Fix bug 9736 'Lua: new Int64/UInt64 functions don't prevent division by zero'

OK, in all fairness this does a bit more than just fix that bug. It also
adds a 'Int64()' and 'UInt64()' __call metamethods. I generally dislike
using __call metamethods, because they're often unintuitive (for example
the wireshark Field and FielInfo use this in a bizarre fashion).  But this
happens to be a perfect use for it, and very natural, imho.  Another change
is to make the metatables of classes visible to scripts. There was never
really a good reason not to make them visible, and they have to be visible
to do things like use __call on a plain table... not to mention I need them
to be visible to run test scripts verifying evrything is kosher.

I also updated the test suite to test for the div/mod by zero.

Change-Id: Ia4c594c8f59d4e799090716bd032ba2815df032f
Reviewed-on: https://code.wireshark.org/review/149
Reviewed-by: Evan Huus <eapache@gmail.com>

3 files changed, 108 insertions, 39 deletions

diff --git a/epan/wslua/wslua.h b/epan/wslua/wslua.h
index bb4eab2c20..4cb16d2588 100644
--- a/epan/wslua/wslua.h
+++ b/epan/wslua/wslua.h
@@ -337,11 +337,8 @@ typedef int dummy##C
     /* push a copy of the class methods table, and set it to be the metatable's __index field */ \
     lua_pushvalue (L, -2); \
     lua_setfield (L, -2, "__index"); \
-    /* push a copy of the class methods table, and set it to be the metatable's __metatable field, to hide metatable */ \
-    lua_pushvalue (L, -2); \
-    lua_setfield (L, -2, "__metatable"); \
-    /* pop the metatable */ \
-    lua_pop (L, 1); \
+    /* set the metatable to be the class's metatable, so scripts can inspect it, and metamethods work for class tables */ \
+    lua_setmetatable(L, -2); \
     /* set the class methods table as the global class table */ \
     lua_setglobal (L, #C); \
 }
diff --git a/epan/wslua/wslua_int64.c b/epan/wslua/wslua_int64.c
index 5aa6fd6f7d..b5cae7bbd5 100644
--- a/epan/wslua/wslua_int64.c
+++ b/epan/wslua/wslua_int64.c
@@ -179,8 +179,8 @@ WSLUA_CONSTRUCTOR Int64_new(lua_State* L) { /* Creates a Int64 Object */
                 value = (gint64)lua_tonumber(L, WSLUA_OPTARG_Int64_new_VALUE);
                 if (lua_gettop(L) == 2 && lua_type(L, WSLUA_OPTARG_Int64_new_HIGHVALUE) == LUA_TNUMBER) {
                     gint64 h = (gint64)lua_tonumber(L, WSLUA_OPTARG_Int64_new_HIGHVALUE);
-                    value &= 0x00000000FFFFFFFF;
-                    h <<= 32; h &= 0xFFFFFFFF00000000;
+                    value &= G_GUINT64_CONSTANT(0x00000000FFFFFFFF);
+                    h <<= 32; h &= G_GUINT64_CONSTANT(0xFFFFFFFF00000000);
                     value += h;
                 }
                 break;
@@ -199,6 +199,11 @@ WSLUA_CONSTRUCTOR Int64_new(lua_State* L) { /* Creates a Int64 Object */
     WSLUA_RETURN(1); /* The new Int64 object. */
 }
 
+WSLUA_METAMETHOD Int64__call(lua_State* L) { /* Creates a Int64 Object */
+    lua_remove(L,1); /* remove the table */
+    WSLUA_RETURN(Int64_new(L)); /* The new Int64 object. */
+}
+
 WSLUA_CONSTRUCTOR Int64_max(lua_State* L) { /* Gets the max possible value */
     pushInt64(L, G_MAXINT64);
     WSLUA_RETURN(1); /* The new Int64 object of the max value. */
@@ -249,7 +254,7 @@ WSLUA_METHOD Int64_higher(lua_State* L) {
     gint64 b = num;
     lua_Number n;
     if (b < 0) b = -b; /* masking/shifting negative int64 isn't working on some platforms */
-    b &= 0x7FFFFFFF00000000;
+    b &= G_GUINT64_CONSTANT(0x7FFFFFFF00000000);
     b >>= 32;
     n = (lua_Number)(guint32)(b & 0x00000000FFFFFFFFF);
     if (num < 0) n = -n;
@@ -261,7 +266,7 @@ WSLUA_METHOD Int64_lower(lua_State* L) {
     /* Returns a Lua number of the lower 32-bits of the Int64 value. (always positive) */
     gint64 b = getInt64(L,1);
     if (b < 0) b = -b; /* masking/shifting negative int64 isn't working on some platforms */
-    lua_pushnumber(L,(guint32)(b & 0x00000000FFFFFFFFF));
+    lua_pushnumber(L,(guint32)(b & G_GUINT64_CONSTANT(0x00000000FFFFFFFFF)));
     WSLUA_RETURN(1); /* The Lua number */
 }
 
@@ -304,13 +309,25 @@ WSLUA_METAMETHOD Int64__mul(lua_State* L) {
 }
 
 WSLUA_METAMETHOD Int64__div(lua_State* L) {
-    /* Divides two Int64 and returns a new one (integer divide, no remainder) */
-    WSLUA_MATH_OP_FUNC(Int64,/);
+    /* Divides two Int64 and returns a new one (integer divide, no remainder).
+       Trying to divide by zero results in a Lua error. */
+    Int64 num1 = getInt64(L,1);
+    Int64 num2 = getInt64(L,2);
+    if (num2 == 0)
+        luaL_error(L, "Trying to divide Int64 by zero");
+    pushInt64(L, num1 / num2);
+    WSLUA_RETURN(1); /* The Int64 object */
 }
 
 WSLUA_METAMETHOD Int64__mod(lua_State* L) {
-    /* Divides two Int64 and returns a new one of the remainder */
-    WSLUA_MATH_OP_FUNC(Int64,%);
+    /* Divides two Int64 and returns a new one of the remainder.
+       Trying to modulo by zero results in a Lua error. */
+    Int64 num1 = getInt64(L,1);
+    Int64 num2 = getInt64(L,2);
+    if (num2 == 0)
+        luaL_error(L, "Trying to modulo Int64 by zero");
+    pushInt64(L, num1 % num2);
+    WSLUA_RETURN(1); /* The Int64 object */
 }
 
 WSLUA_METAMETHOD Int64__pow(lua_State* L) {
@@ -437,7 +454,7 @@ WSLUA_METHOD Int64_bswap(lua_State* L) {
     size_t i;
     for (i = 0; i < sizeof(gint64); i++) {
         result <<= 8;
-        result |= (b & 0x00000000000000FF);
+        result |= (b & G_GUINT64_CONSTANT(0x00000000000000FF));
         b >>= 8;
     }
     pushInt64(L,(gint64)result);
@@ -475,6 +492,7 @@ static const luaL_Reg Int64_methods[] = {
 
 static const luaL_Reg Int64_meta[] = {
     {"__tostring", Int64__tostring},
+    {"__call", Int64__call},
     {"__concat", wslua__concat},
     {"__unm", Int64__unm},
     {"__add", Int64__add},
@@ -617,8 +635,8 @@ WSLUA_CONSTRUCTOR UInt64_new(lua_State* L) { /* Creates a UInt64 Object */
                 value = (guint64)lua_tonumber(L, WSLUA_OPTARG_UInt64_new_VALUE);
                  if (lua_gettop(L) == 2 && lua_type(L, WSLUA_OPTARG_UInt64_new_HIGHVALUE) == LUA_TNUMBER) {
                     guint64 h = (guint64)lua_tonumber(L, WSLUA_OPTARG_UInt64_new_HIGHVALUE);
-                    value &= 0x00000000FFFFFFFF;
-                    h <<= 32; h &= 0xFFFFFFFF00000000;
+                    value &= G_GUINT64_CONSTANT(0x00000000FFFFFFFF);
+                    h <<= 32; h &= G_GUINT64_CONSTANT(0xFFFFFFFF00000000);
                     value += h;
                 }
                break;
@@ -637,6 +655,11 @@ WSLUA_CONSTRUCTOR UInt64_new(lua_State* L) { /* Creates a UInt64 Object */
     WSLUA_RETURN(1); /* The new UInt64 object. */
 }
 
+WSLUA_METAMETHOD UInt64__call(lua_State* L) { /* Creates a UInt64 Object */
+    lua_remove(L,1); /* remove the table */
+    WSLUA_RETURN(UInt64_new(L)); /* The new UInt64 object. */
+}
+
 WSLUA_CONSTRUCTOR UInt64_max(lua_State* L) { /* Gets the max possible value */
     pushUInt64(L,G_MAXUINT64);
     WSLUA_RETURN(1); /* The max value. */
@@ -695,9 +718,9 @@ WSLUA_METHOD UInt64_higher(lua_State* L) {
     guint64 num = getUInt64(L,1);
     guint64 b = num;
     lua_Number n;
-    b &= 0xFFFFFFFF00000000;
+    b &= G_GUINT64_CONSTANT(0xFFFFFFFF00000000);
     b >>= 32;
-    n = (lua_Number)(guint32)(b & 0x00000000FFFFFFFFF);
+    n = (lua_Number)(guint32)(b & G_GUINT64_CONSTANT(0x00000000FFFFFFFFF));
     lua_pushnumber(L,n);
     WSLUA_RETURN(1); /* The Lua number */
 }
@@ -705,7 +728,7 @@ WSLUA_METHOD UInt64_higher(lua_State* L) {
 WSLUA_METHOD UInt64_lower(lua_State* L) {
     /* Returns a Lua number of the lower 32-bits of the UInt64 value. */
     guint64 b = getUInt64(L,1);
-    lua_pushnumber(L,(guint32)(b & 0x00000000FFFFFFFFF));
+    lua_pushnumber(L,(guint32)(b & G_GUINT64_CONSTANT(0x00000000FFFFFFFFF)));
     WSLUA_RETURN(1); /* The Lua number */
 }
 
@@ -731,13 +754,25 @@ WSLUA_METAMETHOD UInt64__mul(lua_State* L) {
 }
 
 WSLUA_METAMETHOD UInt64__div(lua_State* L) {
-    /* Divides two UInt64 and returns a new one (integer divide, no remainder) */
-    WSLUA_MATH_OP_FUNC(UInt64,/);
+    /* Divides two UInt64 and returns a new one (integer divide, no remainder).
+       Trying to divide by zero results in a Lua error. */
+    UInt64 num1 = getUInt64(L,1);
+    UInt64 num2 = getUInt64(L,2);
+    if (num2 == 0)
+        luaL_error(L, "Trying to divide UInt64 by zero");
+    pushUInt64(L, num1 / num2);
+    WSLUA_RETURN(1); /* The UInt64 result */
 }
 
 WSLUA_METAMETHOD UInt64__mod(lua_State* L) {
-    /* Divides two UInt64 and returns a new one of the remainder */
-    WSLUA_MATH_OP_FUNC(UInt64,%);
+    /* Divides two UInt64 and returns a new one of the remainder.
+       Trying to modulo by zero results in a Lua error. */
+    UInt64 num1 = getUInt64(L,1);
+    UInt64 num2 = getUInt64(L,2);
+    if (num2 == 0)
+        luaL_error(L, "Trying to modulo UInt64 by zero");
+    pushUInt64(L, num1 % num2);
+    WSLUA_RETURN(1); /* The UInt64 result */
 }
 
 WSLUA_METAMETHOD UInt64__pow(lua_State* L) {
@@ -849,7 +884,7 @@ WSLUA_METHOD UInt64_bswap(lua_State* L) {
     size_t i;
     for (i = 0; i < sizeof(guint64); i++) {
         result <<= 8;
-        result |= (b & 0x00000000000000FF);
+        result |= (b & G_GUINT64_CONSTANT(0x00000000000000FF));
         b >>= 8;
     }
     pushUInt64(L,result);
@@ -887,6 +922,7 @@ static const luaL_Reg UInt64_methods[] = {
 
 static const luaL_Reg UInt64_meta[] = {
     {"__tostring", UInt64__tostring},
+    {"__call", UInt64__call},
     {"__concat", wslua__concat},
     {"__unm", UInt64__unm},
     {"__add", UInt64__add},
diff --git a/test/lua/int64.lua b/test/lua/int64.lua
index c0c8f9dd45..8582485b31 100755
--- a/test/lua/int64.lua
+++ b/test/lua/int64.lua
@@ -93,13 +93,14 @@ for i,t in ipairs(testtbl) do
     test("new1",checkeq(my64a,val))
     test("new2",checkeq(my64b,val))
     test("new3",checkeq(my64a,obj.new(my64b)))
+    test("new3b",checkeq(my64a,obj(my64b)))
     test("new4",checkeq(valc,my64c))
     test("new5",checkeq(0,my64z))
     test("new6",obj.new(0,1):tonumber() == (2^32))
     if t.name == "Int64" then
-        test("new7",obj.new(-1):tonumber() == -1)
+        test("new7",obj(-1):tonumber() == -1)
         test("new8",obj.new(0,-1):tonumber() == -4294967296)
-        test("new9",obj.new(obj.new(-1)):tonumber() == -1)
+        test("new9",obj(obj.new(-1)):tonumber() == -1)
     end
 
     test("tonumber1",val == my64a:tonumber())
@@ -126,7 +127,7 @@ for i,t in ipairs(testtbl) do
     test("ge2", my64c >= my64z)
 
     test("neq1",not(my64a ~= my64b))
-    test("neq2",my64a ~= obj.new(0))
+    test("neq2",my64a ~= obj(0))
     test("neq2",my64a ~= my64c)
 
     test("gt1",my64a > my64z)
@@ -166,7 +167,7 @@ for i,t in ipairs(testtbl) do
     test("pow3",checkeq(my64a ^ obj.new(3), val ^ 3))
     test("pow4",checkeq(my64c ^ 1, valc ^ 1))
 
-    test("mul1",checkeq(my64a * obj.new(1), my64b))
+    test("mul1",checkeq(my64a * obj(1), my64b))
     test("mul2",checkeq(my64a * my64b, my64b * my64a))
     test("mul3",checkeq(my64a * 1, my64b))
     test("mul4",checkeq(2 * my64c, 2 * valc))
@@ -268,23 +269,23 @@ for i,t in ipairs(testtbl) do
 
     testing("bit operations")
 
-    test("band1",checkeq(obj.new(1):band(1), 1))
-    test("band2",checkeq(obj.new(1):band(0), 0))
-    test("band3",checkeq(obj.new(4294967295,100):band(4294967295), 4294967295))
-    test("band4",obj.new(4294967295,100):band(obj.new(0,100),obj.new(0,100),obj.new(0,100)) == obj.new(0,100))
-    test("band5",checkeq(obj.new(4294967295,100):band(obj.new(0,100),obj.new(0)), 0))
+    test("band1",checkeq(obj(1):band(1), 1))
+    test("band2",checkeq(obj(1):band(0), 0))
+    test("band3",checkeq(obj(4294967295,100):band(4294967295), 4294967295))
+    test("band4",obj.new(4294967295,100):band(obj(0,100),obj(0,100),obj(0,100)) == obj(0,100))
+    test("band5",checkeq(obj.new(4294967295,100):band(obj.new(0,100),obj(0)), 0))
 
-    test("bor1",checkeq(obj.new(1):bor(1), 1))
-    test("bor2",checkeq(obj.new(1):bor(0), 1))
-    test("bor3",checkeq(obj.new(0):bor(0), 0))
+    test("bor1",checkeq(obj(1):bor(1), 1))
+    test("bor2",checkeq(obj(1):bor(0), 1))
+    test("bor3",checkeq(obj(0):bor(0), 0))
     test("bor4",obj.new(0,100):bor(4294967295) == obj.new(4294967295,100))
-    test("bor5",obj.new(1):bor(obj.new(2),obj.new(4),obj.new(8),16,32,64,128) == obj.new(255))
+    test("bor5",obj.new(1):bor(obj(2),obj.new(4),obj(8),16,32,64,128) == obj(255))
 
     test("bxor1",checkeq(obj.new(1):bxor(1), 0))
     test("bxor2",checkeq(obj.new(1):bxor(0), 1))
     test("bxor3",checkeq(obj.new(0):bxor(0), 0))
-    test("bxor4",obj.new(4294967295,100):bxor(obj.new(0,100)) == obj.new(4294967295))
-    test("bxor5",obj.new(1):bxor(obj.new(2),obj.new(4),obj.new(8),16,32,64,128) == obj.new(255))
+    test("bxor4",obj.new(4294967295,100):bxor(obj(0,100)) == obj.new(4294967295))
+    test("bxor5",obj.new(1):bxor(obj(2),obj(4),obj(8),16,32,64,128) == obj(255))
 
     test("bnot1",checkeq(obj.new(4294967295,4294967295):bnot(), 0))
     test("bnot2",obj.new(0):bnot() == obj.new(4294967295,4294967295))
@@ -336,6 +337,41 @@ test("min3",z==Int64.min())
 
 test("minmax",Int64.min()== - Int64.max() - 1)
 
+testing("error conditions")
+
+local function divtest(f,s)
+    local r = (f / s)
+    if r == 5 then
+        io.stdout:write("ok...")
+    else
+        error("test failed!")
+    end
+end
+
+local function modtest(f,s)
+    local r = (f % s)
+    if r == 5 then
+        io.stdout:write("ok...")
+    else
+        error("test failed!")
+    end
+end
+
+test("error1", pcall(divtest, 10, 2)) -- not an error, but checking the div function works above
+test("error2", not pcall(divtest, Int64(10), 0))
+test("error3", not pcall(divtest, Int64(10), Int64(0)))
+test("error4", not pcall(divtest, Int64(10), UInt64(0)))
+test("error5", not pcall(divtest, UInt64(10), 0))
+test("error6", not pcall(divtest, UInt64(10), Int64(0)))
+test("error7", not pcall(divtest, UInt64(10), UInt64(0)))
+test("error8", pcall(modtest, 17, 6)) -- not an error, but checking the mod function works above
+test("error9", not pcall(modtest, Int64(10), 0))
+test("error10", not pcall(modtest, Int64(10), Int64(0)))
+test("error11", not pcall(modtest, Int64(10), UInt64(0)))
+test("error12", not pcall(modtest, UInt64(10), 0))
+test("error13", not pcall(modtest, UInt64(10), Int64(0)))
+test("error14", not pcall(modtest, UInt64(10), UInt64(0)))
+
 print("\n-----------------------------\n")
 
 print("All tests passed!\n\n")