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[libvirt] [PATCH v2 4/4] Check that QEMU is still alive while reading startup output.



By checking the pid every retry period, we can quickly determine if
the process crashed at startup, rather than make the user wait for
the entire timeout (3 seconds).

Signed-off-by: Cole Robinson <crobinso redhat com>
---
 src/qemu_driver.c |   33 ++++++++++++++++++++++-----------
 1 files changed, 22 insertions(+), 11 deletions(-)

diff --git a/src/qemu_driver.c b/src/qemu_driver.c
index fb4ad64..5c8a883 100644
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -744,29 +744,40 @@ qemudReadLogOutput(virConnectPtr conn,
                    int timeout)
 {
     int retries = timeout*10;
+    int got = 0;
     buf[0] = '\0';
 
     while (retries) {
         ssize_t ret;
-        size_t got = 0;
+        int isdead = 0;
 
-        while((ret = read(fd, buf+got, buflen-got-1)) > 0) {
-            got += ret;
-            buf[got] = '\0';
-            if ((buflen-got-1) == 0) {
-                qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
-                                 _("Out of space while reading %s log output"), what);
-                return -1;
-            }
-        }
+        if (kill(vm->pid, 0) == -1 && errno == ESRCH)
+            isdead = 1;
 
-        if (ret < 0 && errno != EINTR) {
+        ret = saferead(fd, buf+got, buflen-got-1);
+        if (ret < 0) {
             virReportSystemError(conn, errno,
                                  _("Failure while reading %s log output"),
                                  what);
             return -1;
         }
 
+        got += ret;
+        buf[got] = '\0';
+        if (got == buflen-1) {
+            qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
+                             _("Out of space while reading %s log output"),
+                             what);
+            return -1;
+        }
+
+        if (isdead) {
+            qemudReportError(conn, NULL, NULL, VIR_ERR_INTERNAL_ERROR,
+                             _("Process exited while reading %s log output"),
+                             what);
+            return -1;
+        }
+
         ret = func(conn, vm, buf, fd);
         if (ret <= 0)
             return ret;
-- 
1.6.0.6


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