unistd: add getcwd

Signed-off-by: Simon Rozman <simon@rozman.si>

include/MacStd/unistd.hpp

@@ -0,0 +1,34 @@
+/*
+	SPDX-License-Identifier: MIT
+	Copyright © 2023 Amebis
+*/
+
+#pragma once
+
+#include "common.hpp"
+#include <unistd.h>
+#include <string>
+
+///
+/// Copies the absolute pathname of the current working directory
+///
+/// \sa [getcwd function](https://developer.apple.com/library/archive/documentation/System/Conceptual/ManPages_iPhoneOS/man3/getcwd.3.html)
+///
+inline const char* getcwd(std::string& path)
+{
+	char stack_buffer[MACSTD_STACK_BUFFER_BYTES];
+	auto result = getcwd(stack_buffer, MACSTD_STACK_BUFFER_BYTES);
+	if (result) {
+		path = result;
+		return path.data();
+	}
+	if (errno == ERANGE) {
+		result = getcwd(NULL, 0);
+		if (result) {
+			path = result;
+			free(result);
+			return path.data();
+		}
+	}
+	return NULL;
+}