Added FD info debugging function.

3rdparty/libprocess/3rdparty/stout/include/stout/os/open.hpp

@@ -89,6 +89,95 @@ inline Try<int> open(const std::string& path, int oflag, mode_t mode = 0)
   return fd;
 }
 
+
+namespace debug {
+
+// Borrowed from https://oroboro.com/file-handle-leaks-server.
+inline void log_fd(int fd)
+{
+  int fd_flags = fcntl(fd, F_GETFD);
+
+  if (fd_flags < 0) {
+    return;
+  }
+
+  int fl_flags = fcntl(fd, F_GETFL);
+
+  if (fl_flags < 0) {
+    return;
+  }
+
+  std::cerr << fd << " ";
+
+#ifdef __linux__
+  char buf[256];
+  char path[256];
+  sprintf(path, "/proc/self/fd/%d", fd);
+
+  memset(&buf[0], 0, 256);
+  ssize_t s = readlink(path, &buf[0], 256);
+
+  if (s < 0) {
+    std::cerr << " (" << path << "): " << "not available" << "\n";
+    return;
+  }
+  std::cerr << "(" << buf << "): ";
+#endif
+
+  if (fd_flags & FD_CLOEXEC)  std::cerr << "cloexec ";
+
+  // file status
+  if (fl_flags & O_APPEND)    std::cerr << "append ";
+  if (fl_flags & O_NONBLOCK)  std::cerr << "nonblock ";
+
+  // acc mode
+  if (fl_flags & O_RDONLY)    std::cerr << "read-only ";
+  if (fl_flags & O_RDWR)      std::cerr << "read-write ";
+  if (fl_flags & O_WRONLY)    std::cerr << "write-only ";
+
+#ifdef __linux__
+  if (fl_flags & O_DSYNC)     std::cerr << "dsync ";
+  if (fl_flags & O_RSYNC)     std::cerr << "rsync ";
+  if (fl_flags & O_SYNC)      std::cerr << "sync ";
+#endif
+
+  struct flock fl;
+  fl.l_type = F_WRLCK;
+  fl.l_whence = 0;
+  fl.l_start = 0;
+  fl.l_len = 0;
+
+  fcntl(fd, F_GETLK, &fl);
+
+  if (fl.l_type != F_UNLCK) {
+    if (fl.l_type == F_WRLCK) {
+      std::cerr << "write-locked";
+    } else {
+      std::cerr << "read-locked";
+    }
+    std::cerr << "(pid:" << fl.l_pid << ") ";
+  }
+
+  std::cerr << "\n";
+}
+
+inline void log_fds()
+{
+  int handles = getdtablesize();
+
+  for (int i = 0; i < handles; i++) {
+    int fd_flags = fcntl( i, F_GETFD );
+
+    if (fd_flags < 0) {
+      continue;
+    }
+
+    log_fd(i);
+  }
+}
+
+} // namespace debug {
+
 } // namespace os {
 
 #endif // __STOUT_OS_OPEN_HPP__