Improve synchronization

- Fix bugs in kDos2Errno definition
- malloc() should now be thread safe
- Fix bug in rollup.com header generator
- Fix open(O_APPEND) on the New Technology
- Fix select() on the New Technology and test it
- Work towards refactoring i/o for thread safety
- Socket reads and writes on NT now poll for signals
- Work towards i/o completion ports on the New Technology
- Make read() and write() intermittently check for signals
- Blinkenlights keyboard i/o so much better on NT w/ poll()
- You can now poll() files and sockets at the same time on NT
- Fix bug in appendr() that manifests with dlmalloc footers off

test/libc/calls/fcntl_test.c

@@ -17,6 +17,7 @@
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/calls/calls.h"
+#include "libc/dce.h"
 #include "libc/fmt/fmt.h"
 #include "libc/log/check.h"
 #include "libc/macros.internal.h"
@@ -40,9 +41,12 @@ TEST(fcntl_getfl, testRemembersAccessMode) {
 }
 
 TEST(fcntl_setfl, testChangeAppendStatus) {
+  if (IsWindows()) {
+    // no obivous way to do fcntl(fd, F_SETFL, O_APPEND)
+    return;
+  }
   int fd;
   char buf[8] = {0};
-  if (IsWindows()) return; /* doesn't appear possible on windows */
   ASSERT_NE(-1, (fd = open("foo", O_CREAT | O_RDWR, 0644)));
   EXPECT_EQ(3, write(fd, "foo", 3));
   EXPECT_NE(-1, lseek(fd, 0, SEEK_SET));

test/libc/calls/open_test.c

@@ -0,0 +1,59 @@
+/*-*- 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 2020 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/sysv/consts/o.h"
+#include "libc/testlib/testlib.h"
+#include "libc/x/x.h"
+
+char testlib_enable_tmp_setup_teardown;
+
+TEST(open, testOpenExistingForWriteOnly_seeksToStart) {
+  char buf[8] = {0};
+  ASSERT_SYS(0, 0, xbarf("hello.txt", "hello", -1));
+  ASSERT_SYS(0, 3, open("hello.txt", O_WRONLY));
+  EXPECT_SYS(0, 1, write(3, "H", 1));
+  EXPECT_SYS(0, 0, close(3));
+  ASSERT_SYS(0, 3, open("hello.txt", O_RDONLY));
+  EXPECT_SYS(0, 5, read(3, buf, 7));
+  EXPECT_STREQ("Hello", buf);
+  EXPECT_SYS(0, 0, close(3));
+}
+
+TEST(open, testOpenExistingForReadWrite_seeksToStart) {
+  char buf[8] = {0};
+  ASSERT_SYS(0, 0, xbarf("hello.txt", "hello", -1));
+  ASSERT_SYS(0, 3, open("hello.txt", O_RDWR));
+  EXPECT_SYS(0, 1, write(3, "H", 1));
+  EXPECT_SYS(0, 0, close(3));
+  ASSERT_SYS(0, 3, open("hello.txt", O_RDONLY));
+  EXPECT_SYS(0, 5, read(3, buf, 7));
+  EXPECT_STREQ("Hello", buf);
+  EXPECT_SYS(0, 0, close(3));
+}
+
+TEST(open, testOpenExistingForAppendWriteOnly_seeksToEnd) {
+  char buf[8] = {0};
+  ASSERT_SYS(0, 0, xbarf("hello.txt", "hell", -1));
+  ASSERT_SYS(0, 3, open("hello.txt", O_WRONLY | O_APPEND));
+  EXPECT_SYS(0, 1, write(3, "o", 1));
+  EXPECT_SYS(0, 0, close(3));
+  ASSERT_SYS(0, 3, open("hello.txt", O_RDONLY));
+  EXPECT_SYS(0, 5, read(3, buf, 7));
+  EXPECT_STREQ("hello", buf);
+  EXPECT_SYS(0, 0, close(3));
+}