fix(messages): proper multiline Lua print() messages #31205

Problem:  Separate message emitted for each newline present in Lua
          print() arguments.
Solution: Make msg_multiline() handle NUL bytes. Refactor print() to use
          msg_multiline(). Refactor vim.print() to use print().

1 files changed, 19 insertions, 20 deletions

diff --git a/src/nvim/message.c b/src/nvim/message.c
index e8f20916b8..47f33c8967 100644
--- a/src/nvim/message.c
+++ b/src/nvim/message.c
@@ -249,35 +249,33 @@ bool msg(const char *s, const int hl_id)
   return msg_hl_keep(s, hl_id, false, false);
 }
 
-/// Similar to msg_outtrans, but support newlines and tabs.
-void msg_multiline(const char *s, int hl_id, bool check_int, bool hist, bool *need_clear)
+/// Similar to msg_outtrans_len, but support newlines and tabs.
+void msg_multiline(String str, int hl_id, bool check_int, bool hist, bool *need_clear)
   FUNC_ATTR_NONNULL_ALL
 {
-  const char *next_spec = s;
-
-  while (next_spec != NULL) {
+  const char *s = str.data;
+  const char *chunk = s;
+  while ((size_t)(s - str.data) < str.size) {
     if (check_int && got_int) {
       return;
     }
-    next_spec = strpbrk(s, "\t\n\r");
-
-    if (next_spec != NULL) {
-      // Printing all char that are before the char found by strpbrk
-      msg_outtrans_len(s, (int)(next_spec - s), hl_id, hist);
+    if (*s == '\n' || *s == TAB || *s == '\r') {
+      // Print all chars before the delimiter
+      msg_outtrans_len(chunk, (int)(s - chunk), hl_id, hist);
 
-      if (*next_spec != TAB && *need_clear) {
+      if (*s != TAB && *need_clear) {
         msg_clr_eos();
         *need_clear = false;
       }
-      msg_putchar_hl((uint8_t)(*next_spec), hl_id);
-      s = next_spec + 1;
+      msg_putchar_hl((uint8_t)(*s), hl_id);
+      chunk = s + 1;
     }
+    s++;
   }
 
-  // Print the rest of the message. We know there is no special
-  // character because strpbrk returned NULL
-  if (*s != NUL) {
-    msg_outtrans(s, hl_id, hist);
+  // Print the rest of the message
+  if (*chunk != NUL) {
+    msg_outtrans_len(chunk, (int)(str.size - (size_t)(chunk - str.data)), hl_id, hist);
   }
 }
 
@@ -290,7 +288,7 @@ void msg_multihl(HlMessage hl_msg, const char *kind, bool history)
   msg_ext_set_kind(kind);
   for (uint32_t i = 0; i < kv_size(hl_msg); i++) {
     HlMessageChunk chunk = kv_A(hl_msg, i);
-    msg_multiline(chunk.text.data, chunk.hl_id, true, false, &need_clear);
+    msg_multiline(chunk.text, chunk.hl_id, true, false, &need_clear);
   }
   if (history && kv_size(hl_msg)) {
     add_msg_hist_multihl(NULL, 0, 0, true, hl_msg);
@@ -349,7 +347,7 @@ bool msg_hl_keep(const char *s, int hl_id, bool keep, bool multiline)
 
   bool need_clear = true;
   if (multiline) {
-    msg_multiline(s, hl_id, false, false, &need_clear);
+    msg_multiline(cstr_as_string(s), hl_id, false, false, &need_clear);
   } else {
     msg_outtrans(s, hl_id, false);
   }
@@ -2689,12 +2687,13 @@ static void msg_puts_printf(const char *str, const ptrdiff_t maxlen)
     // primitive way to compute the current column
     if (*s == '\r' || *s == '\n') {
       msg_col = 0;
+      msg_didout = false;
     } else {
       msg_col += cw;
+      msg_didout = true;
     }
     s += len;
   }
-  msg_didout = true;  // assume that line is not empty
 }
 
 /// Show the more-prompt and handle the user response.