xref: /openbsd-src/usr.bin/sort/file.c (revision f2da64fbbbf1b03f09f390ab01267c93dfd77c4c) 
1 /*	$OpenBSD: file.c,v 1.20 2015/04/03 10:37:24 tobias Exp $	*/
2 
3 /*-
4  * Copyright (C) 2009 Gabor Kovesdan <gabor@FreeBSD.org>
5  * Copyright (C) 2012 Oleg Moskalenko <mom040267@gmail.com>
6  * All rights reserved.
7  *
8  * Redistribution and use in source and binary forms, with or without
9  * modification, are permitted provided that the following conditions
10  * are met:
11  * 1. Redistributions of source code must retain the above copyright
12  *    notice, this list of conditions and the following disclaimer.
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27  * SUCH DAMAGE.
28  */
29 
30 #include <sys/mman.h>
31 #include <sys/stat.h>
32 #include <sys/types.h>
33 #include <sys/queue.h>
34 
35 #include <err.h>
36 #include <fcntl.h>
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include <signal.h>
40 #include <string.h>
41 #include <unistd.h>
42 #include <wchar.h>
43 #include <wctype.h>
44 
45 #include "coll.h"
46 #include "file.h"
47 #include "radixsort.h"
48 
49 unsigned long long available_free_memory = 1000000;
50 
51 bool use_mmap;
52 
53 const char *tmpdir = "/var/tmp";
54 const char *compress_program;
55 
56 size_t max_open_files = 16;
57 
58 /*
59  * How much space we read from file at once
60  */
61 #define READ_CHUNK 4096
62 
63 /*
64  * File reader structure
65  */
66 struct file_reader {
67 	struct reader_buffer	 rb;
68 	FILE			*file;
69 	char			*fname;
70 	unsigned char		*buffer;
71 	unsigned char		*mmapaddr;
72 	unsigned char		*mmapptr;
73 	size_t			 bsz;
74 	size_t			 cbsz;
75 	size_t			 mmapsize;
76 	size_t			 strbeg;
77 	char			 elsymb;
78 };
79 
80 /*
81  * Structure to be used in file merge process.
82  */
83 struct file_header {
84 	struct file_reader		*fr;
85 	struct sort_list_item		*si; /* current top line */
86 	size_t				 file_pos;
87 };
88 
89 /*
90  * List elements of "cleanable" files list.
91  */
92 struct CLEANABLE_FILE {
93 	char				*fn;
94 	LIST_ENTRY(CLEANABLE_FILE)	 files;
95 };
96 
97 /*
98  * List header of "cleanable" files list.
99  */
100 static LIST_HEAD(CLEANABLE_FILES, CLEANABLE_FILE) tmp_files;
101 
102 /*
103  * Init tmp files list
104  */
105 void
106 init_tmp_files(void)
107 {
108 	LIST_INIT(&tmp_files);
109 }
110 
111 /*
112  * Save name of a tmp file for signal cleanup
113  */
114 void
115 tmp_file_atexit(const char *tmp_file)
116 {
117 	struct CLEANABLE_FILE *item;
118 	sigset_t mask, oldmask;
119 
120 	item = sort_malloc(sizeof(struct CLEANABLE_FILE));
121 	item->fn = sort_strdup(tmp_file);
122 
123 	sigfillset(&mask);
124 	sigprocmask(SIG_BLOCK, &mask, &oldmask);
125 	LIST_INSERT_HEAD(&tmp_files, item, files);
126 	sigprocmask(SIG_SETMASK, &oldmask, NULL);
127 }
128 
129 /*
130  * Clear tmp files
131  */
132 void
133 clear_tmp_files(void)
134 {
135 	struct CLEANABLE_FILE *item;
136 
137 	LIST_FOREACH(item, &tmp_files, files) {
138 		if (item != NULL && item->fn != NULL)
139 			unlink(item->fn);
140 	}
141 }
142 
143 /*
144  * Check whether a file is a temporary file
145  */
146 static bool
147 file_is_tmp(const char *fn)
148 {
149 	struct CLEANABLE_FILE *item;
150 
151 	LIST_FOREACH(item, &tmp_files, files) {
152 		if (item->fn != NULL && strcmp(item->fn, fn) == 0)
153 			return true;
154 	}
155 
156 	return false;
157 }
158 
159 /*
160  * Generate new temporary file name
161  */
162 char *
163 new_tmp_file_name(void)
164 {
165 	char *ret;
166 	int fd;
167 
168 	sort_asprintf(&ret, "%s/.bsdsort.XXXXXXXXXX", tmpdir);
169 	if ((fd = mkstemp(ret)) == -1)
170 		err(2, "%s", ret);
171 	close(fd);
172 	tmp_file_atexit(ret);
173 	return ret;
174 }
175 
176 /*
177  * Initialize file list
178  */
179 void
180 file_list_init(struct file_list *fl, bool tmp)
181 {
182 	fl->count = 0;
183 	fl->sz = 0;
184 	fl->fns = NULL;
185 	fl->tmp = tmp;
186 }
187 
188 /*
189  * Add a file name to the list
190  */
191 void
192 file_list_add(struct file_list *fl, char *fn, bool allocate)
193 {
194 	if (fl->count >= fl->sz) {
195 		fl->fns = sort_reallocarray(fl->fns,
196 		    fl->sz ? fl->sz : (fl->sz = 1), 2 * sizeof(char *));
197 		fl->sz *= 2;
198 	}
199 	fl->fns[fl->count] = allocate ? sort_strdup(fn) : fn;
200 	fl->count += 1;
201 }
202 
203 /*
204  * Populate file list from array of file names
205  */
206 void
207 file_list_populate(struct file_list *fl, int argc, char **argv, bool allocate)
208 {
209 	int i;
210 
211 	for (i = 0; i < argc; i++)
212 		file_list_add(fl, argv[i], allocate);
213 }
214 
215 /*
216  * Clean file list data and delete the files,
217  * if this is a list of temporary files
218  */
219 void
220 file_list_clean(struct file_list *fl)
221 {
222 	if (fl->fns) {
223 		size_t i;
224 
225 		for (i = 0; i < fl->count; i++) {
226 			if (fl->fns[i]) {
227 				if (fl->tmp)
228 					unlink(fl->fns[i]);
229 				sort_free(fl->fns[i]);
230 				fl->fns[i] = NULL;
231 			}
232 		}
233 		sort_free(fl->fns);
234 		fl->fns = NULL;
235 	}
236 	fl->sz = 0;
237 	fl->count = 0;
238 	fl->tmp = false;
239 }
240 
241 /*
242  * Init sort list
243  */
244 void
245 sort_list_init(struct sort_list *l)
246 {
247 	l->count = 0;
248 	l->size = 0;
249 	l->memsize = sizeof(struct sort_list);
250 	l->list = NULL;
251 }
252 
253 /*
254  * Add string to sort list
255  */
256 void
257 sort_list_add(struct sort_list *l, struct bwstring *str)
258 {
259 	size_t indx = l->count;
260 
261 	if ((l->list == NULL) || (indx >= l->size)) {
262 		size_t newsize = (l->size + 1) + 1024;
263 
264 		l->list = sort_reallocarray(l->list, newsize,
265 		    sizeof(struct sort_list_item *));
266 		l->memsize += (newsize - l->size) *
267 		    sizeof(struct sort_list_item *);
268 		l->size = newsize;
269 	}
270 	l->list[indx] = sort_list_item_alloc();
271 	sort_list_item_set(l->list[indx], str);
272 	l->memsize += sort_list_item_size(l->list[indx]);
273 	l->count += 1;
274 }
275 
276 /*
277  * Clean sort list data
278  */
279 void
280 sort_list_clean(struct sort_list *l)
281 {
282 	if (l->list) {
283 		size_t i;
284 
285 		for (i = 0; i < l->count; i++) {
286 			struct sort_list_item *item;
287 
288 			item = l->list[i];
289 
290 			if (item) {
291 				sort_list_item_clean(item);
292 				sort_free(item);
293 				l->list[i] = NULL;
294 			}
295 		}
296 		sort_free(l->list);
297 		l->list = NULL;
298 	}
299 	l->count = 0;
300 	l->size = 0;
301 	l->memsize = sizeof(struct sort_list);
302 }
303 
304 /*
305  * Write sort list to file
306  */
307 void
308 sort_list_dump(struct sort_list *l, const char *fn)
309 {
310 	FILE *f;
311 
312 	f = openfile(fn, "w");
313 	if (f == NULL)
314 		err(2, "%s", fn);
315 
316 	if (l->list) {
317 		size_t i;
318 
319 		if (!sort_opts_vals.uflag) {
320 			for (i = 0; i < l->count; ++i)
321 				bwsfwrite(l->list[i]->str, f,
322 				    sort_opts_vals.zflag);
323 		} else {
324 			struct sort_list_item *last_printed_item = NULL;
325 			struct sort_list_item *item;
326 			for (i = 0; i < l->count; ++i) {
327 				item = l->list[i];
328 				if ((last_printed_item == NULL) ||
329 				    list_coll(&last_printed_item, &item)) {
330 					bwsfwrite(item->str, f, sort_opts_vals.zflag);
331 					last_printed_item = item;
332 				}
333 			}
334 		}
335 	}
336 
337 	closefile(f, fn);
338 }
339 
340 /*
341  * Checks if the given file is sorted.  Stops at the first disorder,
342  * prints the disordered line and returns 1.
343  */
344 int
345 check(const char *fn)
346 {
347 	struct bwstring *s1, *s2;
348 	struct file_reader *fr;
349 	struct keys_array *ka1, *ka2;
350 	int res;
351 	size_t pos, posdisorder;
352 
353 	s1 = s2 = NULL;
354 	ka1 = ka2 = NULL;
355 
356 	fr = file_reader_init(fn);
357 
358 	res = 0;
359 	pos = 1;
360 	posdisorder = 1;
361 
362 	if (fr == NULL)
363 		err(2, "%s", fn);
364 
365 	s1 = file_reader_readline(fr);
366 	if (s1 == NULL)
367 		goto end;
368 
369 	ka1 = keys_array_alloc();
370 	preproc(s1, ka1);
371 
372 	s2 = file_reader_readline(fr);
373 	if (s2 == NULL)
374 		goto end;
375 
376 	ka2 = keys_array_alloc();
377 	preproc(s2, ka2);
378 
379 	for (;;) {
380 
381 		if (debug_sort) {
382 			bwsprintf(stdout, s2, "s1=<", ">");
383 			bwsprintf(stdout, s1, "s2=<", ">");
384 		}
385 		int cmp = key_coll(ka2, ka1, 0);
386 		if (debug_sort)
387 			printf("; cmp1=%d", cmp);
388 
389 		if (!cmp && sort_opts_vals.complex_sort &&
390 		    !(sort_opts_vals.uflag) && !(sort_opts_vals.sflag)) {
391 			cmp = top_level_str_coll(s2, s1);
392 			if (debug_sort)
393 				printf("; cmp2=%d", cmp);
394 		}
395 		if (debug_sort)
396 			printf("\n");
397 
398 		if ((sort_opts_vals.uflag && (cmp <= 0)) || (cmp < 0)) {
399 			if (!(sort_opts_vals.csilentflag)) {
400 				bws_disorder_warnx(s2, fn, posdisorder);
401 				posdisorder = pos;
402 				if (debug_sort)
403 					bws_disorder_warnx(s1, fn, posdisorder);
404 			}
405 			res = 1;
406 			goto end;
407 		}
408 
409 		pos++;
410 
411 		clean_keys_array(s1, ka1);
412 		sort_free(ka1);
413 		ka1 = ka2;
414 		ka2 = NULL;
415 
416 		bwsfree(s1);
417 		s1 = s2;
418 
419 		s2 = file_reader_readline(fr);
420 		if (s2 == NULL)
421 			goto end;
422 
423 		ka2 = keys_array_alloc();
424 		preproc(s2, ka2);
425 	}
426 
427 end:
428 	if (ka1) {
429 		clean_keys_array(s1, ka1);
430 		sort_free(ka1);
431 	}
432 
433 	bwsfree(s1);
434 
435 	if (ka2) {
436 		clean_keys_array(s2, ka2);
437 		sort_free(ka2);
438 	}
439 
440 	bwsfree(s2);
441 
442 	if (fn == NULL || *fn == 0 || strcmp(fn, "-") == 0) {
443 		for (;;) {
444 			s2 = file_reader_readline(fr);
445 			if (s2 == NULL)
446 				break;
447 			bwsfree(s2);
448 		}
449 	}
450 
451 	file_reader_free(fr);
452 
453 	return res;
454 }
455 
456 /*
457  * Opens a file.  If the given filename is "-", stdout will be
458  * opened.
459  */
460 FILE *
461 openfile(const char *fn, const char *mode)
462 {
463 	FILE *file;
464 
465 	if (strcmp(fn, "-") == 0)
466 		return (mode[0] == 'r') ? stdin : stdout;
467 
468 	if (file_is_tmp(fn) && (compress_program != NULL)) {
469 		char *cmd;
470 
471 		fflush(stdout);
472 
473 		if (mode[0] == 'r')
474 			sort_asprintf(&cmd, "%s -d < %s",
475 			    compress_program, fn);
476 		else if (mode[0] == 'w')
477 			sort_asprintf(&cmd, "%s > %s",
478 			    compress_program, fn);
479 		else
480 			err(2, "invalid file mode");
481 
482 		if ((file = popen(cmd, mode)) == NULL)
483 			err(2, "%s", compress_program);
484 
485 		sort_free(cmd);
486 
487 	} else if ((file = fopen(fn, mode)) == NULL)
488 		err(2, "%s", fn);
489 
490 	return file;
491 }
492 
493 /*
494  * Close file
495  */
496 void
497 closefile(FILE *f, const char *fn)
498 {
499 	if (f == NULL) {
500 		;
501 	} else if (f == stdin) {
502 		;
503 	} else if (f == stdout) {
504 		fflush(f);
505 	} else {
506 		if (file_is_tmp(fn) && compress_program != NULL) {
507 			if (pclose(f) < 0)
508 				err(2, NULL);
509 		} else
510 			fclose(f);
511 	}
512 }
513 
514 /*
515  * Reads a file into the internal buffer.
516  */
517 struct file_reader *
518 file_reader_init(const char *fsrc)
519 {
520 	struct file_reader *ret;
521 
522 	if (fsrc == NULL)
523 		fsrc = "-";
524 
525 	ret = sort_calloc(1, sizeof(struct file_reader));
526 
527 	ret->elsymb = '\n';
528 	if (sort_opts_vals.zflag)
529 		ret->elsymb = 0;
530 
531 	ret->fname = sort_strdup(fsrc);
532 
533 	if (strcmp(fsrc, "-") && (compress_program == NULL) && use_mmap) {
534 		struct stat stat_buf;
535 		void *addr;
536 		size_t sz = 0;
537 		int fd;
538 
539 		fd = open(fsrc, O_RDONLY);
540 		if (fd < 0)
541 			err(2, "%s", fsrc);
542 
543 		if (fstat(fd, &stat_buf) < 0)
544 			err(2, "%s", fsrc);
545 		sz = stat_buf.st_size;
546 
547 		addr = mmap(NULL, sz, PROT_READ, 0, fd, 0);
548 		close(fd);
549 		if (addr != MAP_FAILED) {
550 			ret->mmapaddr = addr;
551 			ret->mmapsize = sz;
552 			ret->mmapptr = ret->mmapaddr;
553 			posix_madvise(addr, sz, POSIX_MADV_SEQUENTIAL);
554 		}
555 	}
556 
557 	if (ret->mmapaddr == NULL) {
558 		ret->file = openfile(fsrc, "r");
559 		if (ret->file == NULL)
560 			err(2, "%s", fsrc);
561 
562 		if (strcmp(fsrc, "-")) {
563 			ret->cbsz = READ_CHUNK;
564 			ret->buffer = sort_malloc(ret->cbsz);
565 			ret->bsz = 0;
566 			ret->strbeg = 0;
567 
568 			ret->bsz = fread(ret->buffer, 1, ret->cbsz, ret->file);
569 			if (ret->bsz == 0) {
570 				if (ferror(ret->file))
571 					err(2, NULL);
572 			}
573 		}
574 	}
575 
576 	return ret;
577 }
578 
579 struct bwstring *
580 file_reader_readline(struct file_reader *fr)
581 {
582 	struct bwstring *ret = NULL;
583 
584 	if (fr->mmapaddr) {
585 		unsigned char *mmapend;
586 
587 		mmapend = fr->mmapaddr + fr->mmapsize;
588 		if (fr->mmapptr >= mmapend)
589 			return NULL;
590 		else {
591 			unsigned char *strend;
592 			size_t sz;
593 
594 			sz = mmapend - fr->mmapptr;
595 			strend = memchr(fr->mmapptr, fr->elsymb, sz);
596 
597 			if (strend == NULL) {
598 				ret = bwscsbdup(fr->mmapptr, sz);
599 				fr->mmapptr = mmapend;
600 			} else {
601 				ret = bwscsbdup(fr->mmapptr, strend -
602 				    fr->mmapptr);
603 				fr->mmapptr = strend + 1;
604 			}
605 		}
606 
607 	} else if (fr->file != stdin) {
608 		unsigned char *strend;
609 		size_t bsz1, remsz, search_start;
610 
611 		search_start = 0;
612 		remsz = 0;
613 		strend = NULL;
614 
615 		if (fr->bsz > fr->strbeg)
616 			remsz = fr->bsz - fr->strbeg;
617 
618 		/* line read cycle */
619 		for (;;) {
620 			if (remsz > search_start)
621 				strend = memchr(fr->buffer + fr->strbeg +
622 				    search_start, fr->elsymb, remsz -
623 				    search_start);
624 			else
625 				strend = NULL;
626 
627 			if (strend)
628 				break;
629 			if (feof(fr->file))
630 				break;
631 
632 			if (fr->bsz != fr->cbsz)
633 				/* NOTREACHED */
634 				err(2, "File read software error 1");
635 
636 			if (remsz > (READ_CHUNK >> 1)) {
637 				search_start = fr->cbsz - fr->strbeg;
638 				fr->cbsz += READ_CHUNK;
639 				fr->buffer = sort_reallocarray(fr->buffer,
640 				    1, fr->cbsz);
641 				bsz1 = fread(fr->buffer + fr->bsz, 1,
642 				    READ_CHUNK, fr->file);
643 				if (bsz1 == 0) {
644 					if (ferror(fr->file))
645 						err(2, NULL);
646 					break;
647 				}
648 				fr->bsz += bsz1;
649 				remsz += bsz1;
650 			} else {
651 				if (remsz > 0 && fr->strbeg > 0) {
652 					memmove(fr->buffer,
653 					    fr->buffer + fr->strbeg, remsz);
654 				}
655 				fr->strbeg = 0;
656 				search_start = remsz;
657 				bsz1 = fread(fr->buffer + remsz, 1,
658 				    fr->cbsz - remsz, fr->file);
659 				if (bsz1 == 0) {
660 					if (ferror(fr->file))
661 						err(2, NULL);
662 					break;
663 				}
664 				fr->bsz = remsz + bsz1;
665 				remsz = fr->bsz;
666 			}
667 		}
668 
669 		if (strend == NULL)
670 			strend = fr->buffer + fr->bsz;
671 
672 		if ((fr->buffer + fr->strbeg <= strend) &&
673 		    (fr->strbeg < fr->bsz) && (remsz>0))
674 			ret = bwscsbdup(fr->buffer + fr->strbeg, strend -
675 			    fr->buffer - fr->strbeg);
676 
677 		fr->strbeg = (strend - fr->buffer) + 1;
678 	} else {
679 		size_t len = 0;
680 
681 		ret = bwsfgetln(fr->file, &len, sort_opts_vals.zflag,
682 		    &(fr->rb));
683 	}
684 
685 	return ret;
686 }
687 
688 static void
689 file_reader_clean(struct file_reader *fr)
690 {
691 	if (fr->mmapaddr)
692 		munmap(fr->mmapaddr, fr->mmapsize);
693 
694 	sort_free(fr->buffer);
695 
696 	if (fr->file)
697 		closefile(fr->file, fr->fname);
698 
699 	sort_free(fr->fname);
700 
701 	memset(fr, 0, sizeof(struct file_reader));
702 }
703 
704 void
705 file_reader_free(struct file_reader *fr)
706 {
707 	file_reader_clean(fr);
708 	sort_free(fr);
709 }
710 
711 int
712 procfile(const char *fsrc, struct sort_list *list, struct file_list *fl)
713 {
714 	struct file_reader *fr;
715 
716 	fr = file_reader_init(fsrc);
717 	if (fr == NULL)
718 		err(2, "%s", fsrc);
719 
720 	/* file browse cycle */
721 	for (;;) {
722 		struct bwstring *bws;
723 
724 		bws = file_reader_readline(fr);
725 
726 		if (bws == NULL)
727 			break;
728 
729 		sort_list_add(list, bws);
730 
731 		if (list->memsize >= available_free_memory) {
732 			char *fn;
733 
734 			fn = new_tmp_file_name();
735 			sort_list_to_file(list, fn);
736 			file_list_add(fl, fn, false);
737 			sort_list_clean(list);
738 		}
739 	}
740 
741 	file_reader_free(fr);
742 
743 	return 0;
744 }
745 
746 /*
747  * Compare file headers. Files with EOF always go to the end of the list.
748  */
749 static int
750 file_header_cmp(struct file_header *f1, struct file_header *f2)
751 {
752 	int ret;
753 
754 	if (f1 == f2)
755 		return 0;
756 	if (f1->fr == NULL)
757 		return (f2->fr == NULL) ? 0 : 1;
758 	if (f2->fr == NULL)
759 		return -1;
760 
761 	ret = list_coll(&(f1->si), &(f2->si));
762 	if (!ret)
763 		return (f1->file_pos < f2->file_pos) ? -1 : 1;
764 	return ret;
765 }
766 
767 /*
768  * Allocate and init file header structure
769  */
770 static void
771 file_header_init(struct file_header **fh, const char *fn, size_t file_pos)
772 {
773 	struct bwstring *line;
774 
775 	*fh = sort_malloc(sizeof(struct file_header));
776 	(*fh)->file_pos = file_pos;
777 	(*fh)->fr = file_reader_init(fn);
778 	if ((*fh)->fr == NULL) {
779 		err(2, "Cannot open %s for reading",
780 		    strcmp(fn, "-") == 0 ? "stdin" : fn);
781 	}
782 	line = file_reader_readline((*fh)->fr);
783 	if (line == NULL) {
784 		file_reader_free((*fh)->fr);
785 		(*fh)->fr = NULL;
786 		(*fh)->si = NULL;
787 	} else {
788 		(*fh)->si = sort_list_item_alloc();
789 		sort_list_item_set((*fh)->si, line);
790 	}
791 }
792 
793 /*
794  * Close file
795  */
796 static void
797 file_header_close(struct file_header **fh)
798 {
799 	if ((*fh)->fr) {
800 		file_reader_free((*fh)->fr);
801 		(*fh)->fr = NULL;
802 	}
803 	if ((*fh)->si) {
804 		sort_list_item_clean((*fh)->si);
805 		sort_free((*fh)->si);
806 		(*fh)->si = NULL;
807 	}
808 	sort_free(*fh);
809 	*fh = NULL;
810 }
811 
812 /*
813  * Swap two array elements
814  */
815 static void
816 file_header_swap(struct file_header **fh, size_t i1, size_t i2)
817 {
818 	struct file_header *tmp;
819 
820 	tmp = fh[i1];
821 	fh[i1] = fh[i2];
822 	fh[i2] = tmp;
823 }
824 
825 /* heap algorithm ==>> */
826 
827 /*
828  * See heap sort algorithm
829  * "Raises" last element to its right place
830  */
831 static void
832 file_header_heap_swim(struct file_header **fh, size_t indx)
833 {
834 	if (indx > 0) {
835 		size_t parent_index;
836 
837 		parent_index = (indx - 1) >> 1;
838 
839 		if (file_header_cmp(fh[indx], fh[parent_index]) < 0) {
840 			/* swap child and parent and continue */
841 			file_header_swap(fh, indx, parent_index);
842 			file_header_heap_swim(fh, parent_index);
843 		}
844 	}
845 }
846 
847 /*
848  * Sink the top element to its correct position
849  */
850 static void
851 file_header_heap_sink(struct file_header **fh, size_t indx, size_t size)
852 {
853 	size_t left_child_index;
854 	size_t right_child_index;
855 
856 	left_child_index = indx + indx + 1;
857 	right_child_index = left_child_index + 1;
858 
859 	if (left_child_index < size) {
860 		size_t min_child_index;
861 
862 		min_child_index = left_child_index;
863 
864 		if ((right_child_index < size) &&
865 		    (file_header_cmp(fh[left_child_index],
866 		    fh[right_child_index]) > 0))
867 			min_child_index = right_child_index;
868 		if (file_header_cmp(fh[indx], fh[min_child_index]) > 0) {
869 			file_header_swap(fh, indx, min_child_index);
870 			file_header_heap_sink(fh, min_child_index, size);
871 		}
872 	}
873 }
874 
875 /* <<== heap algorithm */
876 
877 /*
878  * Adds element to the "left" end
879  */
880 static void
881 file_header_list_rearrange_from_header(struct file_header **fh, size_t size)
882 {
883 	file_header_heap_sink(fh, 0, size);
884 }
885 
886 /*
887  * Adds element to the "right" end
888  */
889 static void
890 file_header_list_push(struct file_header *f, struct file_header **fh, size_t size)
891 {
892 	fh[size++] = f;
893 	file_header_heap_swim(fh, size - 1);
894 }
895 
896 struct last_printed
897 {
898 	struct bwstring *str;
899 };
900 
901 /*
902  * Prints the current line of the file
903  */
904 static void
905 file_header_print(struct file_header *fh, FILE *f_out, struct last_printed *lp)
906 {
907 	if (sort_opts_vals.uflag) {
908 		if ((lp->str == NULL) || (str_list_coll(lp->str, &(fh->si)))) {
909 			bwsfwrite(fh->si->str, f_out, sort_opts_vals.zflag);
910 			if (lp->str)
911 				bwsfree(lp->str);
912 			lp->str = bwsdup(fh->si->str);
913 		}
914 	} else
915 		bwsfwrite(fh->si->str, f_out, sort_opts_vals.zflag);
916 }
917 
918 /*
919  * Read next line
920  */
921 static void
922 file_header_read_next(struct file_header *fh)
923 {
924 	struct bwstring *tmp;
925 
926 	tmp = file_reader_readline(fh->fr);
927 	if (tmp == NULL) {
928 		file_reader_free(fh->fr);
929 		fh->fr = NULL;
930 		if (fh->si) {
931 			sort_list_item_clean(fh->si);
932 			sort_free(fh->si);
933 			fh->si = NULL;
934 		}
935 	} else {
936 		if (fh->si == NULL)
937 			fh->si = sort_list_item_alloc();
938 		sort_list_item_set(fh->si, tmp);
939 	}
940 }
941 
942 /*
943  * Merge array of "files headers"
944  */
945 static void
946 file_headers_merge(size_t fnum, struct file_header **fh, FILE *f_out)
947 {
948 	struct last_printed lp;
949 	size_t i;
950 
951 	memset(&lp, 0, sizeof(lp));
952 
953 	/*
954 	 * construct the initial sort structure
955 	 */
956 	for (i = 0; i < fnum; i++)
957 		file_header_list_push(fh[i], fh, i);
958 
959 	while (fh[0]->fr) { /* unfinished files are always in front */
960 		/* output the smallest line: */
961 		file_header_print(fh[0], f_out, &lp);
962 		/* read a new line, if possible: */
963 		file_header_read_next(fh[0]);
964 		/* re-arrange the list: */
965 		file_header_list_rearrange_from_header(fh, fnum);
966 	}
967 
968 	if (lp.str)
969 		bwsfree(lp.str);
970 }
971 
972 /*
973  * Merges the given files into the output file, which can be
974  * stdout.
975  */
976 static void
977 merge_files_array(size_t argc, char **argv, const char *fn_out)
978 {
979 	struct file_header **fh;
980 	FILE *f_out;
981 	size_t i;
982 
983 	f_out = openfile(fn_out, "w");
984 
985 	if (f_out == NULL)
986 		err(2, "%s", fn_out);
987 
988 	fh = sort_reallocarray(NULL, argc + 1, sizeof(struct file_header *));
989 
990 	for (i = 0; i < argc; i++)
991 		file_header_init(fh + i, argv[i], i);
992 
993 	file_headers_merge(argc, fh, f_out);
994 
995 	for (i = 0; i < argc; i++)
996 		file_header_close(fh + i);
997 
998 	sort_free(fh);
999 
1000 	closefile(f_out, fn_out);
1001 }
1002 
1003 /*
1004  * Shrinks the file list until its size smaller than max number of opened files
1005  */
1006 static int
1007 shrink_file_list(struct file_list *fl)
1008 {
1009 	struct file_list new_fl;
1010 	size_t indx = 0;
1011 
1012 	if (fl->count < max_open_files)
1013 		return 0;
1014 
1015 	file_list_init(&new_fl, true);
1016 	while (indx < fl->count) {
1017 		char *fnew;
1018 		size_t num;
1019 
1020 		num = fl->count - indx;
1021 		fnew = new_tmp_file_name();
1022 
1023 		if (num >= max_open_files)
1024 			num = max_open_files - 1;
1025 		merge_files_array(num, fl->fns + indx, fnew);
1026 		if (fl->tmp) {
1027 			size_t i;
1028 
1029 			for (i = 0; i < num; i++)
1030 				unlink(fl->fns[indx + i]);
1031 		}
1032 		file_list_add(&new_fl, fnew, false);
1033 		indx += num;
1034 	}
1035 	fl->tmp = false; /* already taken care of */
1036 	file_list_clean(fl);
1037 
1038 	fl->count = new_fl.count;
1039 	fl->fns = new_fl.fns;
1040 	fl->sz = new_fl.sz;
1041 	fl->tmp = new_fl.tmp;
1042 
1043 	return 1;
1044 }
1045 
1046 /*
1047  * Merge list of files
1048  */
1049 void
1050 merge_files(struct file_list *fl, const char *fn_out)
1051 {
1052 	while (shrink_file_list(fl))
1053 		;
1054 
1055 	merge_files_array(fl->count, fl->fns, fn_out);
1056 }
1057 
1058 static const char *
1059 get_sort_method_name(int sm)
1060 {
1061 	if (sm == SORT_MERGESORT)
1062 		return "mergesort";
1063 	else if (sort_opts_vals.sort_method == SORT_RADIXSORT)
1064 		return "radixsort";
1065 	else if (sort_opts_vals.sort_method == SORT_HEAPSORT)
1066 		return "heapsort";
1067 	else
1068 		return "quicksort";
1069 }
1070 
1071 /*
1072  * Sort list of lines and writes it to the file
1073  */
1074 void
1075 sort_list_to_file(struct sort_list *list, const char *outfile)
1076 {
1077 	struct sort_mods *sm = &(keys[0].sm);
1078 
1079 	if (!sm->Mflag && !sm->Rflag && !sm->Vflag &&
1080 	    !sm->gflag && !sm->hflag && !sm->nflag) {
1081 		if ((sort_opts_vals.sort_method == SORT_DEFAULT) && byte_sort)
1082 			sort_opts_vals.sort_method = SORT_RADIXSORT;
1083 
1084 	} else if (sort_opts_vals.sort_method == SORT_RADIXSORT)
1085 		err(2, "Radix sort cannot be used with these sort options");
1086 
1087 	/*
1088 	 * To handle stable sort and the unique cases in the
1089 	 * right order, we need to use a stable algorithm.
1090 	 */
1091 	if (sort_opts_vals.sflag) {
1092 		switch (sort_opts_vals.sort_method){
1093 		case SORT_MERGESORT:
1094 			break;
1095 		case SORT_RADIXSORT:
1096 			break;
1097 		case SORT_DEFAULT:
1098 			sort_opts_vals.sort_method = SORT_MERGESORT;
1099 			break;
1100 		default:
1101 			errx(2, "The chosen sort method cannot be used with "
1102 			    "stable and/or unique sort");
1103 		};
1104 	}
1105 
1106 	if (sort_opts_vals.sort_method == SORT_DEFAULT)
1107 		sort_opts_vals.sort_method = DEFAULT_SORT_ALGORITHM;
1108 
1109 	if (debug_sort)
1110 		printf("sort_method=%s\n",
1111 		    get_sort_method_name(sort_opts_vals.sort_method));
1112 
1113 	switch (sort_opts_vals.sort_method){
1114 	case SORT_RADIXSORT:
1115 		rxsort(list->list, list->count);
1116 		break;
1117 	case SORT_MERGESORT:
1118 		mergesort(list->list, list->count,
1119 		    sizeof(struct sort_list_item *), list_coll);
1120 		break;
1121 	case SORT_HEAPSORT:
1122 		heapsort(list->list, list->count,
1123 		    sizeof(struct sort_list_item *), list_coll);
1124 		break;
1125 	case SORT_QSORT:
1126 		qsort(list->list, list->count,
1127 		    sizeof(struct sort_list_item *), list_coll);
1128 		break;
1129 	default:
1130 		DEFAULT_SORT_FUNC(list->list, list->count,
1131 		    sizeof(struct sort_list_item *), list_coll);
1132 		break;
1133 	}
1134 	sort_list_dump(list, outfile);
1135 }
1136