Avoid use opendir after fork as its not async safe and may lead to deadlock

https://gitlab.alpinelinux.org/alpine/aports/-/issues/11861

diff --git a/openjdk/jdk/src/solaris/native/java/lang/childproc.c b/openjdk/jdk/src/solaris/native/java/lang/childproc.c
index 1d183cf..05aa6cb 100644
--- openjdk/jdk/src/solaris/native/java/lang/childproc.c
+++ openjdk/jdk/src/solaris/native/java/lang/childproc.c
@@ -23,13 +23,13 @@
  * questions.
  */
 
-#include <dirent.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 #include <limits.h>
+#include <poll.h>
 
 #include "childproc.h"
 
@@ -56,61 +56,47 @@ closeSafely(int fd)
     return (fd == -1) ? 0 : close(fd);
 }
 
-int
-isAsciiDigit(char c)
-{
-  return c >= '0' && c <= '9';
-}
-
-#ifdef _ALLBSD_SOURCE
-#define FD_DIR "/dev/fd"
-#define dirent64 dirent
-#define readdir64 readdir
-#elif defined(_AIX)
-/* AIX does not understand '/proc/self' - it requires the real process ID */
-#define FD_DIR aix_fd_dir
-#else
-#define FD_DIR "/proc/self/fd"
-#endif
-
 int
 closeDescriptors(void)
 {
-    DIR *dp;
-    struct dirent64 *dirp;
     int from_fd = FAIL_FILENO + 1;
+    struct pollfd pfds[1024];
+    int i, total, nclosed = 0;
+    int max_fd = sysconf(_SC_OPEN_MAX);
 
-    /* We're trying to close all file descriptors, but opendir() might
-     * itself be implemented using a file descriptor, and we certainly
-     * don't want to close that while it's in use.  We assume that if
-     * opendir() is implemented using a file descriptor, then it uses
-     * the lowest numbered file descriptor, just like open().  So we
-     * close a couple explicitly.  */
+    if (max_fd < 0)
+        return 0;
 
-    close(from_fd);          /* for possible use by opendir() */
-    close(from_fd + 1);      /* another one for good luck */
+    /* init events */
+    total = max_fd - from_fd;
+    for (i = 0; i < (total < 1024 ? total : 1024); i++) {
+        pfds[i].events = 0;
+    }
 
-#if defined(_AIX)
-    /* AIX does not understand '/proc/self' - it requires the real process ID */
-    char aix_fd_dir[32];     /* the pid has at most 19 digits */
-    snprintf(aix_fd_dir, 32, "/proc/%d/fd", getpid());
-#endif
+    while (from_fd < max_fd) {
+        int nfds, r = 0;
 
-    if ((dp = opendir(FD_DIR)) == NULL)
-        return 0;
+        total = max_fd - from_fd;
+        nfds =  total < 1024 ? total : 1024;
 
-    /* We use readdir64 instead of readdir to work around Solaris bug
-     * 6395699: /proc/self/fd fails to report file descriptors >= 1024 on Solaris 9
-     */
-    while ((dirp = readdir64(dp)) != NULL) {
-        int fd;
-        if (isAsciiDigit(dirp->d_name[0]) &&
-            (fd = strtol(dirp->d_name, NULL, 10)) >= from_fd + 2)
-            close(fd);
-    }
+        for (i = 0; i < nfds; i++)
+            pfds[i].fd = from_fd + i;
 
-    closedir(dp);
+        do {
+            r = poll(pfds, nfds, 0);
+        } while (r == -1 && errno == EINTR);
 
+        if (r < 0)
+            return 0;
+
+
+        for (i = 0; i < nfds; i++)
+            if (pfds[i].revents != POLLNVAL) {
+                nclosed++;
+                close(pfds[i].fd);
+            }
+        from_fd += nfds;
+    }
     return 1;
 }