bin/ksh/var.c

   1 /*      $NetBSD: var.c,v 1.14 2006/03/29 15:51:00 christos Exp $        */
   2
   3 #include <sys/cdefs.h>
   4
   5 #ifndef lint
   6 __RCSID("$NetBSD: var.c,v 1.14 2006/03/29 15:51:00 christos Exp $");
   7 #endif
   8
   9
  10 #include "sh.h"
  11 #include "ksh_time.h"
  12 #include "ksh_limval.h"
  13 #include "ksh_stat.h"
  14 #include <ctype.h>
  15
  16 /*
  17  * Variables
  18  *
  19  * WARNING: unreadable code, needs a rewrite
  20  *
  21  * if (flag&INTEGER), val.i contains integer value, and type contains base.
  22  * otherwise, (val.s + type) contains string value.
  23  * if (flag&EXPORT), val.s contains "name=value" for E-Z exporting.
  24  */
  25 static  struct tbl vtemp;
  26 static  struct table specials;
  27 static char     *formatstr      ARGS((struct tbl *vp, const char *s));
  28 static void     export          ARGS((struct tbl *vp, const char *val));
  29 static int      special         ARGS((const char *name));
  30 static void     unspecial       ARGS((const char *name));
  31 static void     getspec         ARGS((struct tbl *vp));
  32 static void     setspec         ARGS((struct tbl *vp));
  33 static void     unsetspec       ARGS((struct tbl *vp));
  34 static struct tbl *arraysearch  ARGS((struct tbl *, int));
  35
  36 /*
  37  * create a new block for function calls and simple commands
  38  * assume caller has allocated and set up e->loc
  39  */
  40 void
  41 newblock()
  42 {
  43         register struct block *l;
  44         static char *const empty[] = {null};
  45
  46         l = (struct block *) alloc(sizeof(struct block), ATEMP);
  47         l->flags = 0;
  48         ainit(&l->area); /* todo: could use e->area (l->area => l->areap) */
  49         if (!e->loc) {
  50                 l->argc = 0;
  51                 l->argv = (char **) __UNCONST(empty);
  52         } else {
  53                 l->argc = e->loc->argc;
  54                 l->argv = e->loc->argv;
  55         }
  56         l->exit = l->error = NULL;
  57         tinit(&l->vars, &l->area, 0);
  58         tinit(&l->funs, &l->area, 0);
  59         l->next = e->loc;
  60         e->loc = l;
  61 }
  62
  63 /*
  64  * pop a block handling special variables
  65  */
  66 void
  67 popblock()
  68 {
  69         register struct block *l = e->loc;
  70         register struct tbl *vp, **vpp = l->vars.tbls, *vq;
  71         register int i;
  72
  73         e->loc = l->next;       /* pop block */
  74         for (i = l->vars.size; --i >= 0; ) {
  75                 if ((vp = *vpp++) != NULL && (vp->flag&SPECIAL)) {
  76                         if ((vq = global(vp->name))->flag & ISSET)
  77                                 setspec(vq);
  78                         else
  79                                 unsetspec(vq);
  80                 }
  81         }
  82         if (l->flags & BF_DOGETOPTS)
  83                 user_opt = l->getopts_state;
  84         afreeall(&l->area);
  85         afree(l, ATEMP);
  86 }
  87
  88 /* called by main() to initialize variable data structures */
  89 void
  90 initvar()
  91 {
  92         static const struct {
  93                 const char *name;
  94                 int v;
  95         } names[] = {
  96                         { "COLUMNS",            V_COLUMNS },
  97                         { "IFS",                V_IFS },
  98                         { "OPTIND",             V_OPTIND },
  99                         { "PATH",               V_PATH },
 100                         { "POSIXLY_CORRECT",    V_POSIXLY_CORRECT },
 101                         { "TMPDIR",             V_TMPDIR },
 102 #ifdef HISTORY
 103                         { "HISTFILE",           V_HISTFILE },
 104                         { "HISTSIZE",           V_HISTSIZE },
 105 #endif /* HISTORY */
 106 #ifdef EDIT
 107                         { "EDITOR",             V_EDITOR },
 108                         { "VISUAL",             V_VISUAL },
 109 #endif /* EDIT */
 110 #ifdef KSH
 111                         { "MAIL",               V_MAIL },
 112                         { "MAILCHECK",          V_MAILCHECK },
 113                         { "MAILPATH",           V_MAILPATH },
 114                         { "RANDOM",             V_RANDOM },
 115                         { "SECONDS",            V_SECONDS },
 116                         { "TMOUT",              V_TMOUT },
 117 #endif /* KSH */
 118                         { "LINENO",             V_LINENO },
 119                         { (char *) 0,   0 }
 120                 };
 121         int i;
 122         struct tbl *tp;
 123
 124         tinit(&specials, APERM, 32); /* must be 2^n (currently 17 specials) */
 125         for (i = 0; names[i].name; i++) {
 126                 tp = tenter(&specials, names[i].name, hash(names[i].name));
 127                 tp->flag = DEFINED|ISSET;
 128                 tp->type = names[i].v;
 129         }
 130 }
 131
 132 /* Used to calculate an array index for global()/local().  Sets *arrayp to
 133  * non-zero if this is an array, sets *valp to the array index, returns
 134  * the basename of the array.
 135  */
 136 const char *array_index_calc(const char *n, bool_t *arrayp, int *valp);
 137
 138 const char *
 139 array_index_calc(n, arrayp, valp)
 140         const char *n;
 141         bool_t *arrayp;
 142         int *valp;
 143 {
 144         const char *p;
 145         int len;
 146
 147         *arrayp = FALSE;
 148         p = skip_varname(n, FALSE);
 149         if (p != n && *p == '[' && (len = array_ref_len(p))) {
 150                 char *sub, *tmp;
 151                 long rval;
 152
 153                 /* Calculate the value of the subscript */
 154                 *arrayp = TRUE;
 155                 tmp = str_nsave(p+1, len-2, ATEMP);
 156                 sub = substitute(tmp, 0);
 157                 afree(tmp, ATEMP);
 158                 n = str_nsave(n, p - n, ATEMP);
 159                 evaluate(sub, &rval, KSH_UNWIND_ERROR);
 160                 if (rval < 0 || rval > ARRAYMAX)
 161                         errorf("%s: subscript out of range", n);
 162                 *valp = rval;
 163                 afree(sub, ATEMP);
 164         }
 165         return n;
 166 }
 167
 168 /*
 169  * Search for variable, if not found create globally.
 170  */
 171 struct tbl *
 172 global(n)
 173         register const char *n;
 174 {
 175         register struct block *l = e->loc;
 176         register struct tbl *vp;
 177         register int c;
 178         unsigned h;
 179         bool_t   array;
 180         int      val;
 181
 182         /* Check to see if this is an array */
 183         n = array_index_calc(n, &array, &val);
 184         h = hash(n);
 185         c = n[0];
 186         if (!letter(c)) {
 187                 if (array)
 188                         errorf("bad substitution");
 189                 vp = &vtemp;
 190                 vp->flag = DEFINED;
 191                 vp->type = 0;
 192                 vp->areap = ATEMP;
 193                 *vp->name = c;
 194                 if (digit(c)) {
 195                         for (c = 0; digit(*n); n++)
 196                                 c = c*10 + *n-'0';
 197                         if (c <= l->argc)
 198                                 /* setstr can't fail here */
 199                                 setstr(vp, l->argv[c], KSH_RETURN_ERROR);
 200                         vp->flag |= RDONLY;
 201                         return vp;
 202                 }
 203                 vp->flag |= RDONLY;
 204                 if (n[1] != '\0')
 205                         return vp;
 206                 vp->flag |= ISSET|INTEGER;
 207                 switch (c) {
 208                   case '$':
 209                         vp->val.i = kshpid;
 210                         break;
 211                   case '!':
 212                         /* If no job, expand to nothing */
 213                         if ((vp->val.i = j_async()) == 0)
 214                                 vp->flag &= ~(ISSET|INTEGER);
 215                         break;
 216                   case '?':
 217                         vp->val.i = exstat;
 218                         break;
 219                   case '#':
 220                         vp->val.i = l->argc;
 221                         break;
 222                   case '-':
 223                         vp->flag &= ~INTEGER;
 224                         vp->val.s = getoptions();
 225                         break;
 226                   default:
 227                         vp->flag &= ~(ISSET|INTEGER);
 228                 }
 229                 return vp;
 230         }
 231         for (l = e->loc; ; l = l->next) {
 232                 vp = tsearch(&l->vars, n, h);
 233                 if (vp != NULL) {
 234                         if (array)
 235                                 return arraysearch(vp, val);
 236                         else
 237                                 return vp;
 238                 }
 239                 if (l->next == NULL)
 240                         break;
 241         }
 242         vp = tenter(&l->vars, n, h);
 243         if (array)
 244                 vp = arraysearch(vp, val);
 245         vp->flag |= DEFINED;
 246         if (special(n))
 247                 vp->flag |= SPECIAL;
 248         return vp;
 249 }
 250
 251 /*
 252  * Search for local variable, if not found create locally.
 253  */
 254 struct tbl *
 255 local(n, copy)
 256         register const char *n;
 257         bool_t copy;
 258 {
 259         register struct block *l = e->loc;
 260         register struct tbl *vp;
 261         unsigned h;
 262         bool_t   array;
 263         int      val;
 264
 265         /* Check to see if this is an array */
 266         n = array_index_calc(n, &array, &val);
 267         h = hash(n);
 268         if (!letter(*n)) {
 269                 vp = &vtemp;
 270                 vp->flag = DEFINED|RDONLY;
 271                 vp->type = 0;
 272                 vp->areap = ATEMP;
 273                 return vp;
 274         }
 275         vp = tenter(&l->vars, n, h);
 276         if (copy && !(vp->flag & DEFINED)) {
 277                 struct block *ll = l;
 278                 struct tbl *vq = (struct tbl *) 0;
 279
 280                 while ((ll = ll->next) && !(vq = tsearch(&ll->vars, n, h)))
 281                         ;
 282                 if (vq) {
 283                         vp->flag |= vq->flag & (EXPORT|INTEGER|RDONLY
 284                                                 |LJUST|RJUST|ZEROFIL
 285                                                 |LCASEV|UCASEV_AL|INT_U|INT_L);
 286                         if (vq->flag & INTEGER)
 287                                 vp->type = vq->type;
 288                         vp->u2.field = vq->u2.field;
 289                 }
 290         }
 291         if (array)
 292                 vp = arraysearch(vp, val);
 293         vp->flag |= DEFINED;
 294         if (special(n))
 295                 vp->flag |= SPECIAL;
 296         return vp;
 297 }
 298
 299 /* get variable string value */
 300 char *
 301 str_val(vp)
 302         register struct tbl *vp;
 303 {
 304         char *s;
 305
 306         if ((vp->flag&SPECIAL))
 307                 getspec(vp);
 308         if (!(vp->flag&ISSET))
 309                 s = null;               /* special to dollar() */
 310         else if (!(vp->flag&INTEGER))   /* string source */
 311                 s = vp->val.s + vp->type;
 312         else {                          /* integer source */
 313                 /* worst case number length is when base=2, so use BITS(long) */
 314                              /* minus base #     number    null */
 315                 static char strbuf[1 + 2 + 1 + BITS(long) + 1];
 316                 const char *digits = (vp->flag & UCASEV_AL) ?
 317                                   "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
 318                                 : "0123456789abcdefghijklmnopqrstuvwxyz";
 319                 register unsigned long n;
 320                 register int base;
 321
 322                 s = strbuf + sizeof(strbuf);
 323                 if (vp->flag & INT_U)
 324                         n = (unsigned long) vp->val.i;
 325                 else
 326                         n = (vp->val.i < 0) ? -vp->val.i : vp->val.i;
 327                 base = (vp->type == 0) ? 10 : vp->type;
 328
 329                 *--s = '\0';
 330                 do {
 331                         *--s = digits[n % base];
 332                         n /= base;
 333                 } while (n != 0);
 334                 if (base != 10) {
 335                         *--s = '#';
 336                         *--s = digits[base % 10];
 337                         if (base >= 10)
 338                                 *--s = digits[base / 10];
 339                 }
 340                 if (!(vp->flag & INT_U) && vp->val.i < 0)
 341                         *--s = '-';
 342                 if (vp->flag & (RJUST|LJUST)) { /* case already dealt with */
 343                         s = formatstr(vp, s);
 344                         (void)strlcpy(strbuf, s, sizeof(strbuf));
 345                         afree(s, ATEMP);
 346                         s = strbuf;
 347                 }
 348         }
 349         return s;
 350 }
 351
 352 /* get variable integer value, with error checking */
 353 long
 354 intval(vp)
 355         register struct tbl *vp;
 356 {
 357         long num;
 358         int base;
 359
 360         base = getint(vp, &num);
 361         if (base == -1)
 362                 /* XXX check calls - is error here ok by POSIX? */
 363                 errorf("%s: bad number", str_val(vp));
 364         return num;
 365 }
 366
 367 /* set variable to string value */
 368 int
 369 setstr(vq, s, error_ok)
 370         register struct tbl *vq;
 371         const char *s;
 372         int error_ok;
 373 {
 374         char *fs = NULL;
 375         int no_ro_check = error_ok & 0x4;
 376         error_ok &= ~0x4;
 377         if ((vq->flag & RDONLY) && !no_ro_check) {
 378                 warningf(TRUE, "%s: is read only", vq->name);
 379                 if (!error_ok)
 380                         errorf(null);
 381                 return 0;
 382         }
 383         if (!(vq->flag&INTEGER)) { /* string dest */
 384                 if ((vq->flag&ALLOC)) {
 385                         /* debugging */
 386                         if (s >= vq->val.s
 387                             && s <= vq->val.s + strlen(vq->val.s))
 388                                 internal_errorf(TRUE,
 389                                     "setstr: %s=%s: assigning to self",
 390                                     vq->name, s);
 391                         afree((void*)vq->val.s, vq->areap);
 392                 }
 393                 vq->flag &= ~(ISSET|ALLOC);
 394                 vq->type = 0;
 395                 if (s && (vq->flag & (UCASEV_AL|LCASEV|LJUST|RJUST)))
 396                         s = fs = formatstr(vq, s);
 397                 if ((vq->flag&EXPORT))
 398                         export(vq, s);
 399                 else {
 400                         vq->val.s = str_save(s, vq->areap);
 401                         vq->flag |= ALLOC;
 402                 }
 403         } else                  /* integer dest */
 404                 if (!v_evaluate(vq, s, error_ok))
 405                         return 0;
 406         vq->flag |= ISSET;
 407         if ((vq->flag&SPECIAL))
 408                 setspec(vq);
 409         if (fs)
 410                 afree(fs, ATEMP);
 411         return 1;
 412 }
 413
 414 /* set variable to integer */
 415 void
 416 setint(vq, n)
 417         register struct tbl *vq;
 418         long n;
 419 {
 420         if (!(vq->flag&INTEGER)) {
 421                 register struct tbl *vp = &vtemp;
 422                 vp->flag = (ISSET|INTEGER);
 423                 vp->type = 0;
 424                 vp->areap = ATEMP;
 425                 vp->val.i = n;
 426                 /* setstr can't fail here */
 427                 setstr(vq, str_val(vp), KSH_RETURN_ERROR);
 428         } else
 429                 vq->val.i = n;
 430         vq->flag |= ISSET;
 431         if ((vq->flag&SPECIAL))
 432                 setspec(vq);
 433 }
 434
 435 int
 436 getint(vp, nump)
 437         struct tbl *vp;
 438         long *nump;
 439 {
 440         register char *s;
 441         register int c;
 442         int base, neg;
 443         int have_base = 0;
 444         long num;
 445
 446         if (vp->flag&SPECIAL)
 447                 getspec(vp);
 448         /* XXX is it possible for ISSET to be set and val.s to be 0? */
 449         if (!(vp->flag&ISSET) || (!(vp->flag&INTEGER) && vp->val.s == NULL))
 450                 return -1;
 451         if (vp->flag&INTEGER) {
 452                 *nump = vp->val.i;
 453                 return vp->type;
 454         }
 455         s = vp->val.s + vp->type;
 456         if (s == NULL)  /* redundant given initial test */
 457                 s = null;
 458         base = 10;
 459         num = 0;
 460         neg = 0;
 461         if (*s == '-') {
 462                 neg = 1;
 463                 s++;
 464         }
 465         if (s[0] == '0' && s[1] == 'x') {
 466                 base = 16;
 467                 have_base = 1;
 468                 s += 2;
 469         }
 470         for (c = (unsigned char)*s++; c ; c = (unsigned char)*s++) {
 471                 if (c == '#') {
 472                         base = (int) num;
 473                         if (have_base || base < 2 || base > 36)
 474                                 return -1;
 475                         num = 0;
 476                         have_base = 1;
 477                 } else if (letnum(c)) {
 478                         if (isdigit(c))
 479                                 c -= '0';
 480                         else if (islower(c))
 481                                 c -= 'a' - 10; /* todo: assumes ascii */
 482                         else if (isupper(c))
 483                                 c -= 'A' - 10; /* todo: assumes ascii */
 484                         else
 485                                 c = -1; /* _: force error */
 486                         if (c < 0 || c >= base)
 487                                 return -1;
 488                         num = num * base + c;
 489                 } else
 490                         return -1;
 491         }
 492         if (neg)
 493                 num = -num;
 494         *nump = num;
 495         return base;
 496 }
 497
 498 /* convert variable vq to integer variable, setting its value from vp
 499  * (vq and vp may be the same)
 500  */
 501 struct tbl *
 502 setint_v(vq, vp)
 503         register struct tbl *vq, *vp;
 504 {
 505         int base;
 506         long num;
 507
 508         if ((base = getint(vp, &num)) == -1)
 509                 return NULL;
 510         if (!(vq->flag & INTEGER) && (vq->flag & ALLOC)) {
 511                 vq->flag &= ~ALLOC;
 512                 afree(vq->val.s, vq->areap);
 513         }
 514         vq->val.i = num;
 515         if (vq->type == 0) /* default base */
 516                 vq->type = base;
 517         vq->flag |= ISSET|INTEGER;
 518         if (vq->flag&SPECIAL)
 519                 setspec(vq);
 520         return vq;
 521 }
 522
 523 static char *
 524 formatstr(vp, s)
 525         struct tbl *vp;
 526         const char *s;
 527 {
 528         int olen, nlen;
 529         char *p, *q;
 530
 531         olen = strlen(s);
 532
 533         if (vp->flag & (RJUST|LJUST)) {
 534                 if (!vp->u2.field)      /* default field width */
 535                         vp->u2.field = olen;
 536                 nlen = vp->u2.field;
 537         } else
 538                 nlen = olen;
 539
 540         p = (char *) alloc(nlen + 1, ATEMP);
 541         if (vp->flag & (RJUST|LJUST)) {
 542                 int slen;
 543
 544                 if (vp->flag & RJUST) {
 545                         const char *r = s + olen;
 546                         /* strip trailing spaces (at&t ksh uses q[-1] == ' ') */
 547                         while (r > s && isspace((unsigned char)r[-1]))
 548                                 --r;
 549                         slen = r - s;
 550                         if (slen > vp->u2.field) {
 551                                 s += slen - vp->u2.field;
 552                                 slen = vp->u2.field;
 553                         }
 554                         shf_snprintf(p, nlen + 1,
 555                                 ((vp->flag & ZEROFIL) && digit(*s)) ?
 556                                           "%0*s%.*s" : "%*s%.*s",
 557                                 vp->u2.field - slen, null, slen, s);
 558                 } else {
 559                         /* strip leading spaces/zeros */
 560                         while (isspace((unsigned char)*s))
 561                                 s++;
 562                         if (vp->flag & ZEROFIL)
 563                                 while (*s == '0')
 564                                         s++;
 565                         shf_snprintf(p, nlen + 1, "%-*.*s",
 566                                 vp->u2.field, vp->u2.field, s);
 567                 }
 568         } else
 569                 memcpy(p, s, olen + 1);
 570
 571         if (vp->flag & UCASEV_AL) {
 572                 for (q = p; *q; q++)
 573                         if (islower((unsigned char)*q))
 574                                 *q = toupper((unsigned char)*q);
 575         } else if (vp->flag & LCASEV) {
 576                 for (q = p; *q; q++)
 577                         if (isupper((unsigned char)*q))
 578                                 *q = tolower((unsigned char)*q);
 579         }
 580
 581         return p;
 582 }
 583
 584 /*
 585  * make vp->val.s be "name=value" for quick exporting.
 586  */
 587 static void
 588 export(vp, val)
 589         register struct tbl *vp;
 590         const char *val;
 591 {
 592         register char *xp;
 593         char *op = (vp->flag&ALLOC) ? vp->val.s : NULL;
 594         int namelen = strlen(vp->name);
 595         int vallen = strlen(val) + 1;
 596
 597         vp->flag |= ALLOC;
 598         xp = (char*)alloc(namelen + 1 + vallen, vp->areap);
 599         memcpy(vp->val.s = xp, vp->name, namelen);
 600         xp += namelen;
 601         *xp++ = '=';
 602         vp->type = xp - vp->val.s; /* offset to value */
 603         memcpy(xp, val, vallen);
 604         if (op != NULL)
 605                 afree((void*)op, vp->areap);
 606 }
 607
 608 /*
 609  * lookup variable (according to (set&LOCAL)),
 610  * set its attributes (INTEGER, RDONLY, EXPORT, TRACE, LJUST, RJUST, ZEROFIL,
 611  * LCASEV, UCASEV_AL), and optionally set its value if an assignment.
 612  */
 613 struct tbl *
 614 typeset(var, set, clr, field, base)
 615         register const char *var;
 616         Tflag clr, set;
 617         int field, base;
 618 {
 619         register struct tbl *vp;
 620         struct tbl *vpbase, *t;
 621         char *tvar;
 622         const char *val;
 623
 624         /* check for valid variable name, search for value */
 625         val = skip_varname(var, FALSE);
 626         if (val == var)
 627                 return NULL;
 628         if (*val == '[') {
 629                 int len;
 630
 631                 len = array_ref_len(val);
 632                 if (len == 0)
 633                         return NULL;
 634                 /* IMPORT is only used when the shell starts up and is
 635                  * setting up its environment.  Allow only simple array
 636                  * references at this time since parameter/command substitution
 637                  * is preformed on the [expression], which would be a major
 638                  * security hole.
 639                  */
 640                 if (set & IMPORT) {
 641                         int i;
 642                         for (i = 1; i < len - 1; i++)
 643                                 if (!digit(val[i]))
 644                                         return NULL;
 645                 }
 646                 val += len;
 647         }
 648         if (*val == '=')
 649                 tvar = str_nsave(var, val++ - var, ATEMP);
 650         else {
 651                 /* Importing from original environment: must have an = */
 652                 if (set & IMPORT)
 653                         return NULL;
 654                 tvar = (char *) __UNCONST(var);
 655                 val = NULL;
 656         }
 657
 658         /* Prevent typeset from creating a local PATH/ENV/SHELL */
 659         if (Flag(FRESTRICTED) && (strcmp(tvar, "PATH") == 0
 660                                   || strcmp(tvar, "ENV") == 0
 661                                   || strcmp(tvar, "SHELL") == 0))
 662                 errorf("%s: restricted", tvar);
 663
 664         vp = (set&LOCAL) ? local(tvar, (set & LOCAL_COPY) ? TRUE : FALSE)
 665                 : global(tvar);
 666         set &= ~(LOCAL|LOCAL_COPY);
 667
 668         vpbase = (vp->flag & ARRAY) ? global(arrayname(var)) : vp;
 669
 670         /* only allow export flag to be set.  at&t ksh allows any attribute to
 671          * be changed, which means it can be truncated or modified
 672          * (-L/-R/-Z/-i).
 673          */
 674         if ((vpbase->flag&RDONLY)
 675             && (val || clr || (set & ~EXPORT)))
 676                 /* XXX check calls - is error here ok by POSIX? */
 677                 errorf("%s: is read only", tvar);
 678         if (val)
 679                 afree(tvar, ATEMP);
 680
 681         /* most calls are with set/clr == 0 */
 682         if (set | clr) {
 683                 int ok = 1;
 684                 /* XXX if x[0] isn't set, there will be problems: need to have
 685                  * one copy of attributes for arrays...
 686                  */
 687                 for (t = vpbase; t; t = t->u.array) {
 688                         int fake_assign;
 689                         char UNINITIALIZED(*s);
 690                         char UNINITIALIZED(*free_me);
 691
 692                         fake_assign = (t->flag & ISSET) && (!val || t != vp)
 693                                       && ((set & (UCASEV_AL|LCASEV|LJUST|RJUST|ZEROFIL))
 694                                           || ((t->flag & INTEGER) && (clr & INTEGER))
 695                                           || (!(t->flag & INTEGER) && (set & INTEGER)));
 696                         if (fake_assign) {
 697                                 if (t->flag & INTEGER) {
 698                                         s = str_val(t);
 699                                         free_me = (char *) 0;
 700                                 } else {
 701                                         s = t->val.s + t->type;
 702                                         free_me = (t->flag & ALLOC) ? t->val.s
 703                                                                   : (char *) 0;
 704                                 }
 705                                 t->flag &= ~ALLOC;
 706                         }
 707                         if (!(t->flag & INTEGER) && (set & INTEGER)) {
 708                                 t->type = 0;
 709                                 t->flag &= ~ALLOC;
 710                         }
 711                         t->flag = (t->flag | set) & ~clr;
 712                         /* Don't change base if assignment is to be done,
 713                          * in case assignment fails.
 714                          */
 715                         if ((set & INTEGER) && base > 0 && (!val || t != vp))
 716                                 t->type = base;
 717                         if (set & (LJUST|RJUST|ZEROFIL))
 718                                 t->u2.field = field;
 719                         if (fake_assign) {
 720                                 if (!setstr(t, s, KSH_RETURN_ERROR)) {
 721                                         /* Somewhat arbitrary action here:
 722                                          * zap contents of variable, but keep
 723                                          * the flag settings.
 724                                          */
 725                                         ok = 0;
 726                                         if (t->flag & INTEGER)
 727                                                 t->flag &= ~ISSET;
 728                                         else {
 729                                                 if (t->flag & ALLOC)
 730                                                         afree((void*) t->val.s,
 731                                                               t->areap);
 732                                                 t->flag &= ~(ISSET|ALLOC);
 733                                                 t->type = 0;
 734                                         }
 735                                 }
 736                                 if (free_me)
 737                                         afree((void *) free_me, t->areap);
 738                         }
 739                 }
 740                 if (!ok)
 741                     errorf(null);
 742         }
 743
 744         if (val != NULL) {
 745                 if (vp->flag&INTEGER) {
 746                         /* do not zero base before assignment */
 747                         setstr(vp, val, KSH_UNWIND_ERROR | 0x4);
 748                         /* Done after assignment to override default */
 749                         if (base > 0)
 750                                 vp->type = base;
 751                 } else
 752                         /* setstr can't fail (readonly check already done) */
 753                         setstr(vp, val, KSH_RETURN_ERROR | 0x4);
 754         }
 755
 756         /* only x[0] is ever exported, so use vpbase */
 757         if ((vpbase->flag&EXPORT) && !(vpbase->flag&INTEGER)
 758             && vpbase->type == 0)
 759                 export(vpbase, (vpbase->flag&ISSET) ? vpbase->val.s : null);
 760
 761         return vp;
 762 }
 763
 764 /* Unset a variable.  array_ref is set if there was an array reference in
 765  * the name lookup (eg, x[2]).
 766  */
 767 void
 768 unset(vp, array_ref)
 769         register struct tbl *vp;
 770         int array_ref;
 771 {
 772         if (vp->flag & ALLOC)
 773                 afree((void*)vp->val.s, vp->areap);
 774         if ((vp->flag & ARRAY) && !array_ref) {
 775                 struct tbl *a, *tmp;
 776
 777                 /* Free up entire array */
 778                 for (a = vp->u.array; a; ) {
 779                         tmp = a;
 780                         a = a->u.array;
 781                         if (tmp->flag & ALLOC)
 782                                 afree((void *) tmp->val.s, tmp->areap);
 783                         afree(tmp, tmp->areap);
 784                 }
 785                 vp->u.array = (struct tbl *) 0;
 786         }
 787         /* If foo[0] is being unset, the remainder of the array is kept... */
 788         vp->flag &= SPECIAL | (array_ref ? ARRAY|DEFINED : 0);
 789         if (vp->flag & SPECIAL)
 790                 unsetspec(vp);  /* responsible for `unspecial'ing var */
 791 }
 792
 793 /* return a pointer to the first char past a legal variable name (returns the
 794  * argument if there is no legal name, returns * a pointer to the terminating
 795  * null if whole string is legal).
 796  */
 797 char *
 798 skip_varname(s, aok)
 799         const char *s;
 800         int aok;
 801 {
 802         int alen;
 803
 804         if (s && letter(*s)) {
 805                 while (*++s && letnum(*s))
 806                         ;
 807                 if (aok && *s == '[' && (alen = array_ref_len(s)))
 808                         s += alen;
 809         }
 810         return (char *) __UNCONST(s);
 811 }
 812
 813 /* Return a pointer to the first character past any legal variable name.  */
 814 char *
 815 skip_wdvarname(s, aok)
 816         const char *s;
 817         int aok;        /* skip array de-reference? */
 818 {
 819         if (s[0] == CHAR && letter(s[1])) {
 820                 do
 821                         s += 2;
 822                 while (s[0] == CHAR && letnum(s[1]));
 823                 if (aok && s[0] == CHAR && s[1] == '[') {
 824                         /* skip possible array de-reference */
 825                         const char *p = s;
 826                         char c;
 827                         int depth = 0;
 828
 829                         while (1) {
 830                                 if (p[0] != CHAR)
 831                                         break;
 832                                 c = p[1];
 833                                 p += 2;
 834                                 if (c == '[')
 835                                         depth++;
 836                                 else if (c == ']' && --depth == 0) {
 837                                         s = p;
 838                                         break;
 839                                 }
 840                         }
 841                 }
 842         }
 843         return (char *) __UNCONST(s);
 844 }
 845
 846 /* Check if coded string s is a variable name */
 847 int
 848 is_wdvarname(s, aok)
 849         const char *s;
 850         int aok;
 851 {
 852         char *p = skip_wdvarname(s, aok);
 853
 854         return p != s && p[0] == EOS;
 855 }
 856
 857 /* Check if coded string s is a variable assignment */
 858 int
 859 is_wdvarassign(s)
 860         const char *s;
 861 {
 862         char *p = skip_wdvarname(s, TRUE);
 863
 864         return p != s && p[0] == CHAR && p[1] == '=';
 865 }
 866
 867 /*
 868  * Make the exported environment from the exported names in the dictionary.
 869  */
 870 char **
 871 makenv()
 872 {
 873         struct block *l = e->loc;
 874         XPtrV env;
 875         register struct tbl *vp, **vpp;
 876         register int i;
 877
 878         XPinit(env, 64);
 879         for (l = e->loc; l != NULL; l = l->next)
 880                 for (vpp = l->vars.tbls, i = l->vars.size; --i >= 0; )
 881                         if ((vp = *vpp++) != NULL
 882                             && (vp->flag&(ISSET|EXPORT)) == (ISSET|EXPORT)) {
 883                                 register struct block *l2;
 884                                 register struct tbl *vp2;
 885                                 unsigned h = hash(vp->name);
 886
 887                                 /* unexport any redefined instances */
 888                                 for (l2 = l->next; l2 != NULL; l2 = l2->next) {
 889                                         vp2 = tsearch(&l2->vars, vp->name, h);
 890                                         if (vp2 != NULL)
 891                                                 vp2->flag &= ~EXPORT;
 892                                 }
 893                                 if ((vp->flag&INTEGER)) {
 894                                         /* integer to string */
 895                                         char *val;
 896                                         val = str_val(vp);
 897                                         vp->flag &= ~(INTEGER|RDONLY);
 898                                         /* setstr can't fail here */
 899                                         setstr(vp, val, KSH_RETURN_ERROR);
 900                                 }
 901                                 XPput(env, vp->val.s);
 902                         }
 903         XPput(env, NULL);
 904         return (char **) XPclose(env);
 905 }
 906
 907 /*
 908  * Called after a fork in parent to bump the random number generator.
 909  * Done to ensure children will not get the same random number sequence
 910  * if the parent doesn't use $RANDOM.
 911  */
 912 void
 913 change_random()
 914 {
 915     rand();
 916 }
 917
 918 /*
 919  * handle special variables with side effects - PATH, SECONDS.
 920  */
 921
 922 /* Test if name is a special parameter */
 923 static int
 924 special(name)
 925         register const char * name;
 926 {
 927         register struct tbl *tp;
 928
 929         tp = tsearch(&specials, name, hash(name));
 930         return tp && (tp->flag & ISSET) ? tp->type : V_NONE;
 931 }
 932
 933 /* Make a variable non-special */
 934 static void
 935 unspecial(name)
 936         register const char * name;
 937 {
 938         register struct tbl *tp;
 939
 940         tp = tsearch(&specials, name, hash(name));
 941         if (tp)
 942                 tdelete(tp);
 943 }
 944
 945 #ifdef KSH
 946 static  time_t  seconds;                /* time SECONDS last set */
 947 #endif /* KSH */
 948 static  int     user_lineno;            /* what user set $LINENO to */
 949
 950 static void
 951 getspec(vp)
 952         register struct tbl *vp;
 953 {
 954         switch (special(vp->name)) {
 955 #ifdef KSH
 956           case V_SECONDS:
 957                 vp->flag &= ~SPECIAL;
 958                 /* On start up the value of SECONDS is used before seconds
 959                  * has been set - don't do anything in this case
 960                  * (see initcoms[] in main.c).
 961                  */
 962                 if (vp->flag & ISSET)
 963                         setint(vp, (long) (time((time_t *)0) - seconds));
 964                 vp->flag |= SPECIAL;
 965                 break;
 966           case V_RANDOM:
 967                 vp->flag &= ~SPECIAL;
 968                 setint(vp, (long) (rand() & 0x7fff));
 969                 vp->flag |= SPECIAL;
 970                 break;
 971 #endif /* KSH */
 972 #ifdef HISTORY
 973           case V_HISTSIZE:
 974                 vp->flag &= ~SPECIAL;
 975                 setint(vp, (long) histsize);
 976                 vp->flag |= SPECIAL;
 977                 break;
 978 #endif /* HISTORY */
 979           case V_OPTIND:
 980                 vp->flag &= ~SPECIAL;
 981                 setint(vp, (long) user_opt.uoptind);
 982                 vp->flag |= SPECIAL;
 983                 break;
 984           case V_LINENO:
 985                 vp->flag &= ~SPECIAL;
 986                 setint(vp, (long) current_lineno + user_lineno);
 987                 vp->flag |= SPECIAL;
 988                 break;
 989         }
 990 }
 991
 992 static void
 993 setspec(vp)
 994         register struct tbl *vp;
 995 {
 996         char *s;
 997
 998         switch (special(vp->name)) {
 999           case V_PATH:
1000                 if (path)
1001                         afree(path, APERM);
1002                 path = str_save(str_val(vp), APERM);
1003                 flushcom(1);    /* clear tracked aliases */
1004                 break;
1005           case V_IFS:
1006                 setctypes(s = str_val(vp), C_IFS);
1007                 ifs0 = *s;
1008                 break;
1009           case V_OPTIND:
1010                 vp->flag &= ~SPECIAL;
1011                 getopts_reset((int) intval(vp));
1012                 vp->flag |= SPECIAL;
1013                 break;
1014           case V_POSIXLY_CORRECT:
1015                 change_flag(FPOSIX, OF_SPECIAL, 1);
1016                 break;
1017           case V_TMPDIR:
1018                 if (tmpdir) {
1019                         afree(tmpdir, APERM);
1020                         tmpdir = (char *) 0;
1021                 }
1022                 /* Use tmpdir iff it is an absolute path, is writable and
1023                  * searchable and is a directory...
1024                  */
1025                 {
1026                         struct stat statb;
1027                         s = str_val(vp);
1028                         if (ISABSPATH(s) && eaccess(s, W_OK|X_OK) == 0
1029                             && stat(s, &statb) == 0 && S_ISDIR(statb.st_mode))
1030                                 tmpdir = str_save(s, APERM);
1031                 }
1032                 break;
1033 #ifdef HISTORY
1034           case V_HISTSIZE:
1035                 vp->flag &= ~SPECIAL;
1036                 sethistsize((int) intval(vp));
1037                 vp->flag |= SPECIAL;
1038                 break;
1039           case V_HISTFILE:
1040                 sethistfile(str_val(vp));
1041                 break;
1042 #endif /* HISTORY */
1043 #ifdef EDIT
1044           case V_VISUAL:
1045                 set_editmode(str_val(vp));
1046                 break;
1047           case V_EDITOR:
1048                 if (!(global("VISUAL")->flag & ISSET))
1049                         set_editmode(str_val(vp));
1050                 break;
1051           case V_COLUMNS:
1052                 if ((x_cols = intval(vp)) <= MIN_COLS)
1053                         x_cols = MIN_COLS;
1054                 break;
1055 #endif /* EDIT */
1056 #ifdef KSH
1057           case V_MAIL:
1058                 mbset(str_val(vp));
1059                 break;
1060           case V_MAILPATH:
1061                 mpset(str_val(vp));
1062                 break;
1063           case V_MAILCHECK:
1064                 vp->flag &= ~SPECIAL;
1065                 mcset(intval(vp));
1066                 vp->flag |= SPECIAL;
1067                 break;
1068           case V_RANDOM:
1069                 vp->flag &= ~SPECIAL;
1070                 srand((unsigned int)intval(vp));
1071                 vp->flag |= SPECIAL;
1072                 break;
1073           case V_SECONDS:
1074                 vp->flag &= ~SPECIAL;
1075                 seconds = time((time_t*) 0) - intval(vp);
1076                 vp->flag |= SPECIAL;
1077                 break;
1078           case V_TMOUT:
1079                 /* at&t ksh seems to do this (only listen if integer) */
1080                 if (vp->flag & INTEGER)
1081                         ksh_tmout = vp->val.i >= 0 ? vp->val.i : 0;
1082                 break;
1083 #endif /* KSH */
1084           case V_LINENO:
1085                 vp->flag &= ~SPECIAL;
1086                 /* The -1 is because line numbering starts at 1. */
1087                 user_lineno = (unsigned int) intval(vp) - current_lineno - 1;
1088                 vp->flag |= SPECIAL;
1089                 break;
1090         }
1091 }
1092
1093 static void
1094 unsetspec(vp)
1095         register struct tbl *vp;
1096 {
1097         switch (special(vp->name)) {
1098           case V_PATH:
1099                 if (path)
1100                         afree(path, APERM);
1101                 path = str_save(def_path, APERM);
1102                 flushcom(1);    /* clear tracked aliases */
1103                 break;
1104           case V_IFS:
1105                 setctypes(" \t\n", C_IFS);
1106                 ifs0 = ' ';
1107                 break;
1108           case V_TMPDIR:
1109                 /* should not become unspecial */
1110                 if (tmpdir) {
1111                         afree(tmpdir, APERM);
1112                         tmpdir = (char *) 0;
1113                 }
1114                 break;
1115 #ifdef KSH
1116           case V_MAIL:
1117                 mbset((char *) 0);
1118                 break;
1119           case V_MAILPATH:
1120                 mpset((char *) 0);
1121                 break;
1122 #endif /* KSH */
1123
1124           case V_LINENO:
1125 #ifdef KSH
1126           case V_MAILCHECK:     /* at&t ksh leaves previous value in place */
1127           case V_RANDOM:
1128           case V_SECONDS:
1129           case V_TMOUT:         /* at&t ksh leaves previous value in place */
1130 #endif /* KSH */
1131                 unspecial(vp->name);
1132                 break;
1133
1134           /* at&t ksh man page says OPTIND, OPTARG and _ lose special meaning,
1135            * but OPTARG does not (still set by getopts) and _ is also still
1136            * set in various places.
1137            * Don't know what at&t does for:
1138            *            MAIL, MAILPATH, HISTSIZE, HISTFILE,
1139            * Unsetting these in at&t ksh does not loose the `specialness':
1140            *    no effect: IFS, COLUMNS, PATH, TMPDIR,
1141            *            VISUAL, EDITOR,
1142            * pdkshisms: no effect:
1143            *            POSIXLY_CORRECT (use set +o posix instead)
1144            */
1145         }
1146 }
1147
1148 /*
1149  * Search for (and possibly create) a table entry starting with
1150  * vp, indexed by val.
1151  */
1152 static struct tbl *
1153 arraysearch(vp, val)
1154         struct tbl *vp;
1155         int val;
1156 {
1157         struct tbl *prev, *curr, *new;
1158         size_t namelen = strlen(vp->name) + 1;
1159
1160         vp->flag |= ARRAY|DEFINED;
1161
1162         /* The table entry is always [0] */
1163         if (val == 0) {
1164                 vp->index = 0;
1165                 return vp;
1166         }
1167         prev = vp;
1168         curr = vp->u.array;
1169         while (curr && curr->index < val) {
1170                 prev = curr;
1171                 curr = curr->u.array;
1172         }
1173         if (curr && curr->index == val) {
1174                 if (curr->flag&ISSET)
1175                         return curr;
1176                 else
1177                         new = curr;
1178         } else
1179                 new = (struct tbl *)alloc(sizeof(struct tbl) + namelen,
1180                     vp->areap);
1181         strlcpy(new->name, vp->name, namelen);
1182         new->flag = vp->flag & ~(ALLOC|DEFINED|ISSET|SPECIAL);
1183         new->type = vp->type;
1184         new->areap = vp->areap;
1185         new->u2.field = vp->u2.field;
1186         new->index = val;
1187         if (curr != new) {              /* not reusing old array entry */
1188                 prev->u.array = new;
1189                 new->u.array = curr;
1190         }
1191         return new;
1192 }
1193
1194 /* Return the length of an array reference (eg, [1+2]) - cp is assumed
1195  * to point to the open bracket.  Returns 0 if there is no matching closing
1196  * bracket.
1197  */
1198 int
1199 array_ref_len(cp)
1200         const char *cp;
1201 {
1202         const char *s = cp;
1203         int c;
1204         int depth = 0;
1205
1206         while ((c = *s++) && (c != ']' || --depth))
1207                 if (c == '[')
1208                         depth++;
1209         if (!c)
1210                 return 0;
1211         return s - cp;
1212 }
1213
1214 /*
1215  * Make a copy of the base of an array name
1216  */
1217 char *
1218 arrayname(str)
1219         const char *str;
1220 {
1221         const char *p;
1222
1223         if ((p = strchr(str, '[')) == 0)
1224                 /* Shouldn't happen, but why worry? */
1225                 return (char *) __UNCONST(str);
1226
1227         return str_nsave(str, p - str, ATEMP);
1228 }
1229
1230 /* Set (or overwrite, if !reset) the array variable var to the values in vals.
1231  */
1232 void
1233 set_array(var, reset, vals)
1234         const char *var;
1235         int reset;
1236         char **vals;
1237 {
1238         struct tbl *vp, *vq;
1239         int i;
1240
1241         /* to get local array, use "typeset foo; set -A foo" */
1242         vp = global(var);
1243
1244         /* Note: at&t ksh allows set -A but not set +A of a read-only var */
1245         if ((vp->flag&RDONLY))
1246                 errorf("%s: is read only", var);
1247         /* This code is quite non-optimal */
1248         if (reset > 0)
1249                 /* trash existing values and attributes */
1250                 unset(vp, 0);
1251         /* todo: would be nice for assignment to completely succeed or
1252          * completely fail.  Only really effects integer arrays:
1253          * evaluation of some of vals[] may fail...
1254          */
1255         for (i = 0; vals[i]; i++) {
1256                 vq = arraysearch(vp, i);
1257                 /* would be nice to deal with errors here... (see above) */
1258                 setstr(vq, vals[i], KSH_RETURN_ERROR);
1259         }
1260 }