44 lines
1.4 KiB
Go
44 lines
1.4 KiB
Go
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package system
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import (
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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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// look in /proc to find the process start time so that we can verify
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// that this pid has started after ourself
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func GetProcessStartTime(pid int) (string, error) {
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data, err := ioutil.ReadFile(filepath.Join("/proc", strconv.Itoa(pid), "stat"))
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if err != nil {
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return "", err
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}
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return parseStartTime(string(data))
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}
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func parseStartTime(stat string) (string, error) {
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// the starttime is located at pos 22
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// from the man page
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//
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// starttime %llu (was %lu before Linux 2.6)
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// (22) The time the process started after system boot. In kernels before Linux 2.6, this
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// value was expressed in jiffies. Since Linux 2.6, the value is expressed in clock ticks
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// (divide by sysconf(_SC_CLK_TCK)).
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//
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// NOTE:
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// pos 2 could contain space and is inside `(` and `)`:
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// (2) comm %s
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// The filename of the executable, in parentheses.
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// This is visible whether or not the executable is
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// swapped out.
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//
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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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// get parts after last `)`:
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s := strings.Split(stat, ")")
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parts := strings.Split(strings.TrimSpace(s[len(s)-1]), " ")
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return parts[22-3], nil // starts at 3 (after the filename pos `2`)
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}
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