Make improvements

- You can now run `make -j8 toolchain` on Windows
- You can now run `make -j` on MacOS ARM64 and BSD OSes
- You can now use our Emacs dev environment on MacOS/Windows
- Fix bug where the x16 register was being corrupted by --ftrace
- The programs under build/bootstrap/ are updated as fat binaries
- The Makefile now explains how to download cosmocc-0.0.12 toolchain
- The build scripts under bin/ now support "cosmo" branded toolchains
- stat() now goes faster on Windows (shaves 100ms off `make` latency)
- Code cleanup and added review on the Windows signal checking code
- posix_spawnattr_setrlimit() now works around MacOS ARM64 bugs
- Landlock Make now favors posix_spawn() on non-Linux/OpenBSD
- posix_spawn() now has better --strace logging on Windows
- fstatat() can now avoid EACCES in more cases on Windows
- fchmod() can now change the readonly bit on Windows

test/libc/calls/fchmod_test.c

@@ -0,0 +1,41 @@
+/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
+│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8                                :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2023 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ Permission to use, copy, modify, and/or distribute this software for         │
+│ any purpose with or without fee is hereby granted, provided that the         │
+│ above copyright notice and this permission notice appear in all copies.      │
+│                                                                              │
+│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL                │
+│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED                │
+│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE             │
+│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL         │
+│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR        │
+│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER               │
+│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
+│ PERFORMANCE OF THIS SOFTWARE.                                                │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
+#include "libc/calls/struct/stat.h"
+#include "libc/testlib/testlib.h"
+
+void SetUpOnce(void) {
+  testlib_enable_tmp_setup_teardown();
+}
+
+uint32_t GetMode(int fd) {
+  struct stat st;
+  ASSERT_SYS(0, 0, fstat(fd, &st));
+  return st.st_mode & 0777;
+}
+
+TEST(fchmod, canChangeReadOnlyBit) {
+  ASSERT_SYS(0, 3, creat("foo", 0600));
+  ASSERT_EQ(0600, GetMode(3));
+  ASSERT_SYS(0, 0, fchmod(3, 0400));
+  ASSERT_EQ(0400, GetMode(3));
+  ASSERT_SYS(0, 0, fchmod(3, 0600));
+  ASSERT_EQ(0600, GetMode(3));
+  ASSERT_SYS(0, 0, close(3));
+}

test/libc/calls/open_test.c

@@ -495,3 +495,16 @@ TEST(open, mereOpen_doesntTouch) {
   EXPECT_EQ(0, timespec_cmp(st.st_mtim, birth));
   EXPECT_EQ(0, timespec_cmp(st.st_atim, birth));
 }
+
+TEST(open, canTruncateExistingFile) {
+  struct stat st;
+  ASSERT_SYS(0, 0, xbarf("foo", "hello", -1));
+  ASSERT_SYS(0, 0, stat("foo", &st));
+  ASSERT_EQ(5, st.st_size);
+  ASSERT_SYS(0, 3, open("foo", O_RDWR | O_TRUNC));
+  ASSERT_SYS(0, 0, fstat(3, &st));
+  ASSERT_EQ(0, st.st_size);
+  ASSERT_SYS(0, 0, close(3));
+  ASSERT_SYS(0, 0, stat("foo", &st));
+  ASSERT_EQ(0, st.st_size);
+}

test/libc/thread/makecontext_test.c

@@ -21,6 +21,11 @@
 #include "libc/dce.h"
 #include "libc/limits.h"
 #include "libc/mem/gc.internal.h"
+#include "libc/nt/createfile.h"
+#include "libc/nt/enum/accessmask.h"
+#include "libc/nt/enum/creationdisposition.h"
+#include "libc/nt/enum/fileflagandattributes.h"
+#include "libc/nt/enum/filesharemode.h"
 #include "libc/runtime/runtime.h"
 #include "libc/runtime/stack.h"
 #include "libc/runtime/symbols.internal.h"
@@ -89,9 +94,14 @@ TEST(makecontext, crash) {
 TEST(makecontext, backtrace) {
   if (IsTiny()) return;  // doesn't print full crash report
   SPAWN(fork);
-  ASSERT_SYS(0, 0, close(2));
-  ASSERT_SYS(0, 2, creat("log", 0644));
-  __klog_handle = 2;
+  if (IsWindows()) {
+    __klog_handle =
+        CreateFile(u"log", kNtFileAppendData,
+                   kNtFileShareRead | kNtFileShareWrite | kNtFileShareDelete, 0,
+                   kNtOpenAlways, kNtFileAttributeNormal, 0);
+  } else {
+    __klog_handle = creat("log", 0644);
+  }
   getcontext(&uc);
   uc.uc_link = 0;
   uc.uc_stack.ss_sp = NewCosmoStack();

test/libc/thread/test.mk

@@ -29,6 +29,7 @@ TEST_LIBC_THREAD_DIRECTDEPS =				\
 	LIBC_LOG					\
 	LIBC_MEM					\
 	LIBC_NEXGEN32E					\
+	LIBC_NT_KERNEL32				\
 	LIBC_PROC					\
 	LIBC_RUNTIME					\
 	LIBC_SOCK					\