jschoubben
bc77afa6bb
ADR 0508 §9: the operator sees whether every boot menu lists the fallback kernel, and the room left on /boot.
90 lines
2.9 KiB
Go
90 lines
2.9 KiB
Go
package main
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// kernel_boot: which loader booted the machine, its entries, the kernels in /boot, the entry it booted and
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// whether the fallback kernel is on the menu (novox/hq ADR 0508 §9, issue 1841). Reads only.
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import (
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"os"
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"path/filepath"
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"regexp"
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"sort"
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"strings"
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"syscall"
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"unicode/utf16"
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)
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const loaderSelected = "sys/firmware/efi/efivars/LoaderEntrySelected-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f"
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// BootState is what kernel_boot answers.
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type BootState struct {
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Loader string `json:"loader"`
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Entries []string `json:"entries"`
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Kernels []string `json:"kernels"`
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Booted string `json:"booted"`
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FallbackPresent bool `json:"fallback_present"`
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BootFreeKiB int64 `json:"boot_free_kib"`
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}
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var grubKernel = regexp.MustCompile(`(?m)^\s*linux\s+(?:/boot)?/(vmlinuz-\S+)`)
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var grubTitle = regexp.MustCompile(`(?m)^\s*menuentry\s+'([^']*)'`)
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var bootImage = regexp.MustCompile(`BOOT_IMAGE=(?:/boot)?/?(\S+)`)
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// Boot reads the machine, the loader the way the boot-entries script does: the loader's EFI variable means
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// systemd-boot, a grub.cfg without it GRUB.
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func (m *Machine) Boot() (*BootState, error) {
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b := &BootState{Loader: "none", Entries: []string{}, Kernels: []string{}}
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files, _ := filepath.Glob(m.path("boot/vmlinuz-*"))
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for _, f := range files {
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b.Kernels = append(b.Kernels, filepath.Base(f))
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}
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sort.Strings(b.Kernels)
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hasKernel := func(name string) bool {
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for _, k := range b.Kernels {
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if k == name {
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return true
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}
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}
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return false
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}
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var s syscall.Statfs_t
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if err := syscall.Statfs(m.path("boot"), &s); err == nil {
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b.BootFreeKiB = int64(s.Bavail) * int64(s.Bsize) / 1024
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}
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if raw, err := os.ReadFile(m.path(loaderSelected)); err == nil {
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b.Loader = "systemd-boot"
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if len(raw) > 4 {
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var u []uint16
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for i := 4; i+1 < len(raw); i += 2 {
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u = append(u, uint16(raw[i])|uint16(raw[i+1])<<8)
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}
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b.Booted = strings.TrimRight(string(utf16.Decode(u)), "\x00")
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}
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files, _ := filepath.Glob(m.path("boot/loader/entries/*.conf"))
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for _, f := range files {
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b.Entries = append(b.Entries, filepath.Base(f))
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}
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sort.Strings(b.Entries)
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if raw, err := os.ReadFile(m.path("boot/loader/entries/mesh-linux-lts.conf")); err == nil {
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b.FallbackPresent = strings.Contains(string(raw), "/vmlinuz-linux-lts") && hasKernel("vmlinuz-linux-lts")
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}
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return b, nil
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}
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if raw, err := os.ReadFile(m.path("boot/grub/grub.cfg")); err == nil {
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b.Loader = "grub"
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for _, t := range grubTitle.FindAllStringSubmatch(string(raw), -1) {
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b.Entries = append(b.Entries, t[1])
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}
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for _, k := range grubKernel.FindAllStringSubmatch(string(raw), -1) {
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if k[1] == "vmlinuz-linux-lts" && hasKernel("vmlinuz-linux-lts") {
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b.FallbackPresent = true
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}
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}
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if cmd, err := m.read("proc/cmdline"); err == nil {
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if i := bootImage.FindStringSubmatch(cmd); i != nil {
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b.Booted = i[1]
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}
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}
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}
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return b, nil
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}
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