1 /* Copyright (C) 2002, 2003, 2005, 2007, 2008, 2009, 2010
2 Free Software Foundation, Inc.
3 Contributed by Andy Vaught
4 F2003 I/O support contributed by Jerry DeLisle
6 This file is part of the GNU Fortran runtime library (libgfortran).
8 Libgfortran is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
13 Libgfortran is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 Under Section 7 of GPL version 3, you are granted additional
19 permissions described in the GCC Runtime Library Exception, version
20 3.1, as published by the Free Software Foundation.
22 You should have received a copy of the GNU General Public License and
23 a copy of the GCC Runtime Library Exception along with this program;
24 see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
25 <http://www.gnu.org/licenses/>. */
36 UNIT_LOCK is a master lock, protecting UNIT_ROOT tree and UNIT_CACHE.
37 Concurrent use of different units should be supported, so
38 each unit has its own lock, LOCK.
39 Open should be atomic with its reopening of units and list_read.c
40 in several places needs find_unit another unit while holding stdin
41 unit's lock, so it must be possible to acquire UNIT_LOCK while holding
42 some unit's lock. Therefore to avoid deadlocks, it is forbidden
43 to acquire unit's private locks while holding UNIT_LOCK, except
44 for freshly created units (where no other thread can get at their
45 address yet) or when using just trylock rather than lock operation.
46 In addition to unit's private lock each unit has a WAITERS counter
47 and CLOSED flag. WAITERS counter must be either only
48 atomically incremented/decremented in all places (if atomic builtins
49 are supported), or protected by UNIT_LOCK in all places (otherwise).
50 CLOSED flag must be always protected by unit's LOCK.
51 After finding a unit in UNIT_CACHE or UNIT_ROOT with UNIT_LOCK held,
52 WAITERS must be incremented to avoid concurrent close from freeing
53 the unit between unlocking UNIT_LOCK and acquiring unit's LOCK.
54 Unit freeing is always done under UNIT_LOCK. If close_unit sees any
55 WAITERS, it doesn't free the unit but instead sets the CLOSED flag
56 and the thread that decrements WAITERS to zero while CLOSED flag is
57 set is responsible for freeing it (while holding UNIT_LOCK).
58 flush_all_units operation is iterating over the unit tree with
59 increasing UNIT_NUMBER while holding UNIT_LOCK and attempting to
60 flush each unit (and therefore needs the unit's LOCK held as well).
61 To avoid deadlocks, it just trylocks the LOCK and if unsuccessful,
62 remembers the current unit's UNIT_NUMBER, unlocks UNIT_LOCK, acquires
63 unit's LOCK and after flushing reacquires UNIT_LOCK and restarts with
64 the smallest UNIT_NUMBER above the last one flushed.
66 If find_unit/find_or_create_unit/find_file/get_unit routines return
67 non-NULL, the returned unit has its private lock locked and when the
68 caller is done with it, it must call either unlock_unit or close_unit
69 on it. unlock_unit or close_unit must be always called only with the
72 /* Subroutines related to units */
74 GFC_INTEGER_4 next_available_newunit;
75 #define GFC_FIRST_NEWUNIT -10
78 static gfc_unit *unit_cache[CACHE_SIZE];
79 gfc_offset max_offset;
81 #ifdef __GTHREAD_MUTEX_INIT
82 __gthread_mutex_t unit_lock = __GTHREAD_MUTEX_INIT;
84 __gthread_mutex_t unit_lock;
87 /* We use these filenames for error reporting. */
89 static char stdin_name[] = "stdin";
90 static char stdout_name[] = "stdout";
91 static char stderr_name[] = "stderr";
93 /* This implementation is based on Stefan Nilsson's article in the
94 * July 1997 Doctor Dobb's Journal, "Treaps in Java". */
96 /* pseudo_random()-- Simple linear congruential pseudorandom number
97 * generator. The period of this generator is 44071, which is plenty
98 * for our purposes. */
103 static int x0 = 5341;
105 x0 = (22611 * x0 + 10) % 44071;
110 /* rotate_left()-- Rotate the treap left */
113 rotate_left (gfc_unit * t)
118 t->right = t->right->left;
125 /* rotate_right()-- Rotate the treap right */
128 rotate_right (gfc_unit * t)
133 t->left = t->left->right;
141 compare (int a, int b)
152 /* insert()-- Recursive insertion function. Returns the updated treap. */
155 insert (gfc_unit *new, gfc_unit *t)
162 c = compare (new->unit_number, t->unit_number);
166 t->left = insert (new, t->left);
167 if (t->priority < t->left->priority)
168 t = rotate_right (t);
173 t->right = insert (new, t->right);
174 if (t->priority < t->right->priority)
179 internal_error (NULL, "insert(): Duplicate key found!");
185 /* insert_unit()-- Create a new node, insert it into the treap. */
190 gfc_unit *u = get_mem (sizeof (gfc_unit));
191 memset (u, '\0', sizeof (gfc_unit));
193 #ifdef __GTHREAD_MUTEX_INIT
195 __gthread_mutex_t tmp = __GTHREAD_MUTEX_INIT;
199 __GTHREAD_MUTEX_INIT_FUNCTION (&u->lock);
201 __gthread_mutex_lock (&u->lock);
202 u->priority = pseudo_random ();
203 unit_root = insert (u, unit_root);
208 /* destroy_unit_mutex()-- Destroy the mutex and free memory of unit. */
211 destroy_unit_mutex (gfc_unit * u)
213 __gthread_mutex_destroy (&u->lock);
219 delete_root (gfc_unit * t)
225 if (t->right == NULL)
228 if (t->left->priority > t->right->priority)
230 temp = rotate_right (t);
231 temp->right = delete_root (t);
235 temp = rotate_left (t);
236 temp->left = delete_root (t);
243 /* delete_treap()-- Delete an element from a tree. The 'old' value
244 * does not necessarily have to point to the element to be deleted, it
245 * must just point to a treap structure with the key to be deleted.
246 * Returns the new root node of the tree. */
249 delete_treap (gfc_unit * old, gfc_unit * t)
256 c = compare (old->unit_number, t->unit_number);
259 t->left = delete_treap (old, t->left);
261 t->right = delete_treap (old, t->right);
269 /* delete_unit()-- Delete a unit from a tree */
272 delete_unit (gfc_unit * old)
274 unit_root = delete_treap (old, unit_root);
278 /* get_external_unit()-- Given an integer, return a pointer to the unit
279 * structure. Returns NULL if the unit does not exist,
280 * otherwise returns a locked unit. */
283 get_external_unit (int n, int do_create)
288 __gthread_mutex_lock (&unit_lock);
290 for (c = 0; c < CACHE_SIZE; c++)
291 if (unit_cache[c] != NULL && unit_cache[c]->unit_number == n)
300 c = compare (n, p->unit_number);
309 if (p == NULL && do_create)
317 for (c = 0; c < CACHE_SIZE - 1; c++)
318 unit_cache[c] = unit_cache[c + 1];
320 unit_cache[CACHE_SIZE - 1] = p;
325 /* Newly created units have their lock held already
326 from insert_unit. Just unlock UNIT_LOCK and return. */
327 __gthread_mutex_unlock (&unit_lock);
335 if (! __gthread_mutex_trylock (&p->lock))
337 /* assert (p->closed == 0); */
338 __gthread_mutex_unlock (&unit_lock);
342 inc_waiting_locked (p);
345 __gthread_mutex_unlock (&unit_lock);
349 __gthread_mutex_lock (&p->lock);
352 __gthread_mutex_lock (&unit_lock);
353 __gthread_mutex_unlock (&p->lock);
354 if (predec_waiting_locked (p) == 0)
355 destroy_unit_mutex (p);
359 dec_waiting_unlocked (p);
368 return get_external_unit (n, 0);
373 find_or_create_unit (int n)
375 return get_external_unit (n, 1);
380 get_internal_unit (st_parameter_dt *dtp)
383 gfc_offset start_record = 0;
385 /* Allocate memory for a unit structure. */
387 iunit = get_mem (sizeof (gfc_unit));
390 generate_error (&dtp->common, LIBERROR_INTERNAL_UNIT, NULL);
394 memset (iunit, '\0', sizeof (gfc_unit));
395 #ifdef __GTHREAD_MUTEX_INIT
397 __gthread_mutex_t tmp = __GTHREAD_MUTEX_INIT;
401 __GTHREAD_MUTEX_INIT_FUNCTION (&iunit->lock);
403 __gthread_mutex_lock (&iunit->lock);
405 iunit->recl = dtp->internal_unit_len;
407 /* For internal units we set the unit number to -1.
408 Otherwise internal units can be mistaken for a pre-connected unit or
409 some other file I/O unit. */
410 iunit->unit_number = -1;
412 /* Set up the looping specification from the array descriptor, if any. */
414 if (is_array_io (dtp))
416 iunit->rank = GFC_DESCRIPTOR_RANK (dtp->internal_unit_desc);
417 iunit->ls = (array_loop_spec *)
418 get_mem (iunit->rank * sizeof (array_loop_spec));
419 dtp->internal_unit_len *=
420 init_loop_spec (dtp->internal_unit_desc, iunit->ls, &start_record);
422 start_record *= iunit->recl;
425 /* Set initial values for unit parameters. */
426 if (dtp->common.unit)
428 iunit->s = open_internal4 (dtp->internal_unit - start_record,
429 dtp->internal_unit_len, -start_record);
430 fbuf_init (iunit, 256);
433 iunit->s = open_internal (dtp->internal_unit - start_record,
434 dtp->internal_unit_len, -start_record);
436 iunit->bytes_left = iunit->recl;
437 iunit->last_record=0;
439 iunit->current_record=0;
441 iunit->endfile = NO_ENDFILE;
443 /* Set flags for the internal unit. */
445 iunit->flags.access = ACCESS_SEQUENTIAL;
446 iunit->flags.action = ACTION_READWRITE;
447 iunit->flags.blank = BLANK_NULL;
448 iunit->flags.form = FORM_FORMATTED;
449 iunit->flags.pad = PAD_YES;
450 iunit->flags.status = STATUS_UNSPECIFIED;
451 iunit->flags.sign = SIGN_SUPPRESS;
452 iunit->flags.decimal = DECIMAL_POINT;
453 iunit->flags.encoding = ENCODING_DEFAULT;
454 iunit->flags.async = ASYNC_NO;
455 iunit->flags.round = ROUND_COMPATIBLE;
457 /* Initialize the data transfer parameters. */
459 dtp->u.p.advance_status = ADVANCE_YES;
460 dtp->u.p.seen_dollar = 0;
462 dtp->u.p.pending_spaces = 0;
463 dtp->u.p.max_pos = 0;
466 /* This flag tells us the unit is assigned to internal I/O. */
468 dtp->u.p.unit_is_internal = 1;
474 /* free_internal_unit()-- Free memory allocated for internal units if any. */
476 free_internal_unit (st_parameter_dt *dtp)
478 if (!is_internal_unit (dtp))
481 if (unlikely (is_char4_unit (dtp)))
482 fbuf_destroy (dtp->u.p.current_unit);
484 if (dtp->u.p.current_unit != NULL)
486 free (dtp->u.p.current_unit->ls);
488 free (dtp->u.p.current_unit->s);
490 destroy_unit_mutex (dtp->u.p.current_unit);
496 /* get_unit()-- Returns the unit structure associated with the integer
497 unit or the internal file. */
500 get_unit (st_parameter_dt *dtp, int do_create)
503 if ((dtp->common.flags & IOPARM_DT_HAS_INTERNAL_UNIT) != 0)
504 return get_internal_unit (dtp);
506 /* Has to be an external unit. */
508 dtp->u.p.unit_is_internal = 0;
509 dtp->internal_unit_desc = NULL;
511 return get_external_unit (dtp->common.unit, do_create);
515 /*************************/
516 /* Initialize everything. */
524 #ifndef __GTHREAD_MUTEX_INIT
525 __GTHREAD_MUTEX_INIT_FUNCTION (&unit_lock);
528 next_available_newunit = GFC_FIRST_NEWUNIT;
530 if (options.stdin_unit >= 0)
532 u = insert_unit (options.stdin_unit);
533 u->s = input_stream ();
535 u->flags.action = ACTION_READ;
537 u->flags.access = ACCESS_SEQUENTIAL;
538 u->flags.form = FORM_FORMATTED;
539 u->flags.status = STATUS_OLD;
540 u->flags.blank = BLANK_NULL;
541 u->flags.pad = PAD_YES;
542 u->flags.position = POSITION_ASIS;
543 u->flags.sign = SIGN_SUPPRESS;
544 u->flags.decimal = DECIMAL_POINT;
545 u->flags.encoding = ENCODING_DEFAULT;
546 u->flags.async = ASYNC_NO;
547 u->flags.round = ROUND_COMPATIBLE;
549 u->recl = options.default_recl;
550 u->endfile = NO_ENDFILE;
552 u->file_len = strlen (stdin_name);
553 u->file = get_mem (u->file_len);
554 memmove (u->file, stdin_name, u->file_len);
558 __gthread_mutex_unlock (&u->lock);
561 if (options.stdout_unit >= 0)
563 u = insert_unit (options.stdout_unit);
564 u->s = output_stream ();
566 u->flags.action = ACTION_WRITE;
568 u->flags.access = ACCESS_SEQUENTIAL;
569 u->flags.form = FORM_FORMATTED;
570 u->flags.status = STATUS_OLD;
571 u->flags.blank = BLANK_NULL;
572 u->flags.position = POSITION_ASIS;
573 u->flags.sign = SIGN_SUPPRESS;
574 u->flags.decimal = DECIMAL_POINT;
575 u->flags.encoding = ENCODING_DEFAULT;
576 u->flags.async = ASYNC_NO;
577 u->flags.round = ROUND_COMPATIBLE;
579 u->recl = options.default_recl;
580 u->endfile = AT_ENDFILE;
582 u->file_len = strlen (stdout_name);
583 u->file = get_mem (u->file_len);
584 memmove (u->file, stdout_name, u->file_len);
588 __gthread_mutex_unlock (&u->lock);
591 if (options.stderr_unit >= 0)
593 u = insert_unit (options.stderr_unit);
594 u->s = error_stream ();
596 u->flags.action = ACTION_WRITE;
598 u->flags.access = ACCESS_SEQUENTIAL;
599 u->flags.form = FORM_FORMATTED;
600 u->flags.status = STATUS_OLD;
601 u->flags.blank = BLANK_NULL;
602 u->flags.position = POSITION_ASIS;
603 u->flags.sign = SIGN_SUPPRESS;
604 u->flags.decimal = DECIMAL_POINT;
605 u->flags.encoding = ENCODING_DEFAULT;
606 u->flags.async = ASYNC_NO;
607 u->flags.round = ROUND_COMPATIBLE;
609 u->recl = options.default_recl;
610 u->endfile = AT_ENDFILE;
612 u->file_len = strlen (stderr_name);
613 u->file = get_mem (u->file_len);
614 memmove (u->file, stderr_name, u->file_len);
616 fbuf_init (u, 256); /* 256 bytes should be enough, probably not doing
617 any kind of exotic formatting to stderr. */
619 __gthread_mutex_unlock (&u->lock);
622 /* Calculate the maximum file offset in a portable manner.
623 max will be the largest signed number for the type gfc_offset.
624 set a 1 in the LSB and keep a running sum, stopping at MSB-1 bit. */
626 for (i = 0; i < sizeof (max_offset) * 8 - 1; i++)
627 max_offset = max_offset + ((gfc_offset) 1 << i);
632 close_unit_1 (gfc_unit *u, int locked)
636 /* If there are previously written bytes from a write with ADVANCE="no"
637 Reposition the buffer before closing. */
638 if (u->previous_nonadvancing_write)
639 finish_last_advance_record (u);
641 rc = (u->s == NULL) ? 0 : sclose (u->s) == -1;
645 __gthread_mutex_lock (&unit_lock);
647 for (i = 0; i < CACHE_SIZE; i++)
648 if (unit_cache[i] == u)
649 unit_cache[i] = NULL;
657 free_format_hash_table (u);
661 __gthread_mutex_unlock (&u->lock);
663 /* If there are any threads waiting in find_unit for this unit,
664 avoid freeing the memory, the last such thread will free it
667 destroy_unit_mutex (u);
670 __gthread_mutex_unlock (&unit_lock);
676 unlock_unit (gfc_unit *u)
678 __gthread_mutex_unlock (&u->lock);
681 /* close_unit()-- Close a unit. The stream is closed, and any memory
682 associated with the stream is freed. Returns nonzero on I/O error.
683 Should be called with the u->lock locked. */
686 close_unit (gfc_unit *u)
688 return close_unit_1 (u, 0);
692 /* close_units()-- Delete units on completion. We just keep deleting
693 the root of the treap until there is nothing left.
694 Not sure what to do with locking here. Some other thread might be
695 holding some unit's lock and perhaps hold it indefinitely
696 (e.g. waiting for input from some pipe) and close_units shouldn't
697 delay the program too much. */
702 __gthread_mutex_lock (&unit_lock);
703 while (unit_root != NULL)
704 close_unit_1 (unit_root, 1);
705 __gthread_mutex_unlock (&unit_lock);
709 /* High level interface to truncate a file, i.e. flush format buffers,
710 and generate an error or set some flags. Just like POSIX
711 ftruncate, returns 0 on success, -1 on failure. */
714 unit_truncate (gfc_unit * u, gfc_offset pos, st_parameter_common * common)
718 /* Make sure format buffer is flushed. */
719 if (u->flags.form == FORM_FORMATTED)
721 if (u->mode == READING)
722 pos += fbuf_reset (u);
724 fbuf_flush (u, u->mode);
727 /* struncate() should flush the stream buffer if necessary, so don't
728 bother calling sflush() here. */
729 ret = struncate (u->s, pos);
732 generate_error (common, LIBERROR_OS, NULL);
735 u->endfile = AT_ENDFILE;
736 u->flags.position = POSITION_APPEND;
743 /* filename_from_unit()-- If the unit_number exists, return a pointer to the
744 name of the associated file, otherwise return the empty string. The caller
745 must free memory allocated for the filename string. */
748 filename_from_unit (int n)
758 c = compare (n, u->unit_number);
767 /* Get the filename. */
770 filename = (char *) get_mem (u->file_len + 1);
771 unpack_filename (filename, u->file, u->file_len);
775 return (char *) NULL;
779 finish_last_advance_record (gfc_unit *u)
782 if (u->saved_pos > 0)
783 fbuf_seek (u, u->saved_pos, SEEK_CUR);
785 if (!(u->unit_number == options.stdout_unit
786 || u->unit_number == options.stderr_unit))
793 char *p = fbuf_alloc (u, len);
795 os_error ("Completing record after ADVANCE_NO failed");
802 fbuf_flush (u, u->mode);
805 /* Assign a negative number for NEWUNIT in OPEN statements. */
807 get_unique_unit_number (st_parameter_open *opp)
811 __gthread_mutex_lock (&unit_lock);
812 num = next_available_newunit--;
814 /* Do not allow NEWUNIT numbers to wrap. */
815 if (next_available_newunit >= GFC_FIRST_NEWUNIT )
817 __gthread_mutex_unlock (&unit_lock);
818 generate_error (&opp->common, LIBERROR_INTERNAL, "NEWUNIT exhausted");
821 __gthread_mutex_unlock (&unit_lock);