[libvirt] [PATCHv2 5/7] virsh: report exit status of failed lxc-enter-namespace

[Eric Blake]

'virsh lxc-enter-namespace' does not have a way to reflect exit
status to the caller in single-command mode, but we might as well
at least report the exit status.  Prior to this patch,

$ virsh -c lxc:/// lxc-enter-namespace shell /bin/sh 'exit 3'; echo $?
1

now it gives some details:

$ virsh -c lxc:/// lxc-enter-namespace shell /bin/sh -c 'exit 3'; echo $?
error: internal error: Child process (31557) unexpected exit status 3
1

Also useful:

$ virsh -c lxc:/// lxc-enter-namespace shell /bin/sh -c 'kill $$'; echo $?
error: internal error: Child process (31585) unexpected fatal signal 15
1

* tools/virsh-domain.c (cmdLxcEnterNamespace): Avoid magic numbers.
Dispatch any error.
* tools/virsh.pod: Document that non-zero exit status is collapsed.

Signed-off-by: Eric Blake <eblake at redhat.com>
---
 tools/virsh-domain.c | 27 +++++++++++++++++++--------
 tools/virsh.pod      |  3 ++-
 2 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c
index d9b542e..4dc6410 100644
--- a/tools/virsh-domain.c
+++ b/tools/virsh-domain.c
@@ -8140,12 +8140,14 @@ cmdLxcEnterNamespace(vshControl *ctl, const vshCmd *cmd)
     if ((pid = virFork()) < 0)
         goto cleanup;
     if (pid == 0) {
+        int status;
+
         if (setlabel &&
             virDomainLxcEnterSecurityLabel(secmodel,
                                            seclabel,
                                            NULL,
                                            0) < 0)
-            _exit(255);
+            _exit(EXIT_CANCELED);

         if (virDomainLxcEnterNamespace(dom,
                                        nfdlist,
@@ -8153,27 +8155,36 @@ cmdLxcEnterNamespace(vshControl *ctl, const vshCmd *cmd)
                                        NULL,
                                        NULL,
                                        0) < 0)
-            _exit(255);
+            _exit(EXIT_CANCELED);

         /* Fork a second time because entering the
          * pid namespace only takes effect after fork
          */
         if ((pid = virFork()) < 0)
-            _exit(255);
+            _exit(EXIT_CANCELED);
         if (pid == 0) {
             execv(cmdargv[0], cmdargv);
-            _exit(255);
+            _exit(errno == ENOENT ? EXIT_ENOENT : EXIT_CANNOT_INVOKE);
+        }
+        if (virProcessWait(pid, &status) < 0)
+            _exit(EXIT_CANNOT_INVOKE);
+        if (WIFSIGNALED(status)) {
+            raise(WTERMSIG(status));
+            status = WTERMSIG(status) + 128;
+        } else if (WIFEXITED(status)) {
+            status = WEXITSTATUS(status);
         } else {
-            if (virProcessWait(pid, NULL) < 0)
-                _exit(255);
+            status = EXIT_CANNOT_INVOKE;
         }
-        _exit(0);
+        _exit(status);
     } else {
         for (i = 0; i < nfdlist; i++)
             VIR_FORCE_CLOSE(fdlist[i]);
         VIR_FREE(fdlist);
-        if (virProcessWait(pid, NULL) < 0)
+        if (virProcessWait(pid, NULL) < 0) {
+            vshReportError(ctl);
             goto cleanup;
+        }
     }

     ret = true;
diff --git a/tools/virsh.pod b/tools/virsh.pod
index 3534b54..9b24a69 100644
--- a/tools/virsh.pod
+++ b/tools/virsh.pod
@@ -3284,7 +3284,8 @@ Enter the namespace of I<domain> and execute the command C</path/to/binary>
 passing the requested args. The binary path is relative to the container
 root filesystem, not the host root filesystem. The binary will inherit the
 environment variables / console visible to virsh. This command only works
-when connected to the LXC hypervisor driver.
+when connected to the LXC hypervisor driver.  This command succeeds only
+if C</path/to/binary> has 0 exit status.

 =back

-- 
1.8.4.2