From 8a51a268190b39bce1e3b8a40f69b26111385894 Mon Sep 17 00:00:00 2001
From: Andrew Gaul <andrew@gaul.org>
Date: Sat, 24 Apr 2021 12:27:39 +0900
Subject: [PATCH] Allow truncation of open and modified files

Regression introduced in f5bf41cf117e6dfc0d510348cdc1cc11817662ed.
Fixes #1575.
---
 src/fdcache.cpp               |  7 +++++--
 test/integration-test-main.sh |  2 +-
 test/ut_test.py               | 12 ++++++++++++
 3 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/src/fdcache.cpp b/src/fdcache.cpp
index b218a4c..29ed467 100644
--- a/src/fdcache.cpp
+++ b/src/fdcache.cpp
@@ -474,8 +474,11 @@ FdEntity* FdManager::Open(const char* path, headers_t* pmeta, off_t size, time_t
         ent = (*iter).second;
         ent->Dup();
         if(ent->IsModified()){
-            // If the file is being modified, it will not be resized.
-            size = -1;
+            // If the file is being modified and it's size is larger than size parameter, it will not be resized.
+            off_t cur_size = 0;
+            if(ent->GetSize(cur_size) && size <= cur_size){
+                size = -1;
+            }
         }
         close = true;
 
diff --git a/test/integration-test-main.sh b/test/integration-test-main.sh
index b2b2c4b..277731e 100755
--- a/test/integration-test-main.sh
+++ b/test/integration-test-main.sh
@@ -1404,7 +1404,7 @@ function test_ensurespace_move_file() {
         return 1
     fi
     if [ ${MOVED_FILE_LENGTH} -ne ${BIG_FILE_LENGTH} ]; then
-        echo "Failed to move file with file length"
+        echo "Failed to move file with file length: ${MOVED_FILE_LENGTH} ${BIG_FILE_LENGTH}"
         return 1
     fi
 
diff --git a/test/ut_test.py b/test/ut_test.py
index a3abcd6..fa227b2 100755
--- a/test/ut_test.py
+++ b/test/ut_test.py
@@ -94,6 +94,18 @@ class OssfsUnitTest(unittest.TestCase):
         self.assertEqual(len(data1), len(data2))
         self.assertEqual(data1, data2)
 
+    def test_truncate_open_file(self):
+        filename = "%s" % (self.random_string(10))
+        fd = os.open(filename, os.O_CREAT|os.O_RDWR)
+        try:
+            os.write(fd, 'a' * 42)
+            self.assertEqual(os.fstat(fd).st_size, 42)
+            os.ftruncate(fd, 100)
+            self.assertEqual(os.fstat(fd).st_size, 100)
+        finally:
+            os.close(fd)
+        self.assertEqual(100, os.stat(filename).st_size)
+
 
 if __name__ == '__main__':
     unittest.main()