source/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/smbw.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         unlink(name);
  46
  47         shared_fd = set_maxfiles(SMBW_MAX_OPEN);
  48
  49         while (shared_fd && dup2(fd, shared_fd) != shared_fd) shared_fd--;
  50
  51         if (shared_fd == 0) goto failed;
  52
  53         close(fd);
  54
  55         DEBUG(4,("created shared_fd=%d\n", shared_fd));
  56
  57         slprintf(s,sizeof(s)-1,"%d", shared_fd);
  58
  59         smbw_setenv("SMBW_HANDLE", s);
  60
  61         return;
  62
  63  failed:
  64         perror("Failed to setup shared variable area ");
  65         exit(1);
  66 }
  67
  68 static int locked;
  69
  70 /*****************************************************
  71 lock the shared variable area
  72 *******************************************************/
  73 static void lockit(void)
  74 {
  75         if (shared_fd == 0) {
  76                 char *p = getenv("SMBW_HANDLE");
  77                 if (!p) {
  78                         DEBUG(0,("ERROR: can't get smbw shared handle\n"));
  79                         exit(1);
  80                 }
  81                 shared_fd = atoi(p);
  82         }
  83         if (locked==0 &&
  84             fcntl_lock(shared_fd,SMB_F_SETLKW,0,1,F_WRLCK)==False) {
  85                 DEBUG(0,("ERROR: can't get smbw shared lock\n"));
  86                 exit(1);
  87         }
  88         locked++;
  89 }
  90
  91 /*****************************************************
  92 unlock the shared variable area
  93 *******************************************************/
  94 static void unlockit(void)
  95 {
  96         locked--;
  97         if (locked == 0) {
  98                 fcntl_lock(shared_fd,SMB_F_SETLK,0,1,F_UNLCK);
  99         }
 100 }
 101
 102
 103 /*****************************************************
 104 get a variable from the shared area
 105 *******************************************************/
 106 char *smbw_getshared(const char *name)
 107 {
 108         int i;
 109         struct stat st;
 110
 111         lockit();
 112
 113         /* maybe the area has changed */
 114         if (fstat(shared_fd, &st)) goto failed;
 115
 116         if (st.st_size != shared_size) {
 117                 variables = (char *)Realloc(variables, st.st_size);
 118                 if (!variables) goto failed;
 119                 shared_size = st.st_size;
 120                 lseek(shared_fd, 0, SEEK_SET);
 121                 if (read(shared_fd, variables, shared_size) != shared_size) {
 122                         goto failed;
 123                 }
 124         }
 125
 126         unlockit();
 127
 128         i=0;
 129         while (i < shared_size) {
 130                 char *n, *v;
 131                 int l1, l2;
 132
 133                 l1 = SVAL(&variables[i], 0);
 134                 l2 = SVAL(&variables[i], 2);
 135
 136                 n = &variables[i+4];
 137                 v = &variables[i+4+l1];
 138                 i += 4+l1+l2;
 139
 140                 if (strcmp(name,n)) {
 141                         continue;
 142                 }
 143                 return v;
 144         }
 145
 146         return NULL;
 147
 148  failed:
 149         DEBUG(0,("smbw: shared variables corrupt (%s)\n", strerror(errno)));
 150         exit(1);
 151         return NULL;
 152 }
 153
 154
 155
 156 /*****************************************************
 157 set a variable in the shared area
 158 *******************************************************/
 159 void smbw_setshared(const char *name, const char *val)
 160 {
 161         int l1, l2;
 162
 163         /* we don't allow variable overwrite */
 164         if (smbw_getshared(name)) return;
 165
 166         lockit();
 167
 168         l1 = strlen(name)+1;
 169         l2 = strlen(val)+1;
 170
 171         variables = (char *)Realloc(variables, shared_size + l1+l2+4);
 172
 173         if (!variables) {
 174                 DEBUG(0,("out of memory in smbw_setshared\n"));
 175                 exit(1);
 176         }
 177
 178         SSVAL(&variables[shared_size], 0, l1);
 179         SSVAL(&variables[shared_size], 2, l2);
 180
 181         pstrcpy(&variables[shared_size] + 4, name);
 182         pstrcpy(&variables[shared_size] + 4 + l1, val);
 183
 184         shared_size += l1+l2+4;
 185
 186         lseek(shared_fd, 0, SEEK_SET);
 187         if (write(shared_fd, variables, shared_size) != shared_size) {
 188                 DEBUG(0,("smbw_setshared failed (%s)\n", strerror(errno)));
 189                 exit(1);
 190         }
 191
 192         unlockit();
 193 }
 194
 195
 196 /*****************************************************************
 197 set an env variable - some systems don't have this
 198 *****************************************************************/
 199 int smbw_setenv(const char *name, const char *value)
 200 {
 201         pstring s;
 202         char *p;
 203         int ret = -1;
 204
 205         slprintf(s,sizeof(s)-1,"%s=%s", name, value);
 206
 207         p = strdup(s);
 208
 209         if (p) ret = putenv(p);
 210
 211         return ret;
 212 }
 213
 214 /*****************************************************************
 215 return true if the passed fd is the SMBW_HANDLE
 216 *****************************************************************/
 217 int smbw_shared_fd(int fd)
 218 {
 219         return (shared_fd && shared_fd == fd);
 220 }