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/sock/poll_test.c

@@ -16,16 +16,25 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/calls/calls.h"
+#include "libc/calls/sigbits.h"
+#include "libc/dce.h"
+#include "libc/intrin/kprintf.h"
 #include "libc/log/libfatal.internal.h"
+#include "libc/nexgen32e/rdtsc.h"
+#include "libc/nexgen32e/rdtscp.h"
+#include "libc/nt/synchronization.h"
 #include "libc/runtime/gc.internal.h"
 #include "libc/sock/sock.h"
 #include "libc/sysv/consts/af.h"
 #include "libc/sysv/consts/inaddr.h"
 #include "libc/sysv/consts/ipproto.h"
 #include "libc/sysv/consts/poll.h"
+#include "libc/sysv/consts/sig.h"
 #include "libc/sysv/consts/sock.h"
 #include "libc/testlib/testlib.h"
 #include "libc/x/x.h"
+#include "third_party/chibicc/test/test.h"
 #include "tool/decode/lib/flagger.h"
 #include "tool/decode/lib/pollnames.h"
 
@@ -36,6 +45,10 @@ dontdiscard char *FormatPollFd(struct pollfd p[2]) {
                    p[1].fd, gc(RecreateFlags(kPollNames, p[1].revents)));
 }
 
+TEST(poll, allZero_doesNothing_exceptValidateAndCheckForSignals) {
+  EXPECT_SYS(0, 0, poll(0, 0, 0));
+}
+
 TEST(poll, testNegativeOneFd_isIgnored) {
   ASSERT_SYS(0, 3, socket(AF_INET, SOCK_STREAM, IPPROTO_TCP));
   struct sockaddr_in addr = {AF_INET, 0, {htonl(INADDR_LOOPBACK)}};
@@ -48,3 +61,79 @@ TEST(poll, testNegativeOneFd_isIgnored) {
                gc(FormatPollFd(&fds[0])));
   ASSERT_SYS(0, 0, close(3));
 }
+
+TEST(poll, pipe_noInput) {
+  // we can't test stdin here since
+  // we can't assume it isn't /dev/null
+  // since nil is always pollin as eof
+  int pipefds[2];
+  EXPECT_SYS(0, 0, pipe(pipefds));
+  struct pollfd fds[] = {{pipefds[0], POLLIN}};
+  EXPECT_SYS(0, 0, poll(fds, 1, 0));
+  EXPECT_EQ(0, fds[0].revents);
+  EXPECT_SYS(0, 0, close(pipefds[0]));
+  EXPECT_SYS(0, 0, close(pipefds[1]));
+}
+
+TEST(poll, pipe_hasInputFromSameProcess) {
+  char buf[2];
+  int pipefds[2];
+  EXPECT_SYS(0, 0, pipe(pipefds));
+  struct pollfd fds[] = {{pipefds[0], POLLIN}};
+  EXPECT_SYS(0, 2, write(pipefds[1], "hi", 2));
+  EXPECT_SYS(0, 1, poll(fds, 1, 1000));  // flake nt!
+  EXPECT_EQ(POLLIN, fds[0].revents);
+  EXPECT_SYS(0, 2, read(pipefds[0], buf, 2));
+  EXPECT_SYS(0, 0, poll(fds, 1, 0));
+  EXPECT_SYS(0, 0, close(pipefds[0]));
+  EXPECT_SYS(0, 0, close(pipefds[1]));
+}
+
+TEST(poll, pipe_hasInput) {
+  char buf[2];
+  sigset_t chldmask, savemask;
+  int ws, pid, sync[2], pipefds[2];
+  EXPECT_EQ(0, sigemptyset(&chldmask));
+  EXPECT_EQ(0, sigaddset(&chldmask, SIGCHLD));
+  EXPECT_EQ(0, sigprocmask(SIG_BLOCK, &chldmask, &savemask));
+  EXPECT_SYS(0, 0, pipe(pipefds));
+  EXPECT_NE(-1, (pid = fork()));
+  if (!pid) {
+    EXPECT_SYS(0, 0, close(pipefds[0]));
+    EXPECT_SYS(0, 2, write(pipefds[1], "hi", 2));
+    EXPECT_SYS(0, 2, write(pipefds[1], "hi", 2));
+    EXPECT_SYS(0, 0, close(pipefds[1]));
+    _Exit(0);
+  }
+  EXPECT_SYS(0, 0, close(pipefds[1]));
+  EXPECT_SYS(0, 2, read(pipefds[0], buf, 2));
+  struct pollfd fds[] = {{pipefds[0], POLLIN}};
+  EXPECT_SYS(0, 1, poll(fds, 1, -1));
+  EXPECT_EQ(POLLIN, fds[0].revents & POLLIN);
+  EXPECT_SYS(0, 2, read(pipefds[0], buf, 2));
+  EXPECT_SYS(0, 0, close(pipefds[0]));
+  ASSERT_NE(-1, wait(&ws));
+  EXPECT_TRUE(WIFEXITED(ws));
+  EXPECT_EQ(0, WEXITSTATUS(ws));
+  EXPECT_EQ(0, sigprocmask(SIG_SETMASK, &savemask, 0));
+}
+
+#if 0
+TEST(poll, emptyFds_becomesSleep) {
+  // timing tests w/o mocks are always the hardest
+  int64_t a, b, c, p, i = 0;
+  do {
+    if (++i == 5) {
+      kprintf("too much cpu churn%n");
+      return;
+    }
+    p = TSC_AUX_CORE(rdpid());
+    a = rdtsc();
+    EXPECT_SYS(0, 0, poll(0, 0, 5));
+    b = rdtsc();
+    EXPECT_SYS(0, 0, poll(0, 0, 50));
+    c = rdtsc();
+  } while (TSC_AUX_CORE(rdpid()) != p);
+  EXPECT_LT((b - a) * 2, c - b);
+}
+#endif