source: branches/samba-3.3.x/source/smbd/files.c

/* 
   Unix SMB/CIFS implementation.
   Files[] structure handling
   Copyright (C) Andrew Tridgell 1998
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.
   
   This program 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 General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "includes.h"

static int real_max_open_files;

#define VALID_FNUM(fnum)   (((fnum) >= 0) && ((fnum) < real_max_open_files))

#define FILE_HANDLE_OFFSET 0x1000

static struct bitmap *file_bmap;

static files_struct *Files;
 
/* a fsp to use when chaining */
static files_struct *chain_fsp = NULL;

static int files_used;

/* A singleton cache to speed up searching by dev/inode. */
static struct fsp_singleton_cache {
        files_struct *fsp;
        struct file_id id;
} fsp_fi_cache;

/****************************************************************************
 Return a unique number identifying this fsp over the life of this pid.
****************************************************************************/

static unsigned long get_gen_count(void)
{
        static unsigned long file_gen_counter;

        if ((++file_gen_counter) == 0)
                return ++file_gen_counter;
        return file_gen_counter;
}

/****************************************************************************
 Find first available file slot.
****************************************************************************/

NTSTATUS file_new(connection_struct *conn, files_struct **result)
{
        int i;
        static int first_file;
        files_struct *fsp;

        /* we want to give out file handles differently on each new
           connection because of a common bug in MS clients where they try to
           reuse a file descriptor from an earlier smb connection. This code
           increases the chance that the errant client will get an error rather
           than causing corruption */
        if (first_file == 0) {
                first_file = (sys_getpid() ^ (int)time(NULL)) % real_max_open_files;
        }

        /* TODO: Port the id-tree implementation from Samba4 */

        i = bitmap_find(file_bmap, first_file);
        if (i == -1) {
                DEBUG(0,("ERROR! Out of file structures\n"));
                /* TODO: We have to unconditionally return a DOS error here,
                 * W2k3 even returns ERRDOS/ERRnofids for ntcreate&x with
                 * NTSTATUS negotiated */
                return NT_STATUS_TOO_MANY_OPENED_FILES;
        }

        fsp = SMB_MALLOC_P(files_struct);
        if (!fsp) {
                return NT_STATUS_NO_MEMORY;
        }

        ZERO_STRUCTP(fsp);

        fsp->fh = SMB_MALLOC_P(struct fd_handle);
        if (!fsp->fh) {
                SAFE_FREE(fsp);
                return NT_STATUS_NO_MEMORY;
        }

        ZERO_STRUCTP(fsp->fh);

        fsp->fh->ref_count = 1;
        fsp->fh->fd = -1;

        fsp->conn = conn;
        fsp->fh->gen_id = get_gen_count();
        GetTimeOfDay(&fsp->open_time);

        first_file = (i+1) % real_max_open_files;

        bitmap_set(file_bmap, i);
        files_used++;

        fsp->fnum = i + FILE_HANDLE_OFFSET;
        SMB_ASSERT(fsp->fnum < 65536);

        string_set(&fsp->fsp_name,"");
        
        DLIST_ADD(Files, fsp);

        DEBUG(5,("allocated file structure %d, fnum = %d (%d used)\n",
                 i, fsp->fnum, files_used));

        chain_fsp = fsp;

        /* A new fsp invalidates the positive and
          negative fsp_fi_cache as the new fsp is pushed
          at the start of the list and we search from
          a cache hit to the *end* of the list. */

        ZERO_STRUCT(fsp_fi_cache);

        conn->num_files_open++;

        *result = fsp;
        return NT_STATUS_OK;
}

/****************************************************************************
 Close all open files for a connection.
****************************************************************************/

void file_close_conn(connection_struct *conn)
{
        files_struct *fsp, *next;
        
        for (fsp=Files;fsp;fsp=next) {
                next = fsp->next;
                if (fsp->conn == conn) {
                        close_file(fsp,SHUTDOWN_CLOSE); 
                }
        }
}

/****************************************************************************
 Close all open files for a pid and a vuid.
****************************************************************************/

void file_close_pid(uint16 smbpid, int vuid)
{
        files_struct *fsp, *next;
        
        for (fsp=Files;fsp;fsp=next) {
                next = fsp->next;
                if ((fsp->file_pid == smbpid) && (fsp->vuid == vuid)) {
                        close_file(fsp,SHUTDOWN_CLOSE); 
                }
        }
}

/****************************************************************************
 Initialise file structures.
****************************************************************************/

#define MAX_OPEN_FUDGEFACTOR 20

void file_init(void)
{
        int request_max_open_files = lp_max_open_files();
        int real_lim;

        /*
         * Set the max_open files to be the requested
         * max plus a fudgefactor to allow for the extra
         * fd's we need such as log files etc...
         */
        real_lim = set_maxfiles(request_max_open_files + MAX_OPEN_FUDGEFACTOR);

        real_max_open_files = real_lim - MAX_OPEN_FUDGEFACTOR;

        if (real_max_open_files + FILE_HANDLE_OFFSET + MAX_OPEN_PIPES > 65536)
                real_max_open_files = 65536 - FILE_HANDLE_OFFSET - MAX_OPEN_PIPES;

        if(real_max_open_files != request_max_open_files) {
                DEBUG(1,("file_init: Information only: requested %d \
open files, %d are available.\n", request_max_open_files, real_max_open_files));
        }

        SMB_ASSERT(real_max_open_files > 100);

        file_bmap = bitmap_allocate(real_max_open_files);
        
        if (!file_bmap) {
                exit_server("out of memory in file_init");
        }
        
        /*
         * Ensure that pipe_handle_oppset is set correctly.
         */
        set_pipe_handle_offset(real_max_open_files);
}

/****************************************************************************
 Close files open by a specified vuid.
****************************************************************************/

void file_close_user(int vuid)
{
        files_struct *fsp, *next;

        for (fsp=Files;fsp;fsp=next) {
                next=fsp->next;
                if (fsp->vuid == vuid) {
                        close_file(fsp,SHUTDOWN_CLOSE);
                }
        }
}

/****************************************************************************
 Debug to enumerate all open files in the smbd.
****************************************************************************/

void file_dump_open_table(void)
{
        int count=0;
        files_struct *fsp;

        for (fsp=Files;fsp;fsp=fsp->next,count++) {
                DEBUG(10,("Files[%d], fnum = %d, name %s, fd = %d, gen = %lu, fileid=%s\n",
                        count, fsp->fnum, fsp->fsp_name, fsp->fh->fd, (unsigned long)fsp->fh->gen_id,
                          file_id_string_tos(&fsp->file_id)));
        }
}

/****************************************************************************
 Find a fsp given a file descriptor.
****************************************************************************/

files_struct *file_find_fd(int fd)
{
        int count=0;
        files_struct *fsp;

        for (fsp=Files;fsp;fsp=fsp->next,count++) {
                if (fsp->fh->fd == fd) {
                        if (count > 10) {
                                DLIST_PROMOTE(Files, fsp);
                        }
                        return fsp;
                }
        }

        return NULL;
}

/****************************************************************************
 Find a fsp given a device, inode and file_id.
****************************************************************************/

files_struct *file_find_dif(struct file_id id, unsigned long gen_id)
{
        int count=0;
        files_struct *fsp;

        for (fsp=Files;fsp;fsp=fsp->next,count++) {
                /* We can have a fsp->fh->fd == -1 here as it could be a stat open. */
                if (file_id_equal(&fsp->file_id, &id) &&
                    fsp->fh->gen_id == gen_id ) {
                        if (count > 10) {
                                DLIST_PROMOTE(Files, fsp);
                        }
                        /* Paranoia check. */
                        if ((fsp->fh->fd == -1) &&
                            (fsp->oplock_type != NO_OPLOCK) &&
                            (fsp->oplock_type != FAKE_LEVEL_II_OPLOCK)) {
                                DEBUG(0,("file_find_dif: file %s file_id = %s, gen = %u \
oplock_type = %u is a stat open with oplock type !\n", fsp->fsp_name, 
                                         file_id_string_tos(&fsp->file_id),
                                         (unsigned int)fsp->fh->gen_id,
                                         (unsigned int)fsp->oplock_type ));
                                smb_panic("file_find_dif");
                        }
                        return fsp;
                }
        }

        return NULL;
}

/****************************************************************************
 Check if an fsp still exists.
****************************************************************************/

files_struct *file_find_fsp(files_struct *orig_fsp)
{
        files_struct *fsp;

        for (fsp=Files;fsp;fsp=fsp->next) {
                if (fsp == orig_fsp)
                        return fsp;
        }

        return NULL;
}

/****************************************************************************
 Find the first fsp given a device and inode.
 We use a singleton cache here to speed up searching from getfilepathinfo
 calls.
****************************************************************************/

files_struct *file_find_di_first(struct file_id id)
{
        files_struct *fsp;

        if (file_id_equal(&fsp_fi_cache.id, &id)) {
                /* Positive or negative cache hit. */
                return fsp_fi_cache.fsp;
        }

        fsp_fi_cache.id = id;

        for (fsp=Files;fsp;fsp=fsp->next) {
                if (file_id_equal(&fsp->file_id, &id)) {
                        /* Setup positive cache. */
                        fsp_fi_cache.fsp = fsp;
                        return fsp;
                }
        }

        /* Setup negative cache. */
        fsp_fi_cache.fsp = NULL;
        return NULL;
}

/****************************************************************************
 Find the next fsp having the same device and inode.
****************************************************************************/

files_struct *file_find_di_next(files_struct *start_fsp)
{
        files_struct *fsp;

        for (fsp = start_fsp->next;fsp;fsp=fsp->next) {
                if (file_id_equal(&fsp->file_id, &start_fsp->file_id)) {
                        return fsp;
                }
        }

        return NULL;
}

/****************************************************************************
 Find a fsp that is open for printing.
****************************************************************************/

files_struct *file_find_print(void)
{
        files_struct *fsp;

        for (fsp=Files;fsp;fsp=fsp->next) {
                if (fsp->print_file) {
                        return fsp;
                }
        } 

        return NULL;
}

/****************************************************************************
 Find any fsp open with a pathname below that of an already open path.
****************************************************************************/

bool file_find_subpath(files_struct *dir_fsp)
{
        files_struct *fsp;
        size_t dlen;
        char *d_fullname = talloc_asprintf(talloc_tos(),
                                        "%s/%s",
                                        dir_fsp->conn->connectpath,
                                        dir_fsp->fsp_name);

        if (!d_fullname) {
                return false;
        }

        dlen = strlen(d_fullname);

        for (fsp=Files;fsp;fsp=fsp->next) {
                char *d1_fullname;

                if (fsp == dir_fsp) {
                        continue;
                }

                d1_fullname = talloc_asprintf(talloc_tos(),
                                        "%s/%s",
                                        fsp->conn->connectpath,
                                        fsp->fsp_name);

                /*
                 * If the open file has a path that is a longer
                 * component, then it's a subpath.
                 */
                if (strnequal(d_fullname, d1_fullname, dlen) &&
                                (d1_fullname[dlen] == '/')) {
                        TALLOC_FREE(d_fullname);
                        TALLOC_FREE(d1_fullname);
                        return true;
                }
                TALLOC_FREE(d1_fullname);
        }

        TALLOC_FREE(d_fullname);
        return false;
}

/****************************************************************************
 Sync open files on a connection.
****************************************************************************/

void file_sync_all(connection_struct *conn)
{
        files_struct *fsp, *next;

        for (fsp=Files;fsp;fsp=next) {
                next=fsp->next;
                if ((conn == fsp->conn) && (fsp->fh->fd != -1)) {
                        sync_file(conn, fsp, True /* write through */);
                }
        }
}

/****************************************************************************
 Free up a fsp.
****************************************************************************/

void file_free(files_struct *fsp)
{
        DLIST_REMOVE(Files, fsp);

        string_free(&fsp->fsp_name);

        TALLOC_FREE(fsp->fake_file_handle);

        if (fsp->fh->ref_count == 1) {
                SAFE_FREE(fsp->fh);
        } else {
                fsp->fh->ref_count--;
        }

        if (fsp->notify) {
                notify_remove(fsp->conn->notify_ctx, fsp);
                TALLOC_FREE(fsp->notify);
        }

        /* Ensure this event will never fire. */
        TALLOC_FREE(fsp->oplock_timeout);

        /* Ensure this event will never fire. */
        TALLOC_FREE(fsp->update_write_time_event);

        bitmap_clear(file_bmap, fsp->fnum - FILE_HANDLE_OFFSET);
        files_used--;

        DEBUG(5,("freed files structure %d (%d used)\n",
                 fsp->fnum, files_used));

        fsp->conn->num_files_open--;

        if (fsp == chain_fsp) {
                chain_fsp = NULL;
        }

        /* Closing a file can invalidate the positive cache. */
        if (fsp == fsp_fi_cache.fsp) {
                ZERO_STRUCT(fsp_fi_cache);
        }

        /* Drop all remaining extensions. */
        while (fsp->vfs_extension) {
                vfs_remove_fsp_extension(fsp->vfs_extension->owner, fsp);
        }

        /* this is paranoia, just in case someone tries to reuse the
           information */
        ZERO_STRUCTP(fsp);

        SAFE_FREE(fsp);
}

/****************************************************************************
 Get an fsp from a 16 bit fnum.
****************************************************************************/

files_struct *file_fnum(uint16 fnum)
{
        files_struct *fsp;
        int count=0;

        for (fsp=Files;fsp;fsp=fsp->next, count++) {
                if (fsp->fnum == fnum) {
                        if (count > 10) {
                                DLIST_PROMOTE(Files, fsp);
                        }
                        return fsp;
                }
        }
        return NULL;
}

/****************************************************************************
 Get an fsp from a packet given the offset of a 16 bit fnum.
****************************************************************************/

files_struct *file_fsp(uint16 fid)
{
        files_struct *fsp;

        if (chain_fsp) {
                return chain_fsp;
        }

        fsp = file_fnum(fid);
        if (fsp) {
                chain_fsp = fsp;
        }
        return fsp;
}

/****************************************************************************
 Reset the chained fsp - done at the start of a packet reply.
****************************************************************************/

void file_chain_reset(void)
{
        chain_fsp = NULL;
}

/****************************************************************************
 Duplicate the file handle part for a DOS or FCB open.
****************************************************************************/

void dup_file_fsp(files_struct *from,
                                uint32 access_mask,
                                uint32 share_access,
                                uint32 create_options,
                                files_struct *to)
{
        SAFE_FREE(to->fh);

        to->fh = from->fh;
        to->fh->ref_count++;

        to->file_id = from->file_id;
        to->initial_allocation_size = from->initial_allocation_size;
        to->mode = from->mode;
        to->file_pid = from->file_pid;
        to->vuid = from->vuid;
        to->open_time = from->open_time;
        to->access_mask = access_mask;
        to->share_access = share_access;
        to->oplock_type = from->oplock_type;
        to->can_lock = from->can_lock;
        to->can_read = (access_mask & (FILE_READ_DATA)) ? True : False;
        if (!CAN_WRITE(from->conn)) {
                to->can_write = False;
        } else {
                to->can_write = (access_mask & (FILE_WRITE_DATA | FILE_APPEND_DATA)) ? True : False;
        }
        to->print_file = from->print_file;
        to->modified = from->modified;
        to->is_directory = from->is_directory;
        to->aio_write_behind = from->aio_write_behind;
        string_set(&to->fsp_name,from->fsp_name);
}