diff options
| -rw-r--r-- | ChangeLog | 8 | ||||
| -rw-r--r-- | serverloop.c | 58 |
2 files changed, 64 insertions, 2 deletions
@@ -38,6 +38,12 @@ [sshconnect1.c sshconnect2.c sshconnect.c sshd.8 sshd.c sshd_config] [ssh-keygen.c sshlogin.c sshpty.c sshtty.c ttymodes.c uidswap.c] basic KNF done while i was looking for something else + - markus@cvs.openbsd.org 2001/12/19 16:09:39 + [serverloop.c] + fix race between SIGCHLD and select with an additional pipe. writing + to the pipe on SIGCHLD wakes up select(). using pselect() is not + portable and siglongjmp() ugly. W. R. Stevens suggests similar solution. + initial idea by pmenage@ensim.com; ok deraadt@, djm@ 20011219 - (stevesk) OpenBSD CVS sync X11 localhost display @@ -7066,4 +7072,4 @@ - Wrote replacements for strlcpy and mkdtemp - Released 1.0pre1 -$Id: ChangeLog,v 1.1701 2001/12/21 03:45:46 djm Exp $ +$Id: ChangeLog,v 1.1702 2001/12/21 03:53:11 djm Exp $ diff --git a/serverloop.c b/serverloop.c index 1fa1f580..c876dc0c 100644 --- a/serverloop.c +++ b/serverloop.c @@ -35,7 +35,7 @@ */ #include "includes.h" -RCSID("$OpenBSD: serverloop.c,v 1.86 2001/12/19 07:18:56 deraadt Exp $"); +RCSID("$OpenBSD: serverloop.c,v 1.87 2001/12/19 16:09:39 markus Exp $"); #include "xmalloc.h" #include "packet.h" @@ -92,6 +92,51 @@ static volatile sig_atomic_t child_terminated = 0; /* The child has terminated. /* prototypes */ static void server_init_dispatch(void); +/* + * we write to this pipe if a SIGCHLD is caught in order to avoid + * the race between select() and child_terminated + */ +static int notify_pipe[2]; +static void +notify_setup(void) +{ + if (pipe(notify_pipe) < 0) { + error("pipe(notify_pipe) failed %s", strerror(errno)); + } else if ((fcntl(notify_pipe[0], F_SETFD, 1) == -1) || + (fcntl(notify_pipe[1], F_SETFD, 1) == -1)) { + error("fcntl(notify_pipe, F_SETFD) failed %s", strerror(errno)); + close(notify_pipe[0]); + close(notify_pipe[1]); + } else { + set_nonblock(notify_pipe[0]); + set_nonblock(notify_pipe[1]); + return; + } + notify_pipe[0] = -1; /* read end */ + notify_pipe[1] = -1; /* write end */ +} +static void +notify_parent(void) +{ + if (notify_pipe[1] != -1) + write(notify_pipe[1], "", 1); +} +static void +notify_prepare(fd_set *readset) +{ + if (notify_pipe[0] != -1) + FD_SET(notify_pipe[0], readset); +} +static void +notify_done(fd_set *readset) +{ + char c; + + if (notify_pipe[0] != -1 && FD_ISSET(notify_pipe[0], readset)) + while (read(notify_pipe[0], &c, 1) != -1) + debug2("notify_done: reading"); +} + static void sigchld_handler(int sig) { @@ -99,6 +144,7 @@ sigchld_handler(int sig) debug("Received SIGCHLD."); child_terminated = 1; mysignal(SIGCHLD, sigchld_handler); + notify_parent(); errno = save_errno; } @@ -242,6 +288,7 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, if (fdin != -1 && buffer_len(&stdin_buffer) > 0) FD_SET(fdin, *writesetp); } + notify_prepare(*readsetp); /* * If we have buffered packet data going to the client, mark that @@ -279,6 +326,8 @@ wait_until_can_do_something(fd_set **readsetp, fd_set **writesetp, int *maxfdp, error("select: %.100s", strerror(errno)); } else if (ret == 0 && client_alive_scheduled) client_alive_check(); + + notify_done(*readsetp); } /* @@ -468,6 +517,8 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) connection_in = packet_get_connection_in(); connection_out = packet_get_connection_out(); + notify_setup(); + previous_stdout_buffer_bytes = 0; /* Set approximate I/O buffer size. */ @@ -573,6 +624,7 @@ server_loop(pid_t pid, int fdin_arg, int fdout_arg, int fderr_arg) max_fd = MAX(max_fd, fdin); max_fd = MAX(max_fd, fdout); max_fd = MAX(max_fd, fderr); + max_fd = MAX(max_fd, notify_pipe[0]); /* Sleep in select() until we can do something. */ wait_until_can_do_something(&readset, &writeset, &max_fd, @@ -697,7 +749,11 @@ server_loop2(Authctxt *authctxt) connection_in = packet_get_connection_in(); connection_out = packet_get_connection_out(); + notify_setup(); + max_fd = MAX(connection_in, connection_out); + max_fd = MAX(max_fd, notify_pipe[0]); + xxx_authctxt = authctxt; server_init_dispatch(); |