Checks for type 'int' added to binary header

The structure 'AbsLineInfo' is hard-dumped into binary chunks, and
it comprises two 'int' fields.

ldump.c

@@ -253,16 +253,19 @@ static void dumpFunction (DumpState *D, const Proto *f) {
 }
 
 
+#define dumpNumInfo(D, tvar, value)  \
+  { tvar i = value; dumpByte(D, sizeof(tvar)); dumpVar(D, i); }
+
+
 static void dumpHeader (DumpState *D) {
   dumpLiteral(D, LUA_SIGNATURE);
   dumpByte(D, LUAC_VERSION);
   dumpByte(D, LUAC_FORMAT);
   dumpLiteral(D, LUAC_DATA);
-  dumpByte(D, sizeof(Instruction));
-  dumpByte(D, sizeof(lua_Integer));
-  dumpByte(D, sizeof(lua_Number));
-  dumpInteger(D, LUAC_INT);
-  dumpNumber(D, LUAC_NUM);
+  dumpNumInfo(D, int, LUAC_INT);
+  dumpNumInfo(D, Instruction, LUAC_INST);
+  dumpNumInfo(D, lua_Integer, LUAC_INT);
+  dumpNumInfo(D, lua_Number, LUAC_NUM);
 }
 
 

lundump.c

@@ -345,13 +345,29 @@ static void checkliteral (LoadState *S, const char *s, const char *msg) {
 }
 
 
-static void fchecksize (LoadState *S, size_t size, const char *tname) {
-  if (loadByte(S) != size)
-    error(S, luaO_pushfstring(S->L, "%s size mismatch", tname));
+static l_noret numerror (LoadState *S, const char *what, const char *tname) {
+  const char *msg = luaO_pushfstring(S->L, "%s %s mismatch", tname, what);
+  error(S, msg);
 }
 
 
-#define checksize(S,t)	fchecksize(S,sizeof(t),#t)
+static void checknumsize (LoadState *S, int size, const char *tname) {
+  if (size != loadByte(S))
+    numerror(S, "size", tname);
+}
+
+
+static void checknumformat (LoadState *S, int eq, const char *tname) {
+  if (!eq)
+    numerror(S, "format", tname);
+}
+
+
+#define checknum(S,tvar,value,tname)  \
+  { tvar i; checknumsize(S, sizeof(i), tname); \
+    loadVar(S, i); \
+    checknumformat(S, i == value, tname); }
+
 
 static void checkHeader (LoadState *S) {
   /* skip 1st char (already read and checked) */
@@ -361,13 +377,10 @@ static void checkHeader (LoadState *S) {
   if (loadByte(S) != LUAC_FORMAT)
     error(S, "format mismatch");
   checkliteral(S, LUAC_DATA, "corrupted chunk");
-  checksize(S, Instruction);
-  checksize(S, lua_Integer);
-  checksize(S, lua_Number);
-  if (loadInteger(S) != LUAC_INT)
-    error(S, "integer format mismatch");
-  if (loadNumber(S) != LUAC_NUM)
-    error(S, "float format mismatch");
+  checknum(S, int, LUAC_INT, "int");
+  checknum(S, Instruction, LUAC_INST, "instruction");
+  checknum(S, lua_Integer, LUAC_INT, "Lua integer");
+  checknum(S, lua_Number, LUAC_NUM, "Lua number");
 }
 
 
@@ -398,7 +411,8 @@ LClosure *luaU_undump (lua_State *L, ZIO *Z, const char *name, int fixed) {
   cl->p = luaF_newproto(L);
   luaC_objbarrier(L, cl, cl->p);
   loadFunction(&S, cl->p);
-  lua_assert(cl->nupvalues == cl->p->sizeupvalues);
+  if (cl->nupvalues != cl->p->sizeupvalues)
+    error(&S, "corrupted chunk");
   luai_verifycode(L, cl->p);
   L->top.p--;  /* pop table */
   return cl;

lundump.h

@@ -17,8 +17,9 @@
 /* data to catch conversion errors */
 #define LUAC_DATA	"\x19\x93\r\n\x1a\n"
 
-#define LUAC_INT	0x5678
-#define LUAC_NUM	cast_num(370.5)
+#define LUAC_INT	-0x5678
+#define LUAC_INST	0x12345678
+#define LUAC_NUM	cast_num(-370.5)
 
 /*
 ** Encode major-minor version in one byte, one nibble for each

testes/calls.lua

@@ -480,15 +480,22 @@ assert((function (a) return a end)() == nil)
 
 print("testing binary chunks")
 do
-  local header = string.pack("c4BBc6BBB",
-    "\27Lua",                                  -- signature
-    0x55,                                      -- version 5.5 (0x55)
-    0,                                         -- format
-    "\x19\x93\r\n\x1a\n",                      -- data
-    4,                                         -- size of instruction
-    string.packsize("j"),                      -- sizeof(lua integer)
-    string.packsize("n")                       -- sizeof(lua number)
-  )
+  local headformat = "c4BBc6BiBI4BjBn"
+  local header = {  -- header components
+    "\27Lua",               -- signature
+    0x55,                   -- version 5.5 (0x55)
+    0,                      -- format
+    "\x19\x93\r\n\x1a\n",   -- a binary string
+    string.packsize("i"),   -- size of an int
+    -0x5678,                -- an int
+    4,                      -- size of an instruction
+    0x12345678,             -- an instruction (4 bytes)
+    string.packsize("j"),   -- size of a Lua integer
+    -0x5678,                -- a Lua integer
+    string.packsize("n"),   -- size of a Lua float
+    -370.5,                 -- a Lua float
+  }
+
   local c = string.dump(function ()
     local a = 1; local b = 3;
     local f = function () return a + b + _ENV.c; end    -- upvalues
@@ -500,17 +507,23 @@ do
   assert(assert(load(c))() == 10)
 
   -- check header
-  assert(string.sub(c, 1, #header) == header)
-  -- check LUAC_INT and LUAC_NUM
-  local ci, cn = string.unpack("jn", c, #header + 1)
-  assert(ci == 0x5678 and cn == 370.5)
-
-  -- corrupted header
+  local t = {string.unpack(headformat, c)}
   for i = 1, #header do
+    assert(t[i] == header[i])
+  end
+
+  -- Testing corrupted header.
+  -- A single wrong byte in the head invalidates the chunk,
+  -- except for the Lua float check. (If numbers are long double,
+  -- the representation may need padding, and changing that padding
+  -- will not invalidate the chunk.)
+  local headlen = string.packsize(headformat)
+  headlen = headlen - string.packsize("n")     -- remove float check
+  for i = 1, headlen do
     local s = string.sub(c, 1, i - 1) ..
-              string.char(string.byte(string.sub(c, i, i)) + 1) ..
+              string.char((string.byte(string.sub(c, i, i)) + 1) & 0xFF) ..
               string.sub(c, i + 1, -1)
-    assert(#s == #c)
+    assert(#s == #c and s ~= c)
     assert(not load(s))
   end