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78c894234c
gates / gates (push) Successful in 46s
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS
57 lines
1.7 KiB
Go
57 lines
1.7 KiB
Go
//go:build linux
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package system
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import (
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"os"
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"path/filepath"
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"strings"
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)
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// MountIsShutdown reports whether the TOP mount at path is a dead filesystem — ext4's `shutdown` super option, set when
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// the device under it went away (a pulled drive). It reads /proc/self/mountinfo only: NO disk I/O, so it never hangs on
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// the dead device (gates.md: health checks issue no block I/O). A timed `stat` is NOT a substitute: it answered „ok" on
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// a dead drive from the cache (measured 2026-10-14, `15` §10 K4). Pinned by TestMountIsShutdown_*.
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func MountIsShutdown(path string) bool {
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data, err := os.ReadFile(mountinfoPath)
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if err != nil {
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return false
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}
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return mountinfoShutdown(string(data), path)
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}
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var mountinfoPath = "/proc/self/mountinfo"
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// mountinfoShutdown: the LAST mountinfo line whose mount point is path (the top of a stack) carries `shutdown` in its
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// super options (the third field after " - ").
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func mountinfoShutdown(mountinfo, path string) bool {
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path = filepath.Clean(path)
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dead := false
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found := false
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for _, line := range strings.Split(mountinfo, "\n") {
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f := strings.Fields(line)
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if len(f) < 5 || unescapeMountinfo(f[4]) != path {
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continue
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}
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found = true
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dead = false
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if i := strings.Index(line, " - "); i >= 0 {
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tail := strings.Fields(line[i+3:])
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if len(tail) >= 3 {
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for _, o := range strings.Split(tail[2], ",") {
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if o == "shutdown" {
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dead = true
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}
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}
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}
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}
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}
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return found && dead
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}
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// unescapeMountinfo undoes mountinfo's octal escapes for space, tab, newline and backslash.
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func unescapeMountinfo(s string) string {
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r := strings.NewReplacer(`\040`, " ", `\011`, "\t", `\012`, "\n", `\134`, `\`)
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return r.Replace(s)
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}
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