refactor: Remove strncpy/STRNCPY. (#6008)

Closes #731
References #851

Note: This does not remove some intentional legacy usages of strncpy.
      - memcpy isn't equivalent because it doesn't check the string
        length of `src`, and doesn't zero-out the remainder of `dst`.
      - xstrlcpy isn't equivalent because it doesn't zero-out the
        remainder of `dst`. Some Vim logic depends on that (e.g.
        ex_append which calls vim_strnsave).

Helped-by: Douglas Schneider <ds3@ualberta.ca>
Helped-by: oni-link <knil.ino@gmail.com>
Helped-by: James McCoy <jamessan@jamessan.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/src/nvim/path.c b/src/nvim/path.c
index 7e1183d5db..374d72ddd3 100644
--- a/src/nvim/path.c
+++ b/src/nvim/path.c
@@ -586,7 +586,7 @@ static size_t do_path_expand(garray_T *gap, const char_u *path,
     }
     if (has_mbyte) {
       len = (size_t)(*mb_ptr2len)(path_end);
-      STRNCPY(p, path_end, len);
+      memcpy(p, path_end, len);
       p += len;
       path_end += len;
     } else
@@ -2188,7 +2188,8 @@ static int path_get_absolute_path(const char_u *fname, char_u *buf,
         relative_directory[0] = '/';
         relative_directory[1] = NUL;
       } else {
-        STRNCPY(relative_directory, fname, p-fname);
+        assert(p >= fname);
+        memcpy(relative_directory, fname, (size_t)(p - fname));
         relative_directory[p-fname] = NUL;
       }
       end_of_path = (char *) (p + 1);