1 files changed, 342 insertions, 158 deletions

diff --git a/deps/uv/src/unix/signal.c b/deps/uv/src/unix/signal.c
index 8ef640b6fa..45555b52b7 100644
--- a/deps/uv/src/unix/signal.c
+++ b/deps/uv/src/unix/signal.c
@@ -22,248 +22,432 @@
 #include "internal.h"
 
 #include <assert.h>
+#include <errno.h>
+#include <signal.h>
 #include <stdlib.h>
 #include <string.h>
-#include <signal.h>
 #include <unistd.h>
-#include <errno.h>
 
-struct signal_ctx {
-  int pipefd[2];
-  uv__io_t io_watcher;
-  unsigned int nqueues;
-  ngx_queue_t queues[1]; /* variable length */
-};
 
-static void uv__signal_handler(int signum);
-static void uv__signal_event(uv_loop_t* loop, uv__io_t* w, int events);
-static struct signal_ctx* uv__signal_ctx_new(uv_loop_t* loop);
-static void uv__signal_ctx_delete(struct signal_ctx* ctx);
-static void uv__signal_write(int fd, unsigned int val);
-static unsigned int uv__signal_read(int fd);
-static unsigned int uv__signal_max(void);
+typedef struct {
+  uv_signal_t* handle;
+  int signum;
+} uv__signal_msg_t;
 
+RB_HEAD(uv__signal_tree_s, uv_signal_s);
 
-int uv_signal_init(uv_loop_t* loop, uv_signal_t* handle) {
-  uv__handle_init(loop, (uv_handle_t*)handle, UV_SIGNAL);
-  handle->signum = 0;
-  return 0;
+
+static int uv__signal_unlock();
+static void uv__signal_event(uv_loop_t* loop, uv__io_t* watcher, int events);
+static int uv__signal_compare(uv_signal_t* w1, uv_signal_t* w2);
+static void uv__signal_stop(uv_signal_t* handle);
+
+
+static pthread_once_t uv__signal_global_init_guard = PTHREAD_ONCE_INIT;
+static struct uv__signal_tree_s uv__signal_tree =
+    RB_INITIALIZER(uv__signal_tree);
+static int uv__signal_lock_pipefd[2];
+
+
+RB_GENERATE_STATIC(uv__signal_tree_s,
+                   uv_signal_s, tree_entry,
+                   uv__signal_compare)
+
+
+static void uv__signal_global_init() {
+  if (uv__make_pipe(uv__signal_lock_pipefd, 0))
+    abort();
+
+  if (uv__signal_unlock())
+    abort();
 }
 
 
-int uv_signal_start(uv_signal_t* handle, uv_signal_cb signal_cb, int signum_) {
-  struct signal_ctx* ctx;
-  struct sigaction sa;
-  unsigned int signum;
-  uv_loop_t* loop;
-  ngx_queue_t* q;
+void uv__signal_global_once_init(void) {
+  pthread_once(&uv__signal_global_init_guard, uv__signal_global_init);
+}
 
-  /* XXX doing this check in uv_signal_init() - the logical place for it -
-   * leads to an infinite loop when uv__loop_init() inits a signal watcher
-   */
-  /* FIXME */
-  assert(handle->loop == uv_default_loop() &&
-         "uv_signal_t is currently only supported by the default loop");
 
-  loop = handle->loop;
-  signum = signum_;
 
-  if (uv__is_active(handle))
-    return uv__set_artificial_error(loop, UV_EBUSY);
+static int uv__signal_lock() {
+  int r;
+  char data;
+
+  do {
+    r = read(uv__signal_lock_pipefd[0], &data, sizeof data);
+  } while (r < 0 && errno == EINTR);
+
+  return (r < 0) ? -1 : 0;
+}
+
 
-  if (signal_cb == NULL)
-    return uv__set_artificial_error(loop, UV_EINVAL);
+static int uv__signal_unlock() {
+  int r;
+  char data = 42;
 
-  if (signum <= 0)
-    return uv__set_artificial_error(loop, UV_EINVAL);
+  do {
+    r = write(uv__signal_lock_pipefd[1], &data, sizeof data);
+  } while (r < 0 && errno == EINTR);
+
+  return (r < 0) ? -1 : 0;
+}
 
-  ctx = loop->signal_ctx;
 
-  if (ctx == NULL) {
-    ctx = uv__signal_ctx_new(loop);
+static void uv__signal_block_and_lock(sigset_t* saved_sigmask) {
+  sigset_t new_mask;
 
-    if (ctx == NULL)
-      return uv__set_artificial_error(loop, UV_ENOMEM);
+  if (sigfillset(&new_mask))
+    abort();
+
+  if (pthread_sigmask(SIG_SETMASK, &new_mask, saved_sigmask))
+    abort();
+
+  if (uv__signal_lock())
+    abort();
+}
 
-    loop->signal_ctx = ctx;
+
+static void uv__signal_unlock_and_unblock(sigset_t* saved_sigmask) {
+  if (uv__signal_unlock())
+    abort();
+
+  if (pthread_sigmask(SIG_SETMASK, saved_sigmask, NULL))
+    abort();
+}
+
+
+inline static uv_signal_t* uv__signal_first_handle(int signum) {
+  /* This function must be called with the signal lock held. */
+  uv_signal_t lookup;
+  uv_signal_t* handle;
+
+  lookup.signum = signum;
+  lookup.loop = NULL;
+
+  handle = RB_NFIND(uv__signal_tree_s, &uv__signal_tree, &lookup);
+
+  if (handle != NULL && handle->signum == signum)
+    return handle;
+
+  return NULL;
+}
+
+
+void uv__signal_handler(int signum) {
+  uv__signal_msg_t msg;
+  uv_signal_t* handle;
+
+  memset(&msg, 0, sizeof msg);
+
+  uv__signal_lock();
+
+  for (handle = uv__signal_first_handle(signum);
+       handle != NULL && handle->signum == signum;
+       handle = RB_NEXT(uv__signal_tree_s, &uv__signal_tree, handle)) {
+    int r;
+
+    msg.signum = signum;
+    msg.handle = handle;
+
+    /* write() should be atomic for small data chunks, so the entire message
+     * should be written at once. In theory the pipe could become full, in
+     * which case the user is out of luck.
+     */
+    do {
+      r = write(handle->loop->signal_pipefd[1], &msg, sizeof msg);
+    } while (r == -1 && errno == EINTR);
+
+    assert(r == sizeof msg ||
+           (r == -1 && errno != EAGAIN && errno != EWOULDBLOCK));
+
+    if (r != -1)
+      handle->caught_signals++;
   }
 
-  if (signum > ctx->nqueues)
-    return uv__set_artificial_error(loop, UV_EINVAL);
+  uv__signal_unlock();
+}
 
-  q = ctx->queues + signum;
 
-  if (!ngx_queue_empty(q))
-    goto skip;
+static uv_err_t uv__signal_register_handler(int signum) {
+  /* When this function is called, the signal lock must be held. */
+  struct sigaction sa;
 
   /* XXX use a separate signal stack? */
   memset(&sa, 0, sizeof(sa));
+  if (sigfillset(&sa.sa_mask))
+    abort();
   sa.sa_handler = uv__signal_handler;
 
   /* XXX save old action so we can restore it later on? */
   if (sigaction(signum, &sa, NULL))
-    return uv__set_artificial_error(loop, UV_EINVAL);
+    return uv__new_sys_error(errno);
 
-skip:
-  ngx_queue_insert_tail(q, &handle->queue);
-  uv__handle_start(handle);
-  handle->signum = signum;
-  handle->signal_cb = signal_cb;
-
-  return 0;
+  return uv_ok_;
 }
 
 
-int uv_signal_stop(uv_signal_t* handle) {
-  struct signal_ctx* ctx;
+static void uv__signal_unregister_handler(int signum) {
+  /* When this function is called, the signal lock must be held. */
   struct sigaction sa;
-  unsigned int signum;
-  uv_loop_t* loop;
+  int r;
 
-  if (!uv__is_active(handle))
-    return 0;
+  memset(&sa, 0, sizeof(sa));
+  sa.sa_handler = SIG_DFL;
 
-  signum = handle->signum;
-  loop = handle->loop;
-  ctx = loop->signal_ctx;
-  assert(signum > 0);
-  assert(signum <= ctx->nqueues);
+  r = sigaction(signum, &sa, NULL);
+  /* sigaction can only fail with EINVAL or EFAULT; an attempt to deregister a
+   * signal implies that it was successfully registered earlier, so EINVAL
+   * should never happen.
+   */
+  assert(r == 0);
+}
 
-  ngx_queue_remove(&handle->queue);
-  uv__handle_stop(handle);
-  handle->signum = 0;
 
-  if (!ngx_queue_empty(ctx->queues + signum))
-    goto skip;
+static int uv__signal_loop_once_init(uv_loop_t* loop) {
+  /* Return if already initialized. */
+  if (loop->signal_pipefd[0] != -1)
+    return 0;
 
-  memset(&sa, 0, sizeof(sa));
-  sa.sa_handler = SIG_DFL; /* XXX restore previous action? */
+  if (uv__make_pipe(loop->signal_pipefd, UV__F_NONBLOCK))
+    return -1;
 
-  if (sigaction(signum, &sa, NULL))
-    return uv__set_artificial_error(loop, UV_EINVAL);
+  uv__io_init(&loop->signal_io_watcher,
+              uv__signal_event,
+              loop->signal_pipefd[0],
+              UV__IO_READ);
+  uv__io_start(loop, &loop->signal_io_watcher);
 
-skip:
   return 0;
 }
 
 
-void uv__signal_close(uv_signal_t* handle) {
-  uv_signal_stop(handle);
-}
+void uv__signal_loop_cleanup(uv_loop_t* loop) {
+  ngx_queue_t* q;
 
+  /* Stop all the signal watchers that are still attached to this loop. This
+   * ensures that the (shared) signal tree doesn't contain any invalid entries
+   * entries, and that signal handlers are removed when appropriate.
+   */
+  ngx_queue_foreach(q, &loop->handle_queue) {
+    uv_handle_t* handle = ngx_queue_data(q, uv_handle_t, handle_queue);
 
-void uv__signal_unregister(uv_loop_t* loop) {
-  uv__signal_ctx_delete(loop->signal_ctx);
-  loop->signal_ctx = NULL;
+    if (handle->type == UV_SIGNAL)
+      uv__signal_stop((uv_signal_t*) handle);
+  }
+
+  if (loop->signal_pipefd[0] != -1) {
+    close(loop->signal_pipefd[0]);
+    loop->signal_pipefd[0] = -1;
+  }
+
+  if (loop->signal_pipefd[1] != -1) {
+    close(loop->signal_pipefd[1]);
+    loop->signal_pipefd[1] = -1;
+  }
 }
 
 
-static void uv__signal_handler(int signum) {
-  struct signal_ctx* ctx = uv_default_loop()->signal_ctx;
-  uv__signal_write(ctx->pipefd[1], (unsigned int) signum);
+int uv_signal_init(uv_loop_t* loop, uv_signal_t* handle) {
+  if (uv__signal_loop_once_init(loop))
+    return uv__set_sys_error(loop, errno);
+
+  uv__handle_init(loop, (uv_handle_t*) handle, UV_SIGNAL);
+  handle->signum = 0;
+  handle->caught_signals = 0;
+  handle->dispatched_signals = 0;
+
+  return 0;
 }
 
 
-static void uv__signal_event(uv_loop_t* loop, uv__io_t* w, int events) {
-  struct signal_ctx* ctx;
-  unsigned int signum;
-  uv_signal_t* h;
-  ngx_queue_t* q;
+void uv__signal_close(uv_signal_t* handle) {
 
-  ctx = container_of(w, struct signal_ctx, io_watcher);
-  signum = uv__signal_read(ctx->pipefd[0]);
-  assert(signum > 0);
-  assert(signum <= ctx->nqueues);
+  uv__signal_stop(handle);
 
-  ngx_queue_foreach(q, ctx->queues + signum) {
-    h = ngx_queue_data(q, uv_signal_t, queue);
-    h->signal_cb(h, signum);
+  /* If there are any caught signals "trapped" in the signal pipe, we can't
+   * call the close callback yet. Otherwise, add the handle to the finish_close
+   * queue.
+   */
+  if (handle->caught_signals == handle->dispatched_signals) {
+    uv__make_close_pending((uv_handle_t*) handle);
   }
 }
 
 
-static struct signal_ctx* uv__signal_ctx_new(uv_loop_t* loop) {
-  struct signal_ctx* ctx;
-  unsigned int nqueues;
-  unsigned int i;
+int uv_signal_start(uv_signal_t* handle, uv_signal_cb signal_cb, int signum) {
+  sigset_t saved_sigmask;
+
+  assert(!(handle->flags & (UV_CLOSING | UV_CLOSED)));
 
-  nqueues = uv__signal_max();
-  assert(nqueues > 0);
+  /* If the user supplies signum == 0, then return an error already. If the
+   * signum is otherwise invalid then uv__signal_register will find out
+   * eventually.
+   */
+  if (signum == 0) {
+    uv__set_artificial_error(handle->loop, UV_EINVAL);
+    return -1;
+  }
 
-  /* The first ctx->queues entry is never used. It wastes a few bytes of memory
-   * but it saves us from having to substract 1 from the signum all the time -
-   * which inevitably someone will forget to do.
+  /* Short circuit: if the signal watcher is already watching {signum} don't
+   * go through the process of deregistering and registering the handler.
+   * Additionally, this avoids pending signals getting lost in the small time
+   * time frame that handle->signum == 0.
    */
-  ctx = calloc(1, sizeof(*ctx) + sizeof(ctx->queues[0]) * (nqueues + 1));
-  if (ctx == NULL)
-    return NULL;
+  if (signum == handle->signum) {
+    handle->signal_cb = signal_cb;
+    return 0;
+  }
+
+  /* If the signal handler was already active, stop it first. */
+  if (handle->signum != 0) {
+    uv__signal_stop(handle);
+  }
+
+  uv__signal_block_and_lock(&saved_sigmask);
 
-  if (uv__make_pipe(ctx->pipefd, UV__F_NONBLOCK)) {
-    free(ctx);
-    return NULL;
+  /* If at this point there are no active signal watchers for this signum (in
+   * any of the loops), it's time to try and register a handler for it here.
+   */
+  if (uv__signal_first_handle(signum) == NULL) {
+    uv_err_t err = uv__signal_register_handler(signum);
+    if (err.code != UV_OK) {
+      /* Registering the signal handler failed. Must be an invalid signal. */
+      handle->loop->last_err = err;
+      uv__signal_unlock_and_unblock(&saved_sigmask);
+      return -1;
+    }
   }
 
-  uv__io_init(&ctx->io_watcher, uv__signal_event, ctx->pipefd[0], UV__IO_READ);
-  uv__io_start(loop, &ctx->io_watcher);
-  ctx->nqueues = nqueues;
+  handle->signum = signum;
+  RB_INSERT(uv__signal_tree_s, &uv__signal_tree, handle);
 
-  for (i = 1; i <= nqueues; i++)
-    ngx_queue_init(ctx->queues + i);
+  uv__signal_unlock_and_unblock(&saved_sigmask);
 
-  return ctx;
+  handle->signal_cb = signal_cb;
+  uv__handle_start(handle);
+
+  return 0;
 }
 
 
-static void uv__signal_ctx_delete(struct signal_ctx* ctx) {
-  if (ctx == NULL) return;
-  close(ctx->pipefd[0]);
-  close(ctx->pipefd[1]);
-  free(ctx);
+static void uv__signal_event(uv_loop_t* loop, uv__io_t* watcher, int events) {
+  uv__signal_msg_t* msg;
+  uv_signal_t* handle;
+  char buf[sizeof(uv__signal_msg_t) * 32];
+  size_t bytes, end, i;
+  int r;
+
+  bytes = 0;
+
+  do {
+    r = read(loop->signal_pipefd[0], buf + bytes, sizeof(buf) - bytes);
+
+    if (r == -1 && errno == EINTR)
+      continue;
+
+    if (r == -1 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
+      /* If there are bytes in the buffer already (which really is extremely
+       * unlikely if possible at all) we can't exit the function here. We'll
+       * spin until more bytes are read instead.
+       */
+      if (bytes > 0)
+        continue;
+
+      /* Otherwise, there was nothing there. */
+      return;
+    }
+
+    /* Other errors really should never happen. */
+    if (r == -1)
+      abort();
+
+    bytes += r;
+
+    /* `end` is rounded down to a multiple of sizeof(uv__signal_msg_t). */
+    end = (bytes / sizeof(uv__signal_msg_t)) * sizeof(uv__signal_msg_t);
+
+    for (i = 0; i < end; i += sizeof(uv__signal_msg_t)) {
+      msg = (uv__signal_msg_t*) (buf + i);
+      handle = msg->handle;
+
+      if (msg->signum == handle->signum) {
+        assert(!(handle->flags & UV_CLOSING));
+        handle->signal_cb(handle, handle->signum);
+      }
+
+      handle->dispatched_signals++;
+
+      /* If uv_close was called while there were caught signals that were not
+       * yet dispatched, the uv__finish_close was deferred. Make close pending
+       * now if this has happened.
+       */
+      if ((handle->flags & UV_CLOSING) &&
+          (handle->caught_signals == handle->dispatched_signals)) {
+        uv__make_close_pending((uv_handle_t*) handle);
+      }
+    }
+
+    bytes -= end;
+
+    /* If there are any "partial" messages left, move them to the start of the
+     * the buffer, and spin. This should not happen.
+     */
+    if (bytes) {
+      memmove(buf, buf + end, bytes);
+      continue;
+    }
+  } while (end == sizeof buf);
 }
 
 
-static void uv__signal_write(int fd, unsigned int val) {
-  ssize_t n;
+static int uv__signal_compare(uv_signal_t* w1, uv_signal_t* w2) {
+  /* Compare signums first so all watchers with the same signnum end up
+   * adjacent.
+   */
+  if (w1->signum < w2->signum) return -1;
+  if (w1->signum > w2->signum) return 1;
 
-  do
-    n = write(fd, &val, sizeof(val));
-  while (n == -1 && errno == EINTR);
+  /* Sort by loop pointer, so we can easily look up the first item after
+   * { .signum = x, .loop = NULL }.
+   */
+  if (w1->loop < w2->loop) return -1;
+  if (w1->loop > w2->loop) return 1;
 
-  if (n == sizeof(val))
-    return;
+  if (w1 < w2) return -1;
+  if (w1 > w2) return 1;
 
-  if (n == -1 && (errno == EAGAIN || errno == EWOULDBLOCK))
-    return; /* pipe full - nothing we can do about that */
+  return 0;
+}
 
-  abort();
+
+int uv_signal_stop(uv_signal_t* handle) {
+  assert(!(handle->flags & (UV_CLOSING | UV_CLOSED)));
+  uv__signal_stop(handle);
+  return 0;
 }
 
 
-static unsigned int uv__signal_read(int fd) {
-  unsigned int val;
-  ssize_t n;
+static void uv__signal_stop(uv_signal_t* handle) {
+  uv_signal_t* removed_handle;
+  sigset_t saved_sigmask;
 
-  do
-    n = read(fd, &val, sizeof(val));
-  while (n == -1 && errno == EINTR);
+  /* If the watcher wasn't started, this is a no-op. */
+  if (handle->signum == 0)
+    return;
 
-  if (n == sizeof(val))
-    return val;
+  uv__signal_block_and_lock(&saved_sigmask);
 
-  abort();
-}
+  removed_handle = RB_REMOVE(uv__signal_tree_s, &uv__signal_tree, handle);
+  assert(removed_handle == handle);
+
+  /* Check if there are other active signal watchers observing this signal. If
+   * not, unregister the signal handler.
+   */
+  if (uv__signal_first_handle(handle->signum) == NULL)
+    uv__signal_unregister_handler(handle->signum);
 
+  uv__signal_unlock_and_unblock(&saved_sigmask);
 
-static unsigned int uv__signal_max(void) {
-#if defined(_SC_RTSIG_MAX)
-  int max = sysconf(_SC_RTSIG_MAX);
-  if (max != -1) return max;
-#endif
-#if defined(SIGRTMAX)
-  return SIGRTMAX;
-#elif defined(NSIG)
-  return NSIG;
-#else
-  return 32;
-#endif
+  handle->signum = 0;
+  uv__handle_stop(handle);
 }