[Xen-devel] [PATCH v2 2/5] libxl: react correctly to POLLHUP

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

When received POLLHUP on datacopier_readable/writable, kill the
datacopier and call the callback with onwrite=-2. On the bootloader
callback kill the bootloader process and wait for the callback, but
without setting the bl->rc error code.

This is because NetBSD returns POLLHUP when the process on the other
end of the pty exits (even when exiting normally).

Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Signed-off-by: Roger Pau Monne <roger.pau@xxxxxxxxxx>
---
 tools/libxl/libxl_aoutils.c    |   16 ++++++++++++++++
 tools/libxl/libxl_bootloader.c |    9 ++++++---
 tools/libxl/libxl_internal.h   |    1 +
 3 files changed, 23 insertions(+), 3 deletions(-)

diff --git a/tools/libxl/libxl_aoutils.c b/tools/libxl/libxl_aoutils.c
index 99972a2..2ea9b2c 100644
--- a/tools/libxl/libxl_aoutils.c
+++ b/tools/libxl/libxl_aoutils.c
@@ -102,6 +102,14 @@ static void datacopier_readable(libxl__egc *egc, 
libxl__ev_fd *ev,
     libxl__datacopier_state *dc = CONTAINER_OF(ev, *dc, toread);
     STATE_AO_GC(dc->ao);
 
+    if (revents & POLLHUP) {
+        LOG(DEBUG, "received POLLHUP on %s during copy of %s, "
+                   "killing the bootloader process",
+                   dc->readwhat, dc->copywhat);
+        datacopier_callback(egc, dc, -2, 0);
+        return;
+    }
+
     if (revents & ~POLLIN) {
         LOG(ERROR, "unexpected poll event 0x%x (should be POLLIN)"
             " on %s during copy of %s", revents, dc->readwhat, dc->copywhat);
@@ -163,6 +171,14 @@ static void datacopier_writable(libxl__egc *egc, 
libxl__ev_fd *ev,
     libxl__datacopier_state *dc = CONTAINER_OF(ev, *dc, towrite);
     STATE_AO_GC(dc->ao);
 
+    if (revents & POLLHUP) {
+        LOG(DEBUG, "received POLLHUP on %s during copy of %s, "
+                   "killing the bootloader process",
+                   dc->writewhat, dc->copywhat);
+        datacopier_callback(egc, dc, -2, 0);
+        return;
+    }
+
     if (revents & ~POLLOUT) {
         LOG(ERROR, "unexpected poll event 0x%x (should be POLLOUT)"
             " on %s during copy of %s", revents, dc->writewhat, dc->copywhat);
diff --git a/tools/libxl/libxl_bootloader.c b/tools/libxl/libxl_bootloader.c
index ef5a91b..f3d92e2 100644
--- a/tools/libxl/libxl_bootloader.c
+++ b/tools/libxl/libxl_bootloader.c
@@ -285,8 +285,8 @@ static void bootloader_abort(libxl__egc *egc,
     libxl__datacopier_kill(&bl->display);
     if (libxl__ev_child_inuse(&bl->child)) {
         r = kill(bl->child.pid, SIGTERM);
-        if (r) LOGE(WARN, "after failure, failed to kill bootloader [%lu]",
-                    (unsigned long)bl->child.pid);
+        if (r) LOGE(WARN, "%sfailed to kill bootloader [%lu]",
+                    rc ? "after failure, " : "", (unsigned long)bl->child.pid);
     }
     bl->rc = rc;
 }
@@ -567,7 +567,10 @@ static void bootloader_copyfail(libxl__egc *egc, const 
char *which,
     STATE_AO_GC(bl->ao);
     if (!onwrite && !errnoval)
         LOG(ERROR, "unexpected eof copying %s", which);
-    bootloader_abort(egc, bl, ERROR_FAIL);
+    if (onwrite == -2)
+        bootloader_abort(egc, bl, 0);
+    else
+        bootloader_abort(egc, bl, ERROR_FAIL);
 }
 static void bootloader_keystrokes_copyfail(libxl__egc *egc,
        libxl__datacopier_state *dc, int onwrite, int errnoval)
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 3ee3a09..286aa19 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -2073,6 +2073,7 @@ typedef struct libxl__datacopier_buf 
libxl__datacopier_buf;
  *     errnoval==0 means we got eof and all data was written
  *     errnoval!=0 means we had a read error, logged
  * onwrite==-1 means some other internal failure, errnoval not valid, logged
+ * onwrite==-2 means we got a POLLHUP, errnoval not valid, logged
  * in all cases copier is killed before calling this callback */
 typedef void libxl__datacopier_callback(libxl__egc *egc,
      libxl__datacopier_state *dc, int onwrite, int errnoval);
-- 
1.7.7.5 (Apple Git-26)


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