Initial import

lenvironment.c

@@ -0,0 +1,148 @@
+/***
+ * Getting and setting
+ * environment variables.
+ * @module environment
+ */
+
+#include <stdlib.h>
+#include <errno.h>
+#ifdef __linux__
+#	include <bsd/string.h>
+#else
+/* assume BSD */
+#	include <string.h>
+#endif
+
+#include <lua.h>
+#include <lauxlib.h>
+
+#include "lenvironment.h"
+#include "lcallisto.h"
+
+
+/***
+ * Returns the value of the given environment
+ * variable.
+ *
+ * If *var* does not exist in the environment
+ * and *defaultvalue* is not nil,
+ * *defaultvalue* will be returned.
+ *
+ * @function get
+ * @usage environment.get("HOME", "/root")
+ * @tparam       string var The environment variable to get.
+ * @param[opt] defaultvalue The value to return in case the environment variable was not found.
+ */
+static int
+environment_get(lua_State *L)
+{
+	const char *variable;
+	char *ret;
+
+	variable = luaL_checkstring(L, 1);
+	ret = getenv(variable);
+
+	if (ret == NULL)
+		if (!lua_isnoneornil(L, 2))
+			lua_pushvalue(L, 2);
+		else
+			lua_pushnil(L);
+	else
+		lua_pushstring(L, ret);
+	return 1;
+}
+
+/***
+ * Sets the value of the given environment variable.
+ *
+ * This function will throw an error if the value of
+ * *var* is invalid for the name of an environment
+ * variable, or if there is insufficient memory
+ * available to perform the operation.
+ *
+ * @function set
+ * @usage environment.set("MYVAR", "1")
+ * @tparam string   var The environment variable to set.
+ * @tparam string value The value to set for *var*.
+ */
+static int
+environment_set(lua_State *L)
+{
+	int ret;
+	const char *variable;
+	const char *value;
+
+	variable = luaL_checkstring(L, 1);
+	value    = luaL_checkstring(L, 2);
+	ret      = setenv(variable, value, 1);
+
+	if (ret == 0)
+		return 0;
+
+	switch (errno) {
+		case EINVAL:
+			return luaL_error(L, "invalid input string");
+			break;
+		case ENOMEM:
+			return luaL_error(L, "insufficient memory");
+			break;
+	}
+	return 0;
+}
+
+/***
+ * Clears the environment.
+ *
+ * If *var* is not nil, only clears the value of that
+ * environment variable (not the whole environment).
+ *
+ * This function will throw an error if the value of
+ * *var* is invalid for the name of an environment
+ * variable, or if there is insufficient memory
+ * available to perform the operation.
+ *
+ * @function clear
+ * @usage environment.clear("MYVAR")
+ * @tparam[opt] string var The environment variable to clear.
+ */
+static int
+environment_clear(lua_State *L)
+{
+	const char *variable;
+	int ret;
+
+	if (lua_isnoneornil(L, 1)) {
+		clearenv();
+		return 0;
+	}
+
+	variable = luaL_checkstring(L, 1);
+	ret = unsetenv(variable);
+
+	if (ret == 0)
+		return 0;
+
+	switch (errno) {
+		case EINVAL:
+			return luaL_error(L, "invalid input string");
+			break;
+		case ENOMEM:
+			return luaL_error(L, "insufficient memory");
+			break;
+	}
+	return 0;
+}
+
+static const luaL_Reg envlib[] = {
+	{"get",   environment_get},
+	{"set",   environment_set},
+	{"clear", environment_clear},
+	{NULL, NULL}
+};
+
+int
+callistoopen_environment(lua_State *L)
+{
+	luaL_newlib(L, envlib);
+	return 1;
+}