Add environment variables to signal feature and version to the CLI

This PR ensures environment variables are set before any invocation of
the CLI.  Here is a list of vars that are set:

https://github.com/github/codeql-coreql-team/issues/1124#issuecomment-852463521

This ensures the CLI knows the features and versions of the containing
actions/runner.

Additionally:

- Fix the user agent so that it more closely aligns with user agent
  spec
- Refactor environment variable initialization so that it all happens in
  one place and call.
- Move Mode, getRequiredEnvParam, setMode, getMode out of actions-util
  and into util. actions-util is meant for utils only called by the
  action, not the runner.

The `prepareLocalRunEnvironment()` method is most likely deprecated and
should be removed. I originally added it because I had a way of working
where I would run the action from my local machine to test out changes,
but this was always a little flaky. So, I no longer use this way of
working. I will probably remove it soon.

lib/util.js

@@ -39,7 +39,9 @@ exports.getExtraOptionsEnvParam = getExtraOptionsEnvParam;
 function isLocalRun() {
     return (!!process.env.CODEQL_LOCAL_RUN &&
         process.env.CODEQL_LOCAL_RUN !== "false" &&
-        process.env.CODEQL_LOCAL_RUN !== "0");
+        process.env.CODEQL_LOCAL_RUN !== "0" &&
+        // local runs only allowed for actions
+        isActions());
 }
 exports.isLocalRun = isLocalRun;
 /**
@@ -242,7 +244,7 @@ function checkGitHubVersionInRange(version, logger, toolName) {
         logger.warning(`GitHub Enterprise ${version.version} is too old to be compatible with this version of the CodeQL ${toolName}. If you experience issues, please upgrade to a more recent version of GitHub Enterprise or use an older version of the CodeQL ${toolName}.`);
     }
     hasBeenWarnedAboutVersion = true;
-    if (actions_util_1.isActions()) {
+    if (isActions()) {
         core.exportVariable(CODEQL_ACTION_WARNED_ABOUT_VERSION_ENV_VAR, true);
     }
 }
@@ -330,4 +332,89 @@ function assertNever(value) {
     throw new ExhaustivityCheckingError(value);
 }
 exports.assertNever = assertNever;
+var Mode;
+(function (Mode) {
+    Mode["actions"] = "Action";
+    Mode["runner"] = "Runner";
+})(Mode = exports.Mode || (exports.Mode = {}));
+/**
+ * Environment variables to be set by codeql-action and used by the
+ * CLI. These environment variables are relevant for both the runner
+ * and the action.
+ */
+var EnvVar;
+(function (EnvVar) {
+    // either 'actions' or 'runner'
+    EnvVar["RUN_MODE"] = "CODEQL_ACTION_RUN_MODE";
+    // semver of this action
+    EnvVar["VERSION"] = "CODEQL_ACTION_VERSION";
+    // if set to a truthy value, then the action might combine SARIF
+    // output from several `interpret-results` runs for the same language
+    EnvVar["FEATURE_SARIF_COMBINE"] = "CODEQL_ACTION_FEATURE_SARIF_COMBINE";
+    // if set to a truthy value, then the action will upload SARIF,
+    // not the CLI
+    EnvVar["FEATURE_WILL_UPLOAD"] = "CODEQL_ACTION_FEATURE_WILL_UPLOAD";
+    // if set to a truthy value, then the action is using its
+    // own deprecated and non-standard way of scanning for multiple
+    // languages
+    EnvVar["FEATURE_MULTI_LANGUAGE"] = "CODEQL_ACTION_FEATURE_MULTI_LANGUAGE";
+    // if set to a truthy value, then the action is using its
+    // own sandwiched workflow mechanism
+    EnvVar["FEATURE_SANDWICH"] = "CODEQL_ACTION_FEATURE_SANDWICH";
+})(EnvVar || (EnvVar = {}));
+function initializeEnvironment(mode, version) {
+    // avoid accessing actions core when in runner mode
+    if (mode === Mode.actions) {
+        core.exportVariable(EnvVar.RUN_MODE, mode);
+        core.exportVariable(EnvVar.VERSION, version);
+        core.exportVariable(EnvVar.FEATURE_SARIF_COMBINE, "true");
+        core.exportVariable(EnvVar.FEATURE_WILL_UPLOAD, "true");
+        core.exportVariable(EnvVar.FEATURE_MULTI_LANGUAGE, "true");
+        core.exportVariable(EnvVar.FEATURE_SANDWICH, "true");
+        actions_util_1.prepareLocalRunEnvironment();
+    }
+    else {
+        process.env[EnvVar.RUN_MODE] = mode;
+        process.env[EnvVar.VERSION] = version;
+        process.env[EnvVar.FEATURE_SARIF_COMBINE] = "true";
+        process.env[EnvVar.FEATURE_WILL_UPLOAD] = "true";
+        process.env[EnvVar.FEATURE_MULTI_LANGUAGE] = "true";
+        process.env[EnvVar.FEATURE_SANDWICH] = "true";
+    }
+}
+exports.initializeEnvironment = initializeEnvironment;
+function getMode() {
+    // Make sure we fail fast if the env var is missing. This should
+    // only happen if there is a bug in our code and we neglected
+    // to set the mode early in the process.
+    const mode = getRequiredEnvParam(EnvVar.RUN_MODE);
+    if (mode !== Mode.actions && mode !== Mode.runner) {
+        throw new Error(`Unknown mode: ${mode}.`);
+    }
+    return mode;
+}
+exports.getMode = getMode;
+function isActions() {
+    return getMode() === Mode.actions;
+}
+exports.isActions = isActions;
+/**
+ * Get an environment parameter, but throw an error if it is not set.
+ */
+function getRequiredEnvParam(paramName) {
+    const value = process.env[paramName];
+    if (value === undefined || value.length === 0) {
+        throw new Error(`${paramName} environment variable must be set`);
+    }
+    core.debug(`${paramName}=${value}`);
+    return value;
+}
+exports.getRequiredEnvParam = getRequiredEnvParam;
+function getTemporaryDirectory() {
+    const value = process.env["CODEQL_ACTION_TEMP"];
+    return value !== undefined && value !== ""
+        ? value
+        : getRequiredEnvParam("RUNNER_TEMP");
+}
+exports.getTemporaryDirectory = getTemporaryDirectory;
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