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Sweden-Number/server/fd.c

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/*
* Server-side file descriptor management
*
* Copyright (C) 2000, 2003 Alexandre Julliard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "config.h"
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#ifdef HAVE_SYS_POLL_H
#include <sys/poll.h>
#endif
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include "object.h"
#include "file.h"
#include "handle.h"
#include "process.h"
#include "request.h"
/* Because of the stupid Posix locking semantics, we need to keep
* track of all file descriptors referencing a given file, and not
* close a single one until all the locks are gone (sigh).
*/
/* file descriptor object */
/* closed_fd is used to keep track of the unix fd belonging to a closed fd object */
struct closed_fd
{
struct closed_fd *next; /* next fd in close list */
int fd; /* the unix file descriptor */
};
struct fd
{
struct object obj; /* object header */
const struct fd_ops *fd_ops; /* file descriptor operations */
struct inode *inode; /* inode that this fd belongs to */
struct list inode_entry; /* entry in inode fd list */
struct closed_fd *closed; /* structure to store the unix fd at destroy time */
struct object *user; /* object using this file descriptor */
struct list locks; /* list of locks on this fd */
int unix_fd; /* unix file descriptor */
int fs_locks; /* can we use filesystem locks for this fd? */
int poll_index; /* index of fd in poll array */
};
static void fd_dump( struct object *obj, int verbose );
static void fd_destroy( struct object *obj );
static const struct object_ops fd_ops =
{
sizeof(struct fd), /* size */
fd_dump, /* dump */
no_add_queue, /* add_queue */
NULL, /* remove_queue */
NULL, /* signaled */
NULL, /* satisfied */
no_get_fd, /* get_fd */
fd_destroy /* destroy */
};
/* inode object */
struct inode
{
struct object obj; /* object header */
struct list entry; /* inode hash list entry */
unsigned int hash; /* hashing code */
dev_t dev; /* device number */
ino_t ino; /* inode number */
struct list open; /* list of open file descriptors */
struct list locks; /* list of file locks */
struct closed_fd *closed; /* list of file descriptors to close at destroy time */
};
static void inode_dump( struct object *obj, int verbose );
static void inode_destroy( struct object *obj );
static const struct object_ops inode_ops =
{
sizeof(struct inode), /* size */
inode_dump, /* dump */
no_add_queue, /* add_queue */
NULL, /* remove_queue */
NULL, /* signaled */
NULL, /* satisfied */
no_get_fd, /* get_fd */
inode_destroy /* destroy */
};
/* file lock object */
struct file_lock
{
struct object obj; /* object header */
struct fd *fd; /* fd owning this lock */
struct list fd_entry; /* entry in list of locks on a given fd */
struct list inode_entry; /* entry in inode list of locks */
int shared; /* shared lock? */
file_pos_t start; /* locked region is interval [start;end) */
file_pos_t end;
struct process *process; /* process owning this lock */
struct list proc_entry; /* entry in list of locks owned by the process */
};
static void file_lock_dump( struct object *obj, int verbose );
static int file_lock_signaled( struct object *obj, struct thread *thread );
static const struct object_ops file_lock_ops =
{
sizeof(struct file_lock), /* size */
file_lock_dump, /* dump */
add_queue, /* add_queue */
remove_queue, /* remove_queue */
file_lock_signaled, /* signaled */
no_satisfied, /* satisfied */
no_get_fd, /* get_fd */
no_destroy /* destroy */
};
#define OFF_T_MAX (~((file_pos_t)1 << (8*sizeof(off_t)-1)))
#define FILE_POS_T_MAX (~(file_pos_t)0)
static file_pos_t max_unix_offset = OFF_T_MAX;
#define DUMP_LONG_LONG(val) do { \
if (sizeof(val) > sizeof(unsigned long) && (val) > ~0UL) \
fprintf( stderr, "%lx%08lx", (unsigned long)((val) >> 32), (unsigned long)(val) ); \
else \
fprintf( stderr, "%lx", (unsigned long)(val) ); \
} while (0)
/****************************************************************/
/* timeouts support */
struct timeout_user
{
struct timeout_user *next; /* next in sorted timeout list */
struct timeout_user *prev; /* prev in sorted timeout list */
struct timeval when; /* timeout expiry (absolute time) */
timeout_callback callback; /* callback function */
void *private; /* callback private data */
};
static struct timeout_user *timeout_head; /* sorted timeouts list head */
static struct timeout_user *timeout_tail; /* sorted timeouts list tail */
/* add a timeout user */
struct timeout_user *add_timeout_user( struct timeval *when, timeout_callback func, void *private )
{
struct timeout_user *user;
struct timeout_user *pos;
if (!(user = mem_alloc( sizeof(*user) ))) return NULL;
user->when = *when;
user->callback = func;
user->private = private;
/* Now insert it in the linked list */
for (pos = timeout_head; pos; pos = pos->next)
if (!time_before( &pos->when, when )) break;
if (pos) /* insert it before 'pos' */
{
if ((user->prev = pos->prev)) user->prev->next = user;
else timeout_head = user;
user->next = pos;
pos->prev = user;
}
else /* insert it at the tail */
{
user->next = NULL;
if (timeout_tail) timeout_tail->next = user;
else timeout_head = user;
user->prev = timeout_tail;
timeout_tail = user;
}
return user;
}
/* remove a timeout user */
void remove_timeout_user( struct timeout_user *user )
{
if (user->next) user->next->prev = user->prev;
else timeout_tail = user->prev;
if (user->prev) user->prev->next = user->next;
else timeout_head = user->next;
free( user );
}
/* add a timeout in milliseconds to an absolute time */
void add_timeout( struct timeval *when, int timeout )
{
if (timeout)
{
long sec = timeout / 1000;
if ((when->tv_usec += (timeout - 1000*sec) * 1000) >= 1000000)
{
when->tv_usec -= 1000000;
when->tv_sec++;
}
when->tv_sec += sec;
}
}
/* handle the next expired timeout */
inline static void handle_timeout(void)
{
struct timeout_user *user = timeout_head;
timeout_head = user->next;
if (user->next) user->next->prev = user->prev;
else timeout_tail = user->prev;
user->callback( user->private );
free( user );
}
/****************************************************************/
/* poll support */
static struct fd **poll_users; /* users array */
static struct pollfd *pollfd; /* poll fd array */
static int nb_users; /* count of array entries actually in use */
static int active_users; /* current number of active users */
static int allocated_users; /* count of allocated entries in the array */
static struct fd **freelist; /* list of free entries in the array */
/* add a user in the poll array and return its index, or -1 on failure */
static int add_poll_user( struct fd *fd )
{
int ret;
if (freelist)
{
ret = freelist - poll_users;
freelist = (struct fd **)poll_users[ret];
}
else
{
if (nb_users == allocated_users)
{
struct fd **newusers;
struct pollfd *newpoll;
int new_count = allocated_users ? (allocated_users + allocated_users / 2) : 16;
if (!(newusers = realloc( poll_users, new_count * sizeof(*poll_users) ))) return -1;
if (!(newpoll = realloc( pollfd, new_count * sizeof(*pollfd) )))
{
if (allocated_users)
poll_users = newusers;
else
free( newusers );
return -1;
}
poll_users = newusers;
pollfd = newpoll;
allocated_users = new_count;
}
ret = nb_users++;
}
pollfd[ret].fd = -1;
pollfd[ret].events = 0;
pollfd[ret].revents = 0;
poll_users[ret] = fd;
active_users++;
return ret;
}
/* remove a user from the poll list */
static void remove_poll_user( struct fd *fd, int user )
{
assert( user >= 0 );
assert( poll_users[user] == fd );
pollfd[user].fd = -1;
pollfd[user].events = 0;
pollfd[user].revents = 0;
poll_users[user] = (struct fd *)freelist;
freelist = &poll_users[user];
active_users--;
}
/* server main poll() loop */
void main_loop(void)
{
int ret;
while (active_users)
{
long diff = -1;
if (timeout_head)
{
struct timeval now;
gettimeofday( &now, NULL );
while (timeout_head)
{
if (!time_before( &now, &timeout_head->when )) handle_timeout();
else
{
diff = (timeout_head->when.tv_sec - now.tv_sec) * 1000
+ (timeout_head->when.tv_usec - now.tv_usec) / 1000;
break;
}
}
if (!active_users) break; /* last user removed by a timeout */
}
ret = poll( pollfd, nb_users, diff );
if (ret > 0)
{
int i;
for (i = 0; i < nb_users; i++)
{
if (pollfd[i].revents)
{
fd_poll_event( poll_users[i], pollfd[i].revents );
if (!--ret) break;
}
}
}
}
}
/****************************************************************/
/* inode functions */
#define HASH_SIZE 37
static struct list inode_hash[HASH_SIZE];
/* close all pending file descriptors in the closed list */
static void inode_close_pending( struct inode *inode )
{
while (inode->closed)
{
struct closed_fd *fd = inode->closed;
inode->closed = fd->next;
close( fd->fd );
free( fd );
}
}
static void inode_dump( struct object *obj, int verbose )
{
struct inode *inode = (struct inode *)obj;
fprintf( stderr, "Inode dev=" );
DUMP_LONG_LONG( inode->dev );
fprintf( stderr, " ino=" );
DUMP_LONG_LONG( inode->ino );
fprintf( stderr, "\n" );
}
static void inode_destroy( struct object *obj )
{
struct inode *inode = (struct inode *)obj;
assert( list_empty(&inode->open) );
assert( list_empty(&inode->locks) );
list_remove( &inode->entry );
inode_close_pending( inode );
}
/* retrieve the inode object for a given fd, creating it if needed */
static struct inode *get_inode( dev_t dev, ino_t ino )
{
struct list *ptr;
struct inode *inode;
unsigned int hash = (dev ^ ino) % HASH_SIZE;
if (inode_hash[hash].next)
{
LIST_FOR_EACH( ptr, &inode_hash[hash] )
{
inode = LIST_ENTRY( ptr, struct inode, entry );
if (inode->dev == dev && inode->ino == ino)
return (struct inode *)grab_object( inode );
}
}
else list_init( &inode_hash[hash] );
/* not found, create it */
if ((inode = alloc_object( &inode_ops )))
{
inode->hash = hash;
inode->dev = dev;
inode->ino = ino;
inode->closed = NULL;
list_init( &inode->open );
list_init( &inode->locks );
list_add_head( &inode_hash[hash], &inode->entry );
}
return inode;
}
/* add fd to the indoe list of file descriptors to close */
static void inode_add_closed_fd( struct inode *inode, struct closed_fd *fd )
{
if (!list_empty( &inode->locks ))
{
fd->next = inode->closed;
inode->closed = fd;
}
else /* no locks on this inode, we can close the fd right away */
{
close( fd->fd );
free( fd );
}
}
/****************************************************************/
/* file lock functions */
static void file_lock_dump( struct object *obj, int verbose )
{
struct file_lock *lock = (struct file_lock *)obj;
fprintf( stderr, "Lock %s fd=%p proc=%p start=",
lock->shared ? "shared" : "excl", lock->fd, lock->process );
DUMP_LONG_LONG( lock->start );
fprintf( stderr, " end=" );
DUMP_LONG_LONG( lock->end );
fprintf( stderr, "\n" );
}
static int file_lock_signaled( struct object *obj, struct thread *thread )
{
struct file_lock *lock = (struct file_lock *)obj;
/* lock is signaled if it has lost its owner */
return !lock->process;
}
/* set (or remove) a Unix lock if possible for the given range */
static int set_unix_lock( struct fd *fd, file_pos_t start, file_pos_t end, int type )
{
struct flock fl;
if (!fd->fs_locks) return 1; /* no fs locks possible for this fd */
for (;;)
{
if (start == end) return 1; /* can't set zero-byte lock */
if (start > max_unix_offset) return 1; /* ignore it */
fl.l_type = type;
fl.l_whence = SEEK_SET;
fl.l_start = start;
if (!end || end > max_unix_offset) fl.l_len = 0;
else fl.l_len = end - start;
if (fcntl( fd->unix_fd, F_SETLK, &fl ) != -1) return 1;
switch(errno)
{
case EACCES:
/* check whether locks work at all on this file system */
if (fcntl( fd->unix_fd, F_GETLK, &fl ) != -1)
{
set_error( STATUS_FILE_LOCK_CONFLICT );
return 0;
}
/* fall through */
case EIO:
case ENOLCK:
/* no locking on this fs, just ignore it */
fd->fs_locks = 0;
return 1;
case EAGAIN:
set_error( STATUS_FILE_LOCK_CONFLICT );
return 0;
case EBADF:
/* this can happen if we try to set a write lock on a read-only file */
/* we just ignore that error */
if (fl.l_type == F_WRLCK) return 1;
set_error( STATUS_ACCESS_DENIED );
return 0;
case EOVERFLOW:
case EINVAL:
/* this can happen if off_t is 64-bit but the kernel only supports 32-bit */
/* in that case we shrink the limit and retry */
if (max_unix_offset > INT_MAX)
{
max_unix_offset = INT_MAX;
break; /* retry */
}
/* fall through */
default:
file_set_error();
return 0;
}
}
}
/* check if interval [start;end) overlaps the lock */
inline static int lock_overlaps( struct file_lock *lock, file_pos_t start, file_pos_t end )
{
if (lock->end && start >= lock->end) return 0;
if (end && lock->start >= end) return 0;
return 1;
}
/* remove Unix locks for all bytes in the specified area that are no longer locked */
static void remove_unix_locks( struct fd *fd, file_pos_t start, file_pos_t end )
{
struct hole
{
struct hole *next;
struct hole *prev;
file_pos_t start;
file_pos_t end;
} *first, *cur, *next, *buffer;
struct list *ptr;
int count = 0;
if (!fd->inode) return;
if (!fd->fs_locks) return;
if (start == end || start > max_unix_offset) return;
if (!end || end > max_unix_offset) end = max_unix_offset + 1;
/* count the number of locks overlapping the specified area */
LIST_FOR_EACH( ptr, &fd->inode->locks )
{
struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, inode_entry );
if (lock->start == lock->end) continue;
if (lock_overlaps( lock, start, end )) count++;
}
if (!count) /* no locks at all, we can unlock everything */
{
set_unix_lock( fd, start, end, F_UNLCK );
return;
}
/* allocate space for the list of holes */
/* max. number of holes is number of locks + 1 */
if (!(buffer = malloc( sizeof(*buffer) * (count+1) ))) return;
first = buffer;
first->next = NULL;
first->prev = NULL;
first->start = start;
first->end = end;
next = first + 1;
/* build a sorted list of unlocked holes in the specified area */
LIST_FOR_EACH( ptr, &fd->inode->locks )
{
struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, inode_entry );
if (lock->start == lock->end) continue;
if (!lock_overlaps( lock, start, end )) continue;
/* go through all the holes touched by this lock */
for (cur = first; cur; cur = cur->next)
{
if (cur->end <= lock->start) continue; /* hole is before start of lock */
if (lock->end && cur->start >= lock->end) break; /* hole is after end of lock */
/* now we know that lock is overlapping hole */
if (cur->start >= lock->start) /* lock starts before hole, shrink from start */
{
cur->start = lock->end;
if (cur->start && cur->start < cur->end) break; /* done with this lock */
/* now hole is empty, remove it */
if (cur->next) cur->next->prev = cur->prev;
if (cur->prev) cur->prev->next = cur->next;
else if (!(first = cur->next)) goto done; /* no more holes at all */
}
else if (!lock->end || cur->end <= lock->end) /* lock larger than hole, shrink from end */
{
cur->end = lock->start;
assert( cur->start < cur->end );
}
else /* lock is in the middle of hole, split hole in two */
{
next->prev = cur;
next->next = cur->next;
cur->next = next;
next->start = lock->end;
next->end = cur->end;
cur->end = lock->start;
assert( next->start < next->end );
assert( cur->end < next->start );
next++;
break; /* done with this lock */
}
}
}
/* clear Unix locks for all the holes */
for (cur = first; cur; cur = cur->next)
set_unix_lock( fd, cur->start, cur->end, F_UNLCK );
done:
free( buffer );
}
/* create a new lock on a fd */
static struct file_lock *add_lock( struct fd *fd, int shared, file_pos_t start, file_pos_t end )
{
struct file_lock *lock;
if (!fd->inode) /* not a regular file */
{
set_error( STATUS_INVALID_HANDLE );
return NULL;
}
if (!(lock = alloc_object( &file_lock_ops ))) return NULL;
lock->shared = shared;
lock->start = start;
lock->end = end;
lock->fd = fd;
lock->process = current->process;
/* now try to set a Unix lock */
if (!set_unix_lock( lock->fd, lock->start, lock->end, lock->shared ? F_RDLCK : F_WRLCK ))
{
release_object( lock );
return NULL;
}
list_add_head( &fd->locks, &lock->fd_entry );
list_add_head( &fd->inode->locks, &lock->inode_entry );
list_add_head( &lock->process->locks, &lock->proc_entry );
return lock;
}
/* remove an existing lock */
static void remove_lock( struct file_lock *lock, int remove_unix )
{
struct inode *inode = lock->fd->inode;
list_remove( &lock->fd_entry );
list_remove( &lock->inode_entry );
list_remove( &lock->proc_entry );
if (remove_unix) remove_unix_locks( lock->fd, lock->start, lock->end );
if (list_empty( &inode->locks )) inode_close_pending( inode );
lock->process = NULL;
wake_up( &lock->obj, 0 );
release_object( lock );
}
/* remove all locks owned by a given process */
void remove_process_locks( struct process *process )
{
struct list *ptr;
while ((ptr = list_head( &process->locks )))
{
struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, proc_entry );
remove_lock( lock, 1 ); /* this removes it from the list */
}
}
/* remove all locks on a given fd */
static void remove_fd_locks( struct fd *fd )
{
file_pos_t start = FILE_POS_T_MAX, end = 0;
struct list *ptr;
while ((ptr = list_head( &fd->locks )))
{
struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, fd_entry );
if (lock->start < start) start = lock->start;
if (!lock->end || lock->end > end) end = lock->end - 1;
remove_lock( lock, 0 );
}
if (start < end) remove_unix_locks( fd, start, end + 1 );
}
/* add a lock on an fd */
/* returns handle to wait on */
obj_handle_t lock_fd( struct fd *fd, file_pos_t start, file_pos_t count, int shared, int wait )
{
struct list *ptr;
file_pos_t end = start + count;
/* don't allow wrapping locks */
if (end && end < start)
{
set_error( STATUS_INVALID_PARAMETER );
return 0;
}
/* check if another lock on that file overlaps the area */
LIST_FOR_EACH( ptr, &fd->inode->locks )
{
struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, inode_entry );
if (!lock_overlaps( lock, start, end )) continue;
if (lock->shared && shared) continue;
/* found one */
if (!wait)
{
set_error( STATUS_FILE_LOCK_CONFLICT );
return 0;
}
set_error( STATUS_PENDING );
return alloc_handle( current->process, lock, SYNCHRONIZE, 0 );
}
/* not found, add it */
if (add_lock( fd, shared, start, end )) return 0;
if (get_error() == STATUS_FILE_LOCK_CONFLICT)
{
/* Unix lock conflict -> tell client to wait and retry */
if (wait) set_error( STATUS_PENDING );
}
return 0;
}
/* remove a lock on an fd */
void unlock_fd( struct fd *fd, file_pos_t start, file_pos_t count )
{
struct list *ptr;
file_pos_t end = start + count;
/* find an existing lock with the exact same parameters */
LIST_FOR_EACH( ptr, &fd->locks )
{
struct file_lock *lock = LIST_ENTRY( ptr, struct file_lock, fd_entry );
if ((lock->start == start) && (lock->end == end))
{
remove_lock( lock, 1 );
return;
}
}
set_error( STATUS_FILE_LOCK_CONFLICT );
}
/****************************************************************/
/* file descriptor functions */
static void fd_dump( struct object *obj, int verbose )
{
struct fd *fd = (struct fd *)obj;
fprintf( stderr, "Fd unix_fd=%d user=%p\n", fd->unix_fd, fd->user );
}
static void fd_destroy( struct object *obj )
{
struct fd *fd = (struct fd *)obj;
remove_fd_locks( fd );
list_remove( &fd->inode_entry );
if (fd->poll_index != -1) remove_poll_user( fd, fd->poll_index );
if (fd->inode)
{
inode_add_closed_fd( fd->inode, fd->closed );
release_object( fd->inode );
}
else /* no inode, close it right away */
{
if (fd->unix_fd != -1) close( fd->unix_fd );
}
}
/* set the events that select waits for on this fd */
void set_fd_events( struct fd *fd, int events )
{
int user = fd->poll_index;
assert( poll_users[user] == fd );
if (events == -1) /* stop waiting on this fd completely */
{
pollfd[user].fd = -1;
pollfd[user].events = POLLERR;
pollfd[user].revents = 0;
}
else if (pollfd[user].fd != -1 || !pollfd[user].events)
{
pollfd[user].fd = fd->unix_fd;
pollfd[user].events = events;
}
}
/* allocate an fd object, without setting the unix fd yet */
struct fd *alloc_fd( const struct fd_ops *fd_user_ops, struct object *user )
{
struct fd *fd = alloc_object( &fd_ops );
if (!fd) return NULL;
fd->fd_ops = fd_user_ops;
fd->user = user;
fd->inode = NULL;
fd->closed = NULL;
fd->unix_fd = -1;
fd->fs_locks = 1;
fd->poll_index = -1;
list_init( &fd->inode_entry );
list_init( &fd->locks );
if ((fd->poll_index = add_poll_user( fd )) == -1)
{
release_object( fd );
return NULL;
}
return fd;
}
/* open() wrapper using a struct fd */
/* the fd must have been created with alloc_fd */
/* on error the fd object is released */
struct fd *open_fd( struct fd *fd, const char *name, int flags, mode_t *mode )
{
struct stat st;
struct closed_fd *closed_fd;
assert( fd->unix_fd == -1 );
if (!(closed_fd = mem_alloc( sizeof(*closed_fd) )))
{
release_object( fd );
return NULL;
}
if ((fd->unix_fd = open( name, flags, *mode )) == -1)
{
file_set_error();
release_object( fd );
free( closed_fd );
return NULL;
}
closed_fd->fd = fd->unix_fd;
fstat( fd->unix_fd, &st );
*mode = st.st_mode;
if (S_ISREG(st.st_mode)) /* only bother with an inode for normal files */
{
struct inode *inode = get_inode( st.st_dev, st.st_ino );
if (!inode)
{
/* we can close the fd because there are no others open on the same file,
* otherwise we wouldn't have failed to allocate a new inode
*/
release_object( fd );
free( closed_fd );
return NULL;
}
fd->inode = inode;
fd->closed = closed_fd;
list_add_head( &inode->open, &fd->inode_entry );
}
else
{
free( closed_fd );
}
return fd;
}
/* create an fd for an anonymous file */
/* if the function fails the unix fd is closed */
struct fd *create_anonymous_fd( const struct fd_ops *fd_user_ops, int unix_fd, struct object *user )
{
struct fd *fd = alloc_fd( fd_user_ops, user );
if (fd)
{
fd->unix_fd = unix_fd;
return fd;
}
close( unix_fd );
return NULL;
}
/* retrieve the object that is using an fd */
void *get_fd_user( struct fd *fd )
{
return fd->user;
}
/* retrieve the unix fd for an object */
int get_unix_fd( struct fd *fd )
{
return fd->unix_fd;
}
/* callback for event happening in the main poll() loop */
void fd_poll_event( struct fd *fd, int event )
{
return fd->fd_ops->poll_event( fd, event );
}
/* check if events are pending and if yes return which one(s) */
int check_fd_events( struct fd *fd, int events )
{
struct pollfd pfd;
pfd.fd = fd->unix_fd;
pfd.events = events;
if (poll( &pfd, 1, 0 ) <= 0) return 0;
return pfd.revents;
}
/* default add_queue() routine for objects that poll() on an fd */
int default_fd_add_queue( struct object *obj, struct wait_queue_entry *entry )
{
struct fd *fd = get_obj_fd( obj );
if (!fd) return 0;
if (!obj->head) /* first on the queue */
set_fd_events( fd, fd->fd_ops->get_poll_events( fd ) );
add_queue( obj, entry );
release_object( fd );
return 1;
}
/* default remove_queue() routine for objects that poll() on an fd */
void default_fd_remove_queue( struct object *obj, struct wait_queue_entry *entry )
{
struct fd *fd = get_obj_fd( obj );
grab_object( obj );
remove_queue( obj, entry );
if (!obj->head) /* last on the queue is gone */
set_fd_events( fd, 0 );
release_object( obj );
release_object( fd );
}
/* default signaled() routine for objects that poll() on an fd */
int default_fd_signaled( struct object *obj, struct thread *thread )
{
struct fd *fd = get_obj_fd( obj );
int events = fd->fd_ops->get_poll_events( fd );
int ret = check_fd_events( fd, events ) != 0;
if (ret)
set_fd_events( fd, 0 ); /* stop waiting on select() if we are signaled */
else if (obj->head)
set_fd_events( fd, events ); /* restart waiting on poll() if we are no longer signaled */
release_object( fd );
return ret;
}
/* default handler for poll() events */
void default_poll_event( struct fd *fd, int event )
{
/* an error occurred, stop polling this fd to avoid busy-looping */
if (event & (POLLERR | POLLHUP)) set_fd_events( fd, -1 );
wake_up( fd->user, 0 );
}
/* default flush() routine */
int no_flush( struct fd *fd, struct event **event )
{
set_error( STATUS_OBJECT_TYPE_MISMATCH );
return 0;
}
/* default get_file_info() routine */
int no_get_file_info( struct fd *fd, struct get_file_info_reply *info, int *flags )
{
set_error( STATUS_OBJECT_TYPE_MISMATCH );
*flags = 0;
return FD_TYPE_INVALID;
}
/* default queue_async() routine */
void no_queue_async( struct fd *fd, void* ptr, unsigned int status, int type, int count )
{
set_error( STATUS_OBJECT_TYPE_MISMATCH );
}
/* same as get_handle_obj but retrieve the struct fd associated to the object */
static struct fd *get_handle_fd_obj( struct process *process, obj_handle_t handle,
unsigned int access )
{
struct fd *fd = NULL;
struct object *obj;
if ((obj = get_handle_obj( process, handle, access, NULL )))
{
fd = get_obj_fd( obj );
release_object( obj );
}
return fd;
}
/* flush a file buffers */
DECL_HANDLER(flush_file)
{
struct fd *fd = get_handle_fd_obj( current->process, req->handle, 0 );
struct event * event = NULL;
if (fd)
{
fd->fd_ops->flush( fd, &event );
if( event )
{
reply->event = alloc_handle( current->process, event, SYNCHRONIZE, 0 );
}
release_object( fd );
}
}
/* get a Unix fd to access a file */
DECL_HANDLER(get_handle_fd)
{
struct fd *fd;
reply->fd = -1;
reply->type = FD_TYPE_INVALID;
if ((fd = get_handle_fd_obj( current->process, req->handle, req->access )))
{
int unix_fd = get_handle_unix_fd( current->process, req->handle, req->access );
if (unix_fd != -1) reply->fd = unix_fd;
else if (!get_error())
{
unix_fd = fd->unix_fd;
if (unix_fd != -1) send_client_fd( current->process, unix_fd, req->handle );
}
reply->type = fd->fd_ops->get_file_info( fd, NULL, &reply->flags );
release_object( fd );
}
}
/* get a file information */
DECL_HANDLER(get_file_info)
{
struct fd *fd = get_handle_fd_obj( current->process, req->handle, 0 );
if (fd)
{
int flags;
fd->fd_ops->get_file_info( fd, reply, &flags );
release_object( fd );
}
}
/* create / reschedule an async I/O */
DECL_HANDLER(register_async)
{
struct fd *fd = get_handle_fd_obj( current->process, req->handle, 0 );
/*
* The queue_async method must do the following:
*
* 1. Get the async_queue for the request of given type.
* 2. Call find_async() to look for the specific client request in the queue (=> NULL if not found).
* 3. If status is STATUS_PENDING:
* a) If no async request found in step 2 (new request): call create_async() to initialize one.
* b) Set request's status to STATUS_PENDING.
* c) If the "queue" field of the async request is NULL: call async_insert() to put it into the queue.
* Otherwise:
* If the async request was found in step 2, destroy it by calling destroy_async().
* 4. Carry out any operations necessary to adjust the object's poll events
* Usually: set_elect_events (obj, obj->ops->get_poll_events()).
*
* See also the implementations in file.c, serial.c, and sock.c.
*/
if (fd)
{
fd->fd_ops->queue_async( fd, req->overlapped, req->status, req->type, req->count );
release_object( fd );
}
}
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