From 2e2d1bd3b6c7776b77c33b94f30ead89367a71e6 Mon Sep 17 00:00:00 2001
From: Lexi Winter <lexi@le-fay.org>
Date: Tue, 1 Jul 2025 17:07:04 +0100
Subject: add nihil.std

---
 nihil.posix/getenv.ccm | 22 +++++++++-------------
 1 file changed, 9 insertions(+), 13 deletions(-)

(limited to 'nihil.posix/getenv.ccm')

diff --git a/nihil.posix/getenv.ccm b/nihil.posix/getenv.ccm
index 5967bf7..ddffeb3 100644
--- a/nihil.posix/getenv.ccm
+++ b/nihil.posix/getenv.ccm
@@ -2,18 +2,15 @@
 module;
 
 #include <cerrno>
-#include <expected>
-#include <string>
-#include <system_error>
-#include <vector>
-
-#include <unistd.h>
+#include <stdlib.h> // NOLINT: getenv_r
 
 #include "nihil.hh"
 
 export module nihil.posix:getenv;
 
+import nihil.std;
 import nihil.error;
+import nihil.util;
 
 namespace nihil {
 
@@ -23,9 +20,10 @@ namespace nihil {
 // future calls to setenv().
 export [[nodiscard]] auto getenv(std::string_view varname) -> std::expected<std::string, error>
 {
+	auto errno_guard = save_errno();
 	auto cvarname = std::string(varname);
 
-#ifdef NIHIL_HAVE_GETENV_R
+#if NIHIL_HAVE_GETENV_R == 1
 	// Start with a buffer of this size, and double it every iteration.
 	constexpr auto bufinc = std::size_t{1024};
 
@@ -44,16 +42,14 @@ export [[nodiscard]] auto getenv(std::string_view varname) -> std::expected<std:
 		return std::unexpected(error(std::errc(errno)));
 	}
 #else  // NIHIL_HAVE_GETENV_R
-	errno = 0;
-	auto *v = ::getenv(cvarname.c_str()); // NOLINT
+	// getenv() may not set errno on failure, so initialise it to a reasonable value.
+	errno = ENOENT;
+	auto const *v = ::getenv(cvarname.c_str()); // NOLINT
 
 	if (v != nullptr)
 		return {std::string(v)};
 
-	if (errno != 0)
-		return std::unexpected(error(std::errc(errno)));
-
-	return std::unexpected(error(std::errc::no_such_file_or_directory));
+	return error(sys_error());
 #endif // NIHIL_HAVE_GETENV_R
 }
 
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