From 6b93d358d5c709639f39ef419cb68645bdabbe2c Mon Sep 17 00:00:00 2001
From: Chris Hennick <4961925+Pr0methean@users.noreply.github.com>
Date: Thu, 13 Jun 2024 23:11:32 -0700
Subject: [PATCH] chore: Fix more errors when parsing multiple extra fields

---
 src/read.rs  | 19 +++----------------
 src/write.rs | 14 ++++++++------
 2 files changed, 11 insertions(+), 22 deletions(-)

diff --git a/src/read.rs b/src/read.rs
index 1839d68e..1aa4a1cb 100644
--- a/src/read.rs
+++ b/src/read.rs
@@ -1216,12 +1216,7 @@ pub(crate) fn parse_extra_field(file: &mut ZipFileData) -> ZipResult<()> {
 
     /* TODO: codify this structure into Zip64ExtraFieldBlock fields! */
     while (reader.position() as usize) < len {
-        let len_left = parse_single_extra_field(file, &mut reader)?;
-
-        // We could also check for < 0 to check for errors
-        if len_left > 0 {
-            reader.seek(io::SeekFrom::Current(len_left))?;
-        }
+        parse_single_extra_field(file, &mut reader)?;
     }
     Ok(())
 }
@@ -1229,26 +1224,22 @@ pub(crate) fn parse_extra_field(file: &mut ZipFileData) -> ZipResult<()> {
 pub(crate) fn parse_single_extra_field<R: Read>(
     file: &mut ZipFileData,
     reader: &mut R,
-) -> ZipResult<i64> {
+) -> ZipResult<()> {
     let kind = reader.read_u16_le()?;
     let len = reader.read_u16_le()?;
-    let mut len_left = len as i64;
     match kind {
         // Zip64 extended information extra field
         0x0001 => {
             if file.uncompressed_size == spec::ZIP64_BYTES_THR {
                 file.large_file = true;
                 file.uncompressed_size = reader.read_u64_le()?;
-                len_left -= 8;
             }
             if file.compressed_size == spec::ZIP64_BYTES_THR {
                 file.large_file = true;
                 file.compressed_size = reader.read_u64_le()?;
-                len_left -= 8;
             }
             if file.header_start == spec::ZIP64_BYTES_THR {
                 file.header_start = reader.read_u64_le()?;
-                len_left -= 8;
             }
         }
         0x9901 => {
@@ -1280,7 +1271,6 @@ pub(crate) fn parse_single_extra_field<R: Read>(
                 _ => return Err(ZipError::InvalidArchive("Invalid AES encryption strength")),
             };
             file.compression_method = compression_method;
-            len_left -= 7;
         }
         0x5455 => {
             // extended timestamp
@@ -1289,9 +1279,6 @@ pub(crate) fn parse_single_extra_field<R: Read>(
             file.extra_fields.push(ExtraField::ExtendedTimestamp(
                 ExtendedTimestamp::try_from_reader(reader, len)?,
             ));
-
-            // the reader for ExtendedTimestamp consumes `len` bytes
-            len_left = 0;
         }
         0x6375 => {
             // Info-ZIP Unicode Comment Extra Field
@@ -1315,7 +1302,7 @@ pub(crate) fn parse_single_extra_field<R: Read>(
             // Other fields are ignored
         }
     }
-    Ok(len_left)
+    Ok(())
 }
 
 /// Methods for retrieving information on zip files
diff --git a/src/write.rs b/src/write.rs
index bc863b65..37999e7f 100644
--- a/src/write.rs
+++ b/src/write.rs
@@ -318,14 +318,16 @@ impl ExtendedFileOptions {
     fn validate_extra_data(&self) -> ZipResult<()> {
         let mut data = self.extra_data.to_vec();
         data.extend(self.central_extra_data.iter());
-        if data.len() > u16::MAX as usize {
+        let len = data.len() as u64;
+        if len > u16::MAX as u64 {
             return Err(ZipError::Io(io::Error::new(
                 io::ErrorKind::Other,
                 "Extra-data field can't exceed u16::MAX bytes",
             )));
         }
-        while !data.is_empty() {
-            if data.len() < 2 {
+        let mut data = Cursor::new(data);
+        while data.position() < len {
+            if len - data.position() < 2 {
                 return Err(ZipError::Io(io::Error::new(
                     io::ErrorKind::Other,
                     "Extra-data field needs 2 tag bytes",
@@ -333,7 +335,8 @@ impl ExtendedFileOptions {
             }
             #[cfg(not(feature = "unreserved"))]
             {
-                let header_id = u16::from_le_bytes([data[0], data[1]]);
+                use crate::unstable::LittleEndianReadExt;
+                let header_id = data.read_u16_le()?;
                 if header_id <= 31
                     || EXTRA_FIELD_MAPPING
                     .iter()
@@ -347,8 +350,7 @@ impl ExtendedFileOptions {
                     )));
                 }
             }
-            let len_left = parse_single_extra_field(&mut ZipFileData::default(), &mut Cursor::new(data.to_vec()))?;
-            data = data[(data.len() - len_left as usize)..].to_owned()
+            parse_single_extra_field(&mut ZipFileData::default(), &mut data)?;
         }
         Ok(())
     }