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package container
import (
"bytes"
"os"
"strconv"
"sync"
"hakurei.app/container/fhs"
"hakurei.app/message"
)
var (
kernelOverflowuid int
kernelOverflowgid int
kernelCapLastCap int
sysctlOnce sync.Once
)
const (
kernelOverflowuidPath = fhs.ProcSys + "kernel/overflowuid"
kernelOverflowgidPath = fhs.ProcSys + "kernel/overflowgid"
kernelCapLastCapPath = fhs.ProcSys + "kernel/cap_last_cap"
)
func mustReadSysctl(msg message.Msg) {
sysctlOnce.Do(func() {
if v, err := os.ReadFile(kernelOverflowuidPath); err != nil {
msg.GetLogger().Fatalf("cannot read %q: %v", kernelOverflowuidPath, err)
} else if kernelOverflowuid, err = strconv.Atoi(string(bytes.TrimSpace(v))); err != nil {
msg.GetLogger().Fatalf("cannot interpret %q: %v", kernelOverflowuidPath, err)
}
if v, err := os.ReadFile(kernelOverflowgidPath); err != nil {
msg.GetLogger().Fatalf("cannot read %q: %v", kernelOverflowgidPath, err)
} else if kernelOverflowgid, err = strconv.Atoi(string(bytes.TrimSpace(v))); err != nil {
msg.GetLogger().Fatalf("cannot interpret %q: %v", kernelOverflowgidPath, err)
}
if v, err := os.ReadFile(kernelCapLastCapPath); err != nil {
msg.GetLogger().Fatalf("cannot read %q: %v", kernelCapLastCapPath, err)
} else if kernelCapLastCap, err = strconv.Atoi(string(bytes.TrimSpace(v))); err != nil {
msg.GetLogger().Fatalf("cannot interpret %q: %v", kernelCapLastCapPath, err)
}
})
}
func OverflowUid(msg message.Msg) int { mustReadSysctl(msg); return kernelOverflowuid }
func OverflowGid(msg message.Msg) int { mustReadSysctl(msg); return kernelOverflowgid }
func LastCap(msg message.Msg) uintptr { mustReadSysctl(msg); return uintptr(kernelCapLastCap) }
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