Jeremy Baxter
8c5777fb98
Callisto - standalone scripting platform for Lua 5.4 Copyright (c) 2023-2024 Jeremy Baxter.
120 lines
2.3 KiB
C
120 lines
2.3 KiB
C
/*
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* Callisto - standalone scripting platform for Lua 5.4
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* Copyright (c) 2023-2024 Jeremy Baxter.
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*/
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/***
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* Getting and setting environment variables.
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* @module environ
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*/
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#include <stdlib.h>
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#include <errno.h>
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#include <lua.h>
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#include <lauxlib.h>
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#include "callisto.h"
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extern char **environ;
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/***
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* Table enabling easy access to environment
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* variables.
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*
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* Has metamethods *\_\_index* and *\_\_newindex*,
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* which allow for the table to be indexed with a
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* string to get values of environment variables,
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* or for fields to be set to set an environment
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* variable.
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*
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* @table environ
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* @usage
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-- Print the value of an environment variable:
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print(environ["MYVAR"])
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-- Set an environment variable:
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environ["MYVAR"] = 1
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*/
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/*
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* Returns the value of the given environment variable.
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*/
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static int
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environ_index(lua_State *L)
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{
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const char *variable; /* parameter 2 (string) */
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char *ret;
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variable = luaL_checkstring(L, 2);
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ret = getenv(variable);
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if (ret == NULL) /* no environment variable? */
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lua_pushnil(L);
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else
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lua_pushstring(L, ret); /* push variable value */
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return 1;
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}
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/*
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* Sets the value of the given environment variable.
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*/
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static int
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environ_newindex(lua_State *L)
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{
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int ret;
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const char *variable; /* parameter 2 (string) */
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const char *value; /* parameter 3 (string) */
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variable = luaL_checkstring(L, 2);
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if (lua_isnil(L, 3)) {
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ret = unsetenv(variable); /* remove variable from environ */
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if (ret == 0) /* did unsetenv succeed? */
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return 0;
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/* if unsetenv didn't succeed:
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* (unsetenv only sets errno to EINVAL on error) */
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return luaL_error(L, "invalid input string");
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}
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value = luaL_checkstring(L, 3);
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ret = setenv(variable, value, 1);
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if (ret == 0) /* did setenv succeed? */
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return 0;
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switch (errno) {
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case EINVAL:
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return luaL_error(L, "invalid input string");
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break;
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case ENOMEM:
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return luaL_error(L, "insufficient memory");
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break;
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}
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return 0;
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}
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static const luaL_Reg mt[] = {
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{"__index", environ_index},
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{"__newindex", environ_newindex},
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{NULL, NULL}
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};
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int
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luaopen_environ(lua_State *L)
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{
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const luaL_Reg *lib;
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lua_newtable(L);
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luaL_newmetatable(L, CALLISTO_ENVIRON); /* metatable for environ */
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for (lib = mt; lib->func; lib++) {
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lua_pushcfunction(L, lib->func);
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lua_setfield(L, -2, lib->name);
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}
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lua_setmetatable(L, -2);
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return 1;
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}
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