746e768e4854730b3c445005897cdcdd3270092d
[samba.git] / source3 / printing / printing_db.c
1 /* 
2    Unix SMB/Netbios implementation.
3    Version 3.0
4    printing backend routines
5    Copyright (C) Andrew Tridgell 1992-2000
6    Copyright (C) Jeremy Allison 2002
7    
8    This program is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 3 of the License, or
11    (at your option) any later version.
12    
13    This program is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16    GNU General Public License for more details.
17    
18    You should have received a copy of the GNU General Public License
19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
20 */
21
22 #include "includes.h"
23 #include "printing.h"
24
25 static struct tdb_print_db *print_db_head;
26
27 /****************************************************************************
28   Function to find or create the printer specific job tdb given a printername.
29   Limits the number of tdb's open to MAX_PRINT_DBS_OPEN.
30 ****************************************************************************/
31
32 struct tdb_print_db *get_print_db_byname(const char *printername)
33 {
34         struct tdb_print_db *p = NULL, *last_entry = NULL;
35         int num_open = 0;
36         char *printdb_path = NULL;
37         bool done_become_root = False;
38
39         SMB_ASSERT(printername != NULL);
40
41         for (p = print_db_head, last_entry = print_db_head; p; p = p->next) {
42                 /* Ensure the list terminates... JRA. */
43                 SMB_ASSERT(p->next != print_db_head);
44
45                 if (p->tdb && strequal(p->printer_name, printername)) {
46                         DLIST_PROMOTE(print_db_head, p);
47                         p->ref_count++;
48                         return p;
49                 }
50                 num_open++;
51                 last_entry = p;
52         }
53
54         /* Not found. */
55         if (num_open >= MAX_PRINT_DBS_OPEN) {
56                 /* Try and recycle the last entry. */
57                 if (print_db_head && last_entry) {
58                         DLIST_PROMOTE(print_db_head, last_entry);
59                 }
60
61                 for (p = print_db_head; p; p = p->next) {
62                         if (p->ref_count)
63                                 continue;
64                         if (p->tdb) {
65                                 if (tdb_close(print_db_head->tdb)) {
66                                         DEBUG(0,("get_print_db: Failed to close tdb for printer %s\n",
67                                                                 print_db_head->printer_name ));
68                                         return NULL;
69                                 }
70                         }
71                         p->tdb = NULL;
72                         p->ref_count = 0;
73                         memset(p->printer_name, '\0', sizeof(p->printer_name));
74                         break;
75                 }
76                 if (p && print_db_head) {
77                         DLIST_PROMOTE(print_db_head, p);
78                         p = print_db_head;
79                 }
80         }
81
82         if (!p) {
83                 /* Create one. */
84                 p = SMB_MALLOC_P(struct tdb_print_db);
85                 if (!p) {
86                         DEBUG(0,("get_print_db: malloc fail !\n"));
87                         return NULL;
88                 }
89                 ZERO_STRUCTP(p);
90                 DLIST_ADD(print_db_head, p);
91         }
92
93         if (asprintf(&printdb_path, "%s%s.tdb",
94                                 cache_path("printing/"),
95                                 printername) < 0) {
96                 DLIST_REMOVE(print_db_head, p);
97                 SAFE_FREE(p);
98                 return NULL;
99         }
100
101         if (geteuid() != 0) {
102                 become_root();
103                 done_become_root = True;
104         }
105
106         p->tdb = tdb_open_log(printdb_path, 5000, TDB_DEFAULT, O_RDWR|O_CREAT, 
107                 0600);
108
109         if (done_become_root)
110                 unbecome_root();
111
112         if (!p->tdb) {
113                 DEBUG(0,("get_print_db: Failed to open printer backend database %s.\n",
114                                         printdb_path ));
115                 DLIST_REMOVE(print_db_head, p);
116                 SAFE_FREE(printdb_path);
117                 SAFE_FREE(p);
118                 return NULL;
119         }
120         SAFE_FREE(printdb_path);
121         fstrcpy(p->printer_name, printername);
122         p->ref_count++;
123         return p;
124 }
125
126 /***************************************************************************
127  Remove a reference count.
128 ****************************************************************************/
129
130 void release_print_db( struct tdb_print_db *pdb)
131 {
132         pdb->ref_count--;
133         SMB_ASSERT(pdb->ref_count >= 0);
134 }
135
136 /***************************************************************************
137  Close all open print db entries.
138 ****************************************************************************/
139
140 void close_all_print_db(void)
141 {
142         struct tdb_print_db *p = NULL, *next_p = NULL;
143
144         for (p = print_db_head; p; p = next_p) {
145                 next_p = p->next;
146
147                 if (p->tdb)
148                         tdb_close(p->tdb);
149                 DLIST_REMOVE(print_db_head, p);
150                 ZERO_STRUCTP(p);
151                 SAFE_FREE(p);
152         }
153 }
154
155
156 /****************************************************************************
157  Fetch and clean the pid_t record list for all pids interested in notify
158  messages. data needs freeing on exit.
159 ****************************************************************************/
160
161 TDB_DATA get_printer_notify_pid_list(TDB_CONTEXT *tdb, const char *printer_name, bool cleanlist)
162 {
163         TDB_DATA data;
164         size_t i;
165
166         ZERO_STRUCT(data);
167
168         data = tdb_fetch_bystring( tdb, NOTIFY_PID_LIST_KEY );
169
170         if (!data.dptr) {
171                 ZERO_STRUCT(data);
172                 return data;
173         }
174
175         if (data.dsize % 8) {
176                 DEBUG(0,("get_printer_notify_pid_list: Size of record for printer %s not a multiple of 8 !\n", printer_name ));
177                 tdb_delete_bystring(tdb, NOTIFY_PID_LIST_KEY );
178                 SAFE_FREE(data.dptr);
179                 ZERO_STRUCT(data);
180                 return data;
181         }
182
183         if (!cleanlist)
184                 return data;
185
186         /*
187          * Weed out all dead entries.
188          */
189
190         for( i = 0; i < data.dsize; i += 8) {
191                 pid_t pid = (pid_t)IVAL(data.dptr, i);
192
193                 if (pid == sys_getpid())
194                         continue;
195
196                 /* Entry is dead if process doesn't exist or refcount is zero. */
197
198                 while ((i < data.dsize) && ((IVAL(data.dptr, i + 4) == 0) || !process_exists_by_pid(pid))) {
199
200                         /* Refcount == zero is a logic error and should never happen. */
201                         if (IVAL(data.dptr, i + 4) == 0) {
202                                 DEBUG(0,("get_printer_notify_pid_list: Refcount == 0 for pid = %u printer %s !\n",
203                                                         (unsigned int)pid, printer_name ));
204                         }
205
206                         if (data.dsize - i > 8)
207                                 memmove( &data.dptr[i], &data.dptr[i+8], data.dsize - i - 8);
208                         data.dsize -= 8;
209                 }
210         }
211
212         return data;
213 }
214
215