1 /*
2 ** require("lua") -- A Lua extension for upb.
3 **
4 ** Exposes only the core library
5 ** (sub-libraries are exposed in other extensions).
6 **
7 ** 64-bit woes: Lua can only represent numbers of type lua_Number (which is
8 ** double unless the user specifically overrides this). Doubles can represent
9 ** the entire range of 64-bit integers, but lose precision once the integers are
10 ** greater than 2^53.
11 **
12 ** Lua 5.3 is adding support for integers, which will allow for 64-bit
13 ** integers (which can be interpreted as signed or unsigned).
14 **
15 ** LuaJIT supports 64-bit signed and unsigned boxed representations
16 ** through its "cdata" mechanism, but this is not portable to regular Lua.
17 **
18 ** Hopefully Lua 5.3 will come soon enough that we can either use Lua 5.3
19 ** integer support or LuaJIT 64-bit cdata for users that need the entire
20 ** domain of [u]int64 values.
21 */
22
23 #include "upb/bindings/lua/upb.h"
24
25 #include <float.h>
26 #include <math.h>
27 #include <stdlib.h>
28 #include <string.h>
29
30 #include "lauxlib.h"
31 #include "upb/msg.h"
32
33 /* Lua compatibility code *****************************************************/
34
35 /* Shims for upcoming Lua 5.3 functionality. */
lua_isinteger(lua_State * L,int argn)36 static bool lua_isinteger(lua_State *L, int argn) {
37 LUPB_UNUSED(L);
38 LUPB_UNUSED(argn);
39 return false;
40 }
41
42
43 /* Utility functions **********************************************************/
44
lupb_checkstatus(lua_State * L,upb_status * s)45 void lupb_checkstatus(lua_State *L, upb_status *s) {
46 if (!upb_ok(s)) {
47 lua_pushstring(L, upb_status_errmsg(s));
48 lua_error(L);
49 }
50 }
51
52 /* Pushes a new userdata with the given metatable. */
lupb_newuserdata(lua_State * L,size_t size,int n,const char * type)53 void *lupb_newuserdata(lua_State *L, size_t size, int n, const char *type) {
54 #if LUA_VERSION_NUM >= 504
55 void *ret = lua_newuserdatauv(L, size, n);
56 #else
57 void *ret = lua_newuserdata(L, size);
58 lua_createtable(L, 0, n);
59 lua_setuservalue(L, -2);
60 #endif
61
62 /* Set metatable. */
63 luaL_getmetatable(L, type);
64 assert(!lua_isnil(L, -1)); /* Should have been created by luaopen_upb. */
65 lua_setmetatable(L, -2);
66
67 return ret;
68 }
69
70 #if LUA_VERSION_NUM < 504
lua_setiuservalue(lua_State * L,int index,int n)71 int lua_setiuservalue(lua_State *L, int index, int n) {
72 lua_getuservalue(L, index);
73 lua_insert(L, -2);
74 lua_rawseti(L, -2, n);
75 lua_pop(L, 1);
76 return 1;
77 }
78
lua_getiuservalue(lua_State * L,int index,int n)79 int lua_getiuservalue(lua_State *L, int index, int n) {
80 lua_getuservalue(L, index);
81 lua_rawgeti(L, -1, n);
82 lua_replace(L, -2);
83 return 1;
84 }
85 #endif
86
87 /* We use this function as the __index metamethod when a type has both methods
88 * and an __index metamethod. */
lupb_indexmm(lua_State * L)89 int lupb_indexmm(lua_State *L) {
90 /* Look up in __index table (which is a closure param). */
91 lua_pushvalue(L, 2);
92 lua_rawget(L, lua_upvalueindex(1));
93 if (!lua_isnil(L, -1)) {
94 return 1;
95 }
96
97 /* Not found, chain to user __index metamethod. */
98 lua_pushvalue(L, lua_upvalueindex(2));
99 lua_pushvalue(L, 1);
100 lua_pushvalue(L, 2);
101 lua_call(L, 2, 1);
102 return 1;
103 }
104
lupb_register_type(lua_State * L,const char * name,const luaL_Reg * m,const luaL_Reg * mm)105 void lupb_register_type(lua_State *L, const char *name, const luaL_Reg *m,
106 const luaL_Reg *mm) {
107 luaL_newmetatable(L, name);
108
109 if (mm) {
110 lupb_setfuncs(L, mm);
111 }
112
113 if (m) {
114 lua_createtable(L, 0, 0); /* __index table */
115 lupb_setfuncs(L, m);
116
117 /* Methods go in the mt's __index slot. If the user also specified an
118 * __index metamethod, use our custom lupb_indexmm() that can check both. */
119 lua_getfield(L, -2, "__index");
120 if (lua_isnil(L, -1)) {
121 lua_pop(L, 1);
122 } else {
123 lua_pushcclosure(L, &lupb_indexmm, 2);
124 }
125 lua_setfield(L, -2, "__index");
126 }
127
128 lua_pop(L, 1); /* The mt. */
129 }
130
131 /* Scalar type mapping ********************************************************/
132
133 /* Functions that convert scalar/primitive values (numbers, strings, bool)
134 * between Lua and C/upb. Handles type/range checking. */
135
lupb_checkbool(lua_State * L,int narg)136 bool lupb_checkbool(lua_State *L, int narg) {
137 if (!lua_isboolean(L, narg)) {
138 luaL_error(L, "must be true or false");
139 }
140 return lua_toboolean(L, narg);
141 }
142
143 /* Unlike luaL_checkstring(), this does not allow implicit conversion to
144 * string. */
lupb_checkstring(lua_State * L,int narg,size_t * len)145 const char *lupb_checkstring(lua_State *L, int narg, size_t *len) {
146 if (lua_type(L, narg) != LUA_TSTRING) {
147 luaL_error(L, "Expected string");
148 }
149
150 return lua_tolstring(L, narg, len);
151 }
152
153 /* Unlike luaL_checkinteger, these do not implicitly convert from string or
154 * round an existing double value. We allow floating-point input, but only if
155 * the actual value is integral. */
156 #define INTCHECK(type, ctype) \
157 ctype lupb_check##type(lua_State *L, int narg) { \
158 double n; \
159 ctype i; \
160 if (lua_isinteger(L, narg)) { \
161 return lua_tointeger(L, narg); \
162 } \
163 \
164 /* Prevent implicit conversion from string. */ \
165 luaL_checktype(L, narg, LUA_TNUMBER); \
166 n = lua_tonumber(L, narg); \
167 \
168 i = (ctype)n; \
169 if ((double)i != n) { \
170 /* double -> ctype truncated or rounded. */ \
171 luaL_error(L, "number %f was not an integer or out of range for " #type, \
172 n); \
173 } \
174 return i; \
175 } \
176 void lupb_push##type(lua_State *L, ctype val) { \
177 /* TODO: push integer for Lua >= 5.3, 64-bit cdata for LuaJIT. */ \
178 /* This is lossy for some [u]int64 values, which isn't great, but */ \
179 /* crashing when we encounter these values seems worse. */ \
180 lua_pushnumber(L, val); \
181 }
182
INTCHECK(int64,int64_t)183 INTCHECK(int64, int64_t)
184 INTCHECK(int32, int32_t)
185 INTCHECK(uint64, uint64_t)
186 INTCHECK(uint32, uint32_t)
187
188 double lupb_checkdouble(lua_State *L, int narg) {
189 /* If we were being really hard-nosed here, we'd check whether the input was
190 * an integer that has no precise double representation. But doubles aren't
191 * generally expected to be exact like integers are, and worse this could
192 * cause data-dependent runtime errors: one run of the program could work fine
193 * because the integer calculations happened to be exactly representable in
194 * double, while the next could crash because of subtly different input. */
195
196 luaL_checktype(L, narg, LUA_TNUMBER); /* lua_tonumber() auto-converts. */
197 return lua_tonumber(L, narg);
198 }
199
lupb_checkfloat(lua_State * L,int narg)200 float lupb_checkfloat(lua_State *L, int narg) {
201 /* We don't worry about checking whether the input can be exactly converted to
202 * float -- see above. */
203
204 luaL_checktype(L, narg, LUA_TNUMBER); /* lua_tonumber() auto-converts. */
205 return lua_tonumber(L, narg);
206 }
207
lupb_pushdouble(lua_State * L,double d)208 void lupb_pushdouble(lua_State *L, double d) {
209 lua_pushnumber(L, d);
210 }
211
lupb_pushfloat(lua_State * L,float d)212 void lupb_pushfloat(lua_State *L, float d) {
213 lua_pushnumber(L, d);
214 }
215
216 /* Library entry point ********************************************************/
217
luaopen_lupb(lua_State * L)218 int luaopen_lupb(lua_State *L) {
219 #if LUA_VERSION_NUM == 501
220 const struct luaL_Reg funcs[] = {{NULL, NULL}};
221 luaL_register(L, "upb_c", funcs);
222 #else
223 lua_createtable(L, 0, 8);
224 #endif
225 lupb_def_registertypes(L);
226 lupb_msg_registertypes(L);
227 return 1; /* Return package table. */
228 }
229