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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.vespa.hosted.node.admin.nodeagent;
/**
* @author valerijf
*/
public class UserNamespace {
/** Total number of UID/GID that are mapped for each container */
private static final int ID_RANGE = 65_536; // 2^16
/**
* IDs outside the ID range are translated to the overflow ID before being written to disk:
* https://github.com/torvalds/linux/blob/5bfc75d92efd494db37f5c4c173d3639d4772966/Documentation/admin-guide/sysctl/fs.rst#overflowgid--overflowuid */
private static final int OVERFLOW_ID = 65_534;
private volatile int uidOffset;
private volatile int gidOffset;
public UserNamespace(int uidOffset, int gidOffset) {
this.uidOffset = uidOffset;
this.gidOffset = gidOffset;
}
public int userIdOnHost(int containerUid) { return toHostId(containerUid, uidOffset); }
public int groupIdOnHost(int containerGid) { return toHostId(containerGid, gidOffset); }
public int userIdInContainer(int hostUid) { return toContainerId(hostUid, uidOffset); }
public int groupIdInContainer(int hostGid) { return toContainerId(hostGid, gidOffset); }
public int idRange() { return ID_RANGE; }
public int overflowId() { return OVERFLOW_ID; }
// Remove after migration to mapped namespaces is complete, make fields final
public void setOffsets(int idOffset) {
this.uidOffset = idOffset;
this.gidOffset = idOffset;
}
private static int toHostId(int containerId, int idOffset) {
if (containerId < 0 || containerId > ID_RANGE)
throw new IllegalArgumentException("Invalid container id: " + containerId);
return idOffset + containerId;
}
private static int toContainerId(int hostId, int idOffset) {
hostId = hostId - idOffset;
return hostId < 0 || hostId >= ID_RANGE ? OVERFLOW_ID : hostId;
}
}
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