ircd::util: Add environment iteration convenience tools.

include/ircd/util/env.h

@@ -14,5 +14,14 @@
 namespace ircd {
 inline namespace util
 {
+	using env_closure = closure_bool<std::function, string_view, string_view>;
+
+	// Iterate environment variables starting with prefix
+	bool for_each_env(const string_view &, const env_closure &);
+
+	// Iterate all environment variables
+	bool for_each_env(const env_closure &);
+
+	// Get one environment variable
 	string_view getenv(const string_view &);
 }}

include/ircd/util/util.h

@@ -38,7 +38,6 @@ namespace ircd
 #include "reentrance.h"
 #include "enum.h"
 #include "custom_ptr.h"
-#include "env.h"
 #include "va_rtti.h"
 #include "unique_iterator.h"
 #include "scope_count.h"
@@ -61,6 +60,7 @@ namespace ircd
 #include "pretty.h"
 #include "hash.h"
 #include "closure.h"
+#include "env.h"
 #include "test.h"
 #include "boolean.h"
 #include "maybe.h"

ircd/util.cc

@@ -52,6 +52,38 @@ ircd::util::getenv(const string_view &key)
 	return var;
 }
 
+bool
+ircd::util::for_each_env(const string_view &prefix,
+                         const env_closure &closure)
+{
+	return for_each_env([&prefix, &closure]
+	(const auto &key, const auto &val)
+	{
+		if(!startswith(key, prefix))
+			return true;
+
+		return closure(key, val);
+	});
+}
+
+bool
+ircd::util::for_each_env(const env_closure &closure)
+{
+	assert(environ);
+	for(char **env(environ); *env; ++env)
+	{
+		const auto &[key, val]
+		{
+			split(*env, '=')
+		};
+
+		if(!closure(key, val))
+			return false;
+	}
+
+	return true;
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // util/pretty.h