54 lines
1.1 KiB
Go
54 lines
1.1 KiB
Go
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package main
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import (
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"fmt"
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"log"
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"os"
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"os/exec"
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"strings"
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"syscall"
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)
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const wellKnownBusybox = "/usr/local/bin/busybox"
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// mountBin bind-mounts /bin to a tmpfs.
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func mountBin() error {
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b, err := os.ReadFile("/proc/self/mountinfo")
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if err != nil {
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return err
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}
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for _, line := range strings.Split(strings.TrimSpace(string(b)), "\n") {
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parts := strings.Fields(line)
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if len(parts) < 5 {
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continue
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}
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mountpoint := parts[4]
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log.Printf("Found mountpoint %q", parts[4])
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if mountpoint == "/bin" {
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log.Printf("/bin file system already mounted, nothing to do")
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return nil
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}
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}
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if err := syscall.Mount("tmpfs", "/bin", "tmpfs", 0, ""); err != nil {
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return fmt.Errorf("mounting tmpfs on /bin: %v", err)
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}
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return nil
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}
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func installBusybox() error {
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// /bin is read-only by default, so mount a tmpfs over it
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if err := mountBin(); err != nil {
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return err
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}
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install := exec.Command(wellKnownBusybox, "--install", "-s", "/bin")
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install.Stdout = os.Stdout
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install.Stderr = os.Stderr
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if err := install.Run(); err != nil {
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return fmt.Errorf("%v: %v", install.Args, err)
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}
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return nil
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}
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