[PATCH] util: require command args to be non-NULL

[Daniel P. Berrangé <berrange@xxxxxxxxxx>]

The virCommand APIs do not expect to be given a NULL value for an arg
name or value. Such a mistake can lead to execution of the wrong
command, as the NULL may prematurely terminate the list of args.
Detect this and report suitable error messages.

This identified a flaw in the storage test which was passing a NULL
instead of the volume path. This flaw was then validated by an incorrect
set of qemu-img args as expected data.

Signed-off-by: Daniel P. Berrangé <berrange@xxxxxxxxxx>
---
 src/util/vircommand.c                                | 10 ++++++++++
 tests/storagevolxml2argvdata/qcow2-zerocapacity.argv |  2 +-
 tests/storagevolxml2xmlin/vol-qcow2-zerocapacity.xml |  1 +
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/util/vircommand.c b/src/util/vircommand.c
index 3559f4bafa..d965068369 100644
--- a/src/util/vircommand.c
+++ b/src/util/vircommand.c
@@ -1498,6 +1498,12 @@ virCommandAddArg(virCommandPtr cmd, const char *val)
     if (!cmd || cmd->has_error)
         return;
 
+    if (val == NULL) {
+        cmd->has_error = EINVAL;
+        abort();
+        return;
+    }
+
     if (VIR_STRDUP_QUIET(arg, val) < 0) {
         cmd->has_error = ENOMEM;
         return;
@@ -1595,6 +1601,10 @@ virCommandAddArgFormat(virCommandPtr cmd, const char *format, ...)
 void
 virCommandAddArgPair(virCommandPtr cmd, const char *name, const char *val)
 {
+    if (name == NULL || val == NULL) {
+        cmd->has_error = EINVAL;
+        return;
+    }
     virCommandAddArgFormat(cmd, "%s=%s", name, val);
 }
 
diff --git a/tests/storagevolxml2argvdata/qcow2-zerocapacity.argv b/tests/storagevolxml2argvdata/qcow2-zerocapacity.argv
index d83b08b342..45894931ae 100644
--- a/tests/storagevolxml2argvdata/qcow2-zerocapacity.argv
+++ b/tests/storagevolxml2argvdata/qcow2-zerocapacity.argv
@@ -1 +1 @@
-qemu-img create -f qcow2 -o compat=0.10  0K
+qemu-img create -f qcow2 -o compat=0.10 /var/lib/libvirt/images/OtherDemo.img 0K
diff --git a/tests/storagevolxml2xmlin/vol-qcow2-zerocapacity.xml b/tests/storagevolxml2xmlin/vol-qcow2-zerocapacity.xml
index 1d1e6deac0..027a73b4bf 100644
--- a/tests/storagevolxml2xmlin/vol-qcow2-zerocapacity.xml
+++ b/tests/storagevolxml2xmlin/vol-qcow2-zerocapacity.xml
@@ -1,6 +1,7 @@
 <volume>
   <name>OtherDemo.img</name>
   <target>
+    <path>/var/lib/libvirt/images/OtherDemo.img</path>
     <format type="qcow2"/>
   </target>
   <capacity>0</capacity>
-- 
2.19.2

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