source3/smbwrapper/shared.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 2.0
   4    SMB wrapper functions - shared variables
   5    Copyright (C) Andrew Tridgell 1998
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "includes.h"
  23
  24 extern int DEBUGLEVEL;
  25
  26 static int shared_fd;
  27 static char *variables;
  28 static int shared_size;
  29
  30 /*****************************************************
  31 setup the shared area
  32 *******************************************************/
  33 void smbw_setup_shared(void)
  34 {
  35         int fd;
  36         pstring s, name;
  37
  38         slprintf(s,sizeof(s)-1, "%s/msg.XXXXXX",tmpdir());
  39
  40         fstrcpy(name,(char *)mktemp(s));
  41
  42         /* note zero permissions! don't change this */
  43         fd = open(name,O_RDWR|O_CREAT|O_TRUNC|O_EXCL,0);
  44         if (fd == -1) goto failed;
  45
  46         shared_fd = set_maxfiles(SMBW_MAX_OPEN);
  47
  48         while (shared_fd && dup2(fd, shared_fd) != shared_fd) shared_fd--;
  49
  50         if (shared_fd == 0) goto failed;
  51
  52         close(fd);
  53
  54         DEBUG(4,("created shared_fd=%d\n", shared_fd));
  55
  56         slprintf(s,sizeof(s)-1,"%d", shared_fd);
  57
  58         setenv("SMBW_HANDLE", s, 1);
  59
  60         return;
  61
  62  failed:
  63         perror("Failed to setup shared variable area ");
  64         exit(1);
  65 }
  66
  67
  68 /*****************************************************
  69 lock the shared variable area
  70 *******************************************************/
  71 static void lockit(void)
  72 {
  73         if (shared_fd == 0) {
  74                 char *p = getenv("SMBW_HANDLE");
  75                 if (!p) {
  76                         DEBUG(0,("ERROR: can't get smbw shared handle\n"));
  77                         exit(1);
  78                 }
  79                 shared_fd = atoi(p);
  80         }
  81         if (fcntl_lock(shared_fd,SMB_F_SETLKW,0,1,F_WRLCK)==False) {
  82                 DEBUG(0,("ERROR: can't get smbw shared lock\n"));
  83                 exit(1);
  84         }
  85 }
  86
  87 /*****************************************************
  88 unlock the shared variable area
  89 *******************************************************/
  90 static void unlockit(void)
  91 {
  92         fcntl_lock(shared_fd,SMB_F_SETLK,0,1,F_UNLCK);
  93 }
  94
  95
  96 /*****************************************************
  97 get a variable from the shared area
  98 *******************************************************/
  99 char *smbw_getshared(const char *name)
 100 {
 101         int i;
 102         struct stat st;
 103
 104         lockit();
 105
 106         /* maybe the area has changed */
 107         if (fstat(shared_fd, &st)) goto failed;
 108
 109         if (st.st_size != shared_size) {
 110                 variables = (char *)Realloc(variables, st.st_size);
 111                 if (!variables) goto failed;
 112                 shared_size = st.st_size;
 113                 lseek(shared_fd, 0, SEEK_SET);
 114                 if (read(shared_fd, variables, shared_size) != shared_size) {
 115                         goto failed;
 116                 }
 117         }
 118
 119         unlockit();
 120
 121         i=0;
 122         while (i < shared_size) {
 123                 int len;
 124                 char *n, *v;
 125
 126                 n = &variables[i];
 127                 i += strlen(n)+1;
 128                 v = &variables[i];
 129                 i += strlen(v)+1;
 130
 131                 if (strcmp(name,n)) {
 132                         continue;
 133                 }
 134                 return v;
 135         }
 136
 137         return NULL;
 138
 139  failed:
 140         DEBUG(0,("smbw: shared variables corrupt (%s)\n", strerror(errno)));
 141         exit(1);
 142 }
 143
 144
 145
 146 /*****************************************************
 147 set a variable in the shared area
 148 *******************************************************/
 149 void smbw_setshared(const char *name, const char *val)
 150 {
 151         int len;
 152
 153         /* we don't allow variable overwrite */
 154         if (smbw_getshared(name)) return;
 155
 156         lockit();
 157
 158         len = strlen(name) + strlen(val) + 2;
 159
 160         variables = (char *)Realloc(variables, shared_size + len);
 161
 162         if (!variables) {
 163                 DEBUG(0,("out of memory in smbw_setshared\n"));
 164                 exit(1);
 165         }
 166
 167         pstrcpy(&variables[shared_size], name);
 168         shared_size += strlen(name)+1;
 169         pstrcpy(&variables[shared_size], val);
 170         shared_size += strlen(val)+1;
 171
 172         lseek(shared_fd, 0, SEEK_SET);
 173         if (write(shared_fd, variables, shared_size) != shared_size) {
 174                 DEBUG(0,("smbw_setshared failed (%s)\n", strerror(errno)));
 175                 exit(1);
 176         }
 177
 178         unlockit();
 179 }