qemu: command: Extract opening of TPM backend FDs for mocking purposes

Allow mocking of the file descriptor numbers used for the TPM
passthrough mode by extracting the relevant code into an exported
function.
Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NJohn Ferlan <jferlan@redhat.com>

src/qemu/qemu_command.c

@@ -9688,6 +9688,31 @@ qemuBuildTPMDevStr(const virDomainDef *def,
 }
 
 
+/* this function is exported so that tests can mock the FDs */
+int
+qemuBuildTPMOpenBackendFDs(const char *tpmdev,
+                           const char *cancel_path,
+                           int *tpmfd,
+                           int *cancelfd)
+{
+    if ((*tpmfd = open(tpmdev, O_RDWR)) < 0) {
+        virReportSystemError(errno, _("Could not open TPM device %s"),
+                             tpmdev);
+        return -1;
+    }
+
+    if ((*cancelfd = open(cancel_path, O_WRONLY)) < 0) {
+        virReportSystemError(errno,
+                             _("Could not open TPM device's cancel "
+                               "path %s"), cancel_path);
+        VIR_FORCE_CLOSE(*tpmfd);
+        return -1;
+    }
+
+    return 0;
+}
+
+
 static char *
 qemuBuildTPMBackendStr(const virDomainDef *def,
                        virCommandPtr cmd,
@@ -9726,30 +9751,16 @@ qemuBuildTPMBackendStr(const virDomainDef *def,
             goto error;
 
         if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_ADD_FD)) {
-            *tpmfd = open(tpmdev, O_RDWR);
-            if (*tpmfd < 0) {
-                virReportSystemError(errno, _("Could not open TPM device %s"),
-                                     tpmdev);
+            if (qemuBuildTPMOpenBackendFDs(tpmdev, cancel_path, tpmfd, cancelfd) < 0)
                 goto error;
-            }
 
-            virCommandPassFD(cmd, *tpmfd,
-                             VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+            virCommandPassFD(cmd, *tpmfd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
+            virCommandPassFD(cmd, *cancelfd, VIR_COMMAND_PASS_FD_CLOSE_PARENT);
             devset = qemuVirCommandGetDevSet(cmd, *tpmfd);
             if (devset == NULL)
                 goto error;
 
-            *cancelfd = open(cancel_path, O_WRONLY);
-            if (*cancelfd < 0) {
-                virReportSystemError(errno,
-                                     _("Could not open TPM device's cancel "
-                                       "path %s"), cancel_path);
-                goto error;
-            }
             VIR_FREE(cancel_path);
-
-            virCommandPassFD(cmd, *cancelfd,
-                             VIR_COMMAND_PASS_FD_CLOSE_PARENT);
             cancel_path = qemuVirCommandGetDevSet(cmd, *cancelfd);
             if (cancel_path == NULL)
                 goto error;

src/qemu/qemu_command.h

@@ -219,4 +219,13 @@ qemuBuildVsockDevStr(virDomainDefPtr def,
     ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
     ATTRIBUTE_NONNULL(4);
 
+/* this function is exported so that tests can mock the FDs */
+int
+qemuBuildTPMOpenBackendFDs(const char *tpmdev,
+                           const char *cancel_path,
+                           int *tpmfd,
+                           int *cancelfd)
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(3)
+    ATTRIBUTE_NONNULL(4);
+
 #endif /* __QEMU_COMMAND_H__*/