Codechange: introduce GetEnv that returns optional based on std::getenv

src/fileio.cpp

@@ -733,8 +733,8 @@ static std::string GetHomeDir()
 	find_directory(B_USER_SETTINGS_DIRECTORY, &path);
 	return std::string(path.Path());
 #else
-	const char *home_env = std::getenv("HOME"); // Stack var, shouldn't be freed
-	if (home_env != nullptr) return std::string(home_env);
+	auto home_env = GetEnv("HOME"); // Stack var, shouldn't be freed
+	if (home_env.has_value()) return std::string(*home_env);
 
 	const struct passwd *pw = getpwuid(getuid());
 	if (pw != nullptr) return std::string(pw->pw_dir);
@@ -751,9 +751,8 @@ void DetermineBasePaths(std::string_view exe)
 	std::string tmp;
 	const std::string homedir = GetHomeDir();
 #ifdef USE_XDG
-	const char *xdg_data_home = std::getenv("XDG_DATA_HOME");
-	if (xdg_data_home != nullptr) {
-		tmp = xdg_data_home;
+	if (auto xdg_data_home = GetEnv("XDG_DATA_HOME"); xdg_data_home.has_value()) {
+		tmp = *xdg_data_home;
 		tmp += PATHSEP;
 		tmp += PERSONAL_DIR[0] == '.' ? &PERSONAL_DIR[1] : PERSONAL_DIR;
 		AppendPathSeparator(tmp);
@@ -882,9 +881,8 @@ void DeterminePaths(std::string_view exe, bool only_local_path)
 #ifdef USE_XDG
 	std::string config_home;
 	std::string homedir = GetHomeDir();
-	const char *xdg_config_home = std::getenv("XDG_CONFIG_HOME");
-	if (xdg_config_home != nullptr) {
-		config_home = xdg_config_home;
+	if (auto xdg_config_home = GetEnv("XDG_CONFIG_HOME"); xdg_config_home.has_value()) {
+		config_home = *xdg_config_home;
 		config_home += PATHSEP;
 		config_home += PERSONAL_DIR[0] == '.' ? &PERSONAL_DIR[1] : PERSONAL_DIR;
 	} else if (!homedir.empty()) {

src/network/core/config.cpp

@@ -15,18 +15,6 @@
 
 #include "../../safeguards.h"
 
-/**
- * Get the environment variable using std::getenv and when it is an empty string (or nullptr), return a fallback value instead.
- * @param variable The environment variable to read from.
- * @param fallback The fallback in case the environment variable is not set.
- * @return The environment value, or when that does not exist the given fallback value.
- */
-static std::string_view GetEnv(const char *variable, std::string_view fallback)
-{
-	const char *value = std::getenv(variable);
-	return StrEmpty(value) ? fallback : value;
-}
-
 /**
  * Get the connection string for the game coordinator from the environment variable OTTD_COORDINATOR_CS,
  * or when it has not been set a hard coded default DNS hostname of the production server.
@@ -34,7 +22,7 @@ static std::string_view GetEnv(const char *variable, std::string_view fallback)
  */
 std::string_view NetworkCoordinatorConnectionString()
 {
-	return GetEnv("OTTD_COORDINATOR_CS", "coordinator.openttd.org");
+	return GetEnv("OTTD_COORDINATOR_CS").value_or("coordinator.openttd.org");
 }
 
 /**
@@ -44,7 +32,7 @@ std::string_view NetworkCoordinatorConnectionString()
  */
 std::string_view NetworkStunConnectionString()
 {
-	return GetEnv("OTTD_STUN_CS", "stun.openttd.org");
+	return GetEnv("OTTD_STUN_CS").value_or("stun.openttd.org");
 }
 
 /**
@@ -54,7 +42,7 @@ std::string_view NetworkStunConnectionString()
  */
 std::string_view NetworkContentServerConnectionString()
 {
-	return GetEnv("OTTD_CONTENT_SERVER_CS", "content.openttd.org");
+	return GetEnv("OTTD_CONTENT_SERVER_CS").value_or("content.openttd.org");
 }
 
 /**
@@ -64,7 +52,7 @@ std::string_view NetworkContentServerConnectionString()
  */
 std::string_view NetworkContentMirrorUriString()
 {
-	return GetEnv("OTTD_CONTENT_MIRROR_URI", "https://binaries.openttd.org/bananas");
+	return GetEnv("OTTD_CONTENT_MIRROR_URI").value_or("https://binaries.openttd.org/bananas");
 }
 
 /**
@@ -74,5 +62,5 @@ std::string_view NetworkContentMirrorUriString()
  */
 std::string_view NetworkSurveyUriString()
 {
-	return GetEnv("OTTD_SURVEY_URI", "https://survey-participate.openttd.org/");
+	return GetEnv("OTTD_SURVEY_URI").value_or("https://survey-participate.openttd.org/");
 }

src/string.cpp

@@ -851,3 +851,15 @@ public:
 #endif /* defined(WITH_COCOA) && !defined(STRGEN) && !defined(SETTINGSGEN) */
 
 #endif
+
+/**
+ * Get the environment variable using std::getenv and when it is an empty string (or nullptr), return \c std::nullopt instead.
+ * @param variable The environment variable to read from.
+ * @return The environment value, or \c std::nullopt.
+ */
+std::optional<std::string_view> GetEnv(const char *variable)
+{
+	auto val = std::getenv(variable);
+	if (val == nullptr || *val == '\0') return std::nullopt;
+	return val;
+}

src/string_func.h

@@ -167,4 +167,6 @@ inline bool IsWhitespace(char32_t c)
 #include <sys/param.h>
 #endif
 
+std::optional<std::string_view> GetEnv(const char *variable);
+
 #endif /* STRING_FUNC_H */