4 files changed, 26 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index 327fec1d6..dfaa46795 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,13 @@
  - (dtucker) [README.platform configure.ac openbsd-compat/port-tun.c] Add
    tunnel support for Mac OS X/Darwin via a third-party tun driver.  Patch
    from reyk@, tested by anil@
+ - (dtucker) [channels.c configure.ac serverloop.c] Bug #1102: Around AIX
+   4.3.3 ML3 or so, the AIX pty layer starting passing zero-length writes
+   on the pty slave as zero-length reads on the pty master, which sshd
+   interprets as the descriptor closing.  Since most things don't do zero
+   length writes this rarely matters, but occasionally it happens, and when
+   it does the SSH pty session appears to hang, so we add a special case for
+   this condition.  ok djm@
 
 20060613
  - (djm) [getput.h] This file has been replaced by functions in misc.c
@@ -4690,4 +4697,4 @@
    - (djm) Trim deprecated options from INSTALL. Mention UsePAM
    - (djm) Fix quote handling in sftp; Patch from admorten AT umich.edu
 
-$Id: ChangeLog,v 1.4345 2006/06/23 11:05:12 dtucker Exp $
+$Id: ChangeLog,v 1.4346 2006/06/23 11:24:12 dtucker Exp $
diff --git a/channels.c b/channels.c
index 2fa997edc..239e9dd83 100644
--- a/channels.c
+++ b/channels.c
@@ -1415,10 +1415,15 @@ channel_handle_rfd(Channel *c, fd_set *readset, fd_set *writeset)
 
         if (c->rfd != -1 &&
             FD_ISSET(c->rfd, readset)) {
+                errno = 0;
                 len = read(c->rfd, buf, sizeof(buf));
                 if (len < 0 && (errno == EINTR || errno == EAGAIN))
                         return 1;
+#ifndef PTY_ZEROREAD
                 if (len <= 0) {
+#else
+                if (len < 0 || (len == 0 && errno != 0)) {
+#endif
                         debug2("channel %d: read<=0 rfd %d len %d",
                             c->self, c->rfd, len);
                         if (c->type != SSH_CHANNEL_OPEN) {
diff --git a/configure.ac b/configure.ac
index c3cb68f28..259b5c288 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-# $Id: configure.ac,v 1.340 2006/06/23 11:05:13 dtucker Exp $
+# $Id: configure.ac,v 1.341 2006/06/23 11:24:13 dtucker Exp $
 #
 # Copyright (c) 1999-2004 Damien Miller
 #
@@ -15,7 +15,7 @@
 # OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 
 AC_INIT(OpenSSH, Portable, openssh-unix-dev@mindrot.org)
-AC_REVISION($Revision: 1.340 $)
+AC_REVISION($Revision: 1.341 $)
 AC_CONFIG_SRCDIR([ssh.c])
 
 AC_CONFIG_HEADER(config.h)
@@ -190,6 +190,7 @@ case "$host" in
                 supported by bsd-setproctitle.c])
         AC_DEFINE(SSHPAM_CHAUTHTOK_NEEDS_RUID, 1,
             [AIX 5.2 and 5.3 (and presumably newer) require this])
+        AC_DEFINE(PTY_ZEROREAD, 1, [read(1) can return 0 for a non-closed fd])
         ;;
 *-*-cygwin*)
         check_for_libcrypt_later=1
diff --git a/serverloop.c b/serverloop.c
index 021ba68c0..c1eb28853 100644
--- a/serverloop.c
+++ b/serverloop.c
@@ -387,10 +387,15 @@ process_input(fd_set *readset)
 
         /* Read and buffer any available stdout data from the program. */
         if (!fdout_eof && FD_ISSET(fdout, readset)) {
+                errno = 0;
                 len = read(fdout, buf, sizeof(buf));
                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
                         /* do nothing */
+#ifdef PTY_ZEROREAD
                 } else if (len <= 0) {
+#else
+                } else if (len < 0 || (len == 0 && errno != 0)) {
+#endif
                         fdout_eof = 1;
                 } else {
                         buffer_append(&stdout_buffer, buf, len);
@@ -399,10 +404,15 @@ process_input(fd_set *readset)
         }
         /* Read and buffer any available stderr data from the program. */
         if (!fderr_eof && FD_ISSET(fderr, readset)) {
+                errno = 0;
                 len = read(fderr, buf, sizeof(buf));
                 if (len < 0 && (errno == EINTR || errno == EAGAIN)) {
                         /* do nothing */
+#ifdef PTY_ZEROREAD
                 } else if (len <= 0) {
+#else
+                } else if (len < 0 || (len == 0 && errno != 0)) {
+#endif
                         fderr_eof = 1;
                 } else {
                         buffer_append(&stderr_buffer, buf, len);