fileinfo: implement os_fileinfo_hardlinks

3 files changed, 26 insertions, 3 deletions

diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 245590e7ce..b2d27bd0d1 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -2712,7 +2712,7 @@ buf_write (
        * - it's a symbolic link
        * - we don't have write permission in the directory
        */
-      if (file_info_old.stat.st_nlink > 1
+      if (os_fileinfo_hardlinks(&file_info_old) > 1
           || !os_get_file_info_link((char *)fname, &file_info)
           || !os_file_info_id_equal(&file_info, &file_info_old)) {
         backup_copy = TRUE;
@@ -2770,7 +2770,7 @@ buf_write (
 
       /* Hardlinks. */
       if ((bkc_flags & BKC_BREAKHARDLINK)
-          && file_info_old.stat.st_nlink > 1
+          && os_fileinfo_hardlinks(&file_info_old) > 1
           && (!file_info_link_ok
               || os_file_info_id_equal(&file_info, &file_info_old))) {
         backup_copy = FALSE;
@@ -3201,7 +3201,7 @@ nobackup:
       FileInfo file_info;
 
       /* Don't delete the file when it's a hard or symbolic link. */
-      if ((!newfile && file_info_old.stat.st_nlink > 1)
+      if ((!newfile && os_fileinfo_hardlinks(&file_info) > 1)
           || (os_get_file_info_link((char *)fname, &file_info)
               && !os_file_info_id_equal(&file_info, &file_info_old))) {
         errmsg = (char_u *)_("E166: Can't open linked file for writing");
diff --git a/src/nvim/os/fs.c b/src/nvim/os/fs.c
index 9347afb9bc..70a53edb1c 100644
--- a/src/nvim/os/fs.c
+++ b/src/nvim/os/fs.c
@@ -403,6 +403,15 @@ off_t os_fileinfo_size(const FileInfo *file_info)
   return file_info->stat.st_size;
 }
 
+/// Get the number of hardlinks from a `FileInfo`.
+///
+/// @return number of hardlinks.
+uint64_t os_fileinfo_hardlinks(const FileInfo *file_info)
+  FUNC_ATTR_NONNULL_ALL
+{
+  return file_info->stat.st_nlink;
+}
+
 /// Get the `FileID` for a given path
 ///
 /// @param path Path to the file.
diff --git a/test/unit/os/fs_spec.lua b/test/unit/os/fs_spec.lua
index c92c1513b7..9f6d110e8f 100644
--- a/test/unit/os/fs_spec.lua
+++ b/test/unit/os/fs_spec.lua
@@ -47,6 +47,7 @@ describe('fs function', function()
     os.remove('unit-test-directory/test.file')
     os.remove('unit-test-directory/test_2.file')
     os.remove('unit-test-directory/test_link.file')
+    os.remove('unit-test-directory/test_hlink.file')
     lfs.rmdir('unit-test-directory')
   end)
 
@@ -611,6 +612,19 @@ describe('fs function', function()
       end)
     end)
 
+    describe('os_fileinfo_hardlinks', function()
+      it('returns the correct number of hardlinks', function()
+        local path = 'unit-test-directory/test.file'
+        local path_link = 'unit-test-directory/test_hlink.file'
+        local file_info = file_info_new()
+        assert.is_true(fs.os_get_file_info(path, file_info))
+        eq(1, fs.os_fileinfo_hardlinks(file_info))
+        lfs.link(path, path_link)
+        assert.is_true(fs.os_get_file_info(path, file_info))
+        eq(2, fs.os_fileinfo_hardlinks(file_info))
+      end)
+    end)
+
     describe('os_get_file_id', function()
       it('returns false if given an non-existing file', function()
         local file_id = file_id_new()