source/lib/substitute.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    string substitution functions
   4    Copyright (C) Andrew Tridgell 1992-2000
   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
  22 #include "includes.h"
  23
  24 extern struct current_user current_user;
  25
  26 fstring local_machine="";
  27 fstring remote_arch="UNKNOWN";
  28 userdom_struct current_user_info;
  29 fstring remote_proto="UNKNOWN";
  30
  31 static fstring remote_machine;
  32 static fstring smb_user_name;
  33
  34 /**
  35  * Set the 'local' machine name
  36  * @param local_name the name we are being called
  37  * @param if this is the 'final' name for us, not be be changed again
  38  */
  39
  40 void set_local_machine_name(const char* local_name, BOOL perm)
  41 {
  42         static BOOL already_perm = False;
  43         fstring tmp_local_machine;
  44
  45         fstrcpy(tmp_local_machine,local_name);
  46         trim_char(tmp_local_machine,' ',' ');
  47
  48         /*
  49          * Windows NT/2k uses "*SMBSERVER" and XP uses "*SMBSERV"
  50          * arrggg!!!
  51          */
  52
  53         if ( strequal(tmp_local_machine, "*SMBSERVER") || strequal(tmp_local_machine, "*SMBSERV") )  {
  54                 fstrcpy( local_machine, client_socket_addr() );
  55                 return;
  56         }
  57
  58         if (already_perm)
  59                 return;
  60
  61         already_perm = perm;
  62
  63         alpha_strcpy(local_machine,tmp_local_machine,SAFE_NETBIOS_CHARS,sizeof(local_machine)-1);
  64         strlower_m(local_machine);
  65 }
  66
  67 /**
  68  * Set the 'remote' machine name
  69  * @param remote_name the name our client wants to be called by
  70  * @param if this is the 'final' name for them, not be be changed again
  71  */
  72
  73 void set_remote_machine_name(const char* remote_name, BOOL perm)
  74 {
  75         static BOOL already_perm = False;
  76         fstring tmp_remote_machine;
  77
  78         if (already_perm)
  79                 return;
  80
  81         already_perm = perm;
  82
  83         fstrcpy(tmp_remote_machine,remote_name);
  84         trim_char(tmp_remote_machine,' ',' ');
  85         alpha_strcpy(remote_machine,tmp_remote_machine,SAFE_NETBIOS_CHARS,sizeof(remote_machine)-1);
  86         strlower_m(remote_machine);
  87 }
  88
  89 const char* get_remote_machine_name(void)
  90 {
  91         return remote_machine;
  92 }
  93
  94 const char* get_local_machine_name(void)
  95 {
  96         if (!*local_machine) {
  97                 return global_myname();
  98         }
  99
 100         return local_machine;
 101 }
 102
 103 /*******************************************************************
 104  Setup the string used by %U substitution.
 105 ********************************************************************/
 106
 107 void sub_set_smb_name(const char *name)
 108 {
 109         fstring tmp;
 110         int len;
 111         BOOL is_machine_account = False;
 112
 113         /* don't let anonymous logins override the name */
 114         if (! *name)
 115                 return;
 116
 117
 118         fstrcpy( tmp, name );
 119         trim_char( tmp, ' ', ' ' );
 120         strlower_m( tmp );
 121
 122         len = strlen( tmp );
 123
 124         if ( len == 0 )
 125                 return;
 126
 127         /* long story but here goes....we have to allow usernames
 128            ending in '$' as they are valid machine account names.
 129            So check for a machine account and re-add the '$'
 130            at the end after the call to alpha_strcpy().   --jerry  */
 131
 132         if ( tmp[len-1] == '$' )
 133                 is_machine_account = True;
 134
 135         alpha_strcpy( smb_user_name, tmp, SAFE_NETBIOS_CHARS, sizeof(smb_user_name)-1 );
 136
 137         if ( is_machine_account ) {
 138                 len = strlen( smb_user_name );
 139                 smb_user_name[len-1] = '$';
 140         }
 141 }
 142
 143 char* sub_get_smb_name( void )
 144 {
 145         return smb_user_name;
 146 }
 147
 148 /*******************************************************************
 149  Setup the strings used by substitutions. Called per packet. Ensure
 150  %U name is set correctly also.
 151 ********************************************************************/
 152
 153 void set_current_user_info(const userdom_struct *pcui)
 154 {
 155         current_user_info = *pcui;
 156         /* The following is safe as current_user_info.smb_name
 157          * has already been sanitised in register_vuid. */
 158         fstrcpy(smb_user_name, current_user_info.smb_name);
 159 }
 160
 161 /*******************************************************************
 162  return the current active user name
 163 *******************************************************************/
 164
 165 const char* get_current_username( void )
 166 {
 167         if ( current_user_info.smb_name[0] == '\0' )
 168                 return smb_user_name;
 169
 170         return current_user_info.smb_name;
 171 }
 172
 173 /*******************************************************************
 174  Given a pointer to a %$(NAME) expand it as an environment variable.
 175  Return the number of characters by which the pointer should be advanced.
 176  Based on code by Branko Cibej <branko.cibej@hermes.si>
 177  When this is called p points at the '%' character.
 178 ********************************************************************/
 179
 180 static size_t expand_env_var(char *p, int len)
 181 {
 182         fstring envname;
 183         char *envval;
 184         char *q, *r;
 185         int copylen;
 186
 187         if (p[1] != '$')
 188                 return 1;
 189
 190         if (p[2] != '(')
 191                 return 2;
 192
 193         /*
 194          * Look for the terminating ')'.
 195          */
 196
 197         if ((q = strchr_m(p,')')) == NULL) {
 198                 DEBUG(0,("expand_env_var: Unterminated environment variable [%s]\n", p));
 199                 return 2;
 200         }
 201
 202         /*
 203          * Extract the name from within the %$(NAME) string.
 204          */
 205
 206         r = p+3;
 207         copylen = MIN((q-r),(sizeof(envname)-1));
 208         strncpy(envname,r,copylen);
 209         envname[copylen] = '\0';
 210
 211         if ((envval = getenv(envname)) == NULL) {
 212                 DEBUG(0,("expand_env_var: Environment variable [%s] not set\n", envname));
 213                 return 2;
 214         }
 215
 216         /*
 217          * Copy the full %$(NAME) into envname so it
 218          * can be replaced.
 219          */
 220
 221         copylen = MIN((q+1-p),(sizeof(envname)-1));
 222         strncpy(envname,p,copylen);
 223         envname[copylen] = '\0';
 224         string_sub(p,envname,envval,len);
 225         return 0; /* Allow the environment contents to be parsed. */
 226 }
 227
 228 /*******************************************************************
 229  Given a pointer to a %$(NAME) in p and the whole string in str
 230  expand it as an environment variable.
 231  Return a new allocated and expanded string.
 232  Based on code by Branko Cibej <branko.cibej@hermes.si>
 233  When this is called p points at the '%' character.
 234  May substitute multiple occurrencies of the same env var.
 235 ********************************************************************/
 236
 237
 238 static char * realloc_expand_env_var(char *str, char *p)
 239 {
 240         char *envname;
 241         char *envval;
 242         char *q, *r;
 243         int copylen;
 244
 245         if (p[0] != '%' || p[1] != '$' || p[2] != '(')
 246                 return str;
 247
 248         /*
 249          * Look for the terminating ')'.
 250          */
 251
 252         if ((q = strchr_m(p,')')) == NULL) {
 253                 DEBUG(0,("expand_env_var: Unterminated environment variable [%s]\n", p));
 254                 return str;
 255         }
 256
 257         /*
 258          * Extract the name from within the %$(NAME) string.
 259          */
 260
 261         r = p + 3;
 262         copylen = q - r;
 263         envname = (char *)SMB_MALLOC(copylen + 1 + 4); /* reserve space for use later add %$() chars */
 264         if (envname == NULL) return NULL;
 265         strncpy(envname,r,copylen);
 266         envname[copylen] = '\0';
 267
 268         if ((envval = getenv(envname)) == NULL) {
 269                 DEBUG(0,("expand_env_var: Environment variable [%s] not set\n", envname));
 270                 SAFE_FREE(envname);
 271                 return str;
 272         }
 273
 274         /*
 275          * Copy the full %$(NAME) into envname so it
 276          * can be replaced.
 277          */
 278
 279         copylen = q + 1 - p;
 280         strncpy(envname,p,copylen);
 281         envname[copylen] = '\0';
 282         r = realloc_string_sub(str, envname, envval);
 283         SAFE_FREE(envname);
 284         if (r == NULL) return NULL;
 285         return r;
 286 }
 287
 288 /*******************************************************************
 289  Patch from jkf@soton.ac.uk
 290  Added this to implement %p (NIS auto-map version of %H)
 291 *******************************************************************/
 292
 293 static char *automount_path(const char *user_name)
 294 {
 295         static pstring server_path;
 296
 297         /* use the passwd entry as the default */
 298         /* this will be the default if WITH_AUTOMOUNT is not used or fails */
 299
 300         pstrcpy(server_path, get_user_home_dir(user_name));
 301
 302 #if (defined(HAVE_NETGROUP) && defined (WITH_AUTOMOUNT))
 303
 304         if (lp_nis_home_map()) {
 305                 const char *home_path_start;
 306                 const char *automount_value = automount_lookup(user_name);
 307
 308                 if(strlen(automount_value) > 0) {
 309                         home_path_start = strchr_m(automount_value,':');
 310                         if (home_path_start != NULL) {
 311                                 DEBUG(5, ("NIS lookup succeeded.  Home path is: %s\n",
 312                                                 home_path_start?(home_path_start+1):""));
 313                                 pstrcpy(server_path, home_path_start+1);
 314                         }
 315                 } else {
 316                         /* NIS key lookup failed: default to user home directory from password file */
 317                         DEBUG(5, ("NIS lookup failed. Using Home path from passwd file. Home path is: %s\n", server_path ));
 318                 }
 319         }
 320 #endif
 321
 322         DEBUG(4,("Home server path: %s\n", server_path));
 323
 324         return server_path;
 325 }
 326
 327 /*******************************************************************
 328  Patch from jkf@soton.ac.uk
 329  This is Luke's original function with the NIS lookup code
 330  moved out to a separate function.
 331 *******************************************************************/
 332
 333 static const char *automount_server(const char *user_name)
 334 {
 335         static pstring server_name;
 336         const char *local_machine_name = get_local_machine_name();
 337
 338         /* use the local machine name as the default */
 339         /* this will be the default if WITH_AUTOMOUNT is not used or fails */
 340         if (local_machine_name && *local_machine_name)
 341                 pstrcpy(server_name, local_machine_name);
 342         else
 343                 pstrcpy(server_name, global_myname());
 344
 345 #if (defined(HAVE_NETGROUP) && defined (WITH_AUTOMOUNT))
 346
 347         if (lp_nis_home_map()) {
 348                 int home_server_len;
 349                 char *automount_value = automount_lookup(user_name);
 350                 home_server_len = strcspn(automount_value,":");
 351                 DEBUG(5, ("NIS lookup succeeded.  Home server length: %d\n",home_server_len));
 352                 if (home_server_len > sizeof(pstring))
 353                         home_server_len = sizeof(pstring);
 354                 strncpy(server_name, automount_value, home_server_len);
 355                 server_name[home_server_len] = '\0';
 356         }
 357 #endif
 358
 359         DEBUG(4,("Home server: %s\n", server_name));
 360
 361         return server_name;
 362 }
 363
 364 /****************************************************************************
 365  Do some standard substitutions in a string.
 366  len is the length in bytes of the space allowed in string str. If zero means
 367  don't allow expansions.
 368 ****************************************************************************/
 369
 370 void standard_sub_basic(const char *smb_name, char *str,size_t len)
 371 {
 372         char *p, *s;
 373         fstring pidstr;
 374         struct passwd *pass;
 375         const char *local_machine_name = get_local_machine_name();
 376
 377         for (s=str; (p=strchr_m(s, '%'));s=p) {
 378                 fstring tmp_str;
 379
 380                 int l = (int)len - (int)(p-str);
 381
 382                 if (l < 0)
 383                         l = 0;
 384
 385                 switch (*(p+1)) {
 386                 case 'U' :
 387                         fstrcpy(tmp_str, smb_name);
 388                         strlower_m(tmp_str);
 389                         string_sub(p,"%U",tmp_str,l);
 390                         break;
 391                 case 'G' :
 392                         fstrcpy(tmp_str, smb_name);
 393                         if ((pass = Get_Pwnam(tmp_str))!=NULL) {
 394                                 string_sub(p,"%G",gidtoname(pass->pw_gid),l);
 395                         } else {
 396                                 p += 2;
 397                         }
 398                         break;
 399                 case 'D' :
 400                         fstrcpy(tmp_str, current_user_info.domain);
 401                         strupper_m(tmp_str);
 402                         string_sub(p,"%D", tmp_str,l);
 403                         break;
 404                 case 'I' :
 405                         string_sub(p,"%I", client_addr(),l);
 406                         break;
 407                 case 'i' :
 408                         string_sub(p,"%i", client_socket_addr(),l);
 409                         break;
 410                 case 'L' :
 411                         if (!StrnCaseCmp(p, "%LOGONSERVER%", strlen("%LOGONSERVER%"))) {
 412                                 p++;
 413                                 break;
 414                         }
 415
 416                         if (local_machine_name && *local_machine_name) {
 417                                 string_sub_once(p, "%L", local_machine_name, l);
 418                         } else {
 419                                 pstring temp_name;
 420
 421                                 pstrcpy(temp_name, global_myname());
 422                                 strlower_m(temp_name);
 423                                 string_sub_once(p, "%L", temp_name, l);
 424                         }
 425                         break;
 426                 case 'M' :
 427                         string_sub(p,"%M", client_name(),l);
 428                         break;
 429                 case 'R' :
 430                         string_sub(p,"%R", remote_proto,l);
 431                         break;
 432                 case 'T' :
 433                         string_sub(p,"%T", timestring(False),l);
 434                         break;
 435                 case 'a' :
 436                         string_sub(p,"%a", remote_arch,l);
 437                         break;
 438                 case 'd' :
 439                         slprintf(pidstr,sizeof(pidstr)-1, "%d",(int)sys_getpid());
 440                         string_sub(p,"%d", pidstr,l);
 441                         break;
 442                 case 'h' :
 443                         string_sub(p,"%h", myhostname(),l);
 444                         break;
 445                 case 'm' :
 446                         string_sub(p,"%m", get_remote_machine_name(),l);
 447                         break;
 448                 case 'v' :
 449                         string_sub(p,"%v", SAMBA_VERSION_STRING,l);
 450                         break;
 451                 case 'w' :
 452                         string_sub(p,"%w", lp_winbind_separator(),l);
 453                         break;
 454                 case '$' :
 455                         p += expand_env_var(p,l);
 456                         break; /* Expand environment variables */
 457                 case '\0':
 458                         p++;
 459                         break; /* don't run off the end of the string */
 460
 461                 default: p+=2;
 462                         break;
 463                 }
 464         }
 465 }
 466
 467 static void standard_sub_advanced(int snum, const char *user,
 468                                   const char *connectpath, gid_t gid,
 469                                   const char *smb_name, char *str, size_t len)
 470 {
 471         char *p, *s, *home;
 472
 473         for (s=str; (p=strchr_m(s, '%'));s=p) {
 474                 int l = (int)len - (int)(p-str);
 475
 476                 if (l < 0)
 477                         l = 0;
 478
 479                 switch (*(p+1)) {
 480                 case 'N' :
 481                         string_sub(p,"%N", automount_server(user),l);
 482                         break;
 483                 case 'H':
 484                         if ((home = get_user_home_dir(user)))
 485                                 string_sub(p,"%H",home, l);
 486                         else
 487                                 p += 2;
 488                         break;
 489                 case 'P':
 490                         string_sub(p,"%P", connectpath, l);
 491                         break;
 492                 case 'S':
 493                         if ( snum != -1 )
 494                                 string_sub(p,"%S", lp_servicename(snum), l);
 495                         break;
 496                 case 'g':
 497                         string_sub(p,"%g", gidtoname(gid), l);
 498                         break;
 499                 case 'u':
 500                         string_sub(p,"%u", user, l);
 501                         break;
 502
 503                         /* Patch from jkf@soton.ac.uk Left the %N (NIS
 504                          * server name) in standard_sub_basic as it is
 505                          * a feature for logon servers, hence uses the
 506                          * username.  The %p (NIS server path) code is
 507                          * here as it is used instead of the default
 508                          * "path =" string in [homes] and so needs the
 509                          * service name, not the username.  */
 510                 case 'p':
 511                         if ( snum != -1 )
 512                                 string_sub(p,"%p", automount_path(lp_servicename(snum)), l);
 513                         break;
 514                 case '\0':
 515                         p++;
 516                         break; /* don't run off the end of the string */
 517
 518                 default: p+=2;
 519                         break;
 520                 }
 521         }
 522
 523         standard_sub_basic(smb_name, str, len);
 524 }
 525
 526 /****************************************************************************
 527  Do some standard substitutions in a string.
 528  This function will return an allocated string that have to be freed.
 529 ****************************************************************************/
 530
 531 char *talloc_sub_basic(TALLOC_CTX *mem_ctx, const char *smb_name, const char *str)
 532 {
 533         char *a, *t;
 534         a = alloc_sub_basic(smb_name, str);
 535         if (!a) return NULL;
 536         t = talloc_strdup(mem_ctx, a);
 537         SAFE_FREE(a);
 538         return t;
 539 }
 540
 541 char *alloc_sub_basic(const char *smb_name, const char *str)
 542 {
 543         char *b, *p, *s, *t, *r, *a_string;
 544         fstring pidstr;
 545         struct passwd *pass;
 546         const char *local_machine_name = get_local_machine_name();
 547
 548         /* workaround to prevent a crash while lookinf at bug #687 */
 549
 550         if ( !str ) {
 551                 DEBUG(0,("alloc_sub_basic: NULL source string!  This should not happen\n"));
 552                 return NULL;
 553         }
 554
 555         a_string = SMB_STRDUP(str);
 556         if (a_string == NULL) {
 557                 DEBUG(0, ("alloc_sub_specified: Out of memory!\n"));
 558                 return NULL;
 559         }
 560
 561         for (b = s = a_string; (p = strchr_m(s, '%')); s = a_string + (p - b)) {
 562
 563                 r = NULL;
 564                 b = t = a_string;
 565
 566                 switch (*(p+1)) {
 567                 case 'U' :
 568                         r = strdup_lower(smb_name);
 569                         if (r == NULL) goto error;
 570                         t = realloc_string_sub(t, "%U", r);
 571                         break;
 572                 case 'G' :
 573                         r = SMB_STRDUP(smb_name);
 574                         if (r == NULL) goto error;
 575                         if ((pass = Get_Pwnam(r))!=NULL) {
 576                                 t = realloc_string_sub(t, "%G", gidtoname(pass->pw_gid));
 577                         }
 578                         break;
 579                 case 'D' :
 580                         r = strdup_upper(current_user_info.domain);
 581                         if (r == NULL) goto error;
 582                         t = realloc_string_sub(t, "%D", r);
 583                         break;
 584                 case 'I' :
 585                         t = realloc_string_sub(t, "%I", client_addr());
 586                         break;
 587                 case 'L' :
 588                         if (local_machine_name && *local_machine_name)
 589                                 t = realloc_string_sub(t, "%L", local_machine_name);
 590                         else
 591                                 t = realloc_string_sub(t, "%L", global_myname());
 592                         break;
 593                 case 'N':
 594                         t = realloc_string_sub(t, "%N", automount_server(smb_name));
 595                         break;
 596                 case 'M' :
 597                         t = realloc_string_sub(t, "%M", client_name());
 598                         break;
 599                 case 'R' :
 600                         t = realloc_string_sub(t, "%R", remote_proto);
 601                         break;
 602                 case 'T' :
 603                         t = realloc_string_sub(t, "%T", timestring(False));
 604                         break;
 605                 case 'a' :
 606                         t = realloc_string_sub(t, "%a", remote_arch);
 607                         break;
 608                 case 'd' :
 609                         slprintf(pidstr,sizeof(pidstr)-1, "%d",(int)sys_getpid());
 610                         t = realloc_string_sub(t, "%d", pidstr);
 611                         break;
 612                 case 'h' :
 613                         t = realloc_string_sub(t, "%h", myhostname());
 614                         break;
 615                 case 'm' :
 616                         t = realloc_string_sub(t, "%m", remote_machine);
 617                         break;
 618                 case 'v' :
 619                         t = realloc_string_sub(t, "%v", SAMBA_VERSION_STRING);
 620                         break;
 621                 case 'w' :
 622                         t = realloc_string_sub(t, "%w", lp_winbind_separator());
 623                         break;
 624                 case '$' :
 625                         t = realloc_expand_env_var(t, p); /* Expand environment variables */
 626                         break;
 627
 628                 default:
 629                         break;
 630                 }
 631
 632                 p++;
 633                 SAFE_FREE(r);
 634                 if (t == NULL) goto error;
 635                 a_string = t;
 636         }
 637
 638         return a_string;
 639 error:
 640         SAFE_FREE(a_string);
 641         return NULL;
 642 }
 643
 644 /****************************************************************************
 645  Do some specific substitutions in a string.
 646  This function will return an allocated string that have to be freed.
 647 ****************************************************************************/
 648
 649 char *talloc_sub_specified(TALLOC_CTX *mem_ctx,
 650                         const char *input_string,
 651                         const char *username,
 652                         const char *domain,
 653                         uid_t uid,
 654                         gid_t gid)
 655 {
 656         char *a, *t;
 657         a = alloc_sub_specified(input_string, username, domain, uid, gid);
 658         if (!a) return NULL;
 659         t = talloc_strdup(mem_ctx, a);
 660         SAFE_FREE(a);
 661         return t;
 662 }
 663
 664 char *alloc_sub_specified(const char *input_string,
 665                         const char *username,
 666                         const char *domain,
 667                         uid_t uid,
 668                         gid_t gid)
 669 {
 670         char *a_string, *ret_string;
 671         char *b, *p, *s, *t;
 672
 673         a_string = SMB_STRDUP(input_string);
 674         if (a_string == NULL) {
 675                 DEBUG(0, ("alloc_sub_specified: Out of memory!\n"));
 676                 return NULL;
 677         }
 678
 679         for (b = s = a_string; (p = strchr_m(s, '%')); s = a_string + (p - b)) {
 680
 681                 b = t = a_string;
 682
 683                 switch (*(p+1)) {
 684                 case 'U' :
 685                         t = realloc_string_sub(t, "%U", username);
 686                         break;
 687                 case 'u' :
 688                         t = realloc_string_sub(t, "%u", username);
 689                         break;
 690                 case 'G' :
 691                         if (gid != -1) {
 692                                 t = realloc_string_sub(t, "%G", gidtoname(gid));
 693                         } else {
 694                                 t = realloc_string_sub(t, "%G", "NO_GROUP");
 695                         }
 696                         break;
 697                 case 'g' :
 698                         if (gid != -1) {
 699                                 t = realloc_string_sub(t, "%g", gidtoname(gid));
 700                         } else {
 701                                 t = realloc_string_sub(t, "%g", "NO_GROUP");
 702                         }
 703                         break;
 704                 case 'D' :
 705                         t = realloc_string_sub(t, "%D", domain);
 706                         break;
 707                 case 'N' :
 708                         t = realloc_string_sub(t, "%N", automount_server(username));
 709                         break;
 710                 default:
 711                         break;
 712                 }
 713
 714                 p++;
 715                 if (t == NULL) {
 716                         SAFE_FREE(a_string);
 717                         return NULL;
 718                 }
 719                 a_string = t;
 720         }
 721
 722         ret_string = alloc_sub_basic(username, a_string);
 723         SAFE_FREE(a_string);
 724         return ret_string;
 725 }
 726
 727 char *talloc_sub_advanced(TALLOC_CTX *mem_ctx,
 728                         int snum,
 729                         const char *user,
 730                         const char *connectpath,
 731                         gid_t gid,
 732                         const char *smb_name,
 733                         const char *str)
 734 {
 735         char *a, *t;
 736         a = alloc_sub_advanced(snum, user, connectpath, gid, smb_name, str);
 737         if (!a) return NULL;
 738         t = talloc_strdup(mem_ctx, a);
 739         SAFE_FREE(a);
 740         return t;
 741 }
 742
 743 char *alloc_sub_advanced(int snum, const char *user,
 744                                   const char *connectpath, gid_t gid,
 745                                   const char *smb_name, const char *str)
 746 {
 747         char *a_string, *ret_string;
 748         char *b, *p, *s, *t, *h;
 749
 750         a_string = SMB_STRDUP(str);
 751         if (a_string == NULL) {
 752                 DEBUG(0, ("alloc_sub_specified: Out of memory!\n"));
 753                 return NULL;
 754         }
 755
 756         for (b = s = a_string; (p = strchr_m(s, '%')); s = a_string + (p - b)) {
 757
 758                 b = t = a_string;
 759
 760                 switch (*(p+1)) {
 761                 case 'N' :
 762                         t = realloc_string_sub(t, "%N", automount_server(user));
 763                         break;
 764                 case 'H':
 765                         if ((h = get_user_home_dir(user)))
 766                                 t = realloc_string_sub(t, "%H", h);
 767                         break;
 768                 case 'P':
 769                         t = realloc_string_sub(t, "%P", connectpath);
 770                         break;
 771                 case 'S':
 772                         t = realloc_string_sub(t, "%S", lp_servicename(snum));
 773                         break;
 774                 case 'g':
 775                         t = realloc_string_sub(t, "%g", gidtoname(gid));
 776                         break;
 777                 case 'u':
 778                         t = realloc_string_sub(t, "%u", user);
 779                         break;
 780
 781                         /* Patch from jkf@soton.ac.uk Left the %N (NIS
 782                          * server name) in standard_sub_basic as it is
 783                          * a feature for logon servers, hence uses the
 784                          * username.  The %p (NIS server path) code is
 785                          * here as it is used instead of the default
 786                          * "path =" string in [homes] and so needs the
 787                          * service name, not the username.  */
 788                 case 'p':
 789                         t = realloc_string_sub(t, "%p", automount_path(lp_servicename(snum)));
 790                         break;
 791
 792                 default:
 793                         break;
 794                 }
 795
 796                 p++;
 797                 if (t == NULL) {
 798                         SAFE_FREE(a_string);
 799                         return NULL;
 800                 }
 801                 a_string = t;
 802         }
 803
 804         ret_string = alloc_sub_basic(smb_name, a_string);
 805         SAFE_FREE(a_string);
 806         return ret_string;
 807 }
 808
 809 /****************************************************************************
 810  Do some standard substitutions in a string.
 811 ****************************************************************************/
 812
 813 void standard_sub_conn(connection_struct *conn, char *str, size_t len)
 814 {
 815         standard_sub_advanced(SNUM(conn), conn->user, conn->connectpath,
 816                         conn->gid, smb_user_name, str, len);
 817 }
 818
 819 char *talloc_sub_conn(TALLOC_CTX *mem_ctx, connection_struct *conn, const char *str)
 820 {
 821         return talloc_sub_advanced(mem_ctx, SNUM(conn), conn->user,
 822                         conn->connectpath, conn->gid,
 823                         smb_user_name, str);
 824 }
 825
 826 char *alloc_sub_conn(connection_struct *conn, const char *str)
 827 {
 828         return alloc_sub_advanced(SNUM(conn), conn->user, conn->connectpath,
 829                         conn->gid, smb_user_name, str);
 830 }
 831
 832 /****************************************************************************
 833  Like standard_sub but by snum.
 834 ****************************************************************************/
 835
 836 void standard_sub_snum(int snum, char *str, size_t len)
 837 {
 838         static uid_t cached_uid = -1;
 839         static fstring cached_user;
 840         /* calling uidtoname() on every substitute would be too expensive, so
 841            we cache the result here as nearly every call is for the same uid */
 842
 843         if (cached_uid != current_user.ut.uid) {
 844                 fstrcpy(cached_user, uidtoname(current_user.ut.uid));
 845                 cached_uid = current_user.ut.uid;
 846         }
 847
 848         standard_sub_advanced(snum, cached_user, "", current_user.ut.gid,
 849                               smb_user_name, str, len);
 850 }