packagr-io-beta
60 lines
1.7 KiB
Go
60 lines
1.7 KiB
Go
package ghw
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import "os"
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const (
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defaultChroot = "/"
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envKeyChroot = "GHW_CHROOT"
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)
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// optDefaultChroot returns the value of the GHW_CHROOT environs variable or
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// the default value of "/" if not set
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func envOrDefaultChroot() string {
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// Grab options from the environs by default
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if val, exists := os.LookupEnv(envKeyChroot); exists {
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return val
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}
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return defaultChroot
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}
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// WithOption is used to represent optionally-configured settings. Each field
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// is a pointer to some concrete value so that we can tell when something has
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// been set or left unset.
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type WithOption struct {
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// To facilitate querying of sysfs filesystems that are bind-mounted to a
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// non-default root mountpoint, we allow users to set the GHW_CHROOT environ
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// vairable to an alternate mountpoint. For instance, assume that the user of
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// ghw is a Golang binary being executed from an application container that has
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// certain host filesystems bind-mounted into the container at /host. The user
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// would ensure the GHW_CHROOT environ variable is set to "/host" and ghw will
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// build its paths from that location instead of /
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Chroot *string
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}
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func WithChroot(dir string) *WithOption {
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return &WithOption{Chroot: &dir}
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}
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func mergeOptions(opts ...*WithOption) *WithOption {
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merged := &WithOption{}
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for _, opt := range opts {
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if opt.Chroot != nil {
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merged.Chroot = opt.Chroot
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}
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}
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// Set the default value if missing from mergeOpts
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if merged.Chroot == nil {
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chroot := envOrDefaultChroot()
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merged.Chroot = &chroot
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}
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return merged
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}
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// contextFromEnv returns a pointer to a context struct that has been populated
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// from the environs or default options values
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func contextFromEnv() *context {
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return &context{
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chroot: envOrDefaultChroot(),
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}
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}
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