libgfortran/io/unit.c

   1 /* Copyright (C) 2002-2017 Free Software Foundation, Inc.
   2    Contributed by Andy Vaught
   3    F2003 I/O support contributed by Jerry DeLisle
   4
   5 This file is part of the GNU Fortran runtime library (libgfortran).
   6
   7 Libgfortran 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 3, or (at your option)
  10 any later version.
  11
  12 Libgfortran 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 Under Section 7 of GPL version 3, you are granted additional
  18 permissions described in the GCC Runtime Library Exception, version
  19 3.1, as published by the Free Software Foundation.
  20
  21 You should have received a copy of the GNU General Public License and
  22 a copy of the GCC Runtime Library Exception along with this program;
  23 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  24 <http://www.gnu.org/licenses/>.  */
  25
  26 #include "io.h"
  27 #include "fbuf.h"
  28 #include "format.h"
  29 #include "unix.h"
  30 #include <string.h>
  31 #include <assert.h>
  32
  33
  34 /* IO locking rules:
  35    UNIT_LOCK is a master lock, protecting UNIT_ROOT tree and UNIT_CACHE.
  36    Concurrent use of different units should be supported, so
  37    each unit has its own lock, LOCK.
  38    Open should be atomic with its reopening of units and list_read.c
  39    in several places needs find_unit another unit while holding stdin
  40    unit's lock, so it must be possible to acquire UNIT_LOCK while holding
  41    some unit's lock.  Therefore to avoid deadlocks, it is forbidden
  42    to acquire unit's private locks while holding UNIT_LOCK, except
  43    for freshly created units (where no other thread can get at their
  44    address yet) or when using just trylock rather than lock operation.
  45    In addition to unit's private lock each unit has a WAITERS counter
  46    and CLOSED flag.  WAITERS counter must be either only
  47    atomically incremented/decremented in all places (if atomic builtins
  48    are supported), or protected by UNIT_LOCK in all places (otherwise).
  49    CLOSED flag must be always protected by unit's LOCK.
  50    After finding a unit in UNIT_CACHE or UNIT_ROOT with UNIT_LOCK held,
  51    WAITERS must be incremented to avoid concurrent close from freeing
  52    the unit between unlocking UNIT_LOCK and acquiring unit's LOCK.
  53    Unit freeing is always done under UNIT_LOCK.  If close_unit sees any
  54    WAITERS, it doesn't free the unit but instead sets the CLOSED flag
  55    and the thread that decrements WAITERS to zero while CLOSED flag is
  56    set is responsible for freeing it (while holding UNIT_LOCK).
  57    flush_all_units operation is iterating over the unit tree with
  58    increasing UNIT_NUMBER while holding UNIT_LOCK and attempting to
  59    flush each unit (and therefore needs the unit's LOCK held as well).
  60    To avoid deadlocks, it just trylocks the LOCK and if unsuccessful,
  61    remembers the current unit's UNIT_NUMBER, unlocks UNIT_LOCK, acquires
  62    unit's LOCK and after flushing reacquires UNIT_LOCK and restarts with
  63    the smallest UNIT_NUMBER above the last one flushed.
  64
  65    If find_unit/find_or_create_unit/find_file/get_unit routines return
  66    non-NULL, the returned unit has its private lock locked and when the
  67    caller is done with it, it must call either unlock_unit or close_unit
  68    on it.  unlock_unit or close_unit must be always called only with the
  69    private lock held.  */
  70
  71
  72
  73 /* Table of allocated newunit values.  A simple solution would be to
  74    map OS file descriptors (fd's) to unit numbers, e.g. with newunit =
  75    -fd - 2, however that doesn't work since Fortran allows an existing
  76    unit number to be reassociated with a new file. Thus the simple
  77    approach may lead to a situation where we'd try to assign a
  78    (negative) unit number which already exists. Hence we must keep
  79    track of allocated newunit values ourselves. This is the purpose of
  80    the newunits array. The indices map to newunit values as newunit =
  81    -index + NEWUNIT_FIRST. E.g. newunits[0] having the value true
  82    means that a unit with number NEWUNIT_FIRST exists. Similar to
  83    POSIX file descriptors, we always allocate the lowest (in absolute
  84    value) available unit number.
  85  */
  86 static bool *newunits;
  87 static int newunit_size; /* Total number of elements in the newunits array.  */
  88 /* Low water indicator for the newunits array. Below the LWI all the
  89    units are allocated, above and equal to the LWI there may be both
  90    allocated and free units. */
  91 static int newunit_lwi;
  92 static void newunit_free (int);
  93
  94 /* Unit numbers assigned with NEWUNIT start from here.  */
  95 #define NEWUNIT_START -10
  96
  97
  98 #define NEWUNIT_STACK_SIZE 16
  99
 100 /* A stack to save previously used newunit-assigned unit numbers to
 101    allow them to be reused without reallocating the gfc_unit structure
 102    which is still in the treap.  */
 103 static gfc_saved_unit newunit_stack[NEWUNIT_STACK_SIZE];
 104 static int newunit_tos = 0; /* Index to Top of Stack.  */
 105
 106
 107 #define CACHE_SIZE 3
 108 static gfc_unit *unit_cache[CACHE_SIZE];
 109 gfc_offset max_offset;
 110 gfc_unit *unit_root;
 111 #ifdef __GTHREAD_MUTEX_INIT
 112 __gthread_mutex_t unit_lock = __GTHREAD_MUTEX_INIT;
 113 #else
 114 __gthread_mutex_t unit_lock;
 115 #endif
 116
 117 /* We use these filenames for error reporting.  */
 118
 119 static char stdin_name[] = "stdin";
 120 static char stdout_name[] = "stdout";
 121 static char stderr_name[] = "stderr";
 122
 123
 124 #ifdef HAVE_NEWLOCALE
 125 locale_t c_locale;
 126 #else
 127 /* If we don't have POSIX 2008 per-thread locales, we need to use the
 128    traditional setlocale().  To prevent multiple concurrent threads
 129    doing formatted I/O from messing up the locale, we need to store a
 130    global old_locale, and a counter keeping track of how many threads
 131    are currently doing formatted I/O.  The first thread saves the old
 132    locale, and the last one restores it.  */
 133 char *old_locale;
 134 int old_locale_ctr;
 135 #ifdef __GTHREAD_MUTEX_INIT
 136 __gthread_mutex_t old_locale_lock = __GTHREAD_MUTEX_INIT;
 137 #else
 138 __gthread_mutex_t old_locale_lock;
 139 #endif
 140 #endif
 141
 142
 143 /* This implementation is based on Stefan Nilsson's article in the
 144  * July 1997 Doctor Dobb's Journal, "Treaps in Java". */
 145
 146 /* pseudo_random()-- Simple linear congruential pseudorandom number
 147  * generator.  The period of this generator is 44071, which is plenty
 148  * for our purposes.  */
 149
 150 static int
 151 pseudo_random (void)
 152 {
 153   static int x0 = 5341;
 154
 155   x0 = (22611 * x0 + 10) % 44071;
 156   return x0;
 157 }
 158
 159
 160 /* rotate_left()-- Rotate the treap left */
 161
 162 static gfc_unit *
 163 rotate_left (gfc_unit * t)
 164 {
 165   gfc_unit *temp;
 166
 167   temp = t->right;
 168   t->right = t->right->left;
 169   temp->left = t;
 170
 171   return temp;
 172 }
 173
 174
 175 /* rotate_right()-- Rotate the treap right */
 176
 177 static gfc_unit *
 178 rotate_right (gfc_unit * t)
 179 {
 180   gfc_unit *temp;
 181
 182   temp = t->left;
 183   t->left = t->left->right;
 184   temp->right = t;
 185
 186   return temp;
 187 }
 188
 189
 190 static int
 191 compare (int a, int b)
 192 {
 193   if (a < b)
 194     return -1;
 195   if (a > b)
 196     return 1;
 197
 198   return 0;
 199 }
 200
 201
 202 /* insert()-- Recursive insertion function.  Returns the updated treap. */
 203
 204 static gfc_unit *
 205 insert (gfc_unit *new, gfc_unit *t)
 206 {
 207   int c;
 208
 209   if (t == NULL)
 210     return new;
 211
 212   c = compare (new->unit_number, t->unit_number);
 213
 214   if (c < 0)
 215     {
 216       t->left = insert (new, t->left);
 217       if (t->priority < t->left->priority)
 218         t = rotate_right (t);
 219     }
 220
 221   if (c > 0)
 222     {
 223       t->right = insert (new, t->right);
 224       if (t->priority < t->right->priority)
 225         t = rotate_left (t);
 226     }
 227
 228   if (c == 0)
 229     internal_error (NULL, "insert(): Duplicate key found!");
 230
 231   return t;
 232 }
 233
 234
 235 /* insert_unit()-- Create a new node, insert it into the treap.  */
 236
 237 static gfc_unit *
 238 insert_unit (int n)
 239 {
 240   gfc_unit *u = xcalloc (1, sizeof (gfc_unit));
 241   u->unit_number = n;
 242 #ifdef __GTHREAD_MUTEX_INIT
 243   {
 244     __gthread_mutex_t tmp = __GTHREAD_MUTEX_INIT;
 245     u->lock = tmp;
 246   }
 247 #else
 248   __GTHREAD_MUTEX_INIT_FUNCTION (&u->lock);
 249 #endif
 250   __gthread_mutex_lock (&u->lock);
 251   u->priority = pseudo_random ();
 252   unit_root = insert (u, unit_root);
 253   return u;
 254 }
 255
 256
 257 /* destroy_unit_mutex()-- Destroy the mutex and free memory of unit.  */
 258
 259 static void
 260 destroy_unit_mutex (gfc_unit * u)
 261 {
 262   __gthread_mutex_destroy (&u->lock);
 263   free (u);
 264 }
 265
 266
 267 static gfc_unit *
 268 delete_root (gfc_unit * t)
 269 {
 270   gfc_unit *temp;
 271
 272   if (t->left == NULL)
 273     return t->right;
 274   if (t->right == NULL)
 275     return t->left;
 276
 277   if (t->left->priority > t->right->priority)
 278     {
 279       temp = rotate_right (t);
 280       temp->right = delete_root (t);
 281     }
 282   else
 283     {
 284       temp = rotate_left (t);
 285       temp->left = delete_root (t);
 286     }
 287
 288   return temp;
 289 }
 290
 291
 292 /* delete_treap()-- Delete an element from a tree.  The 'old' value
 293  * does not necessarily have to point to the element to be deleted, it
 294  * must just point to a treap structure with the key to be deleted.
 295  * Returns the new root node of the tree. */
 296
 297 static gfc_unit *
 298 delete_treap (gfc_unit * old, gfc_unit * t)
 299 {
 300   int c;
 301
 302   if (t == NULL)
 303     return NULL;
 304
 305   c = compare (old->unit_number, t->unit_number);
 306
 307   if (c < 0)
 308     t->left = delete_treap (old, t->left);
 309   if (c > 0)
 310     t->right = delete_treap (old, t->right);
 311   if (c == 0)
 312     t = delete_root (t);
 313
 314   return t;
 315 }
 316
 317
 318 /* delete_unit()-- Delete a unit from a tree */
 319
 320 static void
 321 delete_unit (gfc_unit * old)
 322 {
 323   unit_root = delete_treap (old, unit_root);
 324 }
 325
 326
 327 /* get_gfc_unit()-- Given an integer, return a pointer to the unit
 328  * structure.  Returns NULL if the unit does not exist,
 329  * otherwise returns a locked unit. */
 330
 331 static gfc_unit *
 332 get_gfc_unit (int n, int do_create)
 333 {
 334   gfc_unit *p;
 335   int c, created = 0;
 336
 337   __gthread_mutex_lock (&unit_lock);
 338 retry:
 339   for (c = 0; c < CACHE_SIZE; c++)
 340     if (unit_cache[c] != NULL && unit_cache[c]->unit_number == n)
 341       {
 342         p = unit_cache[c];
 343         goto found;
 344       }
 345
 346   p = unit_root;
 347   while (p != NULL)
 348     {
 349       c = compare (n, p->unit_number);
 350       if (c < 0)
 351         p = p->left;
 352       if (c > 0)
 353         p = p->right;
 354       if (c == 0)
 355         break;
 356     }
 357
 358   if (p == NULL && do_create)
 359     {
 360       p = insert_unit (n);
 361       created = 1;
 362     }
 363
 364   if (p != NULL)
 365     {
 366       for (c = 0; c < CACHE_SIZE - 1; c++)
 367         unit_cache[c] = unit_cache[c + 1];
 368
 369       unit_cache[CACHE_SIZE - 1] = p;
 370     }
 371
 372   if (created)
 373     {
 374       /* Newly created units have their lock held already
 375          from insert_unit.  Just unlock UNIT_LOCK and return.  */
 376       __gthread_mutex_unlock (&unit_lock);
 377       return p;
 378     }
 379
 380 found:
 381   if (p != NULL && (p->child_dtio == 0))
 382     {
 383       /* Fast path.  */
 384       if (! __gthread_mutex_trylock (&p->lock))
 385         {
 386           /* assert (p->closed == 0); */
 387           __gthread_mutex_unlock (&unit_lock);
 388           return p;
 389         }
 390
 391       inc_waiting_locked (p);
 392     }
 393
 394
 395   __gthread_mutex_unlock (&unit_lock);
 396
 397   if (p != NULL && (p->child_dtio == 0))
 398     {
 399       __gthread_mutex_lock (&p->lock);
 400       if (p->closed)
 401         {
 402           __gthread_mutex_lock (&unit_lock);
 403           __gthread_mutex_unlock (&p->lock);
 404           if (predec_waiting_locked (p) == 0)
 405             destroy_unit_mutex (p);
 406           goto retry;
 407         }
 408
 409       dec_waiting_unlocked (p);
 410     }
 411   return p;
 412 }
 413
 414
 415 gfc_unit *
 416 find_unit (int n)
 417 {
 418   return get_gfc_unit (n, 0);
 419 }
 420
 421
 422 gfc_unit *
 423 find_or_create_unit (int n)
 424 {
 425   return get_gfc_unit (n, 1);
 426 }
 427
 428
 429 /* Helper function to check rank, stride, format string, and namelist.
 430    This is used for optimization. You can't trim out blanks or shorten
 431    the string if trailing spaces are significant.  */
 432 static bool
 433 is_trim_ok (st_parameter_dt *dtp)
 434 {
 435   /* Check rank and stride.  */
 436   if (dtp->internal_unit_desc)
 437     return false;
 438   /* Format strings can not have 'BZ' or '/'.  */
 439   if (dtp->common.flags & IOPARM_DT_HAS_FORMAT)
 440     {
 441       char *p = dtp->format;
 442       off_t i;
 443       if (dtp->common.flags & IOPARM_DT_HAS_BLANK)
 444         return false;
 445       for (i = 0; i < dtp->format_len; i++)
 446         {
 447           if (p[i] == '/') return false;
 448           if (p[i] == 'b' || p[i] == 'B')
 449             if (p[i+1] == 'z' || p[i+1] == 'Z')
 450               return false;
 451         }
 452     }
 453   if (dtp->u.p.ionml) /* A namelist.  */
 454     return false;
 455   return true;
 456 }
 457
 458
 459 gfc_unit *
 460 set_internal_unit (st_parameter_dt *dtp, gfc_unit *iunit, int kind)
 461 {
 462   gfc_offset start_record = 0;
 463
 464   iunit->recl = dtp->internal_unit_len;
 465   iunit->internal_unit = dtp->internal_unit;
 466   iunit->internal_unit_len = dtp->internal_unit_len;
 467   iunit->internal_unit_kind = kind;
 468
 469   /* As an optimization, adjust the unit record length to not
 470      include trailing blanks. This will not work under certain conditions
 471      where trailing blanks have significance.  */
 472   if (dtp->u.p.mode == READING && is_trim_ok (dtp))
 473     {
 474       int len;
 475       if (kind == 1)
 476           len = string_len_trim (iunit->internal_unit_len,
 477                                                    iunit->internal_unit);
 478       else
 479           len = string_len_trim_char4 (iunit->internal_unit_len,
 480                               (const gfc_char4_t*) iunit->internal_unit);
 481       iunit->internal_unit_len = len;
 482       iunit->recl = iunit->internal_unit_len;
 483     }
 484
 485   /* Set up the looping specification from the array descriptor, if any.  */
 486
 487   if (is_array_io (dtp))
 488     {
 489       iunit->rank = GFC_DESCRIPTOR_RANK (dtp->internal_unit_desc);
 490       iunit->ls = (array_loop_spec *)
 491         xmallocarray (iunit->rank, sizeof (array_loop_spec));
 492       iunit->internal_unit_len *=
 493         init_loop_spec (dtp->internal_unit_desc, iunit->ls, &start_record);
 494
 495       start_record *= iunit->recl;
 496     }
 497
 498   /* Set initial values for unit parameters.  */
 499   if (kind == 4)
 500     iunit->s = open_internal4 (iunit->internal_unit - start_record,
 501                                  iunit->internal_unit_len, -start_record);
 502   else
 503     iunit->s = open_internal (iunit->internal_unit - start_record,
 504                               iunit->internal_unit_len, -start_record);
 505
 506   iunit->bytes_left = iunit->recl;
 507   iunit->last_record=0;
 508   iunit->maxrec=0;
 509   iunit->current_record=0;
 510   iunit->read_bad = 0;
 511   iunit->endfile = NO_ENDFILE;
 512
 513   /* Set flags for the internal unit.  */
 514
 515   iunit->flags.access = ACCESS_SEQUENTIAL;
 516   iunit->flags.action = ACTION_READWRITE;
 517   iunit->flags.blank = BLANK_NULL;
 518   iunit->flags.form = FORM_FORMATTED;
 519   iunit->flags.pad = PAD_YES;
 520   iunit->flags.status = STATUS_UNSPECIFIED;
 521   iunit->flags.sign = SIGN_UNSPECIFIED;
 522   iunit->flags.decimal = DECIMAL_POINT;
 523   iunit->flags.delim = DELIM_UNSPECIFIED;
 524   iunit->flags.encoding = ENCODING_DEFAULT;
 525   iunit->flags.async = ASYNC_NO;
 526   iunit->flags.round = ROUND_UNSPECIFIED;
 527
 528   /* Initialize the data transfer parameters.  */
 529
 530   dtp->u.p.advance_status = ADVANCE_YES;
 531   dtp->u.p.seen_dollar = 0;
 532   dtp->u.p.skips = 0;
 533   dtp->u.p.pending_spaces = 0;
 534   dtp->u.p.max_pos = 0;
 535   dtp->u.p.at_eof = 0;
 536   return iunit;
 537 }
 538
 539
 540 /* stash_internal_unit()-- Push the internal unit number onto the
 541    avaialble stack.  */
 542 void
 543 stash_internal_unit (st_parameter_dt *dtp)
 544 {
 545   __gthread_mutex_lock (&unit_lock);
 546   newunit_tos++;
 547   if (newunit_tos >= NEWUNIT_STACK_SIZE)
 548     internal_error (&dtp->common, "stash_internal_unit(): Stack Size Exceeded");
 549   newunit_stack[newunit_tos].unit_number = dtp->common.unit;
 550   newunit_stack[newunit_tos].unit = dtp->u.p.current_unit;
 551   __gthread_mutex_unlock (&unit_lock);
 552 }
 553
 554
 555
 556 /* get_unit()-- Returns the unit structure associated with the integer
 557    unit or the internal file.  */
 558
 559 gfc_unit *
 560 get_unit (st_parameter_dt *dtp, int do_create)
 561 {
 562   gfc_unit * unit;
 563
 564   if ((dtp->common.flags & IOPARM_DT_HAS_INTERNAL_UNIT) != 0)
 565     {
 566       int kind;
 567       if (dtp->common.unit == GFC_INTERNAL_UNIT)
 568         kind = 1;
 569       else if (dtp->common.unit == GFC_INTERNAL_UNIT4)
 570         kind = 4;
 571       else
 572         internal_error (&dtp->common, "get_unit(): Bad internal unit KIND");
 573
 574       if ((dtp->common.flags & IOPARM_DT_HAS_UDTIO) != 0)
 575         {
 576           dtp->u.p.unit_is_internal = 1;
 577           dtp->common.unit = newunit_alloc ();
 578           unit = get_gfc_unit (dtp->common.unit, do_create);
 579           set_internal_unit (dtp, unit, kind);
 580           fbuf_init (unit, 128);
 581           return unit;
 582         }
 583       else
 584         {
 585           if (newunit_tos)
 586             {
 587               dtp->common.unit = newunit_stack[newunit_tos].unit_number;
 588               unit = newunit_stack[newunit_tos--].unit;
 589               unit->fbuf->act = unit->fbuf->pos = 0;
 590             }
 591           else
 592             {
 593               dtp->common.unit = newunit_alloc ();
 594               unit = xcalloc (1, sizeof (gfc_unit));
 595               fbuf_init (unit, 128);
 596             }
 597           set_internal_unit (dtp, unit, kind);
 598           return unit;
 599         }
 600     }
 601   /* Has to be an external unit.  */
 602   dtp->u.p.unit_is_internal = 0;
 603   dtp->internal_unit = NULL;
 604   dtp->internal_unit_desc = NULL;
 605   /* For an external unit with unit number < 0 creating it on the fly
 606      is not allowed, such units must be created with
 607      OPEN(NEWUNIT=...).  */
 608   if (dtp->common.unit < 0)
 609     return get_gfc_unit (dtp->common.unit, 0);
 610   return get_gfc_unit (dtp->common.unit, do_create);
 611 }
 612
 613
 614 /*************************/
 615 /* Initialize everything.  */
 616
 617 void
 618 init_units (void)
 619 {
 620   gfc_unit *u;
 621   unsigned int i;
 622
 623 #ifdef HAVE_NEWLOCALE
 624   c_locale = newlocale (0, "C", 0);
 625 #else
 626 #ifndef __GTHREAD_MUTEX_INIT
 627   __GTHREAD_MUTEX_INIT_FUNCTION (&old_locale_lock);
 628 #endif
 629 #endif
 630
 631 #ifndef __GTHREAD_MUTEX_INIT
 632   __GTHREAD_MUTEX_INIT_FUNCTION (&unit_lock);
 633 #endif
 634
 635   if (options.stdin_unit >= 0)
 636     {                           /* STDIN */
 637       u = insert_unit (options.stdin_unit);
 638       u->s = input_stream ();
 639
 640       u->flags.action = ACTION_READ;
 641
 642       u->flags.access = ACCESS_SEQUENTIAL;
 643       u->flags.form = FORM_FORMATTED;
 644       u->flags.status = STATUS_OLD;
 645       u->flags.blank = BLANK_NULL;
 646       u->flags.pad = PAD_YES;
 647       u->flags.position = POSITION_ASIS;
 648       u->flags.sign = SIGN_UNSPECIFIED;
 649       u->flags.decimal = DECIMAL_POINT;
 650       u->flags.delim = DELIM_UNSPECIFIED;
 651       u->flags.encoding = ENCODING_DEFAULT;
 652       u->flags.async = ASYNC_NO;
 653       u->flags.round = ROUND_UNSPECIFIED;
 654       u->flags.share = SHARE_UNSPECIFIED;
 655       u->flags.cc = CC_LIST;
 656
 657       u->recl = options.default_recl;
 658       u->endfile = NO_ENDFILE;
 659
 660       u->filename = strdup (stdin_name);
 661
 662       fbuf_init (u, 0);
 663
 664       __gthread_mutex_unlock (&u->lock);
 665     }
 666
 667   if (options.stdout_unit >= 0)
 668     {                           /* STDOUT */
 669       u = insert_unit (options.stdout_unit);
 670       u->s = output_stream ();
 671
 672       u->flags.action = ACTION_WRITE;
 673
 674       u->flags.access = ACCESS_SEQUENTIAL;
 675       u->flags.form = FORM_FORMATTED;
 676       u->flags.status = STATUS_OLD;
 677       u->flags.blank = BLANK_NULL;
 678       u->flags.position = POSITION_ASIS;
 679       u->flags.sign = SIGN_UNSPECIFIED;
 680       u->flags.decimal = DECIMAL_POINT;
 681       u->flags.delim = DELIM_UNSPECIFIED;
 682       u->flags.encoding = ENCODING_DEFAULT;
 683       u->flags.async = ASYNC_NO;
 684       u->flags.round = ROUND_UNSPECIFIED;
 685       u->flags.share = SHARE_UNSPECIFIED;
 686       u->flags.cc = CC_LIST;
 687
 688       u->recl = options.default_recl;
 689       u->endfile = AT_ENDFILE;
 690
 691       u->filename = strdup (stdout_name);
 692
 693       fbuf_init (u, 0);
 694
 695       __gthread_mutex_unlock (&u->lock);
 696     }
 697
 698   if (options.stderr_unit >= 0)
 699     {                           /* STDERR */
 700       u = insert_unit (options.stderr_unit);
 701       u->s = error_stream ();
 702
 703       u->flags.action = ACTION_WRITE;
 704
 705       u->flags.access = ACCESS_SEQUENTIAL;
 706       u->flags.form = FORM_FORMATTED;
 707       u->flags.status = STATUS_OLD;
 708       u->flags.blank = BLANK_NULL;
 709       u->flags.position = POSITION_ASIS;
 710       u->flags.sign = SIGN_UNSPECIFIED;
 711       u->flags.decimal = DECIMAL_POINT;
 712       u->flags.encoding = ENCODING_DEFAULT;
 713       u->flags.async = ASYNC_NO;
 714       u->flags.round = ROUND_UNSPECIFIED;
 715       u->flags.share = SHARE_UNSPECIFIED;
 716       u->flags.cc = CC_LIST;
 717
 718       u->recl = options.default_recl;
 719       u->endfile = AT_ENDFILE;
 720
 721       u->filename = strdup (stderr_name);
 722
 723       fbuf_init (u, 256);  /* 256 bytes should be enough, probably not doing
 724                               any kind of exotic formatting to stderr.  */
 725
 726       __gthread_mutex_unlock (&u->lock);
 727     }
 728
 729   /* Calculate the maximum file offset in a portable manner.
 730      max will be the largest signed number for the type gfc_offset.
 731      set a 1 in the LSB and keep a running sum, stopping at MSB-1 bit.  */
 732   max_offset = 0;
 733   for (i = 0; i < sizeof (max_offset) * 8 - 1; i++)
 734     max_offset = max_offset + ((gfc_offset) 1 << i);
 735
 736   /* Initialize the newunit stack.  */
 737   memset (newunit_stack, 0, NEWUNIT_STACK_SIZE * sizeof(gfc_saved_unit));
 738   newunit_tos = 0;
 739 }
 740
 741
 742 static int
 743 close_unit_1 (gfc_unit *u, int locked)
 744 {
 745   int i, rc;
 746
 747   /* If there are previously written bytes from a write with ADVANCE="no"
 748      Reposition the buffer before closing.  */
 749   if (u->previous_nonadvancing_write)
 750     finish_last_advance_record (u);
 751
 752   rc = (u->s == NULL) ? 0 : sclose (u->s) == -1;
 753
 754   u->closed = 1;
 755   if (!locked)
 756     __gthread_mutex_lock (&unit_lock);
 757
 758   for (i = 0; i < CACHE_SIZE; i++)
 759     if (unit_cache[i] == u)
 760       unit_cache[i] = NULL;
 761
 762   delete_unit (u);
 763
 764   free (u->filename);
 765   u->filename = NULL;
 766
 767   free_format_hash_table (u);
 768   fbuf_destroy (u);
 769
 770   if (u->unit_number <= NEWUNIT_START)
 771     newunit_free (u->unit_number);
 772
 773   if (!locked)
 774     __gthread_mutex_unlock (&u->lock);
 775
 776   /* If there are any threads waiting in find_unit for this unit,
 777      avoid freeing the memory, the last such thread will free it
 778      instead.  */
 779   if (u->waiting == 0)
 780     destroy_unit_mutex (u);
 781
 782   if (!locked)
 783     __gthread_mutex_unlock (&unit_lock);
 784
 785   return rc;
 786 }
 787
 788 void
 789 unlock_unit (gfc_unit *u)
 790 {
 791   __gthread_mutex_unlock (&u->lock);
 792 }
 793
 794 /* close_unit()-- Close a unit.  The stream is closed, and any memory
 795    associated with the stream is freed.  Returns nonzero on I/O error.
 796    Should be called with the u->lock locked. */
 797
 798 int
 799 close_unit (gfc_unit *u)
 800 {
 801   return close_unit_1 (u, 0);
 802 }
 803
 804
 805 /* close_units()-- Delete units on completion.  We just keep deleting
 806    the root of the treap until there is nothing left.
 807    Not sure what to do with locking here.  Some other thread might be
 808    holding some unit's lock and perhaps hold it indefinitely
 809    (e.g. waiting for input from some pipe) and close_units shouldn't
 810    delay the program too much.  */
 811
 812 void
 813 close_units (void)
 814 {
 815   __gthread_mutex_lock (&unit_lock);
 816   while (unit_root != NULL)
 817     close_unit_1 (unit_root, 1);
 818   __gthread_mutex_unlock (&unit_lock);
 819
 820   while (newunit_tos != 0)
 821     if (newunit_stack[newunit_tos].unit)
 822       {
 823         fbuf_destroy (newunit_stack[newunit_tos].unit);
 824         free (newunit_stack[newunit_tos].unit->s);
 825         free (newunit_stack[newunit_tos--].unit);
 826       }
 827
 828   free (newunits);
 829
 830 #ifdef HAVE_FREELOCALE
 831   freelocale (c_locale);
 832 #endif
 833 }
 834
 835
 836 /* High level interface to truncate a file, i.e. flush format buffers,
 837    and generate an error or set some flags.  Just like POSIX
 838    ftruncate, returns 0 on success, -1 on failure.  */
 839
 840 int
 841 unit_truncate (gfc_unit * u, gfc_offset pos, st_parameter_common * common)
 842 {
 843   int ret;
 844
 845   /* Make sure format buffer is flushed.  */
 846   if (u->flags.form == FORM_FORMATTED)
 847     {
 848       if (u->mode == READING)
 849         pos += fbuf_reset (u);
 850       else
 851         fbuf_flush (u, u->mode);
 852     }
 853
 854   /* struncate() should flush the stream buffer if necessary, so don't
 855      bother calling sflush() here.  */
 856   ret = struncate (u->s, pos);
 857
 858   if (ret != 0)
 859     generate_error (common, LIBERROR_OS, NULL);
 860   else
 861     {
 862       u->endfile = AT_ENDFILE;
 863       u->flags.position = POSITION_APPEND;
 864     }
 865
 866   return ret;
 867 }
 868
 869
 870 /* filename_from_unit()-- If the unit_number exists, return a pointer to the
 871    name of the associated file, otherwise return the empty string.  The caller
 872    must free memory allocated for the filename string.  */
 873
 874 char *
 875 filename_from_unit (int n)
 876 {
 877   gfc_unit *u;
 878   int c;
 879
 880   /* Find the unit.  */
 881   u = unit_root;
 882   while (u != NULL)
 883     {
 884       c = compare (n, u->unit_number);
 885       if (c < 0)
 886         u = u->left;
 887       if (c > 0)
 888         u = u->right;
 889       if (c == 0)
 890         break;
 891     }
 892
 893   /* Get the filename.  */
 894   if (u != NULL && u->filename != NULL)
 895     return strdup (u->filename);
 896   else
 897     return (char *) NULL;
 898 }
 899
 900 void
 901 finish_last_advance_record (gfc_unit *u)
 902 {
 903
 904   if (u->saved_pos > 0)
 905     fbuf_seek (u, u->saved_pos, SEEK_CUR);
 906
 907   if (!(u->unit_number == options.stdout_unit
 908         || u->unit_number == options.stderr_unit))
 909     {
 910 #ifdef HAVE_CRLF
 911       const int len = 2;
 912 #else
 913       const int len = 1;
 914 #endif
 915       char *p = fbuf_alloc (u, len);
 916       if (!p)
 917         os_error ("Completing record after ADVANCE_NO failed");
 918 #ifdef HAVE_CRLF
 919       *(p++) = '\r';
 920 #endif
 921       *p = '\n';
 922     }
 923
 924   fbuf_flush (u, u->mode);
 925 }
 926
 927
 928 /* Assign a negative number for NEWUNIT in OPEN statements or for
 929    internal units.  */
 930 int
 931 newunit_alloc (void)
 932 {
 933   __gthread_mutex_lock (&unit_lock);
 934   if (!newunits)
 935     {
 936       newunits = xcalloc (16, 1);
 937       newunit_size = 16;
 938     }
 939
 940   /* Search for the next available newunit.  */
 941   for (int ii = newunit_lwi; ii < newunit_size; ii++)
 942     {
 943       if (!newunits[ii])
 944         {
 945           newunits[ii] = true;
 946           newunit_lwi = ii + 1;
 947           __gthread_mutex_unlock (&unit_lock);
 948           return -ii + NEWUNIT_START;
 949         }
 950     }
 951
 952   /* Search failed, bump size of array and allocate the first
 953      available unit.  */
 954   int old_size = newunit_size;
 955   newunit_size *= 2;
 956   newunits = xrealloc (newunits, newunit_size);
 957   memset (newunits + old_size, 0, old_size);
 958   newunits[old_size] = true;
 959   newunit_lwi = old_size + 1;
 960     __gthread_mutex_unlock (&unit_lock);
 961   return -old_size + NEWUNIT_START;
 962 }
 963
 964
 965 /* Free a previously allocated newunit= unit number.  unit_lock must
 966    be held when calling.  */
 967
 968 static void
 969 newunit_free (int unit)
 970 {
 971   int ind = -unit + NEWUNIT_START;
 972   assert(ind >= 0 && ind < newunit_size);
 973   newunits[ind] = false;
 974   if (ind < newunit_lwi)
 975     newunit_lwi = ind;
 976 }