Re: [libvirt] [PATCH v5 04/11] Helper functions for host TPM support

12 Apr 2013

      On 04/12/2013 06:24 AM, Daniel P. Berrange wrote:
...
On Thu, Apr 11, 2013 at 04:04:46PM -0400, Stefan Berger wrote:
...
Implement helper functions to find the TPM's sysfs cancel file.
Signed-off-by: Stefan Berger <stefanb@linux.vnet.ibm.com>
Reviewed-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Tested-by: Corey Bryant <coreyb@linux.vnet.ibm.com>
Hmm, actually on second thoughts the entirely approach for this
method is just flawed.
In the XML description you have:
<device path='/dev/tpm0'/>
So we should not be iterating over /sys/fs/misc/tpmNNN at all.
We know exactly which TPM device we want - it is 'tpm0'. Just
kill all this pointless readdir code & pass in the device name
we want to get the cancel path for.
Indeed, the following is better:

/**
  * virTPMFindCancelPath:
  * @devpath: Path to the TPM device
  *
  * Find the cancel path given the path to the TPM device
  */
char *
virTPMFindCancelPath(const char *devpath)
{
     char *basepath = NULL;
     char *path = NULL;
     const char *dev;

     if (devpath) {
         dev = rindex(devpath, '/');
         if (dev) {
             dev++;
             if (virAsprintf(&basepath, "/sys/class/misc/%s/device",
                             dev) < 0) {
                 virReportOOMError();
                 goto cleanup;
             }
             path = virTPMCheckSysfsCancel(basepath);
         } else {
             virReportError(VIR_ERR_INTERNAL_ERROR,
                            _("TPM device path %s is invalid"), devpath);
         }
     } else {
         virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
                        _("Missing TPM device path"));
     }

cleanup:
     VIR_FREE(basepath);

     return path;
}

Thank you.

Stefan