From 29e1107d3ebe24dea1a244607480c708e012a6d5 Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sun, 17 Sep 2017 15:43:57 +0200
Subject: [PATCH 1/2] Add file abstraction function to check whether path
 exists

---
 lib/core/libimagstore/src/file_abstraction/fs.rs        | 4 ++++
 lib/core/libimagstore/src/file_abstraction/inmemory.rs  | 7 +++++++
 lib/core/libimagstore/src/file_abstraction/mod.rs       | 2 ++
 lib/core/libimagstore/src/file_abstraction/stdio/mod.rs | 4 ++++
 lib/core/libimagstore/src/file_abstraction/stdio/out.rs | 4 ++++
 5 files changed, 21 insertions(+)

diff --git a/lib/core/libimagstore/src/file_abstraction/fs.rs b/lib/core/libimagstore/src/file_abstraction/fs.rs
index 51206314..2c649c22 100644
--- a/lib/core/libimagstore/src/file_abstraction/fs.rs
+++ b/lib/core/libimagstore/src/file_abstraction/fs.rs
@@ -133,6 +133,10 @@ impl FileAbstraction for FSFileAbstraction {
         create_dir_all(path).chain_err(|| SEK::DirNotCreated)
     }
 
+    fn exists(&self, path: &PathBuf) -> Result<bool, SE> {
+        Ok(path.exists())
+    }
+
     fn new_instance(&self, p: PathBuf) -> Box<FileAbstractionInstance> {
         Box::new(FSFileAbstractionInstance::Absent(p))
     }
diff --git a/lib/core/libimagstore/src/file_abstraction/inmemory.rs b/lib/core/libimagstore/src/file_abstraction/inmemory.rs
index 5134281b..909aad9d 100644
--- a/lib/core/libimagstore/src/file_abstraction/inmemory.rs
+++ b/lib/core/libimagstore/src/file_abstraction/inmemory.rs
@@ -152,6 +152,13 @@ impl FileAbstraction for InMemoryFileAbstraction {
         Ok(())
     }
 
+    fn exists(&self, pb: &PathBuf) -> Result<bool, SE> {
+        let mut mtx = self.backend().lock().expect("Locking Mutex failed");
+        let backend = mtx.get_mut();
+
+        Ok(backend.contains_key(pb))
+    }
+
     fn new_instance(&self, p: PathBuf) -> Box<FileAbstractionInstance> {
         Box::new(InMemoryFileAbstractionInstance::new(self.backend().clone(), p))
     }
diff --git a/lib/core/libimagstore/src/file_abstraction/mod.rs b/lib/core/libimagstore/src/file_abstraction/mod.rs
index f34a6f1e..47b24da4 100644
--- a/lib/core/libimagstore/src/file_abstraction/mod.rs
+++ b/lib/core/libimagstore/src/file_abstraction/mod.rs
@@ -43,6 +43,8 @@ pub trait FileAbstraction : Debug {
     fn rename(&self, from: &PathBuf, to: &PathBuf) -> Result<(), SE>;
     fn create_dir_all(&self, _: &PathBuf) -> Result<(), SE>;
 
+    fn exists(&self, &PathBuf) -> Result<bool, SE>;
+
     fn new_instance(&self, p: PathBuf) -> Box<FileAbstractionInstance>;
 
     fn drain(&self) -> Result<Drain, SE>;
diff --git a/lib/core/libimagstore/src/file_abstraction/stdio/mod.rs b/lib/core/libimagstore/src/file_abstraction/stdio/mod.rs
index 725ecf5a..a9606c91 100644
--- a/lib/core/libimagstore/src/file_abstraction/stdio/mod.rs
+++ b/lib/core/libimagstore/src/file_abstraction/stdio/mod.rs
@@ -115,6 +115,10 @@ impl<W: Write, M: Mapper> FileAbstraction for StdIoFileAbstraction<W, M> {
         self.0.new_instance(p)
     }
 
+    fn exists(&self, p: &PathBuf) -> Result<bool, SE> {
+        self.0.exists(p)
+    }
+
     fn drain(&self) -> Result<Drain, SE> {
         self.0.drain()
     }
diff --git a/lib/core/libimagstore/src/file_abstraction/stdio/out.rs b/lib/core/libimagstore/src/file_abstraction/stdio/out.rs
index 23f961f2..456fe9d4 100644
--- a/lib/core/libimagstore/src/file_abstraction/stdio/out.rs
+++ b/lib/core/libimagstore/src/file_abstraction/stdio/out.rs
@@ -136,6 +136,10 @@ impl<W: Write, M: Mapper> FileAbstraction for StdoutFileAbstraction<W, M> {
         self.mem.new_instance(p)
     }
 
+    fn exists(&self, p: &PathBuf) -> Result<bool, SE> {
+        self.mem.exists(p)
+    }
+
     fn drain(&self) -> Result<Drain, SE> {
         self.backend_cloned().map(Drain::new)
     }

From a01a2c18f879bf9b5426279a0aa3abcc7e2b7746 Mon Sep 17 00:00:00 2001
From: Matthias Beyer <mail@beyermatthias.de>
Date: Sun, 17 Sep 2017 15:44:19 +0200
Subject: [PATCH 2/2] Check in Store::move_by_id() whether target exists, not
 only in cache but also on FS

---
 lib/core/libimagstore/src/store.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/core/libimagstore/src/store.rs b/lib/core/libimagstore/src/store.rs
index 7b48e500..5ba3754f 100644
--- a/lib/core/libimagstore/src/store.rs
+++ b/lib/core/libimagstore/src/store.rs
@@ -755,6 +755,10 @@ impl Store {
             let old_id_pb = try!(old_id.clone().with_base(self.path().clone()).into_pathbuf());
             let new_id_pb = try!(new_id.clone().with_base(self.path().clone()).into_pathbuf());
 
+            if try!(self.backend.exists(&new_id_pb)) {
+                return Err(SE::from_kind(SEK::EntryAlreadyExists(new_id.clone())));
+            }
+
             match self.backend.rename(&old_id_pb, &new_id_pb) {
                 Err(e) => return Err(e).chain_err(|| SEK::EntryRenameError(old_id_pb, new_id_pb)),
                 Ok(_) => {