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Stop access to global vars. Not configurable.

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After considering the interaction between ability to delcare globals in
scripts using the 'global' function, and the complexities related to
hanlding replication and AOF in a sane way with globals AND ability to
turn protection On and Off, we reconsidered the design. The new design
makes clear that there is only one good way to write Redis scripts, that
is not using globals. In the rare cases state must be retained across
calls a Redis key can be used.
This commit is contained in:
antirez
2012-04-13 13:26:59 +02:00
parent 6255a5ae66
commit 97cab30993
5 changed files with 4 additions and 57 deletions
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25
src/scripting.c
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@ -416,10 +416,7 @@ void luaLoadLibraries(lua_State *lua) {
* the creation of globals accidentally.
*
* It should be the last to be called in the scripting engine initialization
* sequence, because it may interact with creation of globals.
* Note that the function is designed to be called multiple times if needed
* without issues, because it is possible to enabled/disable globals protection
* at runtime with CONFIG SET. */
* sequence, because it may interact with creation of globals. */
void scriptingEnableGlobalsProtection(lua_State *lua) {
char *s[32];
sds code = sdsempty();
@ -434,7 +431,7 @@ void scriptingEnableGlobalsProtection(lua_State *lua) {
s[j++]=" if not mt.declared[n] and debug.getinfo(2) then\n";
s[j++]=" local w = debug.getinfo(2, \"S\").what\n";
s[j++]=" if w ~= \"main\" and w ~= \"C\" then\n";
s[j++]=" error(\"assignment to undeclared global variable '\"..n..\"'\", 2)\n";
s[j++]=" error(\"Script attempted to create global variable '\"..tostring(n)..\"'\", 2)\n";
s[j++]=" end\n";
s[j++]=" mt.declared[n] = true\n";
s[j++]=" end\n";
@ -442,17 +439,10 @@ void scriptingEnableGlobalsProtection(lua_State *lua) {
s[j++]="end\n";
s[j++]="mt.__index = function (t, n)\n";
s[j++]=" if debug.getinfo(2) and not mt.declared[n] and debug.getinfo(2, \"S\").what ~= \"C\" then\n";
s[j++]=" error(\"global variable '\"..n..\"' is not declared\", 2)\n";
s[j++]=" error(\"Script attempted to access unexisting global variable '\"..n..\"'\", 2)\n";
s[j++]=" end\n";
s[j++]=" return rawget(t, n)\n";
s[j++]="end\n";
s[j++]="function global(...)\n";
s[j++]=" local nargs = select(\"#\",...)\n";
s[j++]=" for i = 1, nargs do\n";
s[j++]=" local v = select(i,...)\n";
s[j++]=" mt.declared[v] = true\n";
s[j++]=" end\n";
s[j++]="end\n";
s[j++]=NULL;
for (j = 0; s[j] != NULL; j++) code = sdscatlen(code,s[j],strlen(s[j]));
@ -461,12 +451,6 @@ void scriptingEnableGlobalsProtection(lua_State *lua) {
sdsfree(code);
}
void scriptingDisableGlobalsProtection(lua_State *lua) {
char *s = "setmetatable(_G, nil)\n";
luaL_loadbuffer(lua,s,strlen(s),"disable_strict_lua");
lua_pcall(lua,0,0,0);
}
/* Initialize the scripting environment.
* It is possible to call this function to reset the scripting environment
* assuming that we call scriptingRelease() before.
@ -559,8 +543,7 @@ void scriptingInit(void) {
/* Lua beginners ofter don't use "local", this is likely to introduce
* subtle bugs in their code. To prevent problems we protect accesses
* to global variables. */
if (server.lua_protect_globals)
scriptingEnableGlobalsProtection(lua);
scriptingEnableGlobalsProtection(lua);
server.lua = lua;
}