#!/usr/bin/env python3
# Copyright 2015 Canonical Ltd.
# All rights reserved.
#
# Written by:
#   Zygmunt Krynicki <zygmunt.krynicki@canonical.com>


"""Collect information about all sysfs attributes related to TPM."""

import os

import guacamole


class tpm_sysfs_resource(guacamole.Command):

    """
    Collect information about all sysfs attributes related to TPM.

    This program traverses all the TPM device nodes found in /sys/class/tpm/.
    Each present device is subsequently inspected by reading all readable files
    in /sys/class/tpm/*/device/* and presenting the data present there as
    subsequent RFC822 records. There is one record per TPM chip. In order to
    differentiate each chip, each record contains the field x-sysfs-device-name
    that stores the full sysfs directory name of the chip.

    @EPILOG@

    Unreadable files (typically due to permissions) are silently skipped.
    """

    def invoked(self, ctx):
        # This is found on 4.2 kernels
        sysfs_root_tpm = '/sys/class/tpm/'
        # This is found on 3.19 kernels
        sysfs_root_misc = '/sys/class/misc/'
        if os.path.isdir(sysfs_root_tpm):
            sysfs_root = sysfs_root_tpm
        elif os.path.isdir(sysfs_root_misc):
            sysfs_root = sysfs_root_misc
        else:
            return
        for tpm_id in sorted(os.listdir(sysfs_root)):
            if sysfs_root == sysfs_root_misc and not tpm_id.startswith('tpm'):
                continue
            print("x-sysfs-device-name: {}".format(tpm_id))
            tpm_dirname = os.path.join(sysfs_root, tpm_id, 'device')
            for tpm_attr in sorted(os.listdir(tpm_dirname)):
                tpm_filename = os.path.join(tpm_dirname, tpm_attr)
                if not os.path.isfile(tpm_filename):
                    continue
                if not os.access(tpm_filename, os.R_OK):
                    continue
                with open(tpm_filename, 'rt', encoding='utf-8') as stream:
                    tpm_data = stream.read()
                tpm_data = tpm_data.rstrip()
                if '\n' in tpm_data:
                    print("{}:".format(tpm_attr))
                    for tpm_data_chunk in tpm_data.splitlines():
                        print(" {}".format(tpm_data_chunk))
                else:
                    print("{}: {}".format(tpm_attr, tpm_data))
            print()


if __name__ == "__main__":
    tpm_sysfs_resource().main()