feat(*): add environment variable and random functions

1 files changed, 173 insertions, 0 deletions

diff --git a/src/environment.c b/src/environment.c
new file mode 100644
index 0000000..5f1c3da
--- /dev/null
+++ b/src/environment.c
@@ -0,0 +1,173 @@
+/// @submodule system
+#include <lua.h>
+#include <lauxlib.h>
+#include "compat.h"
+#include <stdlib.h>
+#include <string.h>
+
+#ifdef _WIN32
+#include "windows.h"
+#endif
+
+/***
+Gets the value of an environment variable.
+
+__NOTE__: Windows has multiple copies of environment variables. For this reason,
+the `setenv` function will not work with Lua's `os.getenv` on Windows. If you want
+to use `setenv` then consider patching `os.getenv` with this implementation of `getenv`.
+@function getenv
+@tparam string name name of the environment variable
+@treturn string|nil value of the environment variable, or nil if the variable is not set
+*/
+static int lua_get_environment_variable(lua_State* L) {
+    const char* variableName = luaL_checkstring(L, 1);
+
+#ifdef _WIN32
+    // On Windows, use GetEnvironmentVariable to retrieve the value
+    DWORD bufferSize = GetEnvironmentVariable(variableName, NULL, 0);
+    if (bufferSize > 0) {
+        char* buffer = (char*)malloc(bufferSize);
+        if (GetEnvironmentVariable(variableName, buffer, bufferSize) > 0) {
+            lua_pushstring(L, buffer);
+            free(buffer);
+            return 1;
+        }
+        free(buffer);
+    }
+#else
+    // On non-Windows platforms, use getenv to retrieve the value
+    const char* variableValue = getenv(variableName);
+    if (variableValue != NULL) {
+        lua_pushstring(L, variableValue);
+        return 1;
+    }
+#endif
+
+    // If the variable is not set or an error occurs, push nil
+    lua_pushnil(L);
+    return 1;
+}
+
+
+/***
+Returns a table with all environment variables.
+@function getenvs
+@treturn table table with all environment variables and their values
+*/
+static int lua_list_environment_variables(lua_State* L) {
+    lua_newtable(L);
+
+#ifdef _WIN32
+    char* envStrings = GetEnvironmentStrings();
+    char* envString = envStrings;
+
+    if (envStrings == NULL) {
+        lua_pushnil(L);
+        return 1;
+    }
+
+    while (*envString != '\0') {
+        const char* envVar = envString;
+
+        // Split the environment variable into key and value
+        char* equals = strchr(envVar, '=');
+        if (equals != NULL) {
+            lua_pushlstring(L, envVar, equals - envVar); // Push the key
+            lua_pushstring(L, equals + 1); // Push the value
+            lua_settable(L, -3); // Set the key-value pair in the table
+        }
+
+        envString += strlen(envString) + 1;
+    }
+
+    FreeEnvironmentStrings(envStrings);
+#else
+    extern char** environ;
+
+    if (environ != NULL) {
+        for (char** envVar = environ; *envVar != NULL; envVar++) {
+            const char* envVarStr = *envVar;
+
+            // Split the environment variable into key and value
+            char* equals = strchr(envVarStr, '=');
+            if (equals != NULL) {
+                lua_pushlstring(L, envVarStr, equals - envVarStr); // Push the key
+                lua_pushstring(L, equals + 1); // Push the value
+                lua_settable(L, -3); // Set the key-value pair in the table
+            }
+        }
+    }
+#endif
+
+    return 1;
+}
+
+
+/***
+Sets an environment variable.
+
+__NOTE__: Windows has multiple copies of environment variables. For this reason, the
+`setenv` function will not work with Lua's `os.getenv` on Windows. If you want to use
+it then consider patching `os.getenv` with the implementation of `system.getenv`.
+@function setenv
+@tparam string name name of the environment variable
+@tparam[opt] string value value of the environment variable, if `nil` the variable will be deleted (on
+Windows, setting an empty string, will also delete the variable)
+@treturn boolean success
+*/
+static int lua_set_environment_variable(lua_State* L) {
+    const char* variableName = luaL_checkstring(L, 1);
+    const char* variableValue = luaL_optstring(L, 2, NULL);
+
+#ifdef _WIN32
+    // if (variableValue == NULL) {
+    //     // If the value is nil, delete the environment variable
+    //     if (SetEnvironmentVariable(variableName, NULL)) {
+    //         lua_pushboolean(L, 1);
+    //     } else {
+    //         lua_pushboolean(L, 0);
+    //     }
+    // } else {
+        // Set the environment variable with the provided value
+        if (SetEnvironmentVariable(variableName, variableValue)) {
+            lua_pushboolean(L, 1);
+        } else {
+            lua_pushboolean(L, 0);
+        }
+    // }
+#else
+    if (variableValue == NULL) {
+        // If the value is nil, delete the environment variable
+        if (unsetenv(variableName) == 0) {
+            lua_pushboolean(L, 1);
+        } else {
+            lua_pushboolean(L, 0);
+        }
+    } else {
+        // Set the environment variable with the provided value
+        if (setenv(variableName, variableValue, 1) == 0) {
+            lua_pushboolean(L, 1);
+        } else {
+            lua_pushboolean(L, 0);
+        }
+    }
+#endif
+
+    return 1;
+}
+
+
+
+static luaL_Reg func[] = {
+    { "getenv", lua_get_environment_variable },
+    { "setenv", lua_set_environment_variable },
+    { "getenvs", lua_list_environment_variables },
+    { NULL, NULL }
+};
+
+/*-------------------------------------------------------------------------
+ * Initializes module
+ *-------------------------------------------------------------------------*/
+void environment_open(lua_State *L) {
+    luaL_setfuncs(L, func, 0);
+}