From e26a7027a2ae95fd9aad8f3f4399e8485a9c297f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Aur=C3=A9lien=20Jacobs?= <aurel@gnuage.org>
Date: Fri, 26 Jul 2024 17:34:55 +0200
Subject: [PATCH] Return an error when encountering corrupted lfn entry

---
 embedded-fatfs/src/dir.rs | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/embedded-fatfs/src/dir.rs b/embedded-fatfs/src/dir.rs
index 01a6ea5..9395a31 100644
--- a/embedded-fatfs/src/dir.rs
+++ b/embedded-fatfs/src/dir.rs
@@ -779,7 +779,7 @@ impl<'a, IO: ReadWriteSeek, TP: TimeProvider, OCC> DirIter<'a, IO, TP, OCC> {
                 DirEntryData::Lfn(data) => {
                     // Append to LFN buffer
                     trace!("lfn entry");
-                    lfn_builder.process(&data);
+                    lfn_builder.process::<IO>(&data)?;
                 }
             }
         }
@@ -1003,14 +1003,14 @@ impl LongNameBuilder {
         self.index == 0
     }
 
-    fn process(&mut self, data: &DirLfnEntryData) {
+    fn process<IO: ReadWriteSeek>(&mut self, data: &DirLfnEntryData) -> Result<(), Error<IO::Error>> {
         let is_last = (data.order() & LFN_ENTRY_LAST_FLAG) != 0;
         let index = data.order() & 0x1F;
         if index == 0 || usize::from(index) > MAX_LONG_DIR_ENTRIES {
             // Corrupted entry
             warn!("corrupted lfn entry! {:x}", data.order());
             self.clear();
-            return;
+            return Err(Error::CorruptedFileSystem);
         }
         if is_last {
             // last entry is actually first entry in stream
@@ -1027,7 +1027,7 @@ impl LongNameBuilder {
                 self.chksum
             );
             self.clear();
-            return;
+            return Err(Error::CorruptedFileSystem);
         } else {
             // Decrement LFN index only for non-last entries
             self.index -= 1;
@@ -1035,6 +1035,7 @@ impl LongNameBuilder {
         let pos = LFN_PART_LEN * usize::from(index - 1);
         // copy name parts into LFN buffer
         data.copy_name_to_slice(&mut self.buf.ucs2_units[pos..pos + 13]);
+        Ok(())
     }
 
     fn validate_chksum(&mut self, short_name: &[u8; SFN_SIZE]) {
@@ -1061,7 +1062,9 @@ impl LongNameBuilder {
     fn clear(&mut self) {}
     fn into_vec(self) {}
     fn truncate(&mut self) {}
-    fn process(&mut self, _data: &DirLfnEntryData) {}
+    fn process<IO: ReadWriteSeek>(&mut self, _data: &DirLfnEntryData) -> Result<(), Error<IO::Error>> {
+        Ok(())
+    }
     fn validate_chksum(&mut self, _short_name: &[u8; SFN_SIZE]) {}
 }