eval: Make writefile() able to disable fsync()

3 files changed, 18 insertions, 10 deletions

diff --git a/src/nvim/eval.c b/src/nvim/eval.c
index f0d78a2508..8a3e3f3e22 100644
--- a/src/nvim/eval.c
+++ b/src/nvim/eval.c
@@ -17421,6 +17421,7 @@ static void f_writefile(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 
   bool binary = false;
   bool append = false;
+  bool do_fsync = true;
   if (argvars[2].v_type != VAR_UNKNOWN) {
     const char *const flags = tv_get_string_chk(&argvars[2]);
     if (flags == NULL) {
@@ -17432,6 +17433,9 @@ static void f_writefile(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     if (strchr(flags, 'a')) {
       append = true;
     }
+    if (strchr(flags, 'S')) {
+      do_fsync = false;
+    }
   }
 
   char buf[NUMBUFLEN];
@@ -17453,7 +17457,7 @@ static void f_writefile(typval_T *argvars, typval_T *rettv, FunPtr fptr)
     if (write_list(&fp, argvars[0].vval.v_list, binary)) {
       rettv->vval.v_number = 0;
     }
-    if ((error = file_close(&fp)) != 0) {
+    if ((error = file_close(&fp, do_fsync)) != 0) {
       emsgf(_("E80: Error when closing file %s: %s"),
             fname, os_strerror(error));
     }
diff --git a/src/nvim/os/fileio.c b/src/nvim/os/fileio.c
index 3c928363cc..4b7b53fc7f 100644
--- a/src/nvim/os/fileio.c
+++ b/src/nvim/os/fileio.c
@@ -113,27 +113,31 @@ FileDescriptor *file_open_new(int *const error, const char *const fname,
 /// Close file and free its buffer
 ///
 /// @param[in,out]  fp  File to close.
+/// @param[in]  do_fsync  If true, use fsync() to write changes to disk.
 ///
 /// @return 0 or error code.
-int file_close(FileDescriptor *const fp) FUNC_ATTR_NONNULL_ALL
+int file_close(FileDescriptor *const fp, const bool do_fsync)
+  FUNC_ATTR_NONNULL_ALL
 {
-  const int error = file_fsync(fp);
-  const int error2 = os_close(fp->fd);
+  const int flush_error = (do_fsync ? file_fsync(fp) : file_flush(fp));
+  const int close_error = os_close(fp->fd);
   rbuffer_free(fp->rv);
-  if (error2 != 0) {
-    return error2;
+  if (close_error != 0) {
+    return close_error;
   }
-  return error;
+  return flush_error;
 }
 
 /// Close and free file obtained using file_open_new()
 ///
 /// @param[in,out]  fp  File to close.
+/// @param[in]  do_fsync  If true, use fsync() to write changes to disk.
 ///
 /// @return 0 or error code.
-int file_free(FileDescriptor *const fp) FUNC_ATTR_NONNULL_ALL
+int file_free(FileDescriptor *const fp, const bool do_fsync)
+  FUNC_ATTR_NONNULL_ALL
 {
-  const int ret = file_close(fp);
+  const int ret = file_close(fp, do_fsync);
   xfree(fp);
   return ret;
 }
diff --git a/src/nvim/shada.c b/src/nvim/shada.c
index f65fdaf1c0..c7b95958e0 100644
--- a/src/nvim/shada.c
+++ b/src/nvim/shada.c
@@ -811,7 +811,7 @@ static int open_shada_file_for_reading(const char *const fname,
 /// Wrapper for closing file descriptors
 static void close_file(void *cookie)
 {
-  const int error = file_free(cookie);
+  const int error = file_free(cookie, true);
   if (error != 0) {
     emsgf(_(SERR "System error while closing ShaDa file: %s"),
           os_strerror(error));