From a3ef5c820dde927dc416c69509e54f71e0643f6c Mon Sep 17 00:00:00 2001
From: Robb Kistler <code@robbkistler.com>
Date: Tue, 3 Nov 2015 21:47:15 -0800
Subject: [PATCH 1/2] Add file truncate test

This test creates a file with contents, truncates it to
zero and verifies that it is zero length.
---
 test/integration-test-main.sh | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/test/integration-test-main.sh b/test/integration-test-main.sh
index f920bc9..f03e22c 100755
--- a/test/integration-test-main.sh
+++ b/test/integration-test-main.sh
@@ -81,6 +81,24 @@ function test_append_file {
     rm_test_file
 }
 
+function test_truncate_file {
+    echo "Testing truncate file ..."
+    # Write a small test file
+    echo "${TEST_TEXT}" > ${TEST_TEXT_FILE}
+ 
+    # Truncate file to 0 length.  This should trigger open(path, O_RDWR | O_TRUNC...)
+    : > ${TEST_TEXT_FILE}
+  
+    # Verify file is zero length
+    if [ -s ${TEST_TEXT_FILE} ]
+    then
+        echo "error: expected ${TEST_TEXT_FILE} to be zero length"
+        exit 1
+    fi
+    rm_test_file
+}
+
+
 function test_mv_file {
     echo "Testing mv file function ..."
 
@@ -362,6 +380,7 @@ function test_extended_attributes {
 
 function run_all_tests {
     test_append_file
+    test_truncate_file
     test_mv_file
     test_mv_directory
     test_redirects

From dd7d9268f20c0dd915e87b94f71836a9f286d288 Mon Sep 17 00:00:00 2001
From: Robb Kistler <code@robbkistler.com>
Date: Tue, 3 Nov 2015 22:04:16 -0800
Subject: [PATCH 2/2] Force flush in s3fs_open() if file is truncated.

---
 src/s3fs.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/s3fs.cpp b/src/s3fs.cpp
index 7ef5244..16c9025 100644
--- a/src/s3fs.cpp
+++ b/src/s3fs.cpp
@@ -2002,6 +2002,7 @@ static int s3fs_open(const char* path, struct fuse_file_info* fi)
 {
   int result;
   struct stat st;
+  bool needs_flush = false;
 
   S3FS_PRN_INFO("[path=%s][flags=%d]", path, fi->flags);
 
@@ -2026,6 +2027,7 @@ static int s3fs_open(const char* path, struct fuse_file_info* fi)
 
   if((unsigned int)fi->flags & O_TRUNC){
     st.st_size = 0;
+    needs_flush = true;
   }
   if(!S_ISREG(st.st_mode) || S_ISLNK(st.st_mode)){
     st.st_mtime = -1;
@@ -2037,6 +2039,15 @@ static int s3fs_open(const char* path, struct fuse_file_info* fi)
   if(NULL == (ent = FdManager::get()->Open(path, &meta, static_cast<ssize_t>(st.st_size), st.st_mtime, false, true))){
     return -EIO;
   }
+  
+  if (needs_flush){
+    if(0 != (result = ent->RowFlush(path, true))){
+      S3FS_PRN_ERR("could not upload file(%s): result=%d", path, result);
+      FdManager::get()->Close(ent);
+      return result;
+    }
+  }
+
   fi->fh = ent->GetFd();
   S3FS_MALLOCTRIM(0);