From f9715392af00bc1419dc54b203810d41cc430305 Mon Sep 17 00:00:00 2001
From: Dominik Maier <domenukk@gmail.com>
Date: Fri, 14 Feb 2025 02:07:14 +0100
Subject: [PATCH] Try to solve corpus issue related to #2981 (#2982)

* Try to solve corpus issue related to #2981

* clippy
---
 libafl/src/corpus/inmemory_ondisk.rs | 30 +++++++++++++++++-----------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/libafl/src/corpus/inmemory_ondisk.rs b/libafl/src/corpus/inmemory_ondisk.rs
index 1e8d469bba..690bd82a58 100644
--- a/libafl/src/corpus/inmemory_ondisk.rs
+++ b/libafl/src/corpus/inmemory_ondisk.rs
@@ -362,7 +362,7 @@ impl<I> InMemoryOnDiskCorpus<I> {
             testcase.input().as_ref().unwrap().generate_name(id)
         });
 
-        let mut ctr = String::new();
+        let mut ctr = 1;
         if self.locking {
             let lockfile_name = format!(".{file_name}");
             let lockfile_path = self.dir_path.join(lockfile_name);
@@ -375,15 +375,14 @@ impl<I> InMemoryOnDiskCorpus<I> {
             );
             lockfile.lock_exclusive()?;
 
-            lockfile.read_to_string(&mut ctr)?;
-            ctr = if ctr.is_empty() {
-                String::from("1")
-            } else {
-                (ctr.trim().parse::<u32>()? + 1).to_string()
-            };
+            let mut old_ctr = String::new();
+            lockfile.read_to_string(&mut old_ctr)?;
+            if !old_ctr.is_empty() {
+                ctr = old_ctr.trim().parse::<u32>()? + 1;
+            }
 
             lockfile.seek(SeekFrom::Start(0))?;
-            lockfile.write_all(ctr.as_bytes())?;
+            lockfile.write_all(ctr.to_string().as_bytes())?;
         }
 
         if testcase.file_path().is_none() {
@@ -432,11 +431,18 @@ impl<I> InMemoryOnDiskCorpus<I> {
             *testcase.metadata_path_mut() = Some(metafile_path);
         }
 
-        if let Err(err) = self.store_input_from(testcase) {
-            if self.locking {
-                return Err(err);
+        // Only try to write the data if the counter is 1.
+        // Otherwise we already have a file with this name, and
+        // we can assume the data has already been written.
+        if ctr == 1 {
+            if let Err(err) = self.store_input_from(testcase) {
+                if self.locking {
+                    return Err(err);
+                }
+                log::error!(
+                    "An error occurred when trying to write a testcase without locking: {err}"
+                );
             }
-            log::error!("An error occurred when trying to write a testcase without locking: {err}");
         }
         Ok(())
     }