sourcemod/core/systems/HandleSys.cpp

#include "HandleSys.h"
#include "ShareSys.h"
#include "PluginSys.h"
#include <assert.h>

HandleSystem g_HandleSys;

QHandle *ignore_handle;

inline HandleType_t TypeParent(HandleType_t type)
{
	return (type & ~HANDLESYS_SUBTYPE_MASK);
}

inline HandleError IdentityHandle(IdentityToken_t *token, unsigned int *index)
{
	return g_HandleSys.GetHandle(token->ident, g_ShareSys.GetIdentRoot(), &ignore_handle, index);
}

HandleSystem::HandleSystem()
{
	m_Handles = new QHandle[HANDLESYS_MAX_HANDLES + 1];
	memset(m_Handles, 0, sizeof(QHandle) * (HANDLESYS_MAX_HANDLES + 1));

	m_Types = new QHandleType[HANDLESYS_TYPEARRAY_SIZE];
	memset(m_Types, 0, sizeof(QHandleType) * HANDLESYS_TYPEARRAY_SIZE);

	m_TypeLookup = sm_trie_create();
	m_strtab = new BaseStringTable(512);

	m_TypeTail = 0;
}

HandleSystem::~HandleSystem()
{
	delete [] m_Handles;
	delete [] m_Types;
	sm_trie_destroy(m_TypeLookup);
	delete m_strtab;
}


HandleType_t HandleSystem::CreateType(const char *name, 
									  IHandleTypeDispatch *dispatch, 
									  HandleType_t parent, 
									  const TypeAccess *typeAccess, 
									  const HandleAccess *hndlAccess, 
									  IdentityToken_t *ident,
									  HandleError *err)
{
	if (!dispatch)
	{
		if (err)
		{
			*err = HandleError_Parameter;
		}
		return 0;
	}

	if (typeAccess && typeAccess->hsVersion > SMINTERFACE_HANDLESYSTEM_VERSION)
	{
		if (err)
		{
			*err = HandleError_Version;
		}
		return 0;
	}

	if (hndlAccess && hndlAccess->hsVersion > SMINTERFACE_HANDLESYSTEM_VERSION)
	{
		if (err)
		{
			*err = HandleError_Version;
		}
		return 0;
	}

	bool isChild = false;

	if (parent != 0)
	{
		isChild = true;
		if (parent & HANDLESYS_SUBTYPE_MASK)
		{
			if (err)
			{
				*err = HandleError_NoInherit;
			}
			return 0;
		}
		if (parent >= HANDLESYS_TYPEARRAY_SIZE
			|| m_Types[parent].dispatch == NULL)
		{
			if (err)
			{
				*err = HandleError_Parameter;
			}
			return 0;
		}
		if (m_Types[parent].typeSec.access[HTypeAccess_Inherit] == false
			&& (m_Types[parent].typeSec.ident != ident))
		{
			if (err)
			{
				*err = HandleError_Access;
			}
			return 0;
		}
	}

	if (name && name[0] != '\0')
	{
		if (sm_trie_retrieve(m_TypeLookup, name, NULL))
		{
			if (err)
			{
				*err = HandleError_Parameter;
			}
			return 0;
		}
	}

	unsigned int index;

	if (isChild)
	{
		QHandleType *pParent = &m_Types[parent];
		if (pParent->children >= HANDLESYS_MAX_SUBTYPES)
		{
			if (err)
			{
				*err = HandleError_Limit;
			}
			return 0;
		}
		index = 0;
		for (unsigned int i=1; i<=HANDLESYS_MAX_SUBTYPES; i++)
		{
			if (m_Types[parent + i].dispatch == NULL)
			{
				index = parent + i;
				break;
			}
		}
		if (!index)
		{
			if (err)
			{
				*err = HandleError_Limit;
			}
			return 0;
		}
		pParent->children++;
	} else {
		if (m_FreeTypes == 0)
		{
			/* Reserve another index */
			if (m_TypeTail >= HANDLESYS_TYPEARRAY_SIZE)
			{
				if (err)
				{
					*err = HandleError_Limit;
				}
				return 0;
			} else {
				m_TypeTail += (HANDLESYS_MAX_SUBTYPES + 1);
				index = m_TypeTail;
			}
		} else {
			/* The "free array" is compacted into the normal array for easiness */
			index = m_Types[m_FreeTypes--].freeID;
		}
	}

	QHandleType *pType = &m_Types[index];
	
	pType->dispatch = dispatch;
	if (name && name[0] != '\0')
	{
		pType->nameIdx = m_strtab->AddString(name);
		sm_trie_insert(m_TypeLookup, name, (void *)pType);
	} else {
		pType->nameIdx = -1;
	}

	pType->opened = 0;

	if (typeAccess)
	{
		pType->typeSec = *typeAccess;
	} else {
		InitAccessDefaults(&pType->typeSec, NULL);
		pType->typeSec.ident = ident;
	}

	if (hndlAccess)
	{
		pType->hndlSec = *hndlAccess;
	} else {
		InitAccessDefaults(NULL, &pType->hndlSec);
	}

	if (!isChild)
	{
		pType->children = 0;
	}

	return index;
}

bool HandleSystem::FindHandleType(const char *name, HandleType_t *type)
{
	QHandleType *_type;

	if (!sm_trie_retrieve(m_TypeLookup, name, (void **)&_type))
	{
		return false;
	}

	unsigned int offset = _type - m_Types;

	if (type)
	{
		*type = offset;
	}

	return true;
}

HandleError HandleSystem::MakePrimHandle(HandleType_t type, 
						   QHandle **in_pHandle, 
						   unsigned int *in_index, 
						   Handle_t *in_handle,
						   IdentityToken_t *owner)
{
	unsigned int owner_index = 0;

	if (owner && (IdentityHandle(owner, &owner_index) != HandleError_None))
	{
		return HandleError_Identity;
	}

	unsigned int handle;
	if (m_FreeHandles == 0)
	{
		if (m_HandleTail >= HANDLESYS_MAX_HANDLES)
		{
			return HandleError_Limit;;
		}
		handle = ++m_HandleTail;
	} else {
		handle = m_Handles[m_FreeHandles--].freeID;
	}

	QHandle *pHandle = &m_Handles[handle];
	
	assert(pHandle->set == false);

	if (++m_HSerial >= HANDLESYS_MAX_SERIALS)
	{
		m_HSerial = 1;
	}

	/* Set essential information */
	pHandle->set = HandleSet_Used;;
	pHandle->refcount = 1;
	pHandle->type = type;
	pHandle->serial = m_HSerial;
	pHandle->owner = owner;
	pHandle->ch_next = 0;

	/* Create the hash value */
	Handle_t hash = pHandle->serial;
	hash <<= 16;
	hash |= handle;

	/* Add a reference count to the type */
	m_Types[type].opened++;

	/* Output */
	*in_pHandle = pHandle;
	*in_index = handle;
	*in_handle = hash;

	/* Decode the identity token */
	if (owner)
	{
		QHandle *pIdentity = &m_Handles[owner_index];
		if (pIdentity->ch_prev == 0)
		{
			pIdentity->ch_prev = handle;
			pIdentity->ch_next = handle;
			pHandle->ch_prev = 0;
		} else {
			/* Link previous node to us (forward) */
			m_Handles[pIdentity->ch_next].ch_next = handle;
			/* Link us to previous node (backwards) */
			pHandle->ch_prev = pIdentity->ch_next;
			/* Set new tail */
			pIdentity->ch_next = handle;
		}
		pIdentity->refcount++;
	} else {
		pHandle->ch_prev = 0;
	}

	return HandleError_None;
}

void HandleSystem::SetTypeSecurityOwner(HandleType_t type, IdentityToken_t *pToken)
{
	if (!type
		|| type >= HANDLESYS_TYPEARRAY_SIZE
		|| m_Types[type].dispatch == NULL)
	{
		return;
	}

	m_Types[type].typeSec.ident = pToken;
}

Handle_t HandleSystem::CreateHandle(HandleType_t type, void *object, IdentityToken_t *owner, IdentityToken_t *ident, HandleError *err)
{
	if (!type 
		|| type >= HANDLESYS_TYPEARRAY_SIZE
		|| m_Types[type].dispatch == NULL)
	{
		if (err)
		{
			*err = HandleError_Parameter;
		}
		return 0;
	}

	/* Check to see if we're allowed to create this handle type */
	QHandleType *pType = &m_Types[type];
	if (!pType->typeSec.access[HTypeAccess_Create]
		&& (!pType->typeSec.ident
			|| pType->typeSec.ident != ident))
	{
		if (err)
		{
			*err = HandleError_Access;
		}
		return 0;
	}

	unsigned int index;
	Handle_t handle;
	QHandle *pHandle;
	HandleError _err;

	if ((_err=MakePrimHandle(type, &pHandle, &index, &handle, owner)) != HandleError_None)
	{
		if (err)
		{
			*err = _err;
		}
		return 0;
	}

	pHandle->object = object;
	pHandle->clone = 0;

	return handle;
}

bool HandleSystem::TypeCheck(HandleType_t intype, HandleType_t outtype)
{
	/* Check the type inheritance */
	if (intype & HANDLESYS_SUBTYPE_MASK)
	{
		if (intype != outtype
			&& (TypeParent(intype) != TypeParent(outtype)))
		{
			return false;
		}
	} else {
		if (intype != outtype)
		{
			return false;
		}
	}

	return true;
}

HandleError HandleSystem::GetHandle(Handle_t handle,
									IdentityToken_t *ident, 
									QHandle **in_pHandle, 
									unsigned int *in_index,
									bool ignoreFree)
{
	unsigned int serial = (handle >> 16);
	unsigned int index = (handle & HANDLESYS_HANDLE_MASK);

	if (index == 0 || index == 0xFFFF)
	{
		return HandleError_Index;
	}

	QHandle *pHandle = &m_Handles[index];
	QHandleType *pType = &m_Types[pHandle->type];

	if (!pHandle->set
		|| (pHandle->set == HandleSet_Freed && !ignoreFree))
	{
		return HandleError_Freed;
	} else if (pHandle->set == HandleSet_Identity
			   && ident != g_ShareSys.GetIdentRoot())
	{
		/* Only IdentityHandle() can read this! */
		return HandleError_Identity;
	}
	if (pHandle->serial != serial)
	{
		return HandleError_Changed;
	}

	*in_pHandle = pHandle;
	*in_index = index;

	return HandleError_None;
}

bool HandleSystem::CheckAccess(QHandle *pHandle, HandleAccessRight right, const HandleSecurity *pSecurity)
{
	QHandleType *pType = &m_Types[pHandle->type];
	unsigned int access = pType->hndlSec.access[right];

	/* Check if the type's identity matches */
	if (access & HANDLE_RESTRICT_IDENTITY)
	{
		IdentityToken_t *owner = pType->typeSec.ident;
		if (!owner
			|| (!pSecurity || pSecurity->pIdentity != owner))
		{
			return false;
		}
	}

	/* Check if the owner is allowed */
	if (access & HANDLE_RESTRICT_OWNER)
	{
		IdentityToken_t *owner = pHandle->owner;
		if (owner
			&& (!pSecurity || pSecurity->pOwner != owner))
		{
			return false;
		}
	}

	return true;
}

HandleError HandleSystem::CloneHandle(Handle_t handle, Handle_t *newhandle, IdentityToken_t *newOwner, const HandleSecurity *pSecurity)
{
	HandleError err;
	QHandle *pHandle;
	unsigned int index;
	IdentityToken_t *ident = pSecurity ? pSecurity->pIdentity : NULL;

	if ((err=GetHandle(handle, ident, &pHandle, &index)) != HandleError_None)
	{
		return err;
	}

	/* Identities cannot be cloned */
	if (pHandle->set == HandleSet_Identity)
	{
		return HandleError_Identity;
	}

	/* Check if the handle can be cloned */
	if (!CheckAccess(pHandle, HandleAccess_Clone, pSecurity))
	{
		return HandleError_Access;
	}

	/* Get a new Handle ID */
	unsigned int new_index;
	QHandle *pNewHandle;
	Handle_t new_handle;

	if ((err=MakePrimHandle(pHandle->type, &pNewHandle, &new_index, &new_handle, newOwner)) != HandleError_None)
	{
		return err;
	}

	pNewHandle->clone = index;
	pHandle->refcount++;

	*newhandle = new_handle;

	return HandleError_None;
}

HandleError HandleSystem::FreeHandle(Handle_t handle, const HandleSecurity *pSecurity)
{
	unsigned int index;
	QHandle *pHandle;
	HandleError err;
	IdentityToken_t *ident = pSecurity ? pSecurity->pIdentity : NULL;

	if ((err=GetHandle(handle, ident, &pHandle, &index)) != HandleError_None)
	{
		return err;
	}

	if (!CheckAccess(pHandle, HandleAccess_Delete, pSecurity))
	{
		return HandleError_Access;
	}

	QHandleType *pType = &m_Types[pHandle->type];

	bool dofree = false;
	if (pHandle->clone)
	{
		/* If we're a clone, decrease the parent reference count */
		QHandle *pMaster;
		unsigned int master;

		/* Note that if we ever have per-handle security, we would need to re-check
		 * the access on this Handle. */
		master = pHandle->clone;
		pMaster = &m_Handles[master];

		/* Release the clone now */
		ReleasePrimHandle(index);

		/* Decrement the master's reference count */
		if (--pMaster->refcount == 0)
		{
			/* Type should be the same but do this anyway... */
			pType = &m_Types[pMaster->type];
			pType->dispatch->OnHandleDestroy(pMaster->type, pMaster->object);
			ReleasePrimHandle(master);
		}
	} else {
		/* Decrement, free if necessary */
		if (--pHandle->refcount == 0)
		{
			pType->dispatch->OnHandleDestroy(pHandle->type, pHandle->object);
			ReleasePrimHandle(index);
		} else {
			/* We must be cloned, so mark ourselves as freed */
			pHandle->set = HandleSet_Freed;
		}
	}

	return HandleError_None;
}

HandleError HandleSystem::ReadHandle(Handle_t handle, HandleType_t type, const HandleSecurity *pSecurity, void **object)
{
	unsigned int index;
	QHandle *pHandle;
	HandleError err;
	IdentityToken_t *ident = pSecurity ? pSecurity->pIdentity : NULL;

	if ((err=GetHandle(handle, ident, &pHandle, &index)) != HandleError_None)
	{
		return err;
	}

	if (!CheckAccess(pHandle, HandleAccess_Read, pSecurity))
	{
		return HandleError_Access;
	}

	/* Check the type inheritance */
	if (pHandle->type & HANDLESYS_SUBTYPE_MASK)
	{
		if (pHandle->type != type
			&& (TypeParent(pHandle->type) != TypeParent(type)))
		{
			return HandleError_Type;
		}
	} else if (type) {
		if (pHandle->type != type)
		{
			return HandleError_Type;
		}
	}

	if (object)
	{
		/* if we're a clone, the rules change - object is ONLY in our reference */
		if (pHandle->clone)
		{
			pHandle = &m_Handles[pHandle->clone];
		}
		*object = pHandle->object;
	}

	return HandleError_None;
}

void HandleSystem::ReleasePrimHandle(unsigned int index)
{
	QHandle *pHandle = &m_Handles[index];
	
	pHandle->set = HandleSet_None;
	m_Types[pHandle->type].opened--;
	m_Handles[++m_FreeHandles].freeID = index;

	/* Unlink us if necessary */
	if (pHandle->owner)
	{
		unsigned int ident_index;
		if (IdentityHandle(pHandle->owner, &ident_index) != HandleError_None)
		{
			/* Uh-oh! */
			assert(pHandle->owner == 0);
			return;
		}
		/* Note that since 0 is an invalid handle, if any of these links are 0,
		 * the data can still be set.
		 */
		QHandle *pIdentity = &m_Handles[ident_index];

		/* Unlink case: We're the head AND tail node */
		if (index == pIdentity->ch_prev && index == pIdentity->ch_next)
		{
			pIdentity->ch_prev = 0;
			pIdentity->ch_next = 0;
		}
		/* Unlink case: We're the head node */
		else if (index == pIdentity->ch_prev) {
			/* Link us to the next in the chain */
			pIdentity->ch_prev = pHandle->ch_next;
			/* Patch up the previous link */
			m_Handles[pHandle->ch_next].ch_prev = 0;
		}
		/* Unlink case: We're the tail node */
		else if (index == pIdentity->ch_next) {
			/* Link us to the previous in the chain */
			pIdentity->ch_next = pHandle->ch_prev;
			/* Patch up the next link */
			m_Handles[pHandle->ch_prev].ch_next = 0;
		}
		/* Unlink case: We're in the middle! */
		else {
			/* Patch the forward reference */
			m_Handles[pHandle->ch_next].ch_prev = pHandle->ch_prev;
			/* Patch the backward reference */
			m_Handles[pHandle->ch_prev].ch_next = pHandle->ch_next;
		}

		/* Lastly, decrease the reference count */
		pIdentity->refcount--;
	}
}

bool HandleSystem::RemoveType(HandleType_t type, IdentityToken_t *ident)
{
	if (type == 0 || type >= HANDLESYS_TYPEARRAY_SIZE)
	{
		return false;
	}

	QHandleType *pType = &m_Types[type];

	if (pType->typeSec.ident
		&& pType->typeSec.ident != ident)
	{
		return false;
	}

	if (pType->dispatch == NULL)
	{
		return false;
	}

	/* Remove children if we have to */
	if (!(type & HANDLESYS_SUBTYPE_MASK))
	{
		QHandleType *childType;
		for (unsigned int i=1; i<=HANDLESYS_MAX_SUBTYPES; i++)
		{
			childType = &m_Types[type + i];
			if (childType->dispatch)
			{
				RemoveType(type + i, childType->typeSec.ident);
			}
		}
		/* Link us into the free chain */
		m_Types[++m_FreeTypes].freeID = type;
	}

	/* Invalidate the type now */
	IHandleTypeDispatch *dispatch = pType->dispatch;
	pType->dispatch = NULL;

	/* Make sure nothing is using this type. */
	if (pType->opened)
	{
		QHandle *pHandle;
		for (unsigned int i=1; i<m_HandleTail; i++)
		{
			pHandle = &m_Handles[i];
			if (!pHandle->set || pHandle->type != type)
			{
				continue;
			}
			if (pHandle->clone)
			{
				/* Get parent */
				QHandle *pOther = &m_Handles[pHandle->clone];
				if (--pOther->refcount == 0)
				{
					/* Free! */
					dispatch->OnHandleDestroy(type, pOther->object);
					ReleasePrimHandle(pHandle->clone);
				}
				/* Unlink ourselves since we don't have a reference count */
				ReleasePrimHandle(i);
			} else {
				/* If it's not a clone, we still have to check the reference count.
				 * Either way, we'll be destroyed eventually because the handle types do not change.
				 */
				if (--pHandle->refcount == 0)
				{
					/* Free! */
					dispatch->OnHandleDestroy(type, pHandle->object);
					ReleasePrimHandle(i);
				}
			}
			if (pType->opened == 0)
			{
				break;
			}
		}
	}

	return true;
}

void HandleSystem::MarkHandleAsIdentity(Handle_t handle)
{
	QHandle *pHandle;
	unsigned int index;

	if (GetHandle(handle, g_ShareSys.GetIdentRoot(), &pHandle, &index) != HandleError_None)
	{
		return;
	}

	pHandle->set = HandleSet_Identity;
}

bool HandleSystem::InitAccessDefaults(TypeAccess *pTypeAccess, HandleAccess *pHandleAccess)
{
	if (pTypeAccess)
	{
		if (pTypeAccess->hsVersion > SMINTERFACE_HANDLESYSTEM_VERSION)
		{
			return false;
		}
		pTypeAccess->access[HTypeAccess_Create] = false;
		pTypeAccess->access[HTypeAccess_Inherit] = false;
		pTypeAccess->ident = NULL;
	}

	if (pHandleAccess)
	{
		if (pHandleAccess->hsVersion > SMINTERFACE_HANDLESYSTEM_VERSION)
		{
			return false;
		}

		pHandleAccess->access[HandleAccess_Clone] = 0;
		pHandleAccess->access[HandleAccess_Delete] = HANDLE_RESTRICT_OWNER;
		pHandleAccess->access[HandleAccess_Read] = HANDLE_RESTRICT_IDENTITY;
	}

	return true;
}