[PATCH] tpm_emulator: Report an error if chardev is missing

[Stefan Berger <stefanb@linux.vnet.ibm.com>]

This patch fixes the odd error reporting when trying to send a file
descriptor to the TPM emulator if one has not passed a valid chardev.

$ x86_64-softmmu/qemu-system-x86_64 -tpmdev emulator,id=tpm0
qemu-system-x86_64: -tpmdev emulator,id=tpm0: tpm-emulator: Failed to send CMD_SET_DATAFD: Success
qemu-system-x86_64: -tpmdev emulator,id=tpm0: tpm-emulator: Could not cleanly shutdown the TPM: Success

This is the new error report:

$ x86_64-softmmu/qemu-system-x86_64 -tpmdev emulator,id=tpm0
qemu-system-x86_64: -tpmdev emulator,id=tpm0: tpm-emulator: missing chardev

This change does not hide the display of supported TPM types if a non-existent type is passed:

$ x86_64-softmmu/qemu-system-x86_64 -tpmdev nonexistent,id=tpm0
qemu-system-x86_64: -tpmdev nonexistent,id=tpm0: Parameter 'type' expects a TPM backend type
Supported TPM types (choose only one):
 passthrough   Passthrough TPM backend driver
    emulator   TPM emulator backend driver

Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 backends/tpm/tpm_emulator.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/backends/tpm/tpm_emulator.c b/backends/tpm/tpm_emulator.c
index 9605339f93..55cbc9c60e 100644
--- a/backends/tpm/tpm_emulator.c
+++ b/backends/tpm/tpm_emulator.c
@@ -568,6 +568,9 @@ static int tpm_emulator_handle_device_opts(TPMEmulator *tpm_emu, QemuOpts *opts)
         }
 
         tpm_emu->options->chardev = g_strdup(value);
+    } else {
+        error_report("tpm-emulator: missing chardev");
+        goto err;
     }
 
     if (tpm_emulator_prepare_data_fd(tpm_emu) < 0) {
@@ -925,6 +928,11 @@ static void tpm_emulator_shutdown(TPMEmulator *tpm_emu)
 {
     ptm_res res;
 
+    if (!tpm_emu->options->chardev) {
+        /* was never properly initialized */
+        return;
+    }
+
     if (tpm_emulator_ctrlcmd(tpm_emu, CMD_SHUTDOWN, &res, 0, sizeof(res)) < 0) {
         error_report("tpm-emulator: Could not cleanly shutdown the TPM: %s",
                      strerror(errno));
-- 
2.24.1