+#ifdef DEBUG_LEAKING_SCALARS_FORK_DUMP
+ if (destruct_level != 0) {
+ /* Fork here to create a child. Our child's job is to preserve the
+ state of scalars prior to destruction, so that we can instruct it
+ to dump any scalars that we later find have leaked.
+ There's no subtlety in this code - it assumes POSIX, and it doesn't
+ fail gracefully */
+ int fd[2];
+
+ if(socketpair(AF_UNIX, SOCK_STREAM, 0, fd)) {
+ perror("Debug leaking scalars socketpair failed");
+ abort();
+ }
+
+ child = fork();
+ if(child == -1) {
+ perror("Debug leaking scalars fork failed");
+ abort();
+ }
+ if (!child) {
+ /* We are the child */
+ const int sock = fd[1];
+ const int debug_fd = PerlIO_fileno(Perl_debug_log);
+ int f;
+ const char *where;
+ /* Our success message is an integer 0, and a char 0 */
+ static const char success[sizeof(int) + 1];
+
+ close(fd[0]);
+
+ /* We need to close all other file descriptors otherwise we end up
+ with interesting hangs, where the parent closes its end of a
+ pipe, and sits waiting for (another) child to terminate. Only
+ that child never terminates, because it never gets EOF, because
+ we also have the far end of the pipe open. We even need to
+ close the debugging fd, because sometimes it happens to be one
+ end of a pipe, and a process is waiting on the other end for
+ EOF. Normally it would be closed at some point earlier in
+ destruction, but if we happen to cause the pipe to remain open,
+ EOF never occurs, and we get an infinite hang. Hence all the
+ games to pass in a file descriptor if it's actually needed. */
+
+ f = sysconf(_SC_OPEN_MAX);
+ if(f < 0) {
+ where = "sysconf failed";
+ goto abort;
+ }
+ while (f--) {
+ if (f == sock)
+ continue;
+ close(f);
+ }
+
+ while (1) {
+ SV *target;
+ union control_un control;
+ struct msghdr msg;
+ struct iovec vec[1];
+ struct cmsghdr *cmptr;
+ ssize_t got;
+ int got_fd;
+
+ msg.msg_control = control.control;
+ msg.msg_controllen = sizeof(control.control);
+ /* We're a connected socket so we don't need a source */
+ msg.msg_name = NULL;
+ msg.msg_namelen = 0;
+ msg.msg_iov = vec;
+ msg.msg_iovlen = sizeof(vec)/sizeof(vec[0]);
+
+ vec[0].iov_base = (void*)⌖
+ vec[0].iov_len = sizeof(target);
+
+ got = recvmsg(sock, &msg, 0);
+
+ if(got == 0)
+ break;
+ if(got < 0) {
+ where = "recv failed";
+ goto abort;
+ }
+ if(got < sizeof(target)) {
+ where = "short recv";
+ goto abort;
+ }
+
+ if(!(cmptr = CMSG_FIRSTHDR(&msg))) {
+ where = "no cmsg";
+ goto abort;
+ }
+ if(cmptr->cmsg_len != CMSG_LEN(sizeof(int))) {
+ where = "wrong cmsg_len";
+ goto abort;
+ }
+ if(cmptr->cmsg_level != SOL_SOCKET) {
+ where = "wrong cmsg_level";
+ goto abort;
+ }
+ if(cmptr->cmsg_type != SCM_RIGHTS) {
+ where = "wrong cmsg_type";
+ goto abort;
+ }
+
+ got_fd = *(int*)CMSG_DATA(cmptr);
+ /* For our last little bit of trickery, put the file descriptor
+ back into Perl_debug_log, as if we never actually closed it
+ */
+ if(got_fd != debug_fd) {
+ if (dup2(got_fd, debug_fd) == -1) {
+ where = "dup2";
+ goto abort;
+ }
+ }
+ sv_dump(target);
+
+ PerlIO_flush(Perl_debug_log);
+
+ got = write(sock, &success, sizeof(success));
+
+ if(got < 0) {
+ where = "write failed";
+ goto abort;
+ }
+ if(got < sizeof(success)) {
+ where = "short write";
+ goto abort;
+ }
+ }
+ _exit(0);
+ abort:
+ {
+ int send_errno = errno;
+ unsigned char length = (unsigned char) strlen(where);
+ struct iovec failure[3] = {
+ {(void*)&send_errno, sizeof(send_errno)},
+ {&length, 1},
+ {(void*)where, length}
+ };
+ int got = writev(sock, failure, 3);
+ /* Bad news travels fast. Faster than data. We'll get a SIGPIPE
+ in the parent if we try to read from the socketpair after the
+ child has exited, even if there was data to read.
+ So sleep a bit to give the parent a fighting chance of
+ reading the data. */
+ sleep(2);
+ _exit((got == -1) ? errno : 0);
+ }
+ /* End of child. */
+ }
+ PL_dumper_fd = fd[0];
+ close(fd[1]);
+ }
+#endif
+
https://perl5.git.perl.org / perl5.git / blobdiff