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 /* Unit number to be assigned when NEWUNIT is used in an OPEN statement. */
75 #define GFC_FIRST_NEWUNIT -10
76 static GFC_INTEGER_4 next_available_newunit = GFC_FIRST_NEWUNIT;
79 static gfc_unit *unit_cache[CACHE_SIZE];
80 gfc_offset max_offset;
82 #ifdef __GTHREAD_MUTEX_INIT
83 __gthread_mutex_t unit_lock = __GTHREAD_MUTEX_INIT;
85 __gthread_mutex_t unit_lock;
88 /* We use these filenames for error reporting. */
90 static char stdin_name[] = "stdin";
91 static char stdout_name[] = "stdout";
92 static char stderr_name[] = "stderr";
94 /* This implementation is based on Stefan Nilsson's article in the
95 * July 1997 Doctor Dobb's Journal, "Treaps in Java". */
97 /* pseudo_random()-- Simple linear congruential pseudorandom number
98 * generator. The period of this generator is 44071, which is plenty
99 * for our purposes. */
104 static int x0 = 5341;
106 x0 = (22611 * x0 + 10) % 44071;
111 /* rotate_left()-- Rotate the treap left */
114 rotate_left (gfc_unit * t)
119 t->right = t->right->left;
126 /* rotate_right()-- Rotate the treap right */
129 rotate_right (gfc_unit * t)
134 t->left = t->left->right;
142 compare (int a, int b)
153 /* insert()-- Recursive insertion function. Returns the updated treap. */
156 insert (gfc_unit *new, gfc_unit *t)
163 c = compare (new->unit_number, t->unit_number);
167 t->left = insert (new, t->left);
168 if (t->priority < t->left->priority)
169 t = rotate_right (t);
174 t->right = insert (new, t->right);
175 if (t->priority < t->right->priority)
180 internal_error (NULL, "insert(): Duplicate key found!");
186 /* insert_unit()-- Create a new node, insert it into the treap. */
191 gfc_unit *u = get_mem (sizeof (gfc_unit));
192 memset (u, '\0', sizeof (gfc_unit));
194 #ifdef __GTHREAD_MUTEX_INIT
196 __gthread_mutex_t tmp = __GTHREAD_MUTEX_INIT;
200 __GTHREAD_MUTEX_INIT_FUNCTION (&u->lock);
202 __gthread_mutex_lock (&u->lock);
203 u->priority = pseudo_random ();
204 unit_root = insert (u, unit_root);
209 /* destroy_unit_mutex()-- Destroy the mutex and free memory of unit. */
212 destroy_unit_mutex (gfc_unit * u)
214 __gthread_mutex_destroy (&u->lock);
220 delete_root (gfc_unit * t)
226 if (t->right == NULL)
229 if (t->left->priority > t->right->priority)
231 temp = rotate_right (t);
232 temp->right = delete_root (t);
236 temp = rotate_left (t);
237 temp->left = delete_root (t);
244 /* delete_treap()-- Delete an element from a tree. The 'old' value
245 * does not necessarily have to point to the element to be deleted, it
246 * must just point to a treap structure with the key to be deleted.
247 * Returns the new root node of the tree. */
250 delete_treap (gfc_unit * old, gfc_unit * t)
257 c = compare (old->unit_number, t->unit_number);
260 t->left = delete_treap (old, t->left);
262 t->right = delete_treap (old, t->right);
270 /* delete_unit()-- Delete a unit from a tree */
273 delete_unit (gfc_unit * old)
275 unit_root = delete_treap (old, unit_root);
279 /* get_external_unit()-- Given an integer, return a pointer to the unit
280 * structure. Returns NULL if the unit does not exist,
281 * otherwise returns a locked unit. */
284 get_external_unit (int n, int do_create)
289 __gthread_mutex_lock (&unit_lock);
291 for (c = 0; c < CACHE_SIZE; c++)
292 if (unit_cache[c] != NULL && unit_cache[c]->unit_number == n)
301 c = compare (n, p->unit_number);
310 if (p == NULL && do_create)
318 for (c = 0; c < CACHE_SIZE - 1; c++)
319 unit_cache[c] = unit_cache[c + 1];
321 unit_cache[CACHE_SIZE - 1] = p;
326 /* Newly created units have their lock held already
327 from insert_unit. Just unlock UNIT_LOCK and return. */
328 __gthread_mutex_unlock (&unit_lock);
336 if (! __gthread_mutex_trylock (&p->lock))
338 /* assert (p->closed == 0); */
339 __gthread_mutex_unlock (&unit_lock);
343 inc_waiting_locked (p);
346 __gthread_mutex_unlock (&unit_lock);
350 __gthread_mutex_lock (&p->lock);
353 __gthread_mutex_lock (&unit_lock);
354 __gthread_mutex_unlock (&p->lock);
355 if (predec_waiting_locked (p) == 0)
356 destroy_unit_mutex (p);
360 dec_waiting_unlocked (p);
369 return get_external_unit (n, 0);
374 find_or_create_unit (int n)
376 return get_external_unit (n, 1);
381 get_internal_unit (st_parameter_dt *dtp)
384 gfc_offset start_record = 0;
386 /* Allocate memory for a unit structure. */
388 iunit = get_mem (sizeof (gfc_unit));
391 generate_error (&dtp->common, LIBERROR_INTERNAL_UNIT, NULL);
395 memset (iunit, '\0', sizeof (gfc_unit));
396 #ifdef __GTHREAD_MUTEX_INIT
398 __gthread_mutex_t tmp = __GTHREAD_MUTEX_INIT;
402 __GTHREAD_MUTEX_INIT_FUNCTION (&iunit->lock);
404 __gthread_mutex_lock (&iunit->lock);
406 iunit->recl = dtp->internal_unit_len;
408 /* For internal units we set the unit number to -1.
409 Otherwise internal units can be mistaken for a pre-connected unit or
410 some other file I/O unit. */
411 iunit->unit_number = -1;
413 /* Set up the looping specification from the array descriptor, if any. */
415 if (is_array_io (dtp))
417 iunit->rank = GFC_DESCRIPTOR_RANK (dtp->internal_unit_desc);
418 iunit->ls = (array_loop_spec *)
419 get_mem (iunit->rank * sizeof (array_loop_spec));
420 dtp->internal_unit_len *=
421 init_loop_spec (dtp->internal_unit_desc, iunit->ls, &start_record);
423 start_record *= iunit->recl;
426 /* Set initial values for unit parameters. */
427 if (dtp->common.unit)
429 iunit->s = open_internal4 (dtp->internal_unit - start_record,
430 dtp->internal_unit_len, -start_record);
431 fbuf_init (iunit, 256);
434 iunit->s = open_internal (dtp->internal_unit - start_record,
435 dtp->internal_unit_len, -start_record);
437 iunit->bytes_left = iunit->recl;
438 iunit->last_record=0;
440 iunit->current_record=0;
442 iunit->endfile = NO_ENDFILE;
444 /* Set flags for the internal unit. */
446 iunit->flags.access = ACCESS_SEQUENTIAL;
447 iunit->flags.action = ACTION_READWRITE;
448 iunit->flags.blank = BLANK_NULL;
449 iunit->flags.form = FORM_FORMATTED;
450 iunit->flags.pad = PAD_YES;
451 iunit->flags.status = STATUS_UNSPECIFIED;
452 iunit->flags.sign = SIGN_SUPPRESS;
453 iunit->flags.decimal = DECIMAL_POINT;
454 iunit->flags.encoding = ENCODING_DEFAULT;
455 iunit->flags.async = ASYNC_NO;
456 iunit->flags.round = ROUND_COMPATIBLE;
458 /* Initialize the data transfer parameters. */
460 dtp->u.p.advance_status = ADVANCE_YES;
461 dtp->u.p.seen_dollar = 0;
463 dtp->u.p.pending_spaces = 0;
464 dtp->u.p.max_pos = 0;
467 /* This flag tells us the unit is assigned to internal I/O. */
469 dtp->u.p.unit_is_internal = 1;
475 /* free_internal_unit()-- Free memory allocated for internal units if any. */
477 free_internal_unit (st_parameter_dt *dtp)
479 if (!is_internal_unit (dtp))
482 if (unlikely (is_char4_unit (dtp)))
483 fbuf_destroy (dtp->u.p.current_unit);
485 if (dtp->u.p.current_unit != NULL)
487 free (dtp->u.p.current_unit->ls);
489 free (dtp->u.p.current_unit->s);
491 destroy_unit_mutex (dtp->u.p.current_unit);
497 /* get_unit()-- Returns the unit structure associated with the integer
498 unit or the internal file. */
501 get_unit (st_parameter_dt *dtp, int do_create)
504 if ((dtp->common.flags & IOPARM_DT_HAS_INTERNAL_UNIT) != 0)
505 return get_internal_unit (dtp);
507 /* Has to be an external unit. */
509 dtp->u.p.unit_is_internal = 0;
510 dtp->internal_unit_desc = NULL;
512 return get_external_unit (dtp->common.unit, do_create);
516 /*************************/
517 /* Initialize everything. */
525 #ifndef __GTHREAD_MUTEX_INIT
526 __GTHREAD_MUTEX_INIT_FUNCTION (&unit_lock);
529 if (options.stdin_unit >= 0)
531 u = insert_unit (options.stdin_unit);
532 u->s = input_stream ();
534 u->flags.action = ACTION_READ;
536 u->flags.access = ACCESS_SEQUENTIAL;
537 u->flags.form = FORM_FORMATTED;
538 u->flags.status = STATUS_OLD;
539 u->flags.blank = BLANK_NULL;
540 u->flags.pad = PAD_YES;
541 u->flags.position = POSITION_ASIS;
542 u->flags.sign = SIGN_SUPPRESS;
543 u->flags.decimal = DECIMAL_POINT;
544 u->flags.encoding = ENCODING_DEFAULT;
545 u->flags.async = ASYNC_NO;
546 u->flags.round = ROUND_COMPATIBLE;
548 u->recl = options.default_recl;
549 u->endfile = NO_ENDFILE;
551 u->file_len = strlen (stdin_name);
552 u->file = get_mem (u->file_len);
553 memmove (u->file, stdin_name, u->file_len);
557 __gthread_mutex_unlock (&u->lock);
560 if (options.stdout_unit >= 0)
562 u = insert_unit (options.stdout_unit);
563 u->s = output_stream ();
565 u->flags.action = ACTION_WRITE;
567 u->flags.access = ACCESS_SEQUENTIAL;
568 u->flags.form = FORM_FORMATTED;
569 u->flags.status = STATUS_OLD;
570 u->flags.blank = BLANK_NULL;
571 u->flags.position = POSITION_ASIS;
572 u->flags.sign = SIGN_SUPPRESS;
573 u->flags.decimal = DECIMAL_POINT;
574 u->flags.encoding = ENCODING_DEFAULT;
575 u->flags.async = ASYNC_NO;
576 u->flags.round = ROUND_COMPATIBLE;
578 u->recl = options.default_recl;
579 u->endfile = AT_ENDFILE;
581 u->file_len = strlen (stdout_name);
582 u->file = get_mem (u->file_len);
583 memmove (u->file, stdout_name, u->file_len);
587 __gthread_mutex_unlock (&u->lock);
590 if (options.stderr_unit >= 0)
592 u = insert_unit (options.stderr_unit);
593 u->s = error_stream ();
595 u->flags.action = ACTION_WRITE;
597 u->flags.access = ACCESS_SEQUENTIAL;
598 u->flags.form = FORM_FORMATTED;
599 u->flags.status = STATUS_OLD;
600 u->flags.blank = BLANK_NULL;
601 u->flags.position = POSITION_ASIS;
602 u->flags.sign = SIGN_SUPPRESS;
603 u->flags.decimal = DECIMAL_POINT;
604 u->flags.encoding = ENCODING_DEFAULT;
605 u->flags.async = ASYNC_NO;
606 u->flags.round = ROUND_COMPATIBLE;
608 u->recl = options.default_recl;
609 u->endfile = AT_ENDFILE;
611 u->file_len = strlen (stderr_name);
612 u->file = get_mem (u->file_len);
613 memmove (u->file, stderr_name, u->file_len);
615 fbuf_init (u, 256); /* 256 bytes should be enough, probably not doing
616 any kind of exotic formatting to stderr. */
618 __gthread_mutex_unlock (&u->lock);
621 /* Calculate the maximum file offset in a portable manner.
622 max will be the largest signed number for the type gfc_offset.
623 set a 1 in the LSB and keep a running sum, stopping at MSB-1 bit. */
625 for (i = 0; i < sizeof (max_offset) * 8 - 1; i++)
626 max_offset = max_offset + ((gfc_offset) 1 << i);
631 close_unit_1 (gfc_unit *u, int locked)
635 /* If there are previously written bytes from a write with ADVANCE="no"
636 Reposition the buffer before closing. */
637 if (u->previous_nonadvancing_write)
638 finish_last_advance_record (u);
640 rc = (u->s == NULL) ? 0 : sclose (u->s) == -1;
644 __gthread_mutex_lock (&unit_lock);
646 for (i = 0; i < CACHE_SIZE; i++)
647 if (unit_cache[i] == u)
648 unit_cache[i] = NULL;
656 free_format_hash_table (u);
660 __gthread_mutex_unlock (&u->lock);
662 /* If there are any threads waiting in find_unit for this unit,
663 avoid freeing the memory, the last such thread will free it
666 destroy_unit_mutex (u);
669 __gthread_mutex_unlock (&unit_lock);
675 unlock_unit (gfc_unit *u)
677 __gthread_mutex_unlock (&u->lock);
680 /* close_unit()-- Close a unit. The stream is closed, and any memory
681 associated with the stream is freed. Returns nonzero on I/O error.
682 Should be called with the u->lock locked. */
685 close_unit (gfc_unit *u)
687 return close_unit_1 (u, 0);
691 /* close_units()-- Delete units on completion. We just keep deleting
692 the root of the treap until there is nothing left.
693 Not sure what to do with locking here. Some other thread might be
694 holding some unit's lock and perhaps hold it indefinitely
695 (e.g. waiting for input from some pipe) and close_units shouldn't
696 delay the program too much. */
701 __gthread_mutex_lock (&unit_lock);
702 while (unit_root != NULL)
703 close_unit_1 (unit_root, 1);
704 __gthread_mutex_unlock (&unit_lock);
708 /* High level interface to truncate a file, i.e. flush format buffers,
709 and generate an error or set some flags. Just like POSIX
710 ftruncate, returns 0 on success, -1 on failure. */
713 unit_truncate (gfc_unit * u, gfc_offset pos, st_parameter_common * common)
717 /* Make sure format buffer is flushed. */
718 if (u->flags.form == FORM_FORMATTED)
720 if (u->mode == READING)
721 pos += fbuf_reset (u);
723 fbuf_flush (u, u->mode);
726 /* struncate() should flush the stream buffer if necessary, so don't
727 bother calling sflush() here. */
728 ret = struncate (u->s, pos);
731 generate_error (common, LIBERROR_OS, NULL);
734 u->endfile = AT_ENDFILE;
735 u->flags.position = POSITION_APPEND;
742 /* filename_from_unit()-- If the unit_number exists, return a pointer to the
743 name of the associated file, otherwise return the empty string. The caller
744 must free memory allocated for the filename string. */
747 filename_from_unit (int n)
757 c = compare (n, u->unit_number);
766 /* Get the filename. */
769 filename = (char *) get_mem (u->file_len + 1);
770 unpack_filename (filename, u->file, u->file_len);
774 return (char *) NULL;
778 finish_last_advance_record (gfc_unit *u)
781 if (u->saved_pos > 0)
782 fbuf_seek (u, u->saved_pos, SEEK_CUR);
784 if (!(u->unit_number == options.stdout_unit
785 || u->unit_number == options.stderr_unit))
792 char *p = fbuf_alloc (u, len);
794 os_error ("Completing record after ADVANCE_NO failed");
801 fbuf_flush (u, u->mode);
804 /* Assign a negative number for NEWUNIT in OPEN statements. */
806 get_unique_unit_number (st_parameter_open *opp)
810 #ifdef HAVE_SYNC_FETCH_AND_ADD
811 num = __sync_fetch_and_add (&next_available_newunit, -1);
813 __gthread_mutex_lock (&unit_lock);
814 num = next_available_newunit--;
815 __gthread_mutex_unlock (&unit_lock);
818 /* Do not allow NEWUNIT numbers to wrap. */
819 if (num > GFC_FIRST_NEWUNIT )
821 generate_error (&opp->common, LIBERROR_INTERNAL, "NEWUNIT exhausted");