Log output compatible with PKCS#11 Spy

[ueno]

As p11-kit already proxies module access, it would be possible to fully emulate PKCS #11 Spy. This might require addition of a new configuration option or envvar.

[ueno]

From my experience, I think it would be useful if the output is machine readable and includes identifiers to diversify the context (process ID and thread ID) as well as event timestamp, something like:

$ P11_KIT_TRACE_TOKEN=pkcs11: P11_KIT_TRACE_OUTPUT=trace application
...
$ cat trace
[
  {
    "function": "C_Initialize",
    "input-arguments": [{
      "type": "...",
      "name": "init_args",
      "value": "..."
    }],
    "output-arguments": [],
    "rv": "CKR_OK",
    "timestamp": {
      "enter": "...",
      "leave": "..."
    },
    "process": "...",
    "thread": "...
  },
  ...
]