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104 lines
2.6 KiB
Go
104 lines
2.6 KiB
Go
package system
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import (
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"fmt"
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"io/ioutil"
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"path/filepath"
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"strconv"
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"strings"
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)
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// State is the status of a process.
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type State rune
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const ( // Only values for Linux 3.14 and later are listed here
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Dead State = 'X'
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DiskSleep State = 'D'
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Running State = 'R'
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Sleeping State = 'S'
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Stopped State = 'T'
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TracingStop State = 't'
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Zombie State = 'Z'
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)
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// String forms of the state from proc(5)'s documentation for
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// /proc/[pid]/status' "State" field.
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func (s State) String() string {
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switch s {
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case Dead:
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return "dead"
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case DiskSleep:
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return "disk sleep"
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case Running:
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return "running"
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case Sleeping:
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return "sleeping"
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case Stopped:
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return "stopped"
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case TracingStop:
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return "tracing stop"
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case Zombie:
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return "zombie"
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default:
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return fmt.Sprintf("unknown (%c)", s)
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}
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}
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// Stat_t represents the information from /proc/[pid]/stat, as
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// described in proc(5) with names based on the /proc/[pid]/status
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// fields.
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type Stat_t struct {
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// PID is the process ID.
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PID uint
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// Name is the command run by the process.
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Name string
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// State is the state of the process.
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State State
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// StartTime is the number of clock ticks after system boot (since
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// Linux 2.6).
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StartTime uint64
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}
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// Stat returns a Stat_t instance for the specified process.
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func Stat(pid int) (stat Stat_t, err error) {
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bytes, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat"))
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if err != nil {
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return stat, err
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}
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return parseStat(string(bytes))
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}
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func parseStat(data string) (stat Stat_t, err error) {
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// From proc(5), field 2 could contain space and is inside `(` and `)`.
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// The following is an example:
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// 89653 (gunicorn: maste) S 89630 89653 89653 0 -1 4194560 29689 28896 0 3 146 32 76 19 20 0 1 0 2971844 52965376 3920 18446744073709551615 1 1 0 0 0 0 0 16781312 137447943 0 0 0 17 1 0 0 0 0 0 0 0 0 0 0 0 0 0
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i := strings.LastIndex(data, ")")
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if i <= 2 || i >= len(data)-1 {
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return stat, fmt.Errorf("invalid stat data: %q", data)
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}
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parts := strings.SplitN(data[:i], "(", 2)
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if len(parts) != 2 {
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return stat, fmt.Errorf("invalid stat data: %q", data)
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}
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stat.Name = parts[1]
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_, err = fmt.Sscanf(parts[0], "%d", &stat.PID)
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if err != nil {
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return stat, err
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}
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// parts indexes should be offset by 3 from the field number given
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// proc(5), because parts is zero-indexed and we've removed fields
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// one (PID) and two (Name) in the paren-split.
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parts = strings.Split(data[i+2:], " ")
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var state int
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fmt.Sscanf(parts[3-3], "%c", &state) //nolint:staticcheck // "3-3" is more readable in this context.
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stat.State = State(state)
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fmt.Sscanf(parts[22-3], "%d", &stat.StartTime)
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return stat, nil
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}
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