Allow setting of config file path without requiring environment variables.

include/lsl/common.h

@@ -227,3 +227,23 @@ extern LIBLSL_C_API double lsl_local_clock();
  * no free() method is available (e.g., in some scripting languages).
  */
 extern LIBLSL_C_API void lsl_destroy_string(char *s);
+
+/**
+ * Set the name of the configuration file to be used.
+ *
+ * This is a global setting that will be used by all LSL
+ * after this function is called. If, and only if, this function
+ * is called before the first call to any other LSL function.
+ */
+extern LIBLSL_C_API void lsl_set_config_filename(const char *filename);
+
+/**
+ * Set the content of the configuration file to be used.
+ *
+ * This is a global setting that will be used by all LSL
+ * after this function is called. If, and only if, this function
+ * is called before the first call to any other LSL function.
+ *
+ * @note the configuration content is wiped after LSL has initialized.
+ */
+extern LIBLSL_C_API void lsl_set_config_content(const char *content);

src/api_config.cpp

@@ -1,7 +1,6 @@
 #include "api_config.h"
 #include "common.h"
 #include "util/cast.hpp"
-#include "util/inireader.hpp"
 #include "util/strfuns.hpp"
 #include <algorithm>
 #include <cstdlib>
@@ -10,6 +9,7 @@
 #include <loguru.hpp>
 #include <mutex>
 #include <stdexcept>
+#include <sstream>
 
 using namespace lsl;
 
@@ -52,9 +52,36 @@ bool file_is_readable(const std::string &filename) {
 }
 
 api_config::api_config() {
+	// first check to see if a config content was provided
+	if (!api_config_content_.empty()) {
+		try {
+			// if so, load it from the content
+			load_from_content(api_config_content_);
+			// free the content this can only be called once
+			api_config_content_.clear();
+			// config loaded successfully, so return
+			return;
+		} catch (std::exception &e) {
+			LOG_F(ERROR, "Error parsing config content: '%s', rolling back to defaults", e.what());
+			// clear the content, it was invalid anyway
+			api_config_content_.clear();
+		}
+	}
+	// otherwise, load the config from a file
+
 	// for each config file location under consideration...
 	std::vector<std::string> filenames;
 
+	// NOLINTNEXTLINE(concurrency-mt-unsafe)
+	if (!api_config_filename_.empty()) {
+		// if a config file name was set, use it if it is readable
+		if (file_is_readable(api_config_filename_)) {
+			filenames.insert(filenames.begin(), api_config_filename_);
+		} else {
+			LOG_F(ERROR, "Config file %s not found", api_config_filename_.c_str());
+		}
+	}
+
 	// NOLINTNEXTLINE(concurrency-mt-unsafe)
 	if (auto *cfgpath = getenv("LSLAPICFG")) {
 		std::string envcfg(cfgpath);
@@ -82,7 +109,6 @@ api_config::api_config() {
 	load_from_file();
 }
 
-
 void api_config::load_from_file(const std::string &filename) {
 	try {
 		INI pt;
@@ -92,7 +118,35 @@ void api_config::load_from_file(const std::string &filename) {
 				pt.load(infile);
 			}
 		}
+		api_config::load(pt);
+		// log config filename only after setting the verbosity level and all config has been read
+		if (!filename.empty())
+			LOG_F(INFO, "Configuration loaded from %s", filename.c_str());
+		else
+			LOG_F(INFO, "Loaded default config");
+
+	} catch (std::exception &e) {
+		LOG_F(ERROR, "Error parsing config file '%s': '%s', rolling back to defaults",
+			filename.c_str(), e.what());
+		// any error: assign defaults
+		load_from_file();
+		// and rethrow
+		throw e;
+	}
+}
 
+void api_config::load_from_content(const std::string &content) {
+	// load the content into an INI object
+	INI pt;
+	if (!content.empty()) {
+		std::istringstream content_stream(content);
+		pt.load(content_stream);
+	}
+	api_config::load(pt);
+	LOG_F(INFO, "Configuration loaded from content");
+}
+
+void api_config::load(INI &pt) {
 		// read the [log] settings
 		int log_level = pt.get("log.level", (int)loguru::Verbosity_INFO);
 		if (log_level < -3 || log_level > 9)
@@ -264,20 +318,7 @@ void api_config::load_from_file(const std::string &filename) {
 		smoothing_halftime_ = pt.get("tuning.SmoothingHalftime", 90.0F);
 		force_default_timestamps_ = pt.get("tuning.ForceDefaultTimestamps", false);
 
-		// log config filename only after setting the verbosity level and all config has been read
-		if (!filename.empty())
-			LOG_F(INFO, "Configuration loaded from %s", filename.c_str());
-		else
-			LOG_F(INFO, "Loaded default config");
-
-	} catch (std::exception &e) {
-		LOG_F(ERROR, "Error parsing config file '%s': '%s', rolling back to defaults",
-			filename.c_str(), e.what());
-		// any error: assign defaults
-		load_from_file();
-		// and rethrow
-		throw e;
-	}
+
 }
 
 static std::once_flag api_config_once_flag;

src/api_config.h

@@ -2,6 +2,7 @@
 #define API_CONFIG_H
 
 #include "netinterfaces.h"
+#include "util/inireader.hpp"
 #include <cstdint>
 #include <loguru.hpp>
 #include <string>
@@ -14,9 +15,11 @@ namespace lsl {
  * A configuration object: holds all the configurable settings of liblsl.
  * These settings can be set via a configuration file that is automatically searched
  * by stream providers and recipients in a series of locations:
- *  - lsl_api.cfg
- *  - ~/lsl_api/lsl_api.cfg
- *  - /etc/lsl_api/lsl_api.cfg
+ *  - First, the content set via `lsl_set_config_content()`
+ *  - Second, the file set via `lsl_set_config_filename()`
+ *  - Third, the file `lsl_api.cfg` in the current working directory
+ *  - Fourth, the file `lsl_api.cfg` in the home directory (e.g., `~/lsl_api/lsl_api.cfg`)
+ *  - Fifth, the file `lsl_api.cfg` in the system configuration directory (e.g., `/etc/lsl_api/lsl_api.cfg`)
  *
  * Note that, while in some cases it might seem sufficient to override configurations
  * only for a subset of machines involved in a recording session (e.g., the servers),
@@ -76,6 +79,33 @@ class api_config {
 	bool allow_ipv6() const { return allow_ipv6_; }
 	bool allow_ipv4() const { return allow_ipv4_; }
 
+
+
+	/**
+	* @brief Set the configuration directly from a string.
+	* 
+	* This allows passing in configuration content directly rather than from a file.
+	* This MUST be called before the first call to get_instance() to have any effect.
+	*/
+    static void set_api_config_content(const std::string &content) {
+        api_config_content_ = content;
+    }
+
+	/**
+	 * @brief An additional settings path to load configuration from.
+	 */
+	const std::string &api_config_filename() const { return api_config_filename_; }
+
+	/**
+	 * @brief Set the config file name used to load the settings.
+	 * 
+	 * This MUST be called before the first call to get_instance() to have any effect.
+	 */
+	static void set_api_config_filename(const std::string &filename) {
+		api_config_filename_ = filename;
+	}
+
+
 	/**
 	 * @brief The range or scope of stream lookup when using multicast-based discovery
 	 *
@@ -221,6 +251,22 @@ class api_config {
 	 */
 	void load_from_file(const std::string &filename = std::string());
 
+	/**
+	 * @brief Load a configuration from a string.
+	 * @param content The configuration content to parse
+	 */
+	void load_from_content(const std::string &content);
+
+	/**
+	 * @brief Load the configuration from an INI object.
+	 * @param pt The INI object to load the configuration from
+	 */
+	void load(INI &pt);
+
+	// config overrides
+	static std::string api_config_filename_;
+	static std::string api_config_content_;
+
 	// core parameters
 	bool allow_ipv6_, allow_ipv4_;
 	uint16_t base_port_;
@@ -258,6 +304,11 @@ class api_config {
 	float smoothing_halftime_;
 	bool force_default_timestamps_;
 };
+
+// initialize configuration file name
+inline std::string api_config::api_config_filename_ = "";
+inline std::string api_config::api_config_content_ = "";
+
 } // namespace lsl
 
 #endif

src/common.cpp

@@ -26,6 +26,18 @@ LIBLSL_C_API int32_t lsl_protocol_version() {
 	return lsl::api_config::get_instance()->use_protocol_version();
 }
 
+LIBLSL_C_API void lsl_set_config_filename(const char *filename) {
+	if (filename) {
+		lsl::api_config::set_api_config_filename(filename);
+	}
+}
+
+LIBLSL_C_API void lsl_set_config_content(const char *content) {
+	if (content) {
+		lsl::api_config::set_api_config_content(content);
+	}
+}
+
 LIBLSL_C_API int32_t lsl_library_version() { return LSL_LIBRARY_VERSION; }
 
 LIBLSL_C_API double lsl_local_clock() {