From 61a4e64a6667bedaa882571c48a173ef5a4ba73b Mon Sep 17 00:00:00 2001
From: Roberto Ierusalimschy <roberto@inf.puc-rio.br>
Date: Wed, 6 May 2020 14:19:08 -0300
Subject: Back to old encoding of versions in binary files

(Undoing part of commit f53eabeed8.)  It is better to keep this encoding
stable, so that all Lua versions can read at least the version of a
binary file.
---
 ldump.c          | 2 +-
 loadlib.c        | 2 +-
 lundump.c        | 2 +-
 lundump.h        | 7 ++++++-
 testes/calls.lua | 4 ++--
 5 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/ldump.c b/ldump.c
index fbadbcc9..f848b669 100644
--- a/ldump.c
+++ b/ldump.c
@@ -196,7 +196,7 @@ static void dumpFunction (DumpState *D, const Proto *f, TString *psource) {
 
 static void dumpHeader (DumpState *D) {
   dumpLiteral(D, LUA_SIGNATURE);
-  dumpInt(D, LUAC_VERSION);
+  dumpByte(D, LUAC_VERSION);
   dumpByte(D, LUAC_FORMAT);
   dumpLiteral(D, LUAC_DATA);
   dumpByte(D, sizeof(Instruction));
diff --git a/loadlib.c b/loadlib.c
index ddfecca9..c0ec9a13 100644
--- a/loadlib.c
+++ b/loadlib.c
@@ -69,7 +69,7 @@ static const char *const CLIBS = "_CLIBS";
 
 /*
 ** Special type equivalent to '(void*)' for functions in gcc
-** (to supress warnings when converting function pointers)
+** (to suppress warnings when converting function pointers)
 */
 typedef void (*voidf)(void);
 
diff --git a/lundump.c b/lundump.c
index 17364999..d6b249d5 100644
--- a/lundump.c
+++ b/lundump.c
@@ -276,7 +276,7 @@ static void fchecksize (LoadState *S, size_t size, const char *tname) {
 static void checkHeader (LoadState *S) {
   /* skip 1st char (already read and checked) */
   checkliteral(S, &LUA_SIGNATURE[1], "not a binary chunk");
-  if (loadInt(S) != LUAC_VERSION)
+  if (loadByte(S) != LUAC_VERSION)
     error(S, "version mismatch");
   if (loadByte(S) != LUAC_FORMAT)
     error(S, "format mismatch");
diff --git a/lundump.h b/lundump.h
index 5b05fed4..2df6923e 100644
--- a/lundump.h
+++ b/lundump.h
@@ -18,7 +18,12 @@
 #define LUAC_INT	0x5678
 #define LUAC_NUM	cast_num(370.5)
 
-#define LUAC_VERSION	LUA_VERSION_NUM
+/*
+** Encode major-minor version in one byte, one nibble for each
+*/
+#define MYINT(s)	(s[0]-'0')  /* assume one-digit numbers */
+#define LUAC_VERSION	(MYINT(LUA_VERSION_MAJOR)*16+MYINT(LUA_VERSION_MINOR))
+
 #define LUAC_FORMAT	0	/* this is the official format */
 
 /* load one chunk; from lundump.c */
diff --git a/testes/calls.lua b/testes/calls.lua
index 0141ffa4..1701f155 100644
--- a/testes/calls.lua
+++ b/testes/calls.lua
@@ -422,9 +422,9 @@ assert((function (a) return a end)() == nil)
 
 print("testing binary chunks")
 do
-  local header = string.pack("c4BBBc6BBBj",
+  local header = string.pack("c4BBc6BBBj",
     "\27Lua",                                  -- signature
-    (504 >> 7) & 0x7f, (504 & 0x7f) | 0x80,    -- version 5.4 (504)
+    0x54,                                      -- version 5.4 (0x54)
     0,                                         -- format
     "\x19\x93\r\n\x1a\n",                      -- data
     4,                                         -- size of instruction
-- 
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