New toys unified DIFF and USERDEL.

2 files changed, 955 insertions, 0 deletions

diff --git a/toys/pending/diff.c b/toys/pending/diff.c
new file mode 100644
index 00000000..97cb9475
--- /dev/null
+++ b/toys/pending/diff.c
@@ -0,0 +1,839 @@
+/* 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>2B(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))
+
+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
+*/
+
+#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];
+)
+
+#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 {
+  char **list;
+  int nr_elm;
+} dir[2];
+
+struct candidate {
+  int a, b;
+  struct candidate *prev, *next;
+};
+
+static struct file {
+  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[] = "/tmp/diffXXXXXX";
+  int rd, wr, tmpfd = mkstemp(tmp_name);
+
+  if (tmpfd == -1) perror_exit("mkstemp");
+  unlink(tmp_name);
+
+  while (1) {
+    rd = xread(STDIN_FILENO, toybuf, sizeof(toybuf));
+
+    if (!rd) break;
+    if (rd < 0) perror_exit("read error");
+    wr = writeall(tmpfd, toybuf, rd);
+    if (wr < 0) perror_exit("write");
+  }
+  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;
+
+  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("\n\\ No newline at end of file\n");
+        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++;
+      }
+    }
+  }
+}
+
+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 (node->parent && !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 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
+
+      xprintf("--- %s\n", (toys.optflags & FLAG_L) ? llist->arg : files[0]);
+      if (((toys.optflags & FLAG_L) && !llist->next) || !(toys.optflags & FLAG_L))
+        xprintf("+++ %s\n", files[1]);
+      else {
+        while (llist->next) llist = llist->next;
+        xprintf("+++ %s\n", llist->arg);
+      }
+
+    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;
+
+			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("@@\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)
+{
+  struct stat st[2];
+  int j = 0, k = 1, start[2] = {1, 1};
+  char *files[2];
+  struct dirtree *root;
+
+	for (j = 0; j < 2; j++) {
+		files[j] = toys.optargs[j];
+		if (IS_STDIN(files[j])) {
+			if (fstat(0, &st[j]) == -1)
+				perror_exit("can fstat %s", files[j]);
+		} else {
+			if (stat(files[j], &st[j]) == -1)
+				perror_exit("can't stat %s", files[j]);
+		}
+	}
+
+	if (IS_STDIN(files[0]) && IS_STDIN(files[1])) { //compat :(
+    show_status(files);  //check ASAP
+    return;
+  }
+
+  if ((IS_STDIN(files[0]) || IS_STDIN(files[1]))
+      && (S_ISDIR(st[0].st_mode) || S_ISDIR(st[1].st_mode)))
+    error_exit("can't compare stdin to directory");
+
+  if ((st[0].st_ino == st[1].st_ino) //physicaly same device
+      &&(st[0].st_dev == st[1].st_dev)) {
+    show_status(files);
+    return ;
+  }
+
+  if (S_ISDIR(st[0].st_mode) && S_ISDIR(st[1].st_mode)) {
+    for (j = 0; j < 2; j++) {
+      memset(&dir[j], 0, sizeof(dir));
+      root = dirtree_add_node(0, files[j], 1);
+      if (root) dirtree_handle_callback(root, 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(st[0].st_mode) || S_ISDIR(st[1].st_mode)) {
+      int d = S_ISDIR(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], &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
+}
diff --git a/toys/pending/userdel.c b/toys/pending/userdel.c
new file mode 100644
index 00000000..8619a620
--- /dev/null
+++ b/toys/pending/userdel.c
@@ -0,0 +1,116 @@
+/* userdel.c - delete a user
+ *
+ * Copyright 2014 Ashwini Kumar <ak.ashwini1981@gmail.com>
+ *
+ * See http://refspecs.linuxfoundation.org/LSB_4.1.0/LSB-Core-generic/LSB-Core-generic/userdel.html
+
+USE_USERDEL(NEWTOY(userdel, "<1>1r", TOYFLAG_NEEDROOT|TOYFLAG_SBIN))
+USE_USERDEL(OLDTOY(deluser, userdel, OPTSTR_userdel, TOYFLAG_NEEDROOT|TOYFLAG_SBIN))
+
+config USERDEL
+  bool "userdel"
+  default n
+  help
+    usage: userdel [-r] USER
+    usage: deluser [-r] USER
+  
+    Options:
+    -r remove home directory
+    Delete USER from the SYSTEM
+*/
+
+#define FOR_userdel
+#include "toys.h"
+
+static void update_groupfiles(char *filename, char* username)
+{
+  char *filenamesfx = NULL, *sfx = NULL, *line = NULL;
+  FILE *exfp, *newfp;
+  int ulen = strlen(username);
+  struct flock lock;
+
+  filenamesfx = xmprintf("%s+", filename);
+  sfx = strchr(filenamesfx, '+');
+  exfp = xfopen(filename, "r+");
+
+  *sfx = '-';
+  unlink(filenamesfx);
+  if (link(filename, filenamesfx)) error_msg("Can't create backup file");
+
+  *sfx = '+';
+  lock.l_type = F_WRLCK;
+  lock.l_whence = SEEK_SET;
+  lock.l_start = lock.l_len = 0;
+
+  if (fcntl(fileno(exfp), F_SETLK, &lock) < 0)
+    perror_msg("Couldn't lock file %s",filename);
+
+  lock.l_type = F_UNLCK; //unlocking at a later stage
+
+  newfp = xfopen(filenamesfx, "w+");
+
+  while ((line = get_line(fileno(exfp))) != NULL){
+    sprintf(toybuf, "%s:",username);
+    if (!strncmp(line, toybuf, ulen+1)) goto LOOP;
+    else {
+      char *n, *p = strrchr(line, ':');
+
+      if (p && *++p && (n = strstr(p, username))) {
+        do {
+          if (n[ulen] == ',') {
+            *n = '\0';
+            n += ulen + 1;
+            fprintf(newfp, "%s%s\n", line, n);
+            break;
+          } else if (!n[ulen]) {
+            if (n[-1] == ',') n[-1] = *n = '\0';
+            if (n[-1] == ':') *n = '\0';
+            fprintf(newfp, "%s%s\n", line, n);
+            break;
+          } else n += ulen;
+        } while (*n && (n=strstr(n, username)));
+        if (!n) fprintf(newfp, "%s\n", line);
+      } else fprintf(newfp, "%s\n", line);
+    }
+LOOP:
+    free(line);
+  }
+  fcntl(fileno(exfp), F_SETLK, &lock);
+  fclose(exfp);
+  errno = 0;
+  fflush(newfp);
+  fsync(fileno(newfp));
+  fclose(newfp);
+  rename(filenamesfx, filename);
+  if (errno){
+    perror_msg("File Writing/Saving failed: ");
+    unlink(filenamesfx);
+  }
+  free(filenamesfx);
+}
+
+void userdel_main(void)
+{
+  struct passwd *pwd = NULL;
+
+  pwd = xgetpwnam(*toys.optargs);
+  update_password("/etc/passwd", pwd->pw_name, NULL);
+  update_password("/etc/shadow", pwd->pw_name, NULL);
+
+  // delete the group named USER, and remove user from group.
+  // could update_password() be used for this? 
+  // not a good idea, as update_passwd() updates one entry at a time
+  // in this case it will be modifying the files as many times the 
+  // USER appears in group database files. So the customized version
+  // of update_passwd() is here.
+  update_groupfiles("/etc/group", *toys.optargs);
+  update_groupfiles("/etc/gshadow", *toys.optargs);
+
+  if (toys.optflags & FLAG_r) {
+    char *arg[] = {"rm", "-fr", pwd->pw_dir, NULL, NULL};
+
+    sprintf(toybuf, "/var/spool/mail/%s",pwd->pw_name);
+    arg[3] = toybuf;
+    xexec(arg);
+  }
+}