fix: object_store: stop throwing errors when checking generation file

src/lib/object_store/File.cpp

@@ -143,6 +143,20 @@ File::~File()
 	}
 }
 
+// Check if a file exists without trying to open it
+// May be used when a routine just wants to check file existence,
+// and does not want to throw an error by trying to open it.
+bool File::exists(const std::string& path)
+{
+#ifndef _WIN32
+	struct stat buf;
+	return stat(path.c_str(), &buf) == 0;
+#else
+	return _access(path.c_str(), 0) == 0;
+#endif
+}
+
+
 // Check if the file is valid
 bool File::isValid()
 {

src/lib/object_store/File.h

@@ -47,6 +47,11 @@ class File
 	// Destructor
 	virtual ~File();
 
+	// Check if a file exists without trying to open it
+	// May be used when a routine just wants to check file existence,
+	// and does not want to throw an error by trying to open it.
+	static bool exists(const std::string& path);
+
 	// Check if the file is valid
 	bool isValid();
 

src/lib/object_store/Generation.cpp

@@ -88,6 +88,13 @@ bool Generation::sync(File &objectFile)
 // Check if the target was updated
 bool Generation::wasUpdated()
 {
+
+	// Check if path file exists before anything
+	if (!File::exists(path))
+	{
+		return true;
+	}
+
 	if (isToken)
 	{
 		MutexLocker lock(genMutex);

src/lib/object_store/test/FileTests.cpp

@@ -74,16 +74,18 @@ void FileTests::testExistNotExist()
 	// Test pre-condition
 	CPPUNIT_ASSERT(!exists("nonExistentFile"));
 
-	// Attempt to open a file known not to exist
+	// Check the 'exists' static routine, then attempt to open a file known not to exist
 #ifndef _WIN32
+	CPPUNIT_ASSERT(!File::exists("testdir/nonExistentFile"));
 	File doesntExist("testdir/nonExistentFile", DEFAULT_UMASK);
 #else
+	CPPUNIT_ASSERT(!File::exists("testdir\\nonExistentFile"));
 	File doesntExist("testdir\\nonExistentFile", DEFAULT_UMASK);
 #endif
 
 	CPPUNIT_ASSERT(!doesntExist.isValid());
 
-	// Attempt to open a file known to exist
+	// Check the 'exists' static routine, then attempt to open a file known to exist
 #ifndef _WIN32
 	CPPUNIT_ASSERT(!system("echo someStuff > testdir/existingFile"));
 #else
@@ -92,8 +94,10 @@ void FileTests::testExistNotExist()
 	CPPUNIT_ASSERT(exists("existingFile"));
 
 #ifndef _WIN32
+	CPPUNIT_ASSERT(File::exists("testdir/existingFile"));
 	File exists("testdir/existingFile", DEFAULT_UMASK);
 #else
+	CPPUNIT_ASSERT(File::exists("testdir\\existingFile"));
 	File exists("testdir\\existingFile", DEFAULT_UMASK);
 #endif