extraEnd)] [[comment("Extra Fields")]];
-    char comment[fileCommentLength];
+    extra::ExtraField extraFields[while (extra::has_extra_field(extraEnd))] [[comment("Extra Fields")]];
+    padding[extraEnd - $];
+    char comment[fileCommentLength] @ extraEnd;
 };
 
-CentralDirectoryFileHeader centralDirHeaders[fileInfo.CDRCount] @ (fileInfo.CDOffset) [[name("Files")]];
\ No newline at end of file
+CentralDirectoryFileHeader centralDirHeaders[fileInfo.CDRCount] @ (fileInfo.CDOffset) [[name("Files")]];