Make improvements

- Improved async signal safety of read() particularly for longjmp()
- Started adding cancel cleanup handlers for locks / etc on Windows
- Make /dev/tty work better particularly for uses like `foo | less`
- Eagerly read console input into a linked list, so poll can signal
- Fix some libc definitional bugs, which configure scripts detected

libc/sock/select-nt.c

@@ -16,10 +16,12 @@
 │ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR             │
 │ PERFORMANCE OF THIS SOFTWARE.                                                │
 ╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/assert.h"
 #include "libc/calls/bo.internal.h"
 #include "libc/calls/internal.h"
 #include "libc/calls/state.internal.h"
 #include "libc/calls/struct/timeval.h"
+#include "libc/limits.h"
 #include "libc/macros.internal.h"
 #include "libc/sock/select.h"
 #include "libc/sock/sock.h"
@@ -34,11 +36,10 @@
 int sys_select_nt(int nfds, fd_set *readfds, fd_set *writefds,
                   fd_set *exceptfds, struct timeval *timeout,
                   const sigset_t *sigmask) {
-  uint64_t millis;
   int i, pfds, events, fdcount;
-  struct pollfd fds[64];
 
   // convert bitsets to pollfd
+  struct pollfd fds[64];
   for (pfds = i = 0; i < nfds; ++i) {
     events = 0;
     if (readfds && FD_ISSET(i, readfds)) events |= POLLIN;
@@ -57,26 +58,49 @@ int sys_select_nt(int nfds, fd_set *readfds, fd_set *writefds,
   }
 
   // convert the wait time to a word
+  uint32_t millis;
   if (!timeout) {
     millis = -1;
   } else {
-    millis = timeval_tomillis(*timeout);
+    int64_t ms = timeval_tomillis(*timeout);
+    if (ms < 0 || ms > UINT32_MAX) {
+      millis = -1u;
+    } else {
+      millis = ms;
+    }
   }
 
   // call our nt poll implementation
   BEGIN_BLOCKING_OPERATION;
   fdcount = sys_poll_nt(fds, pfds, &millis, sigmask);
+  unassert(fdcount < 64);
   END_BLOCKING_OPERATION;
-  if (fdcount == -1) return -1;
+  if (fdcount < 0) return -1;
 
   // convert pollfd back to bitsets
   if (readfds) FD_ZERO(readfds);
   if (writefds) FD_ZERO(writefds);
   if (exceptfds) FD_ZERO(exceptfds);
-  for (i = 0; i < fdcount; ++i) {
-    if (fds[i].revents & POLLIN) FD_SET(fds[i].fd, readfds);
-    if (fds[i].revents & POLLOUT) FD_SET(fds[i].fd, writefds);
-    if (fds[i].revents & (POLLERR | POLLNVAL)) FD_SET(fds[i].fd, exceptfds);
+  int bits = 0;
+  for (i = 0; i < pfds; ++i) {
+    if (fds[i].revents & POLLIN) {
+      if (readfds) {
+        FD_SET(fds[i].fd, readfds);
+        ++bits;
+      }
+    }
+    if (fds[i].revents & POLLOUT) {
+      if (writefds) {
+        FD_SET(fds[i].fd, writefds);
+        ++bits;
+      }
+    }
+    if (fds[i].revents & (POLLERR | POLLNVAL)) {
+      if (exceptfds) {
+        FD_SET(fds[i].fd, exceptfds);
+        ++bits;
+      }
+    }
   }
 
   // store remaining time back in caller's timeval
@@ -84,7 +108,7 @@ int sys_select_nt(int nfds, fd_set *readfds, fd_set *writefds,
     *timeout = timeval_frommillis(millis);
   }
 
-  return fdcount;
+  return bits;
 }
 
 #endif /* __x86_64__ */