source: branches/samba-3.3.x/source/printing/printing_db.c

/* 
   Unix SMB/Netbios implementation.
   Version 3.0
   printing backend routines
   Copyright (C) Andrew Tridgell 1992-2000
   Copyright (C) Jeremy Allison 2002
   
   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"
#include "printing.h"

static struct tdb_print_db *print_db_head;

/****************************************************************************
  Function to find or create the printer specific job tdb given a printername.
  Limits the number of tdb's open to MAX_PRINT_DBS_OPEN.
****************************************************************************/

struct tdb_print_db *get_print_db_byname(const char *printername)
{
        struct tdb_print_db *p = NULL, *last_entry = NULL;
        int num_open = 0;
        char *printdb_path = NULL;
        bool done_become_root = False;

        SMB_ASSERT(printername != NULL);

        for (p = print_db_head, last_entry = print_db_head; p; p = p->next) {
                /* Ensure the list terminates... JRA. */
                SMB_ASSERT(p->next != print_db_head);

                if (p->tdb && strequal(p->printer_name, printername)) {
                        DLIST_PROMOTE(print_db_head, p);
                        p->ref_count++;
                        return p;
                }
                num_open++;
                last_entry = p;
        }

        /* Not found. */
        if (num_open >= MAX_PRINT_DBS_OPEN) {
                /* Try and recycle the last entry. */
                if (print_db_head && last_entry) {
                        DLIST_PROMOTE(print_db_head, last_entry);
                }

                for (p = print_db_head; p; p = p->next) {
                        if (p->ref_count)
                                continue;
                        if (p->tdb) {
                                if (tdb_close(print_db_head->tdb)) {
                                        DEBUG(0,("get_print_db: Failed to close tdb for printer %s\n",
                                                                print_db_head->printer_name ));
                                        return NULL;
                                }
                        }
                        p->tdb = NULL;
                        p->ref_count = 0;
                        memset(p->printer_name, '\0', sizeof(p->printer_name));
                        break;
                }
                if (p && print_db_head) {
                        DLIST_PROMOTE(print_db_head, p);
                        p = print_db_head;
                }
        }

        if (!p) {
                /* Create one. */
                p = SMB_MALLOC_P(struct tdb_print_db);
                if (!p) {
                        DEBUG(0,("get_print_db: malloc fail !\n"));
                        return NULL;
                }
                ZERO_STRUCTP(p);
                DLIST_ADD(print_db_head, p);
        }

        if (asprintf(&printdb_path, "%s%s.tdb",
                                lock_path("printing/"),
                                printername) < 0) {
                DLIST_REMOVE(print_db_head, p);
                SAFE_FREE(p);
                return NULL;
        }

        if (geteuid() != 0) {
                become_root();
                done_become_root = True;
        }

        p->tdb = tdb_open_log(printdb_path, 5000, TDB_DEFAULT, O_RDWR|O_CREAT, 
                0600);

        if (done_become_root)
                unbecome_root();

        if (!p->tdb) {
                DEBUG(0,("get_print_db: Failed to open printer backend database %s.\n",
                                        printdb_path ));
                DLIST_REMOVE(print_db_head, p);
                SAFE_FREE(printdb_path);
                SAFE_FREE(p);
                return NULL;
        }
        SAFE_FREE(printdb_path);
        fstrcpy(p->printer_name, printername);
        p->ref_count++;
        return p;
}

/***************************************************************************
 Remove a reference count.
****************************************************************************/

void release_print_db( struct tdb_print_db *pdb)
{
        pdb->ref_count--;
        SMB_ASSERT(pdb->ref_count >= 0);
}

/***************************************************************************
 Close all open print db entries.
****************************************************************************/

void close_all_print_db(void)
{
        struct tdb_print_db *p = NULL, *next_p = NULL;

        for (p = print_db_head; p; p = next_p) {
                next_p = p->next;

                if (p->tdb)
                        tdb_close(p->tdb);
                DLIST_REMOVE(print_db_head, p);
                ZERO_STRUCTP(p);
                SAFE_FREE(p);
        }
}


/****************************************************************************
 Fetch and clean the pid_t record list for all pids interested in notify
 messages. data needs freeing on exit.
****************************************************************************/

TDB_DATA get_printer_notify_pid_list(TDB_CONTEXT *tdb, const char *printer_name, bool cleanlist)
{
        TDB_DATA data;
        size_t i;

        ZERO_STRUCT(data);

        data = tdb_fetch_bystring( tdb, NOTIFY_PID_LIST_KEY );

        if (!data.dptr) {
                ZERO_STRUCT(data);
                return data;
        }

        if (data.dsize % 8) {
                DEBUG(0,("get_printer_notify_pid_list: Size of record for printer %s not a multiple of 8 !\n", printer_name ));
                tdb_delete_bystring(tdb, NOTIFY_PID_LIST_KEY );
                SAFE_FREE(data.dptr);
                ZERO_STRUCT(data);
                return data;
        }

        if (!cleanlist)
                return data;

        /*
         * Weed out all dead entries.
         */

        for( i = 0; i < data.dsize; i += 8) {
                pid_t pid = (pid_t)IVAL(data.dptr, i);

                if (pid == sys_getpid())
                        continue;

                /* Entry is dead if process doesn't exist or refcount is zero. */

                while ((i < data.dsize) && ((IVAL(data.dptr, i + 4) == 0) || !process_exists_by_pid(pid))) {

                        /* Refcount == zero is a logic error and should never happen. */
                        if (IVAL(data.dptr, i + 4) == 0) {
                                DEBUG(0,("get_printer_notify_pid_list: Refcount == 0 for pid = %u printer %s !\n",
                                                        (unsigned int)pid, printer_name ));
                        }

                        if (data.dsize - i > 8)
                                memmove( &data.dptr[i], &data.dptr[i+8], data.dsize - i - 8);
                        data.dsize -= 8;
                }
        }

        return data;
}