fix(api): load buffer first on nvim_buf_set_lines (#25823)

Fix #22670
Fix #8659

1 files changed, 16 insertions, 8 deletions

diff --git a/src/nvim/api/buffer.c b/src/nvim/api/buffer.c
index 64dddea5b8..86298efe08 100644
--- a/src/nvim/api/buffer.c
+++ b/src/nvim/api/buffer.c
@@ -359,6 +359,14 @@ void nvim_buf_set_lines(uint64_t channel_id, Buffer buffer, Integer start, Integ
     return;
   }
 
+  // loaded buffer first if it's not loaded
+  if (buf->b_ml.ml_mfp == NULL) {
+    if (!buf_ensure_loaded(buf)) {
+      api_set_error(err, kErrorTypeException, "Failed to load buffer");
+      return;
+    }
+  }
+
   bool oob = false;
   start = normalize_index(buf, start, true, &oob);
   end = normalize_index(buf, end, true, &oob);
@@ -396,10 +404,6 @@ void nvim_buf_set_lines(uint64_t channel_id, Buffer buffer, Integer start, Integ
     goto end;
   }
 
-  if (!buf_ensure_loaded(buf)) {
-    goto end;
-  }
-
   if (u_save_buf(buf, (linenr_T)(start - 1), (linenr_T)end) == FAIL) {
     api_set_error(err, kErrorTypeException, "Failed to save undo information");
     goto end;
@@ -537,6 +541,14 @@ void nvim_buf_set_text(uint64_t channel_id, Buffer buffer, Integer start_row, In
     return;
   }
 
+  // loaded buffer first if it's not loaded
+  if (buf->b_ml.ml_mfp == NULL) {
+    if (!buf_ensure_loaded(buf)) {
+      api_set_error(err, kErrorTypeException, "Failed to load buffer");
+      return;
+    }
+  }
+
   bool oob = false;
 
   // check range is ordered and everything!
@@ -645,10 +657,6 @@ void nvim_buf_set_text(uint64_t channel_id, Buffer buffer, Integer start_row, In
     goto end;
   }
 
-  if (!buf_ensure_loaded(buf)) {
-    goto end;
-  }
-
   // Small note about undo states: unlike set_lines, we want to save the
   // undo state of one past the end_row, since end_row is inclusive.
   if (u_save_buf(buf, (linenr_T)start_row - 1, (linenr_T)end_row + 1) == FAIL) {