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Filename : procfs.py
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#!/usr/bin/python3
# -*- python -*-
# -*- coding: utf-8 -*-
# SPDX-License-Identifier: GPL-2.0-only
#
# Copyright (C) 2007-2015 Red Hat, Inc.
#

import os
import platform
import re
import time
from functools import reduce
from six.moves import range
from procfs.utilist import bitmasklist

VERSION = "0.7.3"


def is_s390():
    """ Return True if running on s390 or s390x """
    machine = platform.machine()
    return bool(re.search('s390', machine))


def process_cmdline(pid_info):
    """
    Returns the process command line, if available in the given `process' class,
    if not available, falls back to using the comm (short process name) in its
    pidstat key.
    """
    if pid_info["cmdline"]:
        return reduce(lambda a, b: a + " %s" % b, pid_info["cmdline"]).strip()

    try:
        """ If a pid disappears before we query it, return None """
        return pid_info["stat"]["comm"]
    except:
        return None


class pidstat:
    """
    Provides a dictionary to access the fields in the
    per process /proc/PID/stat files.

    One can obtain the available fields by asking for the keys of the
    dictionary, e.g.:

        >>> p = procfs.pidstat(1)
        >>> print p.keys()
        ['majflt', 'rss', 'cnswap', 'cstime', 'pid', 'session', 'startstack', 'startcode', 'cmajflt', 'blocked', 'exit_signal', 'minflt', 'nswap', 'environ', 'priority', 'state', 'delayacct_blkio_ticks', 'policy', 'rt_priority', 'ppid', 'nice', 'cutime', 'endcode', 'wchan', 'num_threads', 'sigcatch', 'comm', 'stime', 'sigignore', 'tty_nr', 'kstkeip', 'utime', 'tpgid', 'itrealvalue', 'kstkesp', 'rlim', 'signal', 'pgrp', 'flags', 'starttime', 'cminflt', 'vsize', 'processor']

       And then access the various process properties using it as a dictionary:

        >>> print p['comm']
        systemd
        >>> print p['priority']
        20
        >>> print p['state']
        S

       Please refer to the 'procfs(5)' man page, by using:

        $ man 5 procfs

       To see information for each of the above fields, it is part of the
           'man-pages' RPM package.
    """

    # Entries with the same value, the one with a comment after it is the
    # more recent, having replaced the other name in v4.1-rc kernel times.

    PF_ALIGNWARN = 0x00000001
    PF_STARTING = 0x00000002
    PF_EXITING = 0x00000004
    PF_EXITPIDONE = 0x00000008
    PF_VCPU = 0x00000010
    PF_WQ_WORKER = 0x00000020  # /* I'm a workqueue worker */
    PF_FORKNOEXEC = 0x00000040
    PF_MCE_PROCESS = 0x00000080  # /* process policy on mce errors */
    PF_SUPERPRIV = 0x00000100
    PF_DUMPCORE = 0x00000200
    PF_SIGNALED = 0x00000400
    PF_MEMALLOC = 0x00000800
    # /* set_user noticed that RLIMIT_NPROC was exceeded */
    PF_NPROC_EXCEEDED = 0x00001000
    PF_FLUSHER = 0x00001000
    PF_USED_MATH = 0x00002000
    PF_USED_ASYNC = 0x00004000  # /* used async_schedule*(), used by module init */
    PF_NOFREEZE = 0x00008000
    PF_FROZEN = 0x00010000
    PF_FSTRANS = 0x00020000
    PF_KSWAPD = 0x00040000
    PF_MEMALLOC_NOIO = 0x00080000  # /* Allocating memory without IO involved */
    PF_SWAPOFF = 0x00080000
    PF_LESS_THROTTLE = 0x00100000
    PF_KTHREAD = 0x00200000
    PF_RANDOMIZE = 0x00400000
    PF_SWAPWRITE = 0x00800000
    PF_SPREAD_PAGE = 0x01000000
    PF_SPREAD_SLAB = 0x02000000
    PF_THREAD_BOUND = 0x04000000
    # /* Userland is not allowed to meddle with cpus_allowed */
    PF_NO_SETAFFINITY = 0x04000000
    PF_MCE_EARLY = 0x08000000  # /* Early kill for mce process policy */
    PF_MEMPOLICY = 0x10000000
    PF_MUTEX_TESTER = 0x20000000
    PF_FREEZER_SKIP = 0x40000000
    PF_FREEZER_NOSIG = 0x80000000
    # /* this thread called freeze_processes and should not be frozen */
    PF_SUSPEND_TASK = 0x80000000

    proc_stat_fields = ["pid", "comm", "state", "ppid", "pgrp", "session",
                        "tty_nr", "tpgid", "flags", "minflt", "cminflt",
                        "majflt", "cmajflt", "utime", "stime", "cutime",
                        "cstime", "priority", "nice", "num_threads",
                        "itrealvalue", "starttime", "vsize", "rss",
                        "rlim", "startcode", "endcode", "startstack",
                        "kstkesp", "kstkeip", "signal", "blocked",
                        "sigignore", "sigcatch", "wchan", "nswap",
                        "cnswap", "exit_signal", "processor",
                        "rt_priority", "policy",
                        "delayacct_blkio_ticks", "environ"]

    def __init__(self, pid, basedir="/proc"):
        self.pid = pid
        try:
            self.load(basedir)
        except FileNotFoundError:
            # The file representing the pid has disappeared
            #  propagate the error to the user to handle
            raise

    def __getitem__(self, fieldname):
        return self.fields[fieldname]

    def keys(self):
        return list(self.fields.keys())

    def values(self):
        return list(self.fields.values())

    def has_key(self, fieldname):
        return fieldname in self.fields

    def items(self):
        return self.fields

    def __contains__(self, fieldname):
        return fieldname in self.fields

    def load(self, basedir="/proc"):
        try:
            f = open(f"{basedir}/{self.pid}/stat")
        except FileNotFoundError:
            # The pid has disappeared, propagate the error
            raise
        fields = f.readline().strip().split(') ')
        f.close()
        fields = fields[0].split(' (') + fields[1].split()
        self.fields = {}
        nr_fields = min(len(fields), len(self.proc_stat_fields))
        for i in range(nr_fields):
            attrname = self.proc_stat_fields[i]
            value = fields[i]
            if attrname == "comm":
                self.fields["comm"] = value.strip('()')
            else:
                try:
                    self.fields[attrname] = int(value)
                except:
                    self.fields[attrname] = value

    def is_bound_to_cpu(self):
        """
        Returns true if this process has a fixed smp affinity mask,
                not allowing it to be moved to a different set of CPUs.
        """
        return bool(self.fields["flags"] & self.PF_THREAD_BOUND)

    def process_flags(self):
        """
        Returns a list with all the process flags known, details depend
        on kernel version, declared in the file include/linux/sched.h in
        the kernel sources.

        As of v4.2-rc7 these include (from include/linux/sched.h comments):

            PF_EXITING        Getting shut down
            PF_EXITPIDONE     Pi exit done on shut down
            PF_VCPU           I'm a virtual CPU
            PF_WQ_WORKER      I'm a workqueue worker
            PF_FORKNOEXEC     Forked but didn't exec
            PF_MCE_PROCESS    Process policy on mce errors
            PF_SUPERPRIV      Used super-user privileges
            PF_DUMPCORE       Dumped core
            PF_SIGNALED       Killed by a signal
            PF_MEMALLOC       Allocating memory
            PF_NPROC_EXCEEDED Set_user noticed that RLIMIT_NPROC was exceeded
            PF_USED_MATH      If unset the fpu must be initialized before use
            PF_USED_ASYNC     Used async_schedule*(), used by module init
            PF_NOFREEZE       This thread should not be frozen
            PF_FROZEN          Frozen for system suspend
            PF_FSTRANS         Inside a filesystem transaction
            PF_KSWAPD          I am kswapd
            PF_MEMALLOC_NOIO   Allocating memory without IO involved
            PF_LESS_THROTTLE   Throttle me less: I clean memory
            PF_KTHREAD         I am a kernel thread
            PF_RANDOMIZE       Randomize virtual address space
            PF_SWAPWRITE       Allowed to write to swap
            PF_NO_SETAFFINITY  Userland is not allowed to meddle with cpus_allowed
            PF_MCE_EARLY       Early kill for mce process policy
            PF_MUTEX_TESTER    Thread belongs to the rt mutex tester
            PF_FREEZER_SKIP    Freezer should not count it as freezable
            PF_SUSPEND_TASK    This thread called freeze_processes and
                               should not be frozen

        """
        sflags = []
        for attr in dir(self):
            if attr[:3] != "PF_":
                continue
            value = getattr(self, attr)
            if value & self.fields["flags"]:
                sflags.append(attr)

        return sflags


def cannot_set_affinity(self, pid):
    PF_NO_SETAFFINITY = 0x04000000
    try:
        return bool(int(self.processes[pid]["stat"]["flags"]) &
                    PF_NO_SETAFFINITY)
    except:
        return True


def cannot_set_thread_affinity(self, pid, tid):
    PF_NO_SETAFFINITY = 0x04000000
    try:
        return bool(int(self.processes[pid].threads[tid]["stat"]["flags"]) &
                    PF_NO_SETAFFINITY)
    except:
        return True


class pidstatus:
    """
    Provides a dictionary to access the fields
    in the per process /proc/PID/status files.
    This provides additional information about processes and threads to
    what can be obtained with the procfs.pidstat() class.

    One can obtain the available fields by asking for the keys of the
    dictionary, e.g.:

        >>> import procfs
        >>> p = procfs.pidstatus(1)
        >>> print p.keys()
        ['VmExe', 'CapBnd', 'NSpgid', 'Tgid', 'NSpid', 'VmSize', 'VmPMD', 'ShdPnd', 'State', 'Gid', 'nonvoluntary_ctxt_switches', 'SigIgn', 'VmStk', 'VmData', 'SigCgt', 'CapEff', 'VmPTE', 'Groups', 'NStgid', 'Threads', 'PPid', 'VmHWM', 'NSsid', 'VmSwap', 'Name', 'SigBlk', 'Mems_allowed_list', 'VmPeak', 'Ngid', 'VmLck', 'SigQ', 'VmPin', 'Mems_allowed', 'CapPrm', 'Seccomp', 'VmLib', 'Cpus_allowed', 'Uid', 'SigPnd', 'Pid', 'Cpus_allowed_list', 'TracerPid', 'CapInh', 'voluntary_ctxt_switches', 'VmRSS', 'FDSize']
        >>> print p["Pid"]
        1
        >>> print p["Threads"]
        1
        >>> print p["VmExe"]
        1248 kB
        >>> print p["Cpus_allowed"]
        f
        >>> print p["SigQ"]
        0/30698
        >>> print p["VmPeak"]
        320300 kB
        >>>

    Please refer to the 'procfs(5)' man page, by using:

        $ man 5 procfs

    To see information for each of the above fields, it is part of the
    'man-pages' RPM package.

    In the man page there will be references to further documentation, like
        referring to the "getrlimit(2)" man page when explaining the "SigQ"
        line/field.
    """

    def __init__(self, pid, basedir="/proc"):
        self.pid = pid
        self.load(basedir)

    def __getitem__(self, fieldname):
        return self.fields[fieldname]

    def keys(self):
        return list(self.fields.keys())

    def values(self):
        return list(self.fields.values())

    def has_key(self, fieldname):
        return fieldname in self.fields

    def items(self):
        return self.fields

    def __contains__(self, fieldname):
        return fieldname in self.fields

    def load(self, basedir="/proc"):
        self.fields = {}
        with open(f"{basedir}/{self.pid}/status") as f:
            for line in f.readlines():
                fields = line.split(":")
                if len(fields) != 2:
                    continue
                name = fields[0]
                value = fields[1].strip()
                try:
                    self.fields[name] = int(value)
                except:
                    self.fields[name] = value


class process:
    """
    Information about a process with a given pid, provides a dictionary with
    two entries, instances of different wrappers for /proc/ process related
    meta files: "stat" and "status", see the documentation for procfs.pidstat
    and procfs.pidstatus for further info about those classes.
    """

    def __init__(self, pid, basedir="/proc"):
        self.pid = pid
        self.basedir = basedir

    def __getitem__(self, attr):
        if not hasattr(self, attr):
            if attr in ("stat", "status"):
                if attr == "stat":
                    sclass = pidstat
                else:
                    sclass = pidstatus

                try:
                    setattr(self, attr, sclass(self.pid, self.basedir))
                except FileNotFoundError:
                    # The pid has disappeared, progate the error
                    raise
            elif attr == "cmdline":
                self.load_cmdline()
            elif attr == "threads":
                self.load_threads()
            elif attr == "cgroups":
                self.load_cgroups()
            elif attr == "environ":
                self.load_environ()

        return getattr(self, attr)

    def has_key(self, attr):
        return hasattr(self, attr)

    def __contains__(self, attr):
        return hasattr(self, attr)

    def load_cmdline(self):
        try:
            with open(f"/proc/{self.pid}/cmdline") as f:
                self.cmdline = f.readline().strip().split('\0')[:-1]
        except FileNotFoundError:
            """ This can happen when a pid disappears """
            self.cmdline = None
        except UnicodeDecodeError:
            """ TODO - this shouldn't happen, needs to be investigated """
            self.cmdline = None

    def load_threads(self):
        self.threads = pidstats(f"/proc/{self.pid}/task/")
        # remove thread leader
        del self.threads[self.pid]

    def load_cgroups(self):
        self.cgroups = ""
        with open(f"/proc/{self.pid}/cgroup") as f:
            for line in reversed(f.readlines()):
                if len(self.cgroups) != 0:
                    self.cgroups = self.cgroups + "," + line[:-1]
                else:
                    self.cgroups = line[:-1]

    def load_environ(self):
        """
        Loads the environment variables for this process. The entries then
        become available via the 'environ' member, or via the 'environ'
        dict key when accessing as p["environ"].

        E.g.:


        >>> all_processes = procfs.pidstats()
        >>> firefox_pid = all_processes.find_by_name("firefox")
        >>> firefox_process = all_processes[firefox_pid[0]]
        >>> print firefox_process["environ"]["PWD"]
        /home/acme
        >>> print len(firefox_process.environ.keys())
        66
        >>> print firefox_process["environ"]["SHELL"]
        /bin/bash
        >>> print firefox_process["environ"]["USERNAME"]
        acme
        >>> print firefox_process["environ"]["HOME"]
        /home/acme
        >>> print firefox_process["environ"]["MAIL"]
        /var/spool/mail/acme
        >>>
        """
        self.environ = {}
        with open(f"/proc/{self.pid}/environ") as f:
            for x in f.readline().split('\0'):
                if len(x) > 0:
                    y = x.split('=')
                    self.environ[y[0]] = y[1]


class pidstats:
    """
    Provides access to all the processes in the system, to get a picture of
    how many processes there are at any given moment.

    The entries can be accessed as a dictionary, keyed by pid. Also there are
    methods to find processes that match a given COMM or regular expression.
    """

    def __init__(self, basedir="/proc"):
        self.basedir = basedir
        self.processes = {}
        self.reload()

    def __getitem__(self, key):
        return self.processes[key]

    def __delitem__(self, key):
        # not clear on why this can fail, but it can
        try:
            del self.processes[key]
        except:
            pass

    def keys(self):
        return list(self.processes.keys())

    def values(self):
        return list(self.processes.values())

    def has_key(self, key):
        return key in self.processes

    def items(self):
        return self.processes

    def __contains__(self, key):
        return key in self.processes

    def reload(self):
        """
        This operation will throw away the current dictionary contents,
        if any, and read all the pid files from /proc/, instantiating a
        'process' instance for each of them.

        This is a high overhead operation, and should be avoided if the
        perf python binding can be used to detect when new threads appear
        and existing ones terminate.

        In RHEL it is found in the python-perf rpm package.

        More information about the perf facilities can be found in the
        'perf_event_open' man page.
        """
        del self.processes
        self.processes = {}
        pids = os.listdir(self.basedir)
        for spid in pids:
            try:
                pid = int(spid)
            except:
                continue

            self.processes[pid] = process(pid, self.basedir)

    def reload_threads(self):
        to_remove = []
        for pid in list(self.processes.keys()):
            try:
                self.processes[pid].load_threads()
            except OSError:
                # process vanished, remove it
                to_remove.append(pid)
        for pid in to_remove:
            del self.processes[pid]

    def find_by_name(self, name):
        name = name[:15]
        pids = []
        for pid in list(self.processes.keys()):
            try:
                if name == self.processes[pid]["stat"]["comm"]:
                    pids.append(pid)
            except IOError:
                # We're doing lazy loading of /proc files
                # So if we get this exception is because the
                # process vanished, remove it
                del self.processes[pid]

        return pids

    def find_by_regex(self, regex):
        pids = []
        for pid in list(self.processes.keys()):
            try:
                if regex.match(self.processes[pid]["stat"]["comm"]):
                    pids.append(pid)
            except IOError:
                # We're doing lazy loading of /proc files
                # So if we get this exception is because the
                # process vanished, remove it
                del self.processes[pid]
        return pids

    def find_by_cmdline_regex(self, regex):
        pids = []
        for pid in list(self.processes.keys()):
            try:
                if regex.match(process_cmdline(self.processes[pid])):
                    pids.append(pid)
            except IOError:
                # We're doing lazy loading of /proc files
                # So if we get this exception is because the
                # process vanished, remove it
                del self.processes[pid]
        return pids

    def get_per_cpu_rtprios(self, basename):
        cpu = 0
        priorities = ""
        processed_pids = []
        while True:
            name = f"{basename}/{cpu}"
            pids = self.find_by_name(name)
            if not pids or len([n for n in pids if n not in processed_pids]) == 0:
                break
            for pid in pids:
                try:
                    priorities += f'{self.processes[pid]["stat"]["rt_priority"]}'
                except IOError:
                    # We're doing lazy loading of /proc files
                    # So if we get this exception is because the
                    # process vanished, remove it
                    del self.processes[pid]
            processed_pids += pids
            cpu += 1

        priorities = priorities.strip(',')
        return priorities

    def get_rtprios(self, name):
        cpu = 0
        priorities = ""
        processed_pids = []
        while True:
            pids = self.find_by_name(name)
            if not pids or len([n for n in pids if n not in processed_pids]) == 0:
                break
            for pid in pids:
                try:
                    priorities += f'{self.processes[pid]["stat"]["rt_priority"]}'
                except IOError:
                    # We're doing lazy loading of /proc files
                    # So if we get this exception is because the
                    # process vanished, remove it
                    del self.processes[pid]
            processed_pids += pids
            cpu += 1

        priorities = priorities.strip(',')
        return priorities

    def is_bound_to_cpu(self, pid):
        """
        Checks if a given pid can't have its SMP affinity mask changed.
        """
        return self.processes[pid]["stat"].is_bound_to_cpu()


class interrupts:
    """
    Information about IRQs in the system. A dictionary keyed by IRQ number
    will have as its value another dictionary with "cpu", "type" and "users"
    keys, with the SMP affinity mask, type of IRQ and the drivers associated
    with each interrupt.

    The information comes from the /proc/interrupts file, documented in
    'man procfs(5)', for instance, the 'cpu' dict is an array with one entry
    per CPU present in the sistem, each value being the number of interrupts
    that took place per CPU.

    E.g.:

    >>> import procfs
    >>> interrupts = procfs.interrupts()
    >>> thunderbolt_irq = interrupts.find_by_user("thunderbolt")
    >>> print thunderbolt_irq
    34
    >>> thunderbolt = interrupts[thunderbolt_irq]
    >>> print thunderbolt
    {'affinity': [0, 1, 2, 3], 'type': 'PCI-MSI', 'cpu': [3495, 0, 81, 0], 'users': ['thunderbolt']}
    >>>
    """

    def __init__(self):
        self.interrupts = {}
        self.reload()

    def __getitem__(self, key):
        return self.interrupts[str(key)]

    def keys(self):
        return list(self.interrupts.keys())

    def values(self):
        return list(self.interrupts.values())

    def has_key(self, key):
        return str(key) in self.interrupts

    def items(self):
        return self.interrupts

    def __contains__(self, key):
        return str(key) in self.interrupts

    def reload(self):
        del self.interrupts
        self.interrupts = {}
        with open("/proc/interrupts") as f:
            for line in f.readlines():
                line = line.strip()
                fields = line.split()
                if fields[0][:3] == "CPU":
                    self.nr_cpus = len(fields)
                    continue
                irq = fields[0].strip(":")
                self.interrupts[irq] = {}
                self.interrupts[irq] = self.parse_entry(fields[1:], line)
                try:
                    nirq = int(irq)
                except:
                    continue
                self.interrupts[irq]["affinity"] = self.parse_affinity(nirq)

    def parse_entry(self, fields, line):
        dict = {}
        dict["cpu"] = []
        dict["cpu"].append(int(fields[0]))
        nr_fields = len(fields)
        if nr_fields >= self.nr_cpus:
            dict["cpu"] += [int(i) for i in fields[1:self.nr_cpus]]
            if nr_fields > self.nr_cpus:
                dict["type"] = fields[self.nr_cpus]
                # look if there are users (interrupts 3 and 4 haven't)
                if nr_fields > self.nr_cpus + 1:
                    dict["users"] = [a.strip()
                                     for a in fields[nr_fields - 1].split(',')]
                else:
                    dict["users"] = []
        return dict

    def parse_affinity(self, irq):
        try:
            with open(f"/proc/irq/{irq}/smp_affinity") as f:
                line = f.readline()
            return bitmasklist(line, self.nr_cpus)
        except IOError:
            return [0, ]

    def find_by_user(self, user):
        """
        Looks up a interrupt number by the name of one of its users"

        E.g.:

        >>> import procfs
        >>> interrupts = procfs.interrupts()
        >>> thunderbolt_irq = interrupts.find_by_user("thunderbolt")
        >>> print thunderbolt_irq
        34
        >>> thunderbolt = interrupts[thunderbolt_irq]
        >>> print thunderbolt
        {'affinity': [0, 1, 2, 3], 'type': 'PCI-MSI', 'cpu': [3495, 0, 81, 0], 'users': ['thunderbolt']}
        >>>
        """
        for i in list(self.interrupts.keys()):
            if "users" in self.interrupts[i] and \
               user in self.interrupts[i]["users"]:
                return i
        return None

    def find_by_user_regex(self, regex):
        """
        Looks up a interrupt number by a regex that matches names of its users"

        E.g.:

        >>> import procfs
        >>> import re
        >>> interrupts = procfs.interrupts()
        >>> usb_controllers = interrupts.find_by_user_regex(re.compile(".*hcd"))
        >>> print usb_controllers
        ['22', '23', '31']
        >>> print [ interrupts[irq]["users"] for irq in usb_controllers ]
        [['ehci_hcd:usb4'], ['ehci_hcd:usb3'], ['xhci_hcd']]
        >>>
        """
        irqs = []
        for i in list(self.interrupts.keys()):
            if "users" not in self.interrupts[i]:
                continue
            for user in self.interrupts[i]["users"]:
                if regex.match(user):
                    irqs.append(i)
                    break
        return irqs


class cmdline:
    """
    Parses the kernel command line (/proc/cmdline), turning it into a dictionary."

    Useful to figure out if some kernel boolean knob has been turned on,
    as well as to find the value associated to other kernel knobs.

    It can also be used to find out about parameters passed to the
    init process, such as 'BOOT_IMAGE', etc.

    E.g.:
    >>> import procfs
    >>> kcmd = procfs.cmdline()
    >>> print kcmd.keys()
    ['LANG', 'BOOT_IMAGE', 'quiet', 'rhgb', 'rd.lvm.lv', 'ro', 'root']
    >>> print kcmd["BOOT_IMAGE"]
    /vmlinuz-4.3.0-rc1+
    >>>
    """

    def __init__(self):
        self.options = {}
        self.parse()

    def parse(self):
        with open("/proc/cmdline") as f:
            for option in f.readline().strip().split():
                fields = option.split("=")
                if len(fields) == 1:
                    self.options[fields[0]] = True
                else:
                    self.options[fields[0]] = fields[1]

    def __getitem__(self, key):
        return self.options[key]

    def keys(self):
        return list(self.options.keys())

    def values(self):
        return list(self.options.values())

    def items(self):
        return self.options


class cpuinfo:
    """
    Dictionary with information about CPUs in the system.

    Please refer to 'man procfs(5)' for further information about the
    '/proc/cpuinfo' file, that is the source of the information provided
    by this class. The 'man lscpu(1)' also has information about a program that
    uses the '/proc/cpuinfo' file.

    Using this class one can obtain the number of CPUs in a system:

      >>> cpus = procfs.cpuinfo()
          >>> print cpus.nr_cpus
          4

    It is also possible to figure out aspects of the CPU topology, such as
    how many CPU physical sockets exists, i.e. groups of CPUs sharing
    components such as CPU memory caches:

      >>> print len(cpus.sockets)
      1

    Additionally dictionary with information common to all CPUs in the system
    is available:

      >>> print cpus["model name"]
          Intel(R) Core(TM) i7-3667U CPU @ 2.00GHz
          >>> print cpus["cache size"]
          4096 KB
          >>>
    """

    def __init__(self, filename="/proc/cpuinfo"):
        self.tags = {}
        self.nr_cpus = 0
        self.sockets = []
        self.parse(filename)

    def __getitem__(self, key):
        return self.tags[key.lower()]

    def keys(self):
        return list(self.tags.keys())

    def values(self):
        return list(self.tags.values())

    def items(self):
        return self.tags

    def parse(self, filename):
        with open(filename) as f:
            for line in f.readlines():
                line = line.strip()
                if not line:
                    continue
                fields = line.split(":")
                tagname = fields[0].strip().lower()
                if tagname == "processor":
                    self.nr_cpus += 1
                    continue
                if is_s390() and tagname == "cpu number":
                    self.nr_cpus += 1
                    continue
                if tagname == "core id":
                    continue
                self.tags[tagname] = fields[1].strip()
                if tagname == "physical id":
                    socket_id = self.tags[tagname]
                    if socket_id not in self.sockets:
                        self.sockets.append(socket_id)
        self.nr_sockets = self.sockets and len(self.sockets) or \
            (self.nr_cpus /
             ("siblings" in self.tags and int(self.tags["siblings"]) or 1))
        self.nr_cores = ("cpu cores" in self.tags and int(
            self.tags["cpu cores"]) or 1) * self.nr_sockets


class smaps_lib:
    """
    Representation of an mmap in place for a process. Can be used to figure
    out which processes have an library mapped, etc.

    The 'perm' member can be used to figure out executable mmaps,
    i.e. libraries.

    The 'vm_start' and 'vm_end' in turn can be used when trying to resolve
    processor instruction pointer addresses to a symbol name in a library.
    """

    def __init__(self, lines):
        fields = lines[0].split()
        self.vm_start, self.vm_end = [int(a, 16) for a in fields[0].split("-")]
        self.perms = fields[1]
        self.offset = int(fields[2], 16)
        self.major, self.minor = fields[3].split(":")
        self.inode = int(fields[4])
        if len(fields) > 5:
            self.name = fields[5]
        else:
            self.name = None
        self.tags = {}
        for line in lines[1:]:
            fields = line.split()
            tag = fields[0][:-1].lower()
            try:
                self.tags[tag] = int(fields[1])
            except:
                # VmFlags are strings
                self.tags[tag] = fields

    def __getitem__(self, key):
        return self.tags[key.lower()]

    def keys(self):
        return list(self.tags.keys())

    def values(self):
        return list(self.tags.values())

    def items(self):
        return self.tags


class smaps:
    """
    List of libraries mapped by a process. Parses the lines in
    the /proc/PID/smaps file, that is further documented in the
    procfs(5) man page.

    Example: Listing the executable maps for the 'sshd' process:

          >>> import procfs
          >>> processes = procfs.pidstats()
          >>> sshd = processes.find_by_name("sshd")
          >>> sshd_maps = procfs.smaps(sshd[0])
          >>> for i in range(len(sshd_maps)):
          ...     if 'x' in sshd_maps[i].perms:
          ...         print "%s: %s" % (sshd_maps[i].name, sshd_maps[i].perms)
          ...
          /usr/sbin/sshd: r-xp
          /usr/lib64/libnss_files-2.20.so: r-xp
          /usr/lib64/librt-2.20.so: r-xp
          /usr/lib64/libkeyutils.so.1.5: r-xp
          /usr/lib64/libkrb5support.so.0.1: r-xp
          /usr/lib64/libfreebl3.so: r-xp
          /usr/lib64/libpthread-2.20.so: r-xp
      ...
    """

    def __init__(self, pid):
        self.pid = pid
        self.entries = []
        self.reload()

    def parse_entry(self, f, line):
        lines = []
        if not line:
            line = f.readline().strip()
        if not line:
            return
        lines.append(line)
        while True:
            line = f.readline()
            if not line:
                break
            line = line.strip()
            if line.split()[0][-1] == ':':
                lines.append(line)
            else:
                break
        self.entries.append(smaps_lib(lines))
        return line

    def __len__(self):
        return len(self.entries)

    def __getitem__(self, index):
        return self.entries[index]

    def reload(self):
        line = None
        with open(f"/proc/{self.pid}/smaps") as f:
            while True:
                line = self.parse_entry(f, line)
                if not line:
                    break
        self.nr_entries = len(self.entries)

    def find_by_name_fragment(self, fragment):
        result = []
        for i in range(self.nr_entries):
            if self.entries[i].name and \
               self.entries[i].name.find(fragment) >= 0:
                result.append(self.entries[i])

        return result


class cpustat:
    """
    CPU statistics, obtained from a line in the '/proc/stat' file, Please
    refer to 'man procfs(5)' for further information about the '/proc/stat'
    file, that is the source of the information provided by this class.
    """

    def __init__(self, fields):
        self.name = fields[0]
        (self.user,
         self.nice,
         self.system,
         self.idle,
         self.iowait,
         self.irq,
         self.softirq) = [int(i) for i in fields[1:8]]
        if len(fields) > 7:
            self.steal = int(fields[7])
            if len(fields) > 8:
                self.guest = int(fields[8])

    def __repr__(self):
        s = f"< user: {self.user}, nice: {self.nice}, system: {self.system}, idle: {self.idle}, iowait: {self.iowait}, irq: {self.irq}, softirq: {self.softirq}"
        if hasattr(self, 'steal'):
            s += f", steal: {self.steal}"
        if hasattr(self, 'guest'):
            s += f", guest: {self.guest}"
        return s + ">"


class cpusstats:
    """
    Dictionary with information about CPUs in the system. First entry in the
    dictionary gives an aggregate view of all CPUs, each other entry is about
    separate CPUs. Please refer to 'man procfs(5)' for further information
    about the '/proc/stat' file, that is the source of the information provided
    by this class.
    """

    def __init__(self, filename="/proc/stat"):
        self.entries = {}
        self.time = None
        self.hertz = os.sysconf(2)
        self.filename = filename
        self.reload()

    def __iter__(self):
        return iter(self.entries)

    def __getitem__(self, key):
        return self.entries[key]

    def __len__(self):
        return len(list(self.entries.keys()))

    def keys(self):
        return list(self.entries.keys())

    def values(self):
        return list(self.entries.values())

    def items(self):
        return self.entries

    def reload(self):
        last_entries = self.entries
        self.entries = {}
        with open(self.filename) as f:
            for line in f.readlines():
                fields = line.strip().split()
                if fields[0][:3].lower() != "cpu":
                    continue
                c = cpustat(fields)
                if c.name == "cpu":
                    idx = 0
                else:
                    idx = int(c.name[3:]) + 1
                self.entries[idx] = c
        last_time = self.time
        self.time = time.time()
        if last_entries:
            delta_sec = self.time - last_time
            interval_hz = delta_sec * self.hertz
            for cpu in list(self.entries.keys()):
                if cpu not in last_entries:
                    curr.usage = 0
                    continue
                curr = self.entries[cpu]
                prev = last_entries[cpu]
                delta = (curr.user - prev.user) + \
                    (curr.nice - prev.nice) + \
                    (curr.system - prev.system)
                curr.usage = (delta / interval_hz) * 100
                curr.usage = min(curr.usage, 100)


if __name__ == '__main__':
    import sys

    ints = interrupts()

    for i in list(ints.interrupts.keys()):
        print(f"{i}: {ints.interrupts[i]}")

    options = cmdline()
    for o in list(options.options.keys()):
        print(f"{o}: {options.options[o]}")

    cpu = cpuinfo()
    print(f"\ncpuinfo data: {cpu.nr_cpus} processors")
    for tag in list(cpu.keys()):
        print(f"{tag}={cpu[tag]}")

    print("smaps:\n" + ("-" * 40))
    s = smaps(int(sys.argv[1]))
    for i in range(s.nr_entries):
        print(f"{s.entries[i].vm_start:#x} {s.entries[i].name}")
    print("-" * 40)
    for a in s.find_by_name_fragment(sys.argv[2]):
        print(a["Size"])

    ps = pidstats()
    print(ps[1])

    cs = cpusstats()
    while True:
        time.sleep(1)
        cs.reload()
        for cpu in cs:
            print(f"{cpu}: {cs[cpu]}")
        print("-" * 10)