From: PatR <rankin@nethack.org>
Date: Sat, 28 May 2022 19:49:08 +0000 (-0700)
Subject: display lua warnings instead of ignoring them
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=07a2ba6b540403a5cd4122a59ff8a53835eb7040;p=nethack

display lua warnings instead of ignoring them

This will be an annoyance for wizard mode until someone actually
figures out and fixes the problem.  The complaints from lua during
garbage collection aren't new, they were just being ignored before.
---

diff --git a/doc/fixes3-7-0.txt b/doc/fixes3-7-0.txt
index bf1f7d471..223aed27f 100644
--- a/doc/fixes3-7-0.txt
+++ b/doc/fixes3-7-0.txt
@@ -911,6 +911,11 @@ using a marker to write "novel" or "paperback book" on a known blank spellbook
 	was producing a randomly chosen Pratchett novel; make it fail instead
 when a monster killed a pudding and it left a glob, that glob might not be
 	displayed on the map (wasn't an issue for killed-by-hero case)
+lua's garbage collection doesn't like the way nethack is trying to use it and
+	issues a pair of warnings each time the relevant code gets run; they
+	were vanishing into a bit bucket but now they will be displayed when
+	running in wizard mode; we need to fix the usage rather than just
+	hide the feedback
 
 
 Fixes to 3.7.0-x Problems that Were Exposed Via git Repository
diff --git a/src/nhlua.c b/src/nhlua.c
index a029e82a9..75ab9422d 100644
--- a/src/nhlua.c
+++ b/src/nhlua.c
@@ -2273,6 +2273,32 @@ nhl_panic(lua_State *L)
     return 0; /* return to Lua to abort */
 }
 
+/* called when lua issues a warning message; the text of the message
+   is passed to us in pieces across multiple function calls */
+static void
+nhl_warn(
+    void *userdata UNUSED,
+    const char *msg_fragment,
+    int to_be_continued) /* 0: last fragment; 1: more to come */
+{
+    static char warnbuf[BUFSZ];
+    size_t fraglen, buflen = strlen(warnbuf);
+
+    if (msg_fragment && buflen < sizeof warnbuf - 1) {
+        fraglen = strlen(msg_fragment);
+        if (buflen + fraglen > sizeof warnbuf - 1)
+            fraglen = sizeof warnbuf - 1 - buflen;
+        (void) strncat(warnbuf, msg_fragment, fraglen);
+    }
+    if (!to_be_continued) {
+        /* this is a warning so probably ought to be delivered via
+           impossible() but until the current garbage collection issue
+           gets fixed that would be way too verbose */
+        pline("[lua] %s", warnbuf);
+        warnbuf[0] = '\0';
+    }
+}
+
 #ifdef NHL_SANDBOX
 static void
 nhl_hookfn(lua_State *L, lua_Debug *ar UNUSED)
@@ -2311,7 +2337,9 @@ nhlL_newstate(nhl_sandbox_info *sbi)
 
     lua_atpanic(L, nhl_panic);
 #if LUA_VERSION_NUM == 504
-    lua_setwarnf(L, (lua_WarnFunction) 0, L);
+    /* issue lua warnings only when in wizard mode, at least until
+       someone figures out and fixes the garbage collection problem */
+    lua_setwarnf(L, wizard ? nhl_warn : (lua_WarnFunction) 0, L);
 #endif
 
 #ifdef NHL_SANDBOX