aboutsummaryrefslogtreecommitdiff
path: root/toys/pending/diff.c
blob: d865e8df4a7bd15621f0a1faf661052e084f5356 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
/* diff.c - compare files line by line
 *
 * Copyright 2014 Sandeep Sharma <sandeep.jack2756@gmail.com>
 * Copyright 2014 Ashwini Kumar <ak.ashwini1981@gmail.com>
 *
 * See: http://cm.bell-labs.com/cm/cs/cstr/41.pdf

USE_DIFF(NEWTOY(diff, "<2>2(color)B(ignore-blank-lines)d(minimal)b(ignore-space-change)ut(expand-tabs)w(ignore-all-space)i(ignore-case)T(initial-tab)s(report-identical-files)q(brief)a(text)L(label)*S(starting-file):N(new-file)r(recursive)U(unified)#<0=3", TOYFLAG_USR|TOYFLAG_BIN|TOYFLAG_ARGFAIL(2)))

config DIFF
  bool "diff"
  default n
  help
  usage: diff [-abBdiNqrTstw] [-L LABEL] [-S FILE] [-U LINES] FILE1 FILE2

  -a  Treat all files as text
  -b  Ignore changes in the amount of whitespace
  -B  Ignore changes whose lines are all blank
  -d  Try hard to find a smaller set of changes
  -i  Ignore case differences
  -L  Use LABEL instead of the filename in the unified header
  -N  Treat absent files as empty
  -q  Output only whether files differ
  -r  Recurse
  -S  Start with FILE when comparing directories
  -T  Make tabs line up by prefixing a tab when necessary
  -s  Report when two files are the same
  -t  Expand tabs to spaces in output
  -U  Output LINES lines of context
  -w  Ignore all whitespace

  --color  Colored output
*/

#define FOR_diff
#include "toys.h"

GLOBALS(
  long ct;
  char *start;
  struct arg_list *L_list;

  int dir_num, size, is_binary, status, change, len[2];
  int *offset[2];
  struct stat st[2];
)

#define MIN(x,y) ((x) < (y) ? (x) : (y))
#define MAX(x,y) ((x) > (y) ? (x) : (y))
#define IS_STDIN(s)     ((s)[0] == '-' && !(s)[1])

struct v_vector {
  unsigned serial:31;
  unsigned last:1;
  union {
    unsigned hash;
    unsigned p;
  };
};

struct diff {
  long a, b, c, d, prev, suff;
};

static struct dir_t {
  char **list;
  int nr_elm;
} dir[2];

struct candidate {
  int a, b;
  struct candidate *prev, *next;
};

static struct file_t {
  FILE *fp;
  int len;
} file[2];

enum {
  SAME,
  DIFFER,
};

enum {
  empty = 1 << 9,
  eol = 1 << 10,
  eof = 1 << 11,
  space = 1 << 12
};

static int comp(const void *a, const void* b)
{
  int i = ((struct v_vector *)a)->hash -
    ((struct v_vector *)b)->hash;

  if (!i) i = ((struct v_vector *)a)->serial -
    ((struct v_vector *)b)->serial;
  return i;
}

static int search (struct candidate **K, int r, int k, int j)
{
  int low = r, upper = k, mid;

  mid = (low + upper) / 2;
  while (low <= mid) {
    if (((struct candidate*)(K[mid]))->b < j &&
        ((struct candidate*)(K[mid + 1]))->b > j)
      return mid;

    if (((struct candidate*)(K[mid]))->b < j) low = mid + 1;
    else if (((struct candidate*)(K[mid]))->b > j) upper = mid - 1;
    else return -1;

    mid = (low + upper) / 2;
  }
  return -1;
}

static struct candidate * new_candidate (int i, int j, struct candidate* prev)
{
  struct candidate *c = xzalloc(sizeof(struct candidate));

  c->a = i;
  c->b = j;
  c->prev = prev;
  return c;
}


static void free_candidates(struct candidate *c)
{
  struct candidate *t = c;
  
  while ((t = c)) {
    c = c->next;
    free(t);
  }
}
/*
 * 1. Search K[r: k] for an element K[s] such that K[s]-> b < j and K[s + 1]->b > j
 * 2. if found do
 *  2.a. If K[s + 1]->b > j do K[r] = c; r = s+1 and c = candidate(i, j, K[s]) //we have a candidate
 *  2.b. if s = k (fence reached move it further) do K[k + 2] = K[k + 1], k++
 * 3. if E[p].last true break i.e we have reached at the end of an equiv class
 *    else p = p + 1 //keep traversing the equiv class.
 * 4. K[r] = c //Save the sucessfully filled k-candidate.
 */
static void  do_merge(struct candidate **K, int *k, int i,
    struct v_vector *E, int p)
{
  int r = 0, s, j;
  struct candidate *pr = 0, *c = K[0];

  while (1) {
    j = E[p].serial;
    s = search(K, r, *k, j);
    if (s >= 0 && (((struct candidate*)(K[s]))->b < j &&
          ((struct candidate*)(K[s + 1]))->b > j)) {

      if (((struct candidate*)(K[s + 1]))->b > j) {
        pr = K[s];
        if (r && K[r]) c->next = K[r];
        K[r] = c;
        r = s + 1;
        c = new_candidate(i , j, pr);
      }
      if (s == *k) {
        K[*k + 2] = K[*k + 1];
        *k = *k + 1;
        break;
      }
    }
    if (E[p].last) break;
    else p = p + 1;
  }
  K[r] = c;
}

static FILE* read_stdin()
{
  char *tmp_name;
  int tmpfd = xtempfile("stdin", &tmp_name);

  unlink(tmp_name);
  free(tmp_name);

  xsendfile(0, tmpfd);
  return fdopen(tmpfd, "r");
}

static int read_tok(FILE *fp, off_t *off, int tok)
{
  int t = 0, is_space;

  tok |= empty;
  while (!(tok & eol)) {

    t = fgetc(fp);
    if (off && t != EOF) *off += 1;
    is_space = isspace(t) || (t == EOF);
    tok |= (t & (eof + eol)); //set tok eof+eol when t is eof

    if (t == '\n') tok |= eol;
    if (toys.optflags & FLAG_i)
      if (t >= 'A' && t <= 'Z') t = tolower(t);

    if (toys.optflags & FLAG_w && is_space) continue;

    if (toys.optflags & FLAG_b) {
      if (tok & space) {
        if (is_space) continue;
        tok &= ~space;
      } else if (is_space) t = space + ' ';
    }
    tok &= ~(empty + 0xff);  //remove empty and char too.
    tok |= t; //add most recent char
    break;
  }

  return tok;
}

int bcomp(const void *a, const void *b) 
{
  struct v_vector *l = (struct v_vector*)a,
                  *r = (struct v_vector*)b;
  int ret = l->hash - r->hash;

  if (!ret) {
    if ((r -1)->last) return 0;
    else return -1;
  }
  return ret;
}
/*  file[0] corresponds file 1 and file[1] correspond file 2.
 * 1. calc hashes for both the files and store them in vector(v[0], v[1])
 * 2. sort file[1] with hash as primary and serial as sec. key
 * 3. Form the equivalance class of file[1] stored in e vector. It lists all the equivalence
 *    classes of lines in file[1], with e.last = true on the last element of each class.
 *    The elements are ordered by serial within classes.
 * 4. Form the p vector stored in  p_vector. p_vector[i], if non-zero, now points in e vector
 *    to the begining of the equiv class of lines in file[1] equivalent to line
 *    i in file[0].
 * 5. Form the k-candidates as discribed in do_merge.
 * 6. Create a vector J[i] = j, such that i'th line in file[0] is j'th line of
 *    file[1], i.e J comprises LCS
 */
static int * create_j_vector()
{
  int tok, i, j, size = 100, k;
  off_t off;
  long hash;
  int *p_vector, *J;
  struct v_vector *v[2], *e;
  struct candidate **kcand, *pr;

  for (i = 0; i < 2; i++) {
    tok = off = 0;
    hash = 5831;
    v[i] = xzalloc(size * sizeof(struct v_vector));
    TT.offset[i] = xzalloc(size * sizeof(int));
    file[i].len = 0;
    fseek(file[i].fp, 0, SEEK_SET);

    while (1) {
      tok  = read_tok(file[i].fp, &off, tok);
      if (!(tok & empty)) {
        hash = ((hash << 5) + hash) + (tok & 0xff);
        continue;
      }

      if (size == ++file[i].len) {
        size = size * 11 / 10;
        v[i] = xrealloc(v[i], size*sizeof(struct v_vector));
        TT.offset[i] = xrealloc(TT.offset[i], size*sizeof(int));
      }

      v[i][file[i].len].hash = hash & INT_MAX;
      TT.offset[i][file[i].len] = off;
      if ((tok & eof)) {
        TT.offset[i][file[i].len] = ++off;
        break;
      }
      hash = 5831;  //next line
      tok = 0;
    }
    if (TT.offset[i][file[i].len] - TT.offset[i][file[i].len - 1] == 1)
      file[i].len--;
  }

  for (i = 0; i <= file[1].len; i++) v[1][i].serial = i;
  qsort(v[1] + 1, file[1].len, sizeof(struct v_vector), comp);

  e = v[1];
  e[0].serial = 0;
  e[0].last = 1;
  for ( i = 1; i <= file[1].len; i++) {
    if ((i == file[1].len) || (v[1][i].hash != v[1][i+1].hash)) e[i].last = 1;
    else e[i].last = 0;
  }

  p_vector = xzalloc((file[0].len + 2) * sizeof(int));
  for (i = 1; i <= file[0].len; i++) {
    void *r = bsearch(&v[0][i], (e + 1), file[1].len, sizeof(e[0]), bcomp);
    if (r) p_vector[i] = (struct v_vector*)r - e;
  }

  for (i = 1; i <= file[0].len; i++)
    e[i].p = p_vector[i];
  free(p_vector);

  size = 100;
  kcand = xzalloc(size * sizeof(struct candidate*));

  kcand[0] = new_candidate(0 , 0, NULL);
  kcand[1] = new_candidate(file[0].len+1, file[1].len+1, NULL); //the fence

  k = 0;  //last successfully filled k candidate.
  for (i = 1; i <= file[0].len; i++) {

    if (!e[i].p) continue;
    if ((size - 2) == k) {
      size = size * 11 / 10;
      kcand = xrealloc(kcand, (size * sizeof(struct candidate*)));
    }
    do_merge(kcand, &k, i, e, e[i].p);
  }
  free(v[0]); //no need for v_vector now.
  free(v[1]);

  J = xzalloc((file[0].len + 2) * sizeof(int));

  for (pr = kcand[k]; pr; pr = pr->prev)
    J[pr->a] = pr->b;
  J[file[0].len + 1] = file[1].len+1; //mark boundary

  for (i = k + 1; i >= 0; i--) free_candidates(kcand[i]);
  free(kcand);

  for (i = 1; i <= file[0].len; i++) { // jackpot?
    if (!J[i]) continue;

    fseek(file[0].fp, TT.offset[0][i - 1], SEEK_SET);
    fseek(file[1].fp, TT.offset[1][J[i] - 1], SEEK_SET);

    for (j = J[i]; i <= file[0].len && J[i] == j; i++, j++) {
      int tok0 = 0, tok1 = 0;

      do {
        tok0 = read_tok(file[0].fp, NULL, tok0);
        tok1 = read_tok(file[1].fp, NULL, tok1);
        if (((tok0 ^ tok1) & empty) || ((tok0 & 0xff) != (tok1 & 0xff)))
          J[i] = 0;
      } while (!(tok0 & tok1 & empty));
    }
  }
  return J;
}

static int *diff(char **files)
{
  size_t i ,j;
  int s, t;
  char *bufi, *bufj;

  TT.is_binary = 0; //loop calls to diff
  TT.status = SAME;

  for (i = 0; i < 2; i++) {
    if (IS_STDIN(files[i])) file[i].fp = read_stdin();
    else file[i].fp = fopen(files[i], "r");

    if (!file[i].fp){
      perror_msg("%s",files[i]);
      TT.status = 2;
      return NULL; //return SAME
    }
  }

  s = sizeof(toybuf)/2;
  bufi = toybuf;
  bufj = (toybuf + s);

  fseek(file[0].fp, 0, SEEK_SET);
  fseek(file[1].fp, 0, SEEK_SET);

  if (toys.optflags & FLAG_a) return create_j_vector();

  while (1) {
    i = fread(bufi, 1, s, file[0].fp);
    j = fread(bufj, 1, s, file[1].fp);

    if (i != j) TT.status = DIFFER;

    for (t = 0; t < i && !TT.is_binary; t++)
      if (!bufi[t]) TT.is_binary = 1;
    for (t = 0; t < j && !TT.is_binary; t++)
      if (!bufj[t]) TT.is_binary = 1;

    i = MIN(i, j);
    for (t = 0; t < i; t++)
      if (bufi[t] != bufj[t]) TT.status = DIFFER;

    if (!i || !j) break;
  }
  if (TT.is_binary || (TT.status == SAME)) return NULL;
  return create_j_vector();
}

static void print_diff(int a, int b, char c, int *off_set, FILE *fp)
{
  int i, j, cc, cl;
  char *reset = NULL;

  if (c != ' ' && (toys.optflags & FLAG_color)) {
    printf("\033[%dm", c == '+' ? 32 : 31);
    reset = "\033[0m";
  }

  for (i = a; i <= b; i++) {
    fseek(fp, off_set[i - 1], SEEK_SET);
    putchar(c);
    if (toys.optflags & FLAG_T) putchar('\t');
    for (j = 0, cl = 0; j <  (off_set[i] - off_set[i - 1]); j++) {
      cc = fgetc(fp);
      if (cc == EOF) {
        printf("%s\n\\ No newline at end of file\n", reset ? reset : "");
        return;
      }
      if ((cc == '\t') && (toys.optflags & FLAG_t))
        do putchar(' '); while (++cl & 7);
      else {
        putchar(cc); //xputc has calls to fflush, it hurts performance badly.
        cl++;
      }
    }
  }
  if (reset) printf("%s", reset);
}

static char *concat_file_path(char *path, char *default_path)
{
  char *final_path;

  if ('/' == path[strlen(path) - 1]) {
    while (*default_path == '/') ++default_path;
    final_path = xmprintf("%s%s", path, default_path);
  }
  else if (*default_path != '/')
    final_path = xmprintf("%s/%s", path, default_path);
  else final_path = xmprintf("%s%s", path, default_path);
  return final_path;
}

static int skip(struct dirtree *node)
{
  int len = strlen(toys.optargs[TT.dir_num]), ret = 0;
  char *tmp = NULL, *ptr, *f_path = dirtree_path(node, NULL);
  struct stat st;

  ptr = f_path;
  ptr += len;
  if (ptr[0]) {
    tmp = concat_file_path(toys.optargs[1 - TT.dir_num], ptr);
    if (tmp && !stat(tmp, &st)) ret = 0; //it is there on other side
    else ret = 1; //not present on other side.
  }
  free(f_path);
  if (tmp) free(tmp);
  return ret; //add otherwise
}

static void add_to_list(struct dirtree *node)
{
  char *full_path;

  dir[TT.dir_num].list = xrealloc(dir[TT.dir_num].list,
      (TT.size + 1)*sizeof(char*));
  TT.size++;
  full_path = dirtree_path(node, NULL);
  dir[TT.dir_num].list[TT.size - 1] = full_path;
}

static int list_dir (struct dirtree *node)
{
  int ret = 0;

  if (!dirtree_notdotdot(node)) return 0;

  if (S_ISDIR(node->st.st_mode) && !node->parent) { //add root dirs.
    add_to_list(node);
    return (DIRTREE_RECURSE|DIRTREE_SYMFOLLOW);
  }

  if (S_ISDIR(node->st.st_mode) && (toys.optflags & FLAG_r)) {
    if (!(toys.optflags & FLAG_N)) ret = skip(node);
    if (!ret) return (DIRTREE_RECURSE|DIRTREE_SYMFOLLOW);
    else {
      add_to_list(node); //only at one side.
      return 0;
    }
  } else {
    add_to_list(node);
    return S_ISDIR(node->st.st_mode) ? 0 : (DIRTREE_RECURSE|DIRTREE_SYMFOLLOW);
  }
}

static int cmp(const void *p1, const void *p2)
{
   return strcmp(* (char * const *)p1, * (char * const *)p2);
}

static void show_label(char *prefix, char *filename, struct stat *sb)
{
  char date[36];

  printf("%s %s\t%s\n", prefix, filename,
    format_iso_time(date, sizeof(date), &sb->st_mtim));
}

static void do_diff(char **files)
{

  long i = 1, size = 1, x = 0, change = 0, ignore_white,
   start1, end1, start2, end2;
  struct diff *d;
  struct arg_list *llist = TT.L_list;
  int *J;
  
  TT.offset[0] = TT.offset[1] = NULL;
  J = diff(files);

  if (!J) return; //No need to compare, have to status only

  d = xzalloc(size *sizeof(struct diff));
  do {
    ignore_white = 0;
    for (d[x].a = i; d[x].a <= file[0].len; d[x].a++) {
      if (J[d[x].a] != (J[d[x].a - 1] + 1)) break;
      else continue;
    }
    d[x].c = (J[d[x].a - 1] + 1);

    for (d[x].b = (d[x].a - 1); d[x].b <= file[0].len; d[x].b++) {
      if (J[d[x].b + 1]) break;
      else continue;
    }
    d[x].d = (J[d[x].b + 1] - 1);

    if ((toys.optflags & FLAG_B)) {
      if (d[x].a <= d[x].b) {
        if ((TT.offset[0][d[x].b] - TT.offset[0][d[x].a - 1])
            == (d[x].b - d[x].a + 1))
          ignore_white = 1;
      } else if (d[x].c <= d[x].d){
        if ((TT.offset[1][d[x].d] - TT.offset[1][d[x].c - 1])
            == (d[x].d - d[x].c + 1))
          ignore_white = 1;
      }
    }

    if ((d[x].a <= d[x].b || d[x].c <= d[x].d) && !ignore_white)
      change = 1; //is we have diff ?

    if (!ignore_white) d = xrealloc(d, (x + 2) *sizeof(struct diff));
    i = d[x].b + 1;
    if (i > file[0].len) break;
    J[d[x].b] = d[x].d;
    if (!ignore_white) x++;
  } while (i <= file[0].len);

  i = x+1;
  TT.status = change; //update status, may change bcoz of -w etc.

  if (!(toys.optflags & FLAG_q) && change) {  //start of !FLAG_q
    if (toys.optflags & FLAG_color) printf("\033[1m");
    if (toys.optflags & FLAG_L) printf("--- %s\n", llist->arg);
    else show_label("---", files[0], &(TT).st[0]);
    if (((toys.optflags & FLAG_L) && !llist->next) || !(toys.optflags & FLAG_L))
      show_label("+++", files[1], &(TT).st[1]);
    else {
      while (llist->next) llist = llist->next;
      printf("+++ %s\n", llist->arg);
    }
    if (toys.optflags & FLAG_color) printf("\033[0m");

    struct diff *t, *ptr1 = d, *ptr2 = d;
    while (i) {
      long a,b;

      if (TT.ct > file[0].len) TT.ct = file[0].len; //trim context to file len.
      if (ptr1->b < ptr1->a && ptr1->d < ptr1->c) {
        i--;
        continue;
      }
      //Handle the context stuff
      a =  ptr1->a;
      b =  ptr1->b;

      b  = MIN(file[0].len, b);
      if (i == x + 1) ptr1->suff = MAX(1,a - TT.ct);
      else {
        if ((ptr1 - 1)->prev >= (ptr1->a - TT.ct))
          ptr1->suff = (ptr1 - 1)->prev + 1;
        else ptr1->suff =  ptr1->a - TT.ct;
      }
calc_ct:
      if (i > 1) {
        if ((ptr2->b + TT.ct) >= (ptr2  + 1)->a) {
          ptr2++;
          i--;
          goto calc_ct;
        } else ptr2->prev = ptr2->b + TT.ct;
      } else ptr2->prev = ptr2->b;
      start1 = (ptr2->prev - ptr1->suff + 1);
      end1 = (start1 == 1) ? -1 : start1;
      start2 = MAX(1, ptr1->c - (ptr1->a - ptr1->suff));
      end2 = ptr2->prev - ptr2->b + ptr2->d;

      if (toys.optflags & FLAG_color) printf("\033[36m");
      printf("@@ -%ld", start1 ? ptr1->suff: (ptr1->suff -1));
      if (end1 != -1) printf(",%ld ", ptr2->prev-ptr1->suff + 1);
      else putchar(' ');

      printf("+%ld", (end2 - start2 + 1) ? start2: (start2 -1));
      if ((end2 - start2 +1) != 1) printf(",%ld ", (end2 - start2 +1));
      else putchar(' ');
      printf("@@");
      if (toys.optflags & FLAG_color) printf("\033[0m");
      putchar('\n');

      for (t = ptr1; t <= ptr2; t++) {
        if (t== ptr1) print_diff(t->suff, t->a-1, ' ', TT.offset[0], file[0].fp);
        print_diff(t->a, t->b, '-', TT.offset[0], file[0].fp);
        print_diff(t->c, t->d, '+', TT.offset[1], file[1].fp);
        if (t == ptr2)
          print_diff(t->b+1, (t)->prev, ' ', TT.offset[0], file[0].fp);
        else print_diff(t->b+1, (t+1)->a-1, ' ', TT.offset[0], file[0].fp);
      }
      ptr2++;
      ptr1 = ptr2;
      i--;
    } //end of while
  } //End of !FLAG_q
  free(d);
  free(J);
  free(TT.offset[0]);
  free(TT.offset[1]);
}

static void show_status(char **files)
{
  switch (TT.status) {
    case SAME:
      if (toys.optflags & FLAG_s)
        printf("Files %s and %s are identical\n",files[0], files[1]);
      break;
    case DIFFER:
      if ((toys.optflags & FLAG_q) || TT.is_binary)
        printf("Files %s and %s differ\n",files[0], files[1]);
      break;
  }
}

static void create_empty_entry(int l , int r, int j)
{
  struct stat st[2];
  char *f[2], *path[2];
  int i;

  if (j > 0 && (toys.optflags & FLAG_N)) {
    path[0] = concat_file_path(dir[0].list[0], dir[1].list[r] + TT.len[1]);
    f[0] = "/dev/null";
    path[1] = f[1] = dir[1].list[r];
    stat(f[1], &st[0]);
    st[1] = st[0];
  }
  else if (j < 0 && (toys.optflags & FLAG_N)) {
    path[1] = concat_file_path(dir[1].list[0], dir[0].list[l] + TT.len[0]);
    f[1] = "/dev/null";
    path[0] = f[0] = dir[0].list[l];
    stat(f[0], &st[0]);
    st[1] = st[0];
  }

  if (!j) {
    for (i = 0; i < 2; i++) {
      path[i] = f[i] = dir[i].list[!i ? l: r];
      stat(f[i], &st[i]);
    }
  }

  if (S_ISDIR(st[0].st_mode) && S_ISDIR(st[1].st_mode))
    printf("Common subdirectories: %s and %s\n", path[0], path[1]);
  else if (!S_ISREG(st[0].st_mode) && !S_ISDIR(st[0].st_mode))
    printf("File %s is not a regular file or directory "
        "and was skipped\n", path[0]);
  else if (!S_ISREG(st[1].st_mode) && !S_ISDIR(st[1].st_mode))
    printf("File %s is not a regular file or directory "
        "and was skipped\n", path[1]);
  else if (S_ISDIR(st[0].st_mode) != S_ISDIR(st[1].st_mode)) {
    if (S_ISDIR(st[0].st_mode))
      printf("File %s is a %s while file %s is a"
          " %s\n", path[0], "directory", path[1], "regular file");
    else
      printf("File %s is a %s while file %s is a"
          " %s\n", path[0], "regular file", path[1], "directory");
  } else {
    do_diff(f);
    show_status(path);
    if (file[0].fp) fclose(file[0].fp);
    if (file[1].fp) fclose(file[1].fp);
  }

  if ((toys.optflags & FLAG_N) && j) {
    if (j > 0) free(path[0]);
    else free(path[1]);
  }
}

static void diff_dir(int *start)
{
  int l, r, j = 0;

  l = start[0]; //left side file start
  r = start[1]; //right side file start
  while (l < dir[0].nr_elm && r < dir[1].nr_elm) {
    if ((j = strcmp ((dir[0].list[l] + TT.len[0]),
            (dir[1].list[r] + TT.len[1]))) && !(toys.optflags & FLAG_N)) {
      if (j > 0) {
        printf ("Only in %s: %s\n", dir[1].list[0], dir[1].list[r] + TT.len[1]);
        free(dir[1].list[r]);
        r++;
      } else {
        printf ("Only in %s: %s\n", dir[0].list[0], dir[0].list[l] + TT.len[0]);
        free(dir[0].list[l]);
        l++;
      }
      TT.status = DIFFER;
    } else {
      create_empty_entry(l, r, j); //create non empty dirs/files if -N.
      if (j > 0) {
        free(dir[1].list[r]);
        r++;
      } else if (j < 0) {
        free(dir[0].list[l]);
        l++;
      } else {
        free(dir[1].list[r]);
        free(dir[0].list[l]);
        l++;
        r++;
      }
    }
  }

  if (l == dir[0].nr_elm) {
    while (r < dir[1].nr_elm) {
      if (!(toys.optflags & FLAG_N)) {
        printf ("Only in %s: %s\n", dir[1].list[0], dir[1].list[r] + TT.len[1]);
        TT.status = DIFFER;
      } else create_empty_entry(l, r, 1);
      free(dir[1].list[r]);
      r++;
    }
  } else if (r == dir[1].nr_elm) {
    while (l < dir[0].nr_elm) {
      if (!(toys.optflags & FLAG_N)) {
        printf ("Only in %s: %s\n", dir[0].list[0], dir[0].list[l] + TT.len[0]);
        TT.status = DIFFER;
      } else create_empty_entry(l, r, -1);
      free(dir[0].list[l]);
      l++;
    }
  }
  free(dir[0].list[0]); //we are done, free root nodes too
  free(dir[1].list[0]);
}

void diff_main(void)
{
  int j = 0, k = 1, start[2] = {1, 1};
  char *files[2];

  toys.exitval = 2;

  if ((toys.optflags & FLAG_color) && !isatty(1)) toys.optflags ^= FLAG_color;

  for (j = 0; j < 2; j++) {
    files[j] = toys.optargs[j];
    if (IS_STDIN(files[j])) {
      if (fstat(0, &TT.st[j]) == -1)
        perror_exit("can't fstat %s", files[j]);
    } else {
      xstat(files[j], &TT.st[j]);
    }
  }

  if ((IS_STDIN(files[0]) || IS_STDIN(files[1]))
      && (S_ISDIR(TT.st[0].st_mode) || S_ISDIR(TT.st[1].st_mode)))
    error_exit("can't compare stdin to directory");

  if ((TT.st[0].st_ino == TT.st[1].st_ino) //physicaly same device
      && (TT.st[0].st_dev == TT.st[1].st_dev)) {
    toys.exitval = 0;
    return show_status(files);
  }

  if (S_ISDIR(TT.st[0].st_mode) && S_ISDIR(TT.st[1].st_mode)) {
    for (j = 0; j < 2; j++) {
      memset(&dir[j], 0, sizeof(struct dir_t));
      dirtree_flagread(files[j], DIRTREE_SYMFOLLOW, list_dir);
      dir[j].nr_elm = TT.size; //size updated in list_dir
      qsort(&(dir[j].list[1]), (TT.size - 1), sizeof(char*), cmp);

      TT.len[j] = strlen(dir[j].list[0]); //calc root node len
      TT.len[j] += (dir[j].list[0][TT.len[j] -1] != '/');

      if (toys.optflags & FLAG_S) {
        while (k < TT.size && strcmp(dir[j].list[k] +
              TT.len[j], TT.start) < 0) {
          start[j] += 1;
          k++;
        }
      }
      TT.dir_num++;
      TT.size = 0;
      k = 1;
    }
    diff_dir(start);
    free(dir[0].list); //free array
    free(dir[1].list);
  } else {
    if (S_ISDIR(TT.st[0].st_mode) || S_ISDIR(TT.st[1].st_mode)) {
      int d = S_ISDIR(TT.st[0].st_mode);
      char *slash = strrchr(files[d], '/');

      files[1 - d] = concat_file_path(files[1 - d], slash ? slash + 1 : files[d]);
      if ((stat(files[1 - d], &TT.st[1 - d])) == -1)
        perror_exit("%s", files[1 - d]);
    }
    do_diff(files);
    show_status(files);
    if (file[0].fp) fclose(file[0].fp);
    if (file[1].fp) fclose(file[1].fp);
  }
  toys.exitval = TT.status; //exit status will be the status
}