Sweden-Number/server/handle.c

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/*
* Server-side handle management
*
* Copyright (C) 1998 Alexandre Julliard
*/
#include <assert.h>
#include <limits.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include "winbase.h"
#include "handle.h"
#include "process.h"
#include "thread.h"
#include "request.h"
struct handle_entry
{
struct object *ptr; /* object */
unsigned int access; /* access rights */
int fd; /* file descriptor (in client process) */
};
struct handle_table
{
struct object obj; /* object header */
struct process *process; /* process owning this table */
int count; /* number of allocated entries */
int last; /* last used entry */
int free; /* first entry that may be free */
struct handle_entry *entries; /* handle entries */
};
static struct handle_table *global_table;
/* reserved handle access rights */
#define RESERVED_SHIFT 25
#define RESERVED_INHERIT (HANDLE_FLAG_INHERIT << RESERVED_SHIFT)
#define RESERVED_CLOSE_PROTECT (HANDLE_FLAG_PROTECT_FROM_CLOSE << RESERVED_SHIFT)
#define RESERVED_ALL (RESERVED_INHERIT | RESERVED_CLOSE_PROTECT)
#define MIN_HANDLE_ENTRIES 32
/* handle to table index conversion */
/* handles are a multiple of 4 under NT; handle 0 is not used */
inline static handle_t index_to_handle( int index )
{
return (handle_t)((index + 1) << 2);
}
inline static int handle_to_index( handle_t handle )
{
return ((unsigned int)handle >> 2) - 1;
}
/* global handle conversion */
#define HANDLE_OBFUSCATOR 0x544a4def
inline static int handle_is_global( handle_t handle)
{
return ((unsigned long)handle ^ HANDLE_OBFUSCATOR) < 0x10000;
}
inline static handle_t handle_local_to_global( handle_t handle )
{
if (!handle) return 0;
return (handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
}
inline static handle_t handle_global_to_local( handle_t handle )
{
return (handle_t)((unsigned long)handle ^ HANDLE_OBFUSCATOR);
}
static void handle_table_dump( struct object *obj, int verbose );
static void handle_table_destroy( struct object *obj );
static const struct object_ops handle_table_ops =
{
sizeof(struct handle_table), /* size */
handle_table_dump, /* dump */
no_add_queue, /* add_queue */
NULL, /* remove_queue */
NULL, /* signaled */
NULL, /* satisfied */
NULL, /* get_poll_events */
NULL, /* poll_event */
no_get_fd, /* get_fd */
no_flush, /* flush */
no_get_file_info, /* get_file_info */
NULL, /* queue_async */
handle_table_destroy /* destroy */
};
/* dump a handle table */
static void handle_table_dump( struct object *obj, int verbose )
{
int i;
struct handle_table *table = (struct handle_table *)obj;
struct handle_entry *entry = table->entries;
assert( obj->ops == &handle_table_ops );
fprintf( stderr, "Handle table last=%d count=%d process=%p\n",
table->last, table->count, table->process );
if (!verbose) return;
entry = table->entries;
for (i = 0; i <= table->last; i++, entry++)
{
if (!entry->ptr) continue;
fprintf( stderr, "%9u: %p %08x ",
(unsigned int)index_to_handle(i), entry->ptr, entry->access );
entry->ptr->ops->dump( entry->ptr, 0 );
}
}
/* destroy a handle table */
static void handle_table_destroy( struct object *obj )
{
int i;
struct handle_table *table = (struct handle_table *)obj;
struct handle_entry *entry = table->entries;
assert( obj->ops == &handle_table_ops );
for (i = 0; i <= table->last; i++, entry++)
{
struct object *obj = entry->ptr;
entry->ptr = NULL;
if (obj) release_object( obj );
}
free( table->entries );
}
/* allocate a new handle table */
struct object *alloc_handle_table( struct process *process, int count )
{
struct handle_table *table;
if (count < MIN_HANDLE_ENTRIES) count = MIN_HANDLE_ENTRIES;
if (!(table = alloc_object( &handle_table_ops, -1 )))
return NULL;
table->process = process;
table->count = count;
table->last = -1;
table->free = 0;
if ((table->entries = mem_alloc( count * sizeof(*table->entries) ))) return &table->obj;
release_object( table );
return NULL;
}
/* grow a handle table */
static int grow_handle_table( struct handle_table *table )
{
struct handle_entry *new_entries;
int count = table->count;
if (count >= INT_MAX / 2) return 0;
count *= 2;
if (!(new_entries = realloc( table->entries, count * sizeof(struct handle_entry) )))
{
set_error( STATUS_NO_MEMORY );
return 0;
}
table->entries = new_entries;
table->count = count;
return 1;
}
/* allocate the first free entry in the handle table */
static handle_t alloc_entry( struct handle_table *table, void *obj, unsigned int access )
{
struct handle_entry *entry = table->entries + table->free;
int i;
for (i = table->free; i <= table->last; i++, entry++) if (!entry->ptr) goto found;
if (i >= table->count)
{
if (!grow_handle_table( table )) return 0;
entry = table->entries + i; /* the entries may have moved */
}
table->last = i;
found:
table->free = i + 1;
entry->ptr = grab_object( obj );
entry->access = access;
entry->fd = -1;
return index_to_handle(i);
}
/* allocate a handle for an object, incrementing its refcount */
/* return the handle, or 0 on error */
handle_t alloc_handle( struct process *process, void *obj, unsigned int access, int inherit )
{
struct handle_table *table = (struct handle_table *)process->handles;
assert( table );
assert( !(access & RESERVED_ALL) );
if (inherit) access |= RESERVED_INHERIT;
return alloc_entry( table, obj, access );
}
/* allocate a global handle for an object, incrementing its refcount */
/* return the handle, or 0 on error */
static handle_t alloc_global_handle( void *obj, unsigned int access )
{
if (!global_table)
{
if (!(global_table = (struct handle_table *)alloc_handle_table( NULL, 0 )))
return 0;
}
return handle_local_to_global( alloc_entry( global_table, obj, access ));
}
/* return a handle entry, or NULL if the handle is invalid */
static struct handle_entry *get_handle( struct process *process, handle_t handle )
{
struct handle_table *table = (struct handle_table *)process->handles;
struct handle_entry *entry;
int index;
if (handle_is_global(handle))
{
handle = handle_global_to_local(handle);
table = global_table;
}
if (!table) goto error;
index = handle_to_index( handle );
if (index < 0) goto error;
if (index > table->last) goto error;
entry = table->entries + index;
if (!entry->ptr) goto error;
return entry;
error:
set_error( STATUS_INVALID_HANDLE );
return NULL;
}
/* attempt to shrink a table */
static void shrink_handle_table( struct handle_table *table )
{
struct handle_entry *entry = table->entries + table->last;
struct handle_entry *new_entries;
int count = table->count;
while (table->last >= 0)
{
if (entry->ptr) break;
table->last--;
entry--;
}
if (table->last >= count / 4) return; /* no need to shrink */
if (count < MIN_HANDLE_ENTRIES * 2) return; /* too small to shrink */
count /= 2;
if (!(new_entries = realloc( table->entries, count * sizeof(*new_entries) ))) return;
table->count = count;
table->entries = new_entries;
}
/* copy the handle table of the parent process */
/* return 1 if OK, 0 on error */
struct object *copy_handle_table( struct process *process, struct process *parent )
{
struct handle_table *parent_table = (struct handle_table *)parent->handles;
struct handle_table *table;
int i;
assert( parent_table );
assert( parent_table->obj.ops == &handle_table_ops );
if (!(table = (struct handle_table *)alloc_handle_table( process, parent_table->count )))
return NULL;
if ((table->last = parent_table->last) >= 0)
{
struct handle_entry *ptr = table->entries;
memcpy( ptr, parent_table->entries, (table->last + 1) * sizeof(struct handle_entry) );
for (i = 0; i <= table->last; i++, ptr++)
{
if (!ptr->ptr) continue;
ptr->fd = -1;
if (ptr->access & RESERVED_INHERIT) grab_object( ptr->ptr );
else ptr->ptr = NULL; /* don't inherit this entry */
}
}
/* attempt to shrink the table */
shrink_handle_table( table );
return &table->obj;
}
/* close a handle and decrement the refcount of the associated object */
/* return 1 if OK, 0 on error */
int close_handle( struct process *process, handle_t handle, int *fd )
{
struct handle_table *table;
struct handle_entry *entry;
struct object *obj;
if (!(entry = get_handle( process, handle ))) return 0;
if (entry->access & RESERVED_CLOSE_PROTECT)
{
set_error( STATUS_INVALID_HANDLE );
return 0;
}
obj = entry->ptr;
entry->ptr = NULL;
if (fd) *fd = entry->fd;
else if (entry->fd != -1) return 1; /* silently ignore close attempt if we cannot close the fd */
entry->fd = -1;
table = handle_is_global(handle) ? global_table : (struct handle_table *)process->handles;
if (entry < table->entries + table->free) table->free = entry - table->entries;
if (entry == table->entries + table->last) shrink_handle_table( table );
release_object( obj );
return 1;
}
/* close all the global handles */
void close_global_handles(void)
{
if (global_table)
{
release_object( global_table );
global_table = NULL;
}
}
/* retrieve the object corresponding to one of the magic pseudo-handles */
static inline struct object *get_magic_handle( handle_t handle )
{
switch((unsigned long)handle)
{
case 0xfffffffe: /* current thread pseudo-handle */
return &current->obj;
case 0x7fffffff: /* current process pseudo-handle */
case 0xffffffff: /* current process pseudo-handle */
return (struct object *)current->process;
default:
return NULL;
}
}
/* retrieve the object corresponding to a handle, incrementing its refcount */
struct object *get_handle_obj( struct process *process, handle_t handle,
unsigned int access, const struct object_ops *ops )
{
struct handle_entry *entry;
struct object *obj;
if (!(obj = get_magic_handle( handle )))
{
if (!(entry = get_handle( process, handle ))) return NULL;
if ((entry->access & access) != access)
{
set_error( STATUS_ACCESS_DENIED );
return NULL;
}
obj = entry->ptr;
}
if (ops && (obj->ops != ops))
{
set_error( STATUS_OBJECT_TYPE_MISMATCH ); /* not the right type */
return NULL;
}
return grab_object( obj );
}
/* retrieve the cached fd for a given handle */
int get_handle_fd( struct process *process, handle_t handle, unsigned int access )
{
struct handle_entry *entry;
if (!(entry = get_handle( process, handle ))) return -1;
if ((entry->access & access) != access)
{
set_error( STATUS_ACCESS_DENIED );
return -1;
}
return entry->fd;
}
/* get/set the handle reserved flags */
/* return the old flags (or -1 on error) */
static int set_handle_info( struct process *process, handle_t handle,
int mask, int flags, int *fd )
{
struct handle_entry *entry;
unsigned int old_access;
if (get_magic_handle( handle ))
{
/* we can retrieve but not set info for magic handles */
if (mask) set_error( STATUS_ACCESS_DENIED );
return 0;
}
if (!(entry = get_handle( process, handle ))) return -1;
old_access = entry->access;
mask = (mask << RESERVED_SHIFT) & RESERVED_ALL;
flags = (flags << RESERVED_SHIFT) & mask;
entry->access = (entry->access & ~mask) | flags;
/* if no current fd set it, otherwise return current fd */
if (entry->fd == -1) entry->fd = *fd;
*fd = entry->fd;
return (old_access & RESERVED_ALL) >> RESERVED_SHIFT;
}
/* duplicate a handle */
handle_t duplicate_handle( struct process *src, handle_t src_handle, struct process *dst,
unsigned int access, int inherit, int options )
{
handle_t res;
struct object *obj = get_handle_obj( src, src_handle, 0, NULL );
if (!obj) return 0;
if (options & DUP_HANDLE_SAME_ACCESS)
{
struct handle_entry *entry = get_handle( src, src_handle );
if (entry)
access = entry->access;
else /* pseudo-handle, give it full access */
{
access = STANDARD_RIGHTS_ALL | SPECIFIC_RIGHTS_ALL;
clear_error();
}
}
access &= ~RESERVED_ALL;
if (options & DUP_HANDLE_MAKE_GLOBAL)
res = alloc_global_handle( obj, access );
else
res = alloc_handle( dst, obj, access, inherit );
release_object( obj );
return res;
}
/* open a new handle to an existing object */
handle_t open_object( const WCHAR *name, size_t len, const struct object_ops *ops,
unsigned int access, int inherit )
{
handle_t handle = 0;
struct object *obj = find_object( name, len );
if (obj)
{
if (ops && obj->ops != ops)
set_error( STATUS_OBJECT_TYPE_MISMATCH );
else
handle = alloc_handle( current->process, obj, access, inherit );
release_object( obj );
}
else
set_error( STATUS_OBJECT_NAME_NOT_FOUND );
return handle;
}
/* close a handle */
DECL_HANDLER(close_handle)
{
close_handle( current->process, req->handle, &reply->fd );
}
/* set a handle information */
DECL_HANDLER(set_handle_info)
{
int fd = req->fd;
if (handle_is_global(req->handle)) fd = -1; /* no fd cache for global handles */
reply->old_flags = set_handle_info( current->process, req->handle,
req->mask, req->flags, &fd );
reply->cur_fd = fd;
}
/* duplicate a handle */
DECL_HANDLER(dup_handle)
{
struct process *src, *dst;
reply->handle = 0;
reply->fd = -1;
if ((src = get_process_from_handle( req->src_process, PROCESS_DUP_HANDLE )))
{
if (req->options & DUP_HANDLE_MAKE_GLOBAL)
{
reply->handle = duplicate_handle( src, req->src_handle, NULL,
req->access, req->inherit, req->options );
}
else if ((dst = get_process_from_handle( req->dst_process, PROCESS_DUP_HANDLE )))
{
reply->handle = duplicate_handle( src, req->src_handle, dst,
req->access, req->inherit, req->options );
release_object( dst );
}
/* close the handle no matter what happened */
if (req->options & DUP_HANDLE_CLOSE_SOURCE)
{
if (src == current->process) close_handle( src, req->src_handle, &reply->fd );
else close_handle( src, req->src_handle, NULL );
}
release_object( src );
}
}