Use std::vector in event-loop.cc

In my occasional and continuing campaign against realloc, this patch
changes event-loop.cc to use std::vector to keep track of pollfd
objects.  Regression tested on x86-64 Fedora 38.

Approved-By: Simon Marchi <simon.marchi@efficios.com>
Approved-By: John Baldwin <jhb@FreeBSD.org>

diff --git a/gdbsupport/event-loop.cc b/gdbsupport/event-loop.cc
index b18a9fdaac0ac55b4e502a81f64881d3c2a272a7..4f7ad36d8d625b9b0da2e54471a960c9e102a87b 100644 (file)
--- a/gdbsupport/event-loop.cc
+++ b/gdbsupport/event-loop.cc
@@ -112,8 +112,8 @@ static struct
     file_handler *next_file_handler;
 
 #ifdef HAVE_POLL
-    /* Ptr to array of pollfd structures.  */
-    struct pollfd *poll_fds;
+    /* Descriptors to poll.  */
+    std::vector<struct pollfd> poll_fds;
 
     /* Next file descriptor to handle, for the poll variant.  To level
        the fairness across event sources, we poll the file descriptors
@@ -336,17 +336,11 @@ create_file_handler (int fd, int mask, handler_func * proc,
       if (use_poll)
        {
          gdb_notifier.num_fds++;
-         if (gdb_notifier.poll_fds)
-           gdb_notifier.poll_fds =
-             (struct pollfd *) xrealloc (gdb_notifier.poll_fds,
-                                         (gdb_notifier.num_fds
-                                          * sizeof (struct pollfd)));
-         else
-           gdb_notifier.poll_fds =
-             XNEW (struct pollfd);
-         (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->fd = fd;
-         (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->events = mask;
-         (gdb_notifier.poll_fds + gdb_notifier.num_fds - 1)->revents = 0;
+         struct pollfd new_fd;
+         new_fd.fd = fd;
+         new_fd.events = mask;
+         new_fd.revents = 0;
+         gdb_notifier.poll_fds.push_back (new_fd);
        }
       else
 #endif /* HAVE_POLL */
@@ -426,28 +420,13 @@ delete_file_handler (int fd)
 #ifdef HAVE_POLL
   if (use_poll)
     {
-      int j;
-      struct pollfd *new_poll_fds;
-
-      /* Create a new poll_fds array by copying every fd's information
-        but the one we want to get rid of.  */
-
-      new_poll_fds = (struct pollfd *) 
-       xmalloc ((gdb_notifier.num_fds - 1) * sizeof (struct pollfd));
-
-      for (i = 0, j = 0; i < gdb_notifier.num_fds; i++)
-       {
-         if ((gdb_notifier.poll_fds + i)->fd != fd)
-           {
-             (new_poll_fds + j)->fd = (gdb_notifier.poll_fds + i)->fd;
-             (new_poll_fds + j)->events = (gdb_notifier.poll_fds + i)->events;
-             (new_poll_fds + j)->revents
-               = (gdb_notifier.poll_fds + i)->revents;
-             j++;
-           }
-       }
-      xfree (gdb_notifier.poll_fds);
-      gdb_notifier.poll_fds = new_poll_fds;
+      auto iter = std::remove_if (gdb_notifier.poll_fds.begin (),
+                                 gdb_notifier.poll_fds.end (),
+                                 [=] (const pollfd &item)
+                                 {
+                                   return item.fd == fd;
+                                 });
+      gdb_notifier.poll_fds.erase (iter, gdb_notifier.poll_fds.end());
       gdb_notifier.num_fds--;
     }
   else
@@ -605,7 +584,7 @@ gdb_wait_for_event (int block)
       else
        timeout = 0;
 
-      num_found = poll (gdb_notifier.poll_fds,
+      num_found = poll (gdb_notifier.poll_fds.data (),
                        (unsigned long) gdb_notifier.num_fds, timeout);
 
       /* Don't print anything if we get out of poll because of a
@@ -676,7 +655,7 @@ gdb_wait_for_event (int block)
          i = gdb_notifier.next_poll_fds_index++;
 
          gdb_assert (i < gdb_notifier.num_fds);
-         if ((gdb_notifier.poll_fds + i)->revents)
+         if (gdb_notifier.poll_fds[i].revents)
            break;
        }
 
@@ -684,12 +663,12 @@ gdb_wait_for_event (int block)
           file_ptr != NULL;
           file_ptr = file_ptr->next_file)
        {
-         if (file_ptr->fd == (gdb_notifier.poll_fds + i)->fd)
+         if (file_ptr->fd == gdb_notifier.poll_fds[i].fd)
            break;
        }
       gdb_assert (file_ptr != NULL);
 
-      mask = (gdb_notifier.poll_fds + i)->revents;
+      mask = gdb_notifier.poll_fds[i].revents;
       handle_file_event (file_ptr, mask);
       return 1;
     }