get_env for Win32, @pierrec's get_config_dir and get_home_dir

lib/std/io/path.c3

@@ -448,6 +448,17 @@ fn void Path.free(self)
 	free(self.path_string.ptr);
 }
 
+
+fn usz! Path.to_format(&self, Formatter* formatter) @dynamic
+{
+	return formatter.print(self.str_view());
+}
+
+fn String Path.to_string(&self, Allocator* using = mem::heap()) @dynamic
+{
+	return self.str_view().copy(using);
+}
+
 const bool[256] RESERVED_PATH_CHAR_POSIX = {
 	[0] = true,
 	['/'] = true,

lib/std/io/stream.c3

@@ -430,7 +430,7 @@ macro usz! Stream.write_varint(&self, x)
 {
 	var $Type = $typeof(x);
 	const MAX = MAX_VARS[$Type.sizeof];
-	char[MAX] buffer;
+	char[MAX] buffer @noinit;
 	usz i;
 	while (x >= 0x80)
 	{

lib/std/os/env.c3

@@ -1,4 +1,4 @@
-// Copyright (c) 2021 Christoffer Lerno. All rights reserved.
+// Copyright (c) 2021-2023 Christoffer Lerno. All rights reserved.
 // Use of this source code is governed by the MIT license
 // a copy of which can be found in the LICENSE_STDLIB file.
 module std::os::env;
@@ -7,53 +7,119 @@ import libc;
 /**
  * @param [in] name
  * @require name.len > 0
+ * @return! SearchResult.MISSING
  **/
-fn String! get_var(String name)
+fn String! get_var(String name, Allocator* using = mem::heap())
 {
-	$if env::LIBC && !env::WIN32:
-	@pool()
+	@pool(using)
 	{
+	$switch
+	$case env::LIBC && !env::WIN32:
 		ZString val = libc::getenv(name.zstr_tcopy());
-		return val ? val.str_view() : SearchResult.MISSING?;
+		return val ? val.copy(using) : SearchResult.MISSING?;
+	$case env::WIN32:
+		// https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-getenvironmentvariable
+		const usz BUFSIZE = 1024;
+		WString buff = (WString)tcalloc(BUFSIZE * 2 + 2);
+		WString wstr = name.to_wstring(mem::temp())!;
+		usz len = win32::getEnvironmentVariableW(wstr, buff, BUFSIZE);
+		if (len == 0) return SearchResult.MISSING?;
+		if (len > BUFSIZE)
+		{
+			buff = (WString)tmalloc(len * 2 + 2);
+			win32::getEnvironmentVariableW(wstr, buff, (Win32_DWORD)len);
+		}
+		return string::from_wstring(buff, using);
+	$default:
+		return "";
+	$endswitch
 	};
-	$else
-	return "";
-	$endif
 }
 
+
 /**
  * @param [in] name
  * @param [in] value
  * @require name.len > 0
  **/
-fn void set_var(String name, String value, bool overwrite = true)
+fn bool set_var(String name, String value, bool overwrite = true)
 {
-	$if env::LIBC && !env::WIN32:
 	@pool()
 	{
-		if (libc::setenv(name.zstr_tcopy(), value.zstr_copy(), (int)overwrite))
+	$switch
+	$case env::WIN32:
+		WString wname = name.to_wstring(mem::temp())!!;
+		if (!overwrite)
 		{
-			unreachable();
+			Char16[8] buff;
+			if (win32::getEnvironmentVariableW(wname, &buff, 8) > 0) return true;
 		}
+		// https://learn.microsoft.com/en-us/windows/win32/api/winbase/nf-winbase-setenvironmentvariable
+		return (win32::setEnvironmentVariableW(wname, value.to_wstring(mem::temp())) ?? 1) == 0;
+	$case env::LIBC && !env::WIN32:
+		return libc::setenv(name.zstr_tcopy(), value.zstr_copy(), (int)overwrite) == 0;
+	$default:
+		return false;
+	$endswitch
 	};
+
+}
+
+/**
+ * Returns the current user's home directory.
+ **/
+fn String! get_home_dir(Allocator* using = mem::heap())
+{
+	String home;
+	$if !env::WIN32:
+		home = "HOME";
+	$else
+		home = "USERPROFILE";
 	$endif
+	return get_var(home, using);
 }
 
+/**
+ * Returns the current user's config directory.
+ **/
+fn Path! get_config_dir(Allocator* using = mem::heap())
+{
+	@pool(using)
+	{
+	$if env::WIN32:
+		return path::new(get_var("AppData", .using = mem::temp()), .using = using);
+	$else
+		$if env::DARWIN:
+			String s = get_var("HOME", .using = mem::temp())!;
+			const DIR = "Library/Application Support";
+		$else
+			String s = get_var("XDG_CONFIG_HOME", .using = mem::temp()) ?? get_var("HOME", .using = mem::temp())!;
+			const DIR = ".config";
+		$endif
+		return path::new(s, .using = mem::temp()).append(DIR, .using = using);
+	$endif
+	};
+}
+
+
 /**
  * @param [in] name
  * @require name.len > 0
  **/
-fn void clear_var(String name)
+fn bool clear_var(String name)
 {
-	$if env::LIBC && !env::WIN32:
 	@pool()
 	{
-		if (libc::unsetenv(name.zstr_tcopy()))
-		{
-			unreachable();
-		}
+	$switch
+	$case env::WIN32:
+		WString wname = name.to_wstring(mem::temp())!!;
+		return win32::setEnvironmentVariableW(wname, null) == 0;
+	$case env::LIBC && !env::WIN32:
+		return libc::unsetenv(name.zstr_tcopy()) == 0;
+	$default:
+		return false;
+	$endswitch
 	};
-	$endif
 }
 
 fn String! executable_path(Allocator *using = mem::heap())

lib/std/os/win32/process.c3

@@ -83,7 +83,15 @@ extern fn Win32_BOOL getOverlappedResult(
 	Win32_LPDWORD      lpNumberOfBytesTransferred,
 	Win32_BOOL         bWait
 ) @extern("GetOverlappedResult");
-
+extern fn Win32_DWORD getEnvironmentVariableW(
+	Win32_LPCWSTR lpName,
+	Win32_LPWSTR  lpBuffer,
+    Win32_DWORD   nSize
+) @extern("GetEnvironmentVariableW");
+extern fn Win32_BOOL setEnvironmentVariableW(
+	Win32_LPCWSTR lpName,
+	Win32_LPCWSTR lpValue
+);
 
 struct SystemInfo
 {

test/unit/stdlib/os/env.c3

@@ -0,0 +1,17 @@
+module std::os::env @test;
+
+ fn void! set_get_unset()
+ {
+ 	const NAME = "C3_TEST_ENVVAR";
+ 	const VALUE = "foobar";
+
+ 	env::set_var(NAME, VALUE);
+ 	String v = env::get_var(NAME)!;
+ 	assert(v == VALUE, "got %s; want %s", v, VALUE);
+
+ 	env::clear_var(NAME);
+ 	if (try env::get_var(NAME))
+ 	{
+ 		assert(false, "environment variable should no longer exist");
+ 	}
+ }