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 name, s;
  37
  38         slprintf(name,sizeof(name)-1, "%s/smbw.XXXXXX",tmpdir());
  39
  40         fd = smb_mkstemp(name);
  41
  42         if (fd == -1) goto failed;
  43
  44         unlink(name);
  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         smbw_setenv("SMBW_HANDLE", s);
  59
  60         return;
  61
  62  failed:
  63         perror("Failed to setup shared variable area ");
  64         exit(1);
  65 }
  66
  67 static int locked;
  68
  69 /*****************************************************
  70 lock the shared variable area
  71 *******************************************************/
  72 static void lockit(void)
  73 {
  74         if (shared_fd == 0) {
  75                 char *p = getenv("SMBW_HANDLE");
  76                 if (!p) {
  77                         DEBUG(0,("ERROR: can't get smbw shared handle\n"));
  78                         exit(1);
  79                 }
  80                 shared_fd = atoi(p);
  81         }
  82         if (locked==0 &&
  83             fcntl_lock(shared_fd,SMB_F_SETLKW,0,1,F_WRLCK)==False) {
  84                 DEBUG(0,("ERROR: can't get smbw shared lock (%s)\n", strerror(errno)));
  85                 exit(1);
  86         }
  87         locked++;
  88 }
  89
  90 /*****************************************************
  91 unlock the shared variable area
  92 *******************************************************/
  93 static void unlockit(void)
  94 {
  95         locked--;
  96         if (locked == 0) {
  97                 fcntl_lock(shared_fd,SMB_F_SETLK,0,1,F_UNLCK);
  98         }
  99 }
 100
 101
 102 /*****************************************************
 103 get a variable from the shared area
 104 *******************************************************/
 105 char *smbw_getshared(const char *name)
 106 {
 107         int i;
 108         struct stat st;
 109
 110         lockit();
 111
 112         /* maybe the area has changed */
 113         if (fstat(shared_fd, &st)) goto failed;
 114
 115         if (st.st_size != shared_size) {
 116                 variables = (char *)Realloc(variables, st.st_size);
 117                 if (!variables) goto failed;
 118                 shared_size = st.st_size;
 119                 lseek(shared_fd, 0, SEEK_SET);
 120                 if (read(shared_fd, variables, shared_size) != shared_size) {
 121                         goto failed;
 122                 }
 123         }
 124
 125         unlockit();
 126
 127         i=0;
 128         while (i < shared_size) {
 129                 char *n, *v;
 130                 int l1, l2;
 131
 132                 l1 = SVAL(&variables[i], 0);
 133                 l2 = SVAL(&variables[i], 2);
 134
 135                 n = &variables[i+4];
 136                 v = &variables[i+4+l1];
 137                 i += 4+l1+l2;
 138
 139                 if (strcmp(name,n)) {
 140                         continue;
 141                 }
 142                 return v;
 143         }
 144
 145         return NULL;
 146
 147  failed:
 148         DEBUG(0,("smbw: shared variables corrupt (%s)\n", strerror(errno)));
 149         exit(1);
 150         return NULL;
 151 }
 152
 153
 154
 155 /*****************************************************
 156 set a variable in the shared area
 157 *******************************************************/
 158 void smbw_setshared(const char *name, const char *val)
 159 {
 160         int l1, l2;
 161
 162         /* we don't allow variable overwrite */
 163         if (smbw_getshared(name)) return;
 164
 165         lockit();
 166
 167         l1 = strlen(name)+1;
 168         l2 = strlen(val)+1;
 169
 170         variables = (char *)Realloc(variables, shared_size + l1+l2+4);
 171
 172         if (!variables) {
 173                 DEBUG(0,("out of memory in smbw_setshared\n"));
 174                 exit(1);
 175         }
 176
 177         SSVAL(&variables[shared_size], 0, l1);
 178         SSVAL(&variables[shared_size], 2, l2);
 179
 180         pstrcpy(&variables[shared_size] + 4, name);
 181         pstrcpy(&variables[shared_size] + 4 + l1, val);
 182
 183         shared_size += l1+l2+4;
 184
 185         lseek(shared_fd, 0, SEEK_SET);
 186         if (write(shared_fd, variables, shared_size) != shared_size) {
 187                 DEBUG(0,("smbw_setshared failed (%s)\n", strerror(errno)));
 188                 exit(1);
 189         }
 190
 191         unlockit();
 192 }
 193
 194
 195 /*****************************************************************
 196 set an env variable - some systems don't have this
 197 *****************************************************************/
 198 int smbw_setenv(const char *name, const char *value)
 199 {
 200         pstring s;
 201         char *p;
 202         int ret = -1;
 203
 204         slprintf(s,sizeof(s)-1,"%s=%s", name, value);
 205
 206         p = strdup(s);
 207
 208         if (p) ret = putenv(p);
 209
 210         return ret;
 211 }
 212
 213 /*****************************************************************
 214 return true if the passed fd is the SMBW_HANDLE
 215 *****************************************************************/
 216 int smbw_shared_fd(int fd)
 217 {
 218         return (shared_fd && shared_fd == fd);
 219 }