source3/smbwrapper/shared.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    SMB wrapper functions - shared variables
   4    Copyright (C) Andrew Tridgell 1998
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 static int shared_fd;
  24 static char *variables;
  25 static int shared_size;
  26
  27 /*****************************************************
  28 setup the shared area
  29 *******************************************************/
  30 void smbw_setup_shared(void)
  31 {
  32         int fd;
  33         pstring name, s;
  34
  35         slprintf(name,sizeof(name)-1, "%s/smbw.XXXXXX",tmpdir());
  36
  37         fd = smb_mkstemp(name);
  38
  39         if (fd == -1) goto failed;
  40
  41         unlink(name);
  42
  43         shared_fd = set_maxfiles(SMBW_MAX_OPEN);
  44
  45         while (shared_fd && dup2(fd, shared_fd) != shared_fd) shared_fd--;
  46
  47         if (shared_fd == 0) goto failed;
  48
  49         close(fd);
  50
  51         DEBUG(4,("created shared_fd=%d\n", shared_fd));
  52
  53         slprintf(s,sizeof(s)-1,"%d", shared_fd);
  54
  55         setenv("SMBW_HANDLE", s, 1);
  56
  57         return;
  58
  59  failed:
  60         perror("Failed to setup shared variable area ");
  61         exit(1);
  62 }
  63
  64 static int locked;
  65
  66 /*****************************************************
  67 lock the shared variable area
  68 *******************************************************/
  69 static void lockit(void)
  70 {
  71         if (shared_fd == 0) {
  72                 char *p = getenv("SMBW_HANDLE");
  73                 if (!p) {
  74                         DEBUG(0,("ERROR: can't get smbw shared handle\n"));
  75                         exit(1);
  76                 }
  77                 shared_fd = atoi(p);
  78         }
  79         if (locked==0 &&
  80             fcntl_lock(shared_fd,SMB_F_SETLKW,0,1,F_WRLCK)==False) {
  81                 DEBUG(0,("ERROR: can't get smbw shared lock (%s)\n", strerror(errno)));
  82                 exit(1);
  83         }
  84         locked++;
  85 }
  86
  87 /*****************************************************
  88 unlock the shared variable area
  89 *******************************************************/
  90 static void unlockit(void)
  91 {
  92         locked--;
  93         if (locked == 0) {
  94                 fcntl_lock(shared_fd,SMB_F_SETLK,0,1,F_UNLCK);
  95         }
  96 }
  97
  98
  99 /*****************************************************
 100 get a variable from the shared area
 101 *******************************************************/
 102 char *smbw_getshared(const char *name)
 103 {
 104         int i;
 105         struct stat st;
 106         char *var;
 107
 108         lockit();
 109
 110         /* maybe the area has changed */
 111         if (fstat(shared_fd, &st)) goto failed;
 112
 113         if (st.st_size != shared_size) {
 114                 var = (char *)Realloc(variables, st.st_size);
 115                 if (!var) goto failed;
 116                 else variables = var;
 117                 shared_size = st.st_size;
 118                 lseek(shared_fd, 0, SEEK_SET);
 119                 if (read(shared_fd, variables, shared_size) != shared_size) {
 120                         goto failed;
 121                 }
 122         }
 123
 124         unlockit();
 125
 126         i=0;
 127         while (i < shared_size) {
 128                 char *n, *v;
 129                 int l1, l2;
 130
 131                 l1 = SVAL(&variables[i], 0);
 132                 l2 = SVAL(&variables[i], 2);
 133
 134                 n = &variables[i+4];
 135                 v = &variables[i+4+l1];
 136                 i += 4+l1+l2;
 137
 138                 if (strcmp(name,n)) {
 139                         continue;
 140                 }
 141                 return v;
 142         }
 143
 144         return NULL;
 145
 146  failed:
 147         DEBUG(0,("smbw: shared variables corrupt (%s)\n", strerror(errno)));
 148         exit(1);
 149         return NULL;
 150 }
 151
 152
 153
 154 /*****************************************************
 155 set a variable in the shared area
 156 *******************************************************/
 157 void smbw_setshared(const char *name, const char *val)
 158 {
 159         int l1, l2;
 160         char *var;
 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         var = (char *)Realloc(variables, shared_size + l1+l2+4);
 171
 172         if (!var) {
 173                 DEBUG(0,("out of memory in smbw_setshared\n"));
 174                 exit(1);
 175         }
 176
 177         variables = var;
 178
 179         SSVAL(&variables[shared_size], 0, l1);
 180         SSVAL(&variables[shared_size], 2, l2);
 181
 182         pstrcpy(&variables[shared_size] + 4, name);
 183         pstrcpy(&variables[shared_size] + 4 + l1, val);
 184
 185         shared_size += l1+l2+4;
 186
 187         lseek(shared_fd, 0, SEEK_SET);
 188         if (write(shared_fd, variables, shared_size) != shared_size) {
 189                 DEBUG(0,("smbw_setshared failed (%s)\n", strerror(errno)));
 190                 exit(1);
 191         }
 192
 193         unlockit();
 194 }
 195
 196
 197 /*****************************************************************
 198 return true if the passed fd is the SMBW_HANDLE
 199 *****************************************************************/
 200 int smbw_shared_fd(int fd)
 201 {
 202         return (shared_fd && shared_fd == fd);
 203 }