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// Copyright 2018 psgo authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package proc
import (
"errors"
"fmt"
"io/ioutil"
"strings"
)
// Stat is a direct translation of a `/proc/[pid]/stat` file as described in
// the proc(5) manpage. Please note that it is not a full translation as not
// all fields are in the scope of this library and higher indices are
// Kernel-version dependent.
type Stat struct {
// (1) The process ID
Pid string
// (2) The filename of the executable, in parentheses. This is visible
// whether or not the executable is swapped out.
Comm string
// (3) The process state (e.g., running, sleeping, zombie, dead).
// Refer to proc(5) for further deatils.
State string
// (4) The PID of the parent of this process.
Ppid string
// (5) The process group ID of the process.
Pgrp string
// (6) The session ID of the process.
Session string
// (7) The controlling terminal of the process. (The minor device
// number is contained in the combination of bits 31 to 20 and 7 to 0;
// the major device number is in bits 15 to 8.)
TtyNr string
// (8) The ID of the foreground process group of the controlling
// terminal of the process.
Tpgid string
// (9) The kernel flags word of the process. For bit meanings, see the
// PF_* defines in the Linux kernel source file
// include/linux/sched.h. Details depend on the kernel version.
Flags string
// (10) The number of minor faults the process has made which have not
// required loading a memory page from disk.
Minflt string
// (11) The number of minor faults that the process's waited-for
// children have made.
Cminflt string
// (12) The number of major faults the process has made which have
// required loading a memory page from disk.
Majflt string
// (13) The number of major faults that the process's waited-for
// children have made.
Cmajflt string
// (14) Amount of time that this process has been scheduled in user
// mode, measured in clock ticks (divide by
// sysconf(_SC_CLK_TCK)). This includes guest time, guest_time
// (time spent running a virtual CPU, see below), so that applications
// that are not aware of the guest time field do not lose that time
// from their calculations.
Utime string
// (15) Amount of time that this process has been scheduled in kernel
// mode, measured in clock ticks (divide by sysconf(_SC_CLK_TCK)).
Stime string
// (16) Amount of time that this process's waited-for children have
// been scheduled in user mode, measured in clock ticks (divide by
// sysconf(_SC_CLK_TCK)). (See also times(2).) This includes guest
// time, cguest_time (time spent running a virtual CPU, see below).
Cutime string
// (17) Amount of time that this process's waited-for children have
// been scheduled in kernel mode, measured in clock ticks (divide by
// sysconf(_SC_CLK_TCK)).
Cstime string
// (18) (Explanation for Linux 2.6+) For processes running a real-time
// scheduling policy (policy below; see sched_setscheduler(2)), this is
// the negated scheduling pri- ority, minus one; that is, a number
// in the range -2 to -100, corresponding to real-time priorities 1 to
// 99. For processes running under a non-real-time scheduling
// policy, this is the raw nice value (setpriority(2)) as represented
// in the kernel. The kernel stores nice values as numbers in the
// range 0 (high) to 39 (low), corresponding to the user-visible nice
// range of -20 to 19.
Priority string
// (19) The nice value (see setpriority(2)), a value in the range 19
// (low priority) to -20 (high priority).
Nice string
// (20) Number of threads in this process (since Linux 2.6). Before
// kernel 2.6, this field was hard coded to 0 as a placeholder for an
// earlier removed field.
NumThreads string
// (21) The time in jiffies before the next SIGALRM is sent to the
// process due to an interval timer. Since kernel 2.6.17, this
// field is no longer maintained, and is hard coded as 0.
Itrealvalue string
// (22) The time the process started after system boot. In kernels
// before Linux 2.6, this value was expressed in jiffies. Since
// Linux 2.6, the value is expressed in clock ticks (divide by
// sysconf(_SC_CLK_TCK)).
Starttime string
// (23) Virtual memory size in bytes.
Vsize string
}
// readStat is used for mocking in unit tests.
var readStat = func(path string) (string, error) {
rawData, err := ioutil.ReadFile(path)
if err != nil {
return "", err
}
return string(rawData), nil
}
// ParseStat parses the /proc/$pid/stat file and returns a Stat.
func ParseStat(pid string) (*Stat, error) {
data, err := readStat(fmt.Sprintf("/proc/%s/stat", pid))
if err != nil {
return nil, err
}
firstParen := strings.IndexByte(data, '(')
lastParen := strings.LastIndexByte(data, ')')
if firstParen == -1 || lastParen == -1 {
return nil, errors.New("invalid format in stat")
}
pidstr := data[0 : firstParen-1]
comm := data[firstParen+1 : lastParen]
rest := strings.Fields(data[lastParen+1:])
fields := append([]string{pidstr, comm}, rest...)
fieldAt := func(i int) string {
return fields[i-1]
}
return &Stat{
Pid: fieldAt(1),
Comm: fieldAt(2),
State: fieldAt(3),
Ppid: fieldAt(4),
Pgrp: fieldAt(5),
Session: fieldAt(6),
TtyNr: fieldAt(7),
Tpgid: fieldAt(8),
Flags: fieldAt(9),
Minflt: fieldAt(10),
Cminflt: fieldAt(11),
Majflt: fieldAt(12),
Cmajflt: fieldAt(13),
Utime: fieldAt(14),
Stime: fieldAt(15),
Cutime: fieldAt(16),
Cstime: fieldAt(17),
Priority: fieldAt(18),
Nice: fieldAt(19),
NumThreads: fieldAt(20),
Itrealvalue: fieldAt(21),
Starttime: fieldAt(22),
Vsize: fieldAt(23),
}, nil
}
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