Adding upstream version 0.0~git20221206.8b7148f.upstream/0.0_git20221206.8b7148f

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 129 insertions, 0 deletions

diff --git a/libc-bottom-half/cloudlibc/src/libc/poll/poll.c b/libc-bottom-half/cloudlibc/src/libc/poll/poll.c
new file mode 100644
index 0000000..cde4e81
--- /dev/null
+++ b/libc-bottom-half/cloudlibc/src/libc/poll/poll.c
@@ -0,0 +1,129 @@
+// Copyright (c) 2015-2016 Nuxi, https://nuxi.nl/
+//
+// SPDX-License-Identifier: BSD-2-Clause
+
+#include <wasi/api.h>
+#include <errno.h>
+#include <poll.h>
+#include <stdbool.h>
+
+int poll(struct pollfd *fds, size_t nfds, int timeout) {
+  // Construct events for poll().
+  size_t maxevents = 2 * nfds + 1;
+  __wasi_subscription_t subscriptions[maxevents];
+  size_t nsubscriptions = 0;
+  for (size_t i = 0; i < nfds; ++i) {
+    struct pollfd *pollfd = &fds[i];
+    if (pollfd->fd < 0)
+      continue;
+    bool created_events = false;
+    if ((pollfd->events & POLLRDNORM) != 0) {
+      __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+      *subscription = (__wasi_subscription_t){
+          .userdata = (uintptr_t)pollfd,
+          .u.tag = __WASI_EVENTTYPE_FD_READ,
+          .u.u.fd_read.file_descriptor = pollfd->fd,
+      };
+      created_events = true;
+    }
+    if ((pollfd->events & POLLWRNORM) != 0) {
+      __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+      *subscription = (__wasi_subscription_t){
+          .userdata = (uintptr_t)pollfd,
+          .u.tag = __WASI_EVENTTYPE_FD_WRITE,
+          .u.u.fd_write.file_descriptor = pollfd->fd,
+      };
+      created_events = true;
+    }
+
+    // As entries are decomposed into separate read/write subscriptions,
+    // we cannot detect POLLERR, POLLHUP and POLLNVAL if POLLRDNORM and
+    // POLLWRNORM are not specified. Disallow this for now.
+    if (!created_events) {
+      errno = ENOSYS;
+      return -1;
+    }
+  }
+
+  // Create extra event for the timeout.
+  if (timeout >= 0) {
+    __wasi_subscription_t *subscription = &subscriptions[nsubscriptions++];
+    *subscription = (__wasi_subscription_t){
+        .u.tag = __WASI_EVENTTYPE_CLOCK,
+        .u.u.clock.id = __WASI_CLOCKID_REALTIME,
+        .u.u.clock.timeout = (__wasi_timestamp_t)timeout * 1000000,
+    };
+  }
+
+  // Execute poll().
+  size_t nevents;
+  __wasi_event_t events[nsubscriptions];
+  __wasi_errno_t error =
+      __wasi_poll_oneoff(subscriptions, events, nsubscriptions, &nevents);
+  if (error != 0) {
+    // WASI's poll requires at least one subscription, or else it returns
+    // `EINVAL`. Since a `poll` with nothing to wait for is valid in POSIX,
+    // return `ENOTSUP` to indicate that we don't support that case.
+    //
+    // Wasm has no signal handling, so if none of the user-provided `pollfd`
+    // elements, nor the timeout, led us to producing even one subscription
+    // to wait for, there would be no way for the poll to wake up. WASI
+    // returns `EINVAL` in this case, but for users of `poll`, `ENOTSUP` is
+    // more likely to be understood.
+    if (nsubscriptions == 0)
+      errno = ENOTSUP;
+    else
+      errno = error;
+    return -1;
+  }
+
+  // Clear revents fields.
+  for (size_t i = 0; i < nfds; ++i) {
+    struct pollfd *pollfd = &fds[i];
+    pollfd->revents = 0;
+  }
+
+  // Set revents fields.
+  for (size_t i = 0; i < nevents; ++i) {
+    const __wasi_event_t *event = &events[i];
+    if (event->type == __WASI_EVENTTYPE_FD_READ ||
+        event->type == __WASI_EVENTTYPE_FD_WRITE) {
+      struct pollfd *pollfd = (struct pollfd *)(uintptr_t)event->userdata;
+      if (event->error == __WASI_ERRNO_BADF) {
+        // Invalid file descriptor.
+        pollfd->revents |= POLLNVAL;
+      } else if (event->error == __WASI_ERRNO_PIPE) {
+        // Hangup on write side of pipe.
+        pollfd->revents |= POLLHUP;
+      } else if (event->error != 0) {
+        // Another error occurred.
+        pollfd->revents |= POLLERR;
+      } else {
+        // Data can be read or written.
+        if (event->type == __WASI_EVENTTYPE_FD_READ) {
+            pollfd->revents |= POLLRDNORM;
+            if (event->fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP) {
+              pollfd->revents |= POLLHUP;
+            }
+        } else if (event->type == __WASI_EVENTTYPE_FD_WRITE) {
+            pollfd->revents |= POLLWRNORM;
+            if (event->fd_readwrite.flags & __WASI_EVENTRWFLAGS_FD_READWRITE_HANGUP) {
+              pollfd->revents |= POLLHUP;
+            }
+        }
+      }
+    }
+  }
+
+  // Return the number of events with a non-zero revents value.
+  int retval = 0;
+  for (size_t i = 0; i < nfds; ++i) {
+    struct pollfd *pollfd = &fds[i];
+    // POLLHUP contradicts with POLLWRNORM.
+    if ((pollfd->revents & POLLHUP) != 0)
+      pollfd->revents &= ~POLLWRNORM;
+    if (pollfd->revents != 0)
+      ++retval;
+  }
+  return retval;
+}