diff options
Diffstat (limited to 'tests/sys/socket/sblock_test.c')
| -rw-r--r-- | tests/sys/socket/sblock_test.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/tests/sys/socket/sblock_test.c b/tests/sys/socket/sblock_test.c new file mode 100644 index 0000000..415c4d4 --- /dev/null +++ b/tests/sys/socket/sblock_test.c @@ -0,0 +1,207 @@ +/*- + * Copyright (c) 2007 Robert N. M. Watson + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + * + * $FreeBSD$ + */ + +/* + * Sockets serialize I/O in each direction in order to avoid interlacing of + * I/O by multiple processes or threcvs recving or sending the socket. This + * is done using some form of kernel lock (varies by kernel version), called + * "sblock" in FreeBSD. However, to avoid unkillable processes waiting on + * I/O that may be entirely controlled by a remote network endpoint, that + * lock acquisition must be interruptible. + * + * To test this, set up a local domain stream socket pair and a set of three + * processes. Two processes block in recv(), the first on sbwait (wait for + * I/O), and the second on the sblock waiting for the first to finish. A + * third process is responsible for signalling the second process, then + * writing to the socket. Depending on the error returned in the second + * process, we can tell whether the sblock wait was interrupted, or if + * instead the process only woke up when the write was performed. + */ + +#include <sys/socket.h> + +#include <err.h> +#include <errno.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> + +static int interrupted; +static void +signal_handler(int signum __unused) +{ + + interrupted++; +} + +/* + * Process that will perform a blocking recv on a UNIX domain socket. This + * should return one byte of data. + */ +static void +blocking_recver(int fd) +{ + ssize_t len; + char ch; + + len = recv(fd, &ch, sizeof(ch), 0); + if (len < 0) + err(-1, "FAIL: blocking_recver: recv"); + if (len == 0) + errx(-1, "FAIL: blocking_recver: recv: eof"); + if (len != 1) + errx(-1, "FAIL: blocking_recver: recv: %zd bytes", len); + if (interrupted) + errx(-1, "FAIL: blocking_recver: interrupted wrong pid"); +} + +/* + * Process that will perform a locking recv on a UNIX domain socket. + * + * This is where we figure out if the test worked or not. If it has failed, + * then recv() will return EOF, as the close() arrives before the signal, + * meaning that the wait for the sblock was not interrupted; if it has + * succeeded, we get EINTR as the signal interrupts the lock request. + */ +static void +locking_recver(int fd) +{ + ssize_t len; + char ch; + + if (sleep(1) != 0) + err(-1, "FAIL: locking_recver: sleep"); + len = recv(fd, &ch, sizeof(ch), 0); + if (len < 0 && errno != EINTR) + err(-1, "FAIL: locking_recver: recv"); + if (len < 0 && errno == EINTR) { + fprintf(stderr, "PASS\n"); + exit(0); + } + if (len == 0) + errx(-1, "FAIL: locking_recver: recv: eof"); + if (!interrupted) + errx(-1, "FAIL: locking_recver: not interrupted"); +} + +static void +signaller(pid_t locking_recver_pid, int fd) +{ + ssize_t len; + char ch; + + if (sleep(2) != 0) { + warn("signaller sleep(2)"); + return; + } + if (kill(locking_recver_pid, SIGHUP) < 0) { + warn("signaller kill(%d)", locking_recver_pid); + return; + } + if (sleep(1) != 0) { + warn("signaller sleep(1)"); + return; + } + len = send(fd, &ch, sizeof(ch), 0); + if (len < 0) { + warn("signaller send"); + return; + } + if (len != sizeof(ch)) { + warnx("signaller send ret %zd", len); + return; + } + if (close(fd) < 0) { + warn("signaller close"); + return; + } + if (sleep(1) != 0) { + warn("signaller sleep(1)"); + return; + } +} + +int +main(void) +{ + int error, fds[2], recver_fd, sender_fd; + pid_t blocking_recver_pid; + pid_t locking_recver_pid; + struct sigaction sa; + + if (sigaction(SIGHUP, NULL, &sa) < 0) + err(-1, "FAIL: sigaction(SIGHUP, NULL, &sa)"); + + sa.sa_handler = signal_handler; + if (sa.sa_flags & SA_RESTART) + printf("SIGHUP restartable by default (cleared)\n"); + sa.sa_flags &= ~SA_RESTART; + + if (sigaction(SIGHUP, &sa, NULL) < 0) + err(-1, "FAIL: sigaction(SIGHUP, &sa, NULL)"); + +#if 0 + if (signal(SIGHUP, signal_handler) == SIG_ERR) + err(-1, "FAIL: signal(SIGHUP)"); +#endif + + if (socketpair(PF_LOCAL, SOCK_STREAM, 0, fds) < 0) + err(-1, "FAIL: socketpair(PF_LOCAL, SOGK_STREAM, 0)"); + + sender_fd = fds[0]; + recver_fd = fds[1]; + + blocking_recver_pid = fork(); + if (blocking_recver_pid < 0) + err(-1, "FAIL: fork"); + if (blocking_recver_pid == 0) { + close(sender_fd); + blocking_recver(recver_fd); + exit(0); + } + + locking_recver_pid = fork(); + if (locking_recver_pid < 0) { + error = errno; + kill(blocking_recver_pid, SIGKILL); + errno = error; + err(-1, "FAIL: fork"); + } + if (locking_recver_pid == 0) { + close(sender_fd); + locking_recver(recver_fd); + exit(0); + } + + signaller(locking_recver_pid, sender_fd); + + kill(blocking_recver_pid, SIGKILL); + kill(locking_recver_pid, SIGKILL); + exit(0); +} |
