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+/* Analyze file differences for GNU DIFF.
+ Copyright (C) 1988, 1989, 1992 Free Software Foundation, Inc.
+
+This file is part of GNU DIFF.
+
+GNU DIFF is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU DIFF is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU DIFF; see the file COPYING. If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
+
+/* The basic algorithm is described in:
+ "An O(ND) Difference Algorithm and its Variations", Eugene Myers,
+ Algorithmica Vol. 1 No. 2, 1986, p 251. */
+
+#include "diff.h"
+
+int read_files ();
+void finish_output ();
+void print_context_script ();
+void print_ed_script ();
+void print_ifdef_script ();
+void print_sdiff_script ();
+void print_normal_script ();
+void print_rcs_script ();
+void pr_forward_ed_script ();
+void setup_output ();
+
+extern int no_discards;
+
+static int *xvec, *yvec; /* Vectors being compared. */
+static int *fdiag; /* Vector, indexed by diagonal, containing
+ the X coordinate of the point furthest
+ along the given diagonal in the forward
+ search of the edit matrix. */
+static int *bdiag; /* Vector, indexed by diagonal, containing
+ the X coordinate of the point furthest
+ along the given diagonal in the backward
+ search of the edit matrix. */
+
+/* Find the midpoint of the shortest edit script for a specified
+ portion of the two files.
+
+ We scan from the beginnings of the files, and simultaneously from the ends,
+ doing a breadth-first search through the space of edit-sequence.
+ When the two searches meet, we have found the midpoint of the shortest
+ edit sequence.
+
+ The value returned is the number of the diagonal on which the midpoint lies.
+ The diagonal number equals the number of inserted lines minus the number
+ of deleted lines (counting only lines before the midpoint).
+ The edit cost is stored into *COST; this is the total number of
+ lines inserted or deleted (counting only lines before the midpoint).
+
+ This function assumes that the first lines of the specified portions
+ of the two files do not match, and likewise that the last lines do not
+ match. The caller must trim matching lines from the beginning and end
+ of the portions it is going to specify.
+
+ Note that if we return the "wrong" diagonal value, or if
+ the value of bdiag at that diagonal is "wrong",
+ the worst this can do is cause suboptimal diff output.
+ It cannot cause incorrect diff output. */
+
+static int
+diag (xoff, xlim, yoff, ylim, cost)
+ int xoff, xlim, yoff, ylim;
+ int *cost;
+{
+ int *const fd = fdiag; /* Give the compiler a chance. */
+ int *const bd = bdiag; /* Additional help for the compiler. */
+ int *const xv = xvec; /* Still more help for the compiler. */
+ int *const yv = yvec; /* And more and more . . . */
+ const int dmin = xoff - ylim; /* Minimum valid diagonal. */
+ const int dmax = xlim - yoff; /* Maximum valid diagonal. */
+ const int fmid = xoff - yoff; /* Center diagonal of top-down search. */
+ const int bmid = xlim - ylim; /* Center diagonal of bottom-up search. */
+ int fmin = fmid, fmax = fmid; /* Limits of top-down search. */
+ int bmin = bmid, bmax = bmid; /* Limits of bottom-up search. */
+ int c; /* Cost. */
+ int odd = (fmid - bmid) & 1; /* True if southeast corner is on an odd
+ diagonal with respect to the northwest. */
+
+ fd[fmid] = xoff;
+ bd[bmid] = xlim;
+
+ for (c = 1;; ++c)
+ {
+ int d; /* Active diagonal. */
+ int big_snake = 0;
+
+ /* Extend the top-down search by an edit step in each diagonal. */
+ fmin > dmin ? fd[--fmin - 1] = -1 : ++fmin;
+ fmax < dmax ? fd[++fmax + 1] = -1 : --fmax;
+ for (d = fmax; d >= fmin; d -= 2)
+ {
+ int x, y, oldx, tlo = fd[d - 1], thi = fd[d + 1];
+
+ if (tlo >= thi)
+ x = tlo + 1;
+ else
+ x = thi;
+ oldx = x;
+ y = x - d;
+ while (x < xlim && y < ylim && xv[x] == yv[y])
+ ++x, ++y;
+ if (x - oldx > 20)
+ big_snake = 1;
+ fd[d] = x;
+ if (odd && bmin <= d && d <= bmax && bd[d] <= fd[d])
+ {
+ *cost = 2 * c - 1;
+ return d;
+ }
+ }
+
+ /* Similar extend the bottom-up search. */
+ bmin > dmin ? bd[--bmin - 1] = INT_MAX : ++bmin;
+ bmax < dmax ? bd[++bmax + 1] = INT_MAX : --bmax;
+ for (d = bmax; d >= bmin; d -= 2)
+ {
+ int x, y, oldx, tlo = bd[d - 1], thi = bd[d + 1];
+
+ if (tlo < thi)
+ x = tlo;
+ else
+ x = thi - 1;
+ oldx = x;
+ y = x - d;
+ while (x > xoff && y > yoff && xv[x - 1] == yv[y - 1])
+ --x, --y;
+ if (oldx - x > 20)
+ big_snake = 1;
+ bd[d] = x;
+ if (!odd && fmin <= d && d <= fmax && bd[d] <= fd[d])
+ {
+ *cost = 2 * c;
+ return d;
+ }
+ }
+
+ /* Heuristic: check occasionally for a diagonal that has made
+ lots of progress compared with the edit distance.
+ If we have any such, find the one that has made the most
+ progress and return it as if it had succeeded.
+
+ With this heuristic, for files with a constant small density
+ of changes, the algorithm is linear in the file size. */
+
+ if (c > 200 && big_snake && heuristic)
+ {
+ int best;
+ int bestpos;
+
+ best = 0;
+ for (d = fmax; d >= fmin; d -= 2)
+ {
+ int dd = d - fmid;
+ if ((fd[d] - xoff)*2 - dd > 12 * (c + (dd > 0 ? dd : -dd)))
+ {
+ if (fd[d] * 2 - dd > best
+ && fd[d] - xoff > 20
+ && fd[d] - d - yoff > 20)
+ {
+ int k;
+ int x = fd[d];
+
+ /* We have a good enough best diagonal;
+ now insist that it end with a significant snake. */
+ for (k = 1; k <= 20; k++)
+ if (xvec[x - k] != yvec[x - d - k])
+ break;
+
+ if (k == 21)
+ {
+ best = fd[d] * 2 - dd;
+ bestpos = d;
+ }
+ }
+ }
+ }
+ if (best > 0)
+ {
+ *cost = 2 * c - 1;
+ return bestpos;
+ }
+
+ best = 0;
+ for (d = bmax; d >= bmin; d -= 2)
+ {
+ int dd = d - bmid;
+ if ((xlim - bd[d])*2 + dd > 12 * (c + (dd > 0 ? dd : -dd)))
+ {
+ if ((xlim - bd[d]) * 2 + dd > best
+ && xlim - bd[d] > 20
+ && ylim - (bd[d] - d) > 20)
+ {
+ /* We have a good enough best diagonal;
+ now insist that it end with a significant snake. */
+ int k;
+ int x = bd[d];
+
+ for (k = 0; k < 20; k++)
+ if (xvec[x + k] != yvec[x - d + k])
+ break;
+ if (k == 20)
+ {
+ best = (xlim - bd[d]) * 2 + dd;
+ bestpos = d;
+ }
+ }
+ }
+ }
+ if (best > 0)
+ {
+ *cost = 2 * c - 1;
+ return bestpos;
+ }
+ }
+ }
+}
+
+/* Compare in detail contiguous subsequences of the two files
+ which are known, as a whole, to match each other.
+
+ The results are recorded in the vectors files[N].changed_flag, by
+ storing a 1 in the element for each line that is an insertion or deletion.
+
+ The subsequence of file 0 is [XOFF, XLIM) and likewise for file 1.
+
+ Note that XLIM, YLIM are exclusive bounds.
+ All line numbers are origin-0 and discarded lines are not counted. */
+
+static void
+compareseq (xoff, xlim, yoff, ylim)
+ int xoff, xlim, yoff, ylim;
+{
+ /* Slide down the bottom initial diagonal. */
+ while (xoff < xlim && yoff < ylim && xvec[xoff] == yvec[yoff])
+ ++xoff, ++yoff;
+ /* Slide up the top initial diagonal. */
+ while (xlim > xoff && ylim > yoff && xvec[xlim - 1] == yvec[ylim - 1])
+ --xlim, --ylim;
+
+ /* Handle simple cases. */
+ if (xoff == xlim)
+ while (yoff < ylim)
+ files[1].changed_flag[files[1].realindexes[yoff++]] = 1;
+ else if (yoff == ylim)
+ while (xoff < xlim)
+ files[0].changed_flag[files[0].realindexes[xoff++]] = 1;
+ else
+ {
+ int c, d, f, b;
+
+ /* Find a point of correspondence in the middle of the files. */
+
+ d = diag (xoff, xlim, yoff, ylim, &c);
+ f = fdiag[d];
+ b = bdiag[d];
+
+ if (c == 1)
+ {
+ /* This should be impossible, because it implies that
+ one of the two subsequences is empty,
+ and that case was handled above without calling `diag'.
+ Let's verify that this is true. */
+ abort ();
+#if 0
+ /* The two subsequences differ by a single insert or delete;
+ record it and we are done. */
+ if (d < xoff - yoff)
+ files[1].changed_flag[files[1].realindexes[b - d - 1]] = 1;
+ else
+ files[0].changed_flag[files[0].realindexes[b]] = 1;
+#endif
+ }
+ else
+ {
+ /* Use that point to split this problem into two subproblems. */
+ compareseq (xoff, b, yoff, b - d);
+ /* This used to use f instead of b,
+ but that is incorrect!
+ It is not necessarily the case that diagonal d
+ has a snake from b to f. */
+ compareseq (b, xlim, b - d, ylim);
+ }
+ }
+}
+
+/* Discard lines from one file that have no matches in the other file.
+
+ A line which is discarded will not be considered by the actual
+ comparison algorithm; it will be as if that line were not in the file.
+ The file's `realindexes' table maps virtual line numbers
+ (which don't count the discarded lines) into real line numbers;
+ this is how the actual comparison algorithm produces results
+ that are comprehensible when the discarded lines are counted.
+
+ When we discard a line, we also mark it as a deletion or insertion
+ so that it will be printed in the output. */
+
+void
+discard_confusing_lines (filevec)
+ struct file_data filevec[];
+{
+ unsigned int f, i;
+ char *discarded[2];
+ int *equiv_count[2];
+ int *p;
+
+ /* Allocate our results. */
+ p = (int *) xmalloc ((filevec[0].buffered_lines + filevec[1].buffered_lines)
+ * (2 * sizeof (int)));
+ for (f = 0; f < 2; f++)
+ {
+ filevec[f].undiscarded = p; p += filevec[f].buffered_lines;
+ filevec[f].realindexes = p; p += filevec[f].buffered_lines;
+ }
+
+ /* Set up equiv_count[F][I] as the number of lines in file F
+ that fall in equivalence class I. */
+
+ p = (int *) xmalloc (filevec[0].equiv_max * (2 * sizeof (int)));
+ equiv_count[0] = p;
+ equiv_count[1] = p + filevec[0].equiv_max;
+ bzero (p, filevec[0].equiv_max * (2 * sizeof (int)));
+
+ for (i = 0; i < filevec[0].buffered_lines; ++i)
+ ++equiv_count[0][filevec[0].equivs[i]];
+ for (i = 0; i < filevec[1].buffered_lines; ++i)
+ ++equiv_count[1][filevec[1].equivs[i]];
+
+ /* Set up tables of which lines are going to be discarded. */
+
+ discarded[0] = (char *) xmalloc (filevec[0].buffered_lines
+ + filevec[1].buffered_lines);
+ discarded[1] = discarded[0] + filevec[0].buffered_lines;
+ bzero (discarded[0], filevec[0].buffered_lines + filevec[1].buffered_lines);
+
+ /* Mark to be discarded each line that matches no line of the other file.
+ If a line matches many lines, mark it as provisionally discardable. */
+
+ for (f = 0; f < 2; f++)
+ {
+ unsigned int end = filevec[f].buffered_lines;
+ char *discards = discarded[f];
+ int *counts = equiv_count[1 - f];
+ int *equivs = filevec[f].equivs;
+ unsigned int many = 5;
+ unsigned int tem = end / 64;
+
+ /* Multiply MANY by approximate square root of number of lines.
+ That is the threshold for provisionally discardable lines. */
+ while ((tem = tem >> 2) > 0)
+ many *= 2;
+
+ for (i = 0; i < end; i++)
+ {
+ int nmatch;
+ if (equivs[i] == 0)
+ continue;
+ nmatch = counts[equivs[i]];
+ if (nmatch == 0)
+ discards[i] = 1;
+ else if (nmatch > many)
+ discards[i] = 2;
+ }
+ }
+
+ /* Don't really discard the provisional lines except when they occur
+ in a run of discardables, with nonprovisionals at the beginning
+ and end. */
+
+ for (f = 0; f < 2; f++)
+ {
+ unsigned int end = filevec[f].buffered_lines;
+ register char *discards = discarded[f];
+
+ for (i = 0; i < end; i++)
+ {
+ /* Cancel provisional discards not in middle of run of discards. */
+ if (discards[i] == 2)
+ discards[i] = 0;
+ else if (discards[i] != 0)
+ {
+ /* We have found a nonprovisional discard. */
+ register int j;
+ unsigned int length;
+ unsigned int provisional = 0;
+
+ /* Find end of this run of discardable lines.
+ Count how many are provisionally discardable. */
+ for (j = i; j < end; j++)
+ {
+ if (discards[j] == 0)
+ break;
+ if (discards[j] == 2)
+ ++provisional;
+ }
+
+ /* Cancel provisional discards at end, and shrink the run. */
+ while (j > i && discards[j - 1] == 2)
+ discards[--j] = 0, --provisional;
+
+ /* Now we have the length of a run of discardable lines
+ whose first and last are not provisional. */
+ length = j - i;
+
+ /* If 1/4 of the lines in the run are provisional,
+ cancel discarding of all provisional lines in the run. */
+ if (provisional * 4 > length)
+ {
+ while (j > i)
+ if (discards[--j] == 2)
+ discards[j] = 0;
+ }
+ else
+ {
+ register unsigned int consec;
+ unsigned int minimum = 1;
+ unsigned int tem = length / 4;
+
+ /* MINIMUM is approximate square root of LENGTH/4.
+ A subrun of two or more provisionals can stand
+ when LENGTH is at least 16.
+ A subrun of 4 or more can stand when LENGTH >= 64. */
+ while ((tem = tem >> 2) > 0)
+ minimum *= 2;
+ minimum++;
+
+ /* Cancel any subrun of MINIMUM or more provisionals
+ within the larger run. */
+ for (j = 0, consec = 0; j < length; j++)
+ if (discards[i + j] != 2)
+ consec = 0;
+ else if (minimum == ++consec)
+ /* Back up to start of subrun, to cancel it all. */
+ j -= consec;
+ else if (minimum < consec)
+ discards[i + j] = 0;
+
+ /* Scan from beginning of run
+ until we find 3 or more nonprovisionals in a row
+ or until the first nonprovisional at least 8 lines in.
+ Until that point, cancel any provisionals. */
+ for (j = 0, consec = 0; j < length; j++)
+ {
+ if (j >= 8 && discards[i + j] == 1)
+ break;
+ if (discards[i + j] == 2)
+ consec = 0, discards[i + j] = 0;
+ else if (discards[i + j] == 0)
+ consec = 0;
+ else
+ consec++;
+ if (consec == 3)
+ break;
+ }
+
+ /* I advances to the last line of the run. */
+ i += length - 1;
+
+ /* Same thing, from end. */
+ for (j = 0, consec = 0; j < length; j++)
+ {
+ if (j >= 8 && discards[i - j] == 1)
+ break;
+ if (discards[i - j] == 2)
+ consec = 0, discards[i - j] = 0;
+ else if (discards[i - j] == 0)
+ consec = 0;
+ else
+ consec++;
+ if (consec == 3)
+ break;
+ }
+ }
+ }
+ }
+ }
+
+ /* Actually discard the lines. */
+ for (f = 0; f < 2; f++)
+ {
+ char *discards = discarded[f];
+ unsigned int end = filevec[f].buffered_lines;
+ unsigned int j = 0;
+ for (i = 0; i < end; ++i)
+ if (no_discards || discards[i] == 0)
+ {
+ filevec[f].undiscarded[j] = filevec[f].equivs[i];
+ filevec[f].realindexes[j++] = i;
+ }
+ else
+ filevec[f].changed_flag[i] = 1;
+ filevec[f].nondiscarded_lines = j;
+ }
+
+ free (discarded[0]);
+ free (equiv_count[0]);
+}
+
+/* Adjust inserts/deletes of blank lines to join changes
+ as much as possible.
+
+ We do something when a run of changed lines include a blank
+ line at one end and have an excluded blank line at the other.
+ We are free to choose which blank line is included.
+ `compareseq' always chooses the one at the beginning,
+ but usually it is cleaner to consider the following blank line
+ to be the "change". The only exception is if the preceding blank line
+ would join this change to other changes. */
+
+int inhibit;
+
+static void
+shift_boundaries (filevec)
+ struct file_data filevec[];
+{
+ int f;
+
+ if (inhibit)
+ return;
+
+ for (f = 0; f < 2; f++)
+ {
+ char *changed = filevec[f].changed_flag;
+ char *other_changed = filevec[1-f].changed_flag;
+ int i = 0;
+ int j = 0;
+ int i_end = filevec[f].buffered_lines;
+ int preceding = -1;
+ int other_preceding = -1;
+
+ while (1)
+ {
+ int start, other_start;
+
+ /* Scan forwards to find beginning of another run of changes.
+ Also keep track of the corresponding point in the other file. */
+
+ while (i < i_end && changed[i] == 0)
+ {
+ while (other_changed[j++])
+ /* Non-corresponding lines in the other file
+ will count as the preceding batch of changes. */
+ other_preceding = j;
+ i++;
+ }
+
+ if (i == i_end)
+ break;
+
+ start = i;
+ other_start = j;
+
+ while (1)
+ {
+ /* Now find the end of this run of changes. */
+
+ while (changed[++i] != 0)
+ ;
+
+ /* If the first changed line matches the following unchanged one,
+ and this run does not follow right after a previous run,
+ and there are no lines deleted from the other file here,
+ then classify the first changed line as unchanged
+ and the following line as changed in its place. */
+
+ /* You might ask, how could this run follow right after another?
+ Only because the previous run was shifted here. */
+
+ if (i != i_end
+ && files[f].equivs[start] == files[f].equivs[i]
+ && !other_changed[j]
+ && !(start == preceding || other_start == other_preceding))
+ {
+ changed[start++] = 0;
+ changed[i] = 1;
+ /* Since one line-that-matches is now before this run
+ instead of after, we must advance in the other file
+ to keep in synch. */
+ ++j;
+ }
+ else
+ break;
+ }
+
+ preceding = i;
+ other_preceding = j;
+ }
+ }
+}
+
+/* Cons an additional entry onto the front of an edit script OLD.
+ LINE0 and LINE1 are the first affected lines in the two files (origin 0).
+ DELETED is the number of lines deleted here from file 0.
+ INSERTED is the number of lines inserted here in file 1.
+
+ If DELETED is 0 then LINE0 is the number of the line before
+ which the insertion was done; vice versa for INSERTED and LINE1. */
+
+static struct change *
+add_change (line0, line1, deleted, inserted, old)
+ int line0, line1, deleted, inserted;
+ struct change *old;
+{
+ struct change *new = (struct change *) xmalloc (sizeof (struct change));
+
+ new->line0 = line0;
+ new->line1 = line1;
+ new->inserted = inserted;
+ new->deleted = deleted;
+ new->link = old;
+ return new;
+}
+
+/* Scan the tables of which lines are inserted and deleted,
+ producing an edit script in reverse order. */
+
+static struct change *
+build_reverse_script (filevec)
+ struct file_data filevec[];
+{
+ struct change *script = 0;
+ char *changed0 = filevec[0].changed_flag;
+ char *changed1 = filevec[1].changed_flag;
+ int len0 = filevec[0].buffered_lines;
+ int len1 = filevec[1].buffered_lines;
+
+ /* Note that changedN[len0] does exist, and contains 0. */
+
+ int i0 = 0, i1 = 0;
+
+ while (i0 < len0 || i1 < len1)
+ {
+ if (changed0[i0] || changed1[i1])
+ {
+ int line0 = i0, line1 = i1;
+
+ /* Find # lines changed here in each file. */
+ while (changed0[i0]) ++i0;
+ while (changed1[i1]) ++i1;
+
+ /* Record this change. */
+ script = add_change (line0, line1, i0 - line0, i1 - line1, script);
+ }
+
+ /* We have reached lines in the two files that match each other. */
+ i0++, i1++;
+ }
+
+ return script;
+}
+
+/* Scan the tables of which lines are inserted and deleted,
+ producing an edit script in forward order. */
+
+static struct change *
+build_script (filevec)
+ struct file_data filevec[];
+{
+ struct change *script = 0;
+ char *changed0 = filevec[0].changed_flag;
+ char *changed1 = filevec[1].changed_flag;
+ int i0 = filevec[0].buffered_lines, i1 = filevec[1].buffered_lines;
+
+ /* Note that changedN[-1] does exist, and contains 0. */
+
+ while (i0 >= 0 || i1 >= 0)
+ {
+ if (changed0[i0 - 1] || changed1[i1 - 1])
+ {
+ int line0 = i0, line1 = i1;
+
+ /* Find # lines changed here in each file. */
+ while (changed0[i0 - 1]) --i0;
+ while (changed1[i1 - 1]) --i1;
+
+ /* Record this change. */
+ script = add_change (i0, i1, line0 - i0, line1 - i1, script);
+ }
+
+ /* We have reached lines in the two files that match each other. */
+ i0--, i1--;
+ }
+
+ return script;
+}
+
+/* Report the differences of two files. DEPTH is the current directory
+ depth. */
+int
+diff_2_files (filevec, depth)
+ struct file_data filevec[];
+ int depth;
+{
+ int diags;
+ int i;
+ struct change *e, *p;
+ struct change *script;
+ int changes;
+
+
+ /* If we have detected that either file is binary,
+ compare the two files as binary. This can happen
+ only when the first chunk is read.
+ Also, -q means treat all files as binary. */
+
+ if (read_files (filevec))
+ {
+ /* Files with different lengths must be different. */
+ if (filevec[0].stat.st_size != filevec[1].stat.st_size
+ && (filevec[0].desc < 0 || S_ISREG (filevec[0].stat.st_mode))
+ && (filevec[1].desc < 0 || S_ISREG (filevec[1].stat.st_mode)))
+ changes = 1;
+
+ /* Standard input equals itself. */
+ else if (filevec[0].desc == filevec[1].desc)
+ changes = 0;
+
+ else
+ /* Scan both files, a buffer at a time, looking for a difference. */
+ {
+ /* Allocate same-sized buffers for both files. */
+ int buffer_size = max (STAT_BLOCKSIZE (filevec[0].stat),
+ STAT_BLOCKSIZE (filevec[1].stat));
+ for (i = 0; i < 2; i++)
+ filevec[i].buffer = xrealloc (filevec[i].buffer, buffer_size);
+
+ for (;; filevec[0].buffered_chars = filevec[1].buffered_chars = 0)
+ {
+ /* Read a buffer's worth from both files. */
+ for (i = 0; i < 2; i++)
+ if (0 <= filevec[i].desc)
+ while (filevec[i].buffered_chars != buffer_size)
+ {
+ int r = read (filevec[i].desc,
+ filevec[i].buffer
+ + filevec[i].buffered_chars,
+ buffer_size - filevec[i].buffered_chars);
+ if (r == 0)
+ break;
+ if (r < 0)
+ pfatal_with_name (filevec[i].name);
+ filevec[i].buffered_chars += r;
+ }
+
+ /* If the buffers differ, the files differ. */
+ if (filevec[0].buffered_chars != filevec[1].buffered_chars
+ || bcmp (filevec[0].buffer,
+ filevec[1].buffer,
+ filevec[0].buffered_chars) != 0)
+ {
+ changes = 1;
+ break;
+ }
+
+ /* If we reach end of file, the files are the same. */
+ if (filevec[0].buffered_chars != buffer_size)
+ {
+ changes = 0;
+ break;
+ }
+ }
+ }
+
+ if (changes)
+ message (no_details_flag ? "Files %s and %s differ\n"
+ : "Binary files %s and %s differ\n",
+ filevec[0].name, filevec[1].name);
+ }
+ else
+ {
+ /* Allocate vectors for the results of comparison:
+ a flag for each line of each file, saying whether that line
+ is an insertion or deletion.
+ Allocate an extra element, always zero, at each end of each vector. */
+
+ filevec[0].changed_flag = (char *) xmalloc (filevec[0].buffered_lines
+ + filevec[1].buffered_lines
+ + 4);
+ bzero (filevec[0].changed_flag, filevec[0].buffered_lines
+ + filevec[1].buffered_lines + 4);
+ filevec[0].changed_flag++;
+ filevec[1].changed_flag = filevec[0].changed_flag
+ + filevec[0].buffered_lines + 2;
+
+ /* Some lines are obviously insertions or deletions
+ because they don't match anything. Detect them now, and
+ avoid even thinking about them in the main comparison algorithm. */
+
+ discard_confusing_lines (filevec);
+
+ /* Now do the main comparison algorithm, considering just the
+ undiscarded lines. */
+
+ xvec = filevec[0].undiscarded;
+ yvec = filevec[1].undiscarded;
+ diags = filevec[0].nondiscarded_lines + filevec[1].nondiscarded_lines + 3;
+ fdiag = (int *) xmalloc (diags * (2 * sizeof (int)));
+ bdiag = fdiag + diags;
+ fdiag += filevec[1].nondiscarded_lines + 1;
+ bdiag += filevec[1].nondiscarded_lines + 1;
+
+ files[0] = filevec[0];
+ files[1] = filevec[1];
+
+ compareseq (0, filevec[0].nondiscarded_lines,
+ 0, filevec[1].nondiscarded_lines);
+
+ free (fdiag - (filevec[1].nondiscarded_lines + 1));
+
+ /* Modify the results slightly to make them prettier
+ in cases where that can validly be done. */
+
+ shift_boundaries (filevec);
+
+ /* Get the results of comparison in the form of a chain
+ of `struct change's -- an edit script. */
+
+ if (output_style == OUTPUT_ED)
+ script = build_reverse_script (filevec);
+ else
+ script = build_script (filevec);
+
+ if (script || ! no_diff_means_no_output)
+ {
+ /* Record info for starting up output,
+ to be used if and when we have some output to print. */
+ setup_output (files[0].name, files[1].name, depth);
+
+ switch (output_style)
+ {
+ case OUTPUT_CONTEXT:
+ print_context_script (script, 0);
+ break;
+
+ case OUTPUT_UNIFIED:
+ print_context_script (script, 1);
+ break;
+
+ case OUTPUT_ED:
+ print_ed_script (script);
+ break;
+
+ case OUTPUT_FORWARD_ED:
+ pr_forward_ed_script (script);
+ break;
+
+ case OUTPUT_RCS:
+ print_rcs_script (script);
+ break;
+
+ case OUTPUT_NORMAL:
+ print_normal_script (script);
+ break;
+
+ case OUTPUT_IFDEF:
+ print_ifdef_script (script);
+ break;
+
+ case OUTPUT_SDIFF:
+ print_sdiff_script (script);
+ }
+
+ finish_output ();
+ }
+
+ /* Set CHANGES if we had any diffs that were printed.
+ If some changes are ignored, we must scan the script to decide. */
+ if (ignore_blank_lines_flag || ignore_regexp_list)
+ {
+ struct change *next = script;
+ changes = 0;
+
+ while (next && changes == 0)
+ {
+ struct change *this, *end;
+ int first0, last0, first1, last1, deletes, inserts;
+
+ /* Find a set of changes that belong together. */
+ this = next;
+ end = find_change (next);
+
+ /* Disconnect them from the rest of the changes, making them
+ a hunk, and remember the rest for next iteration. */
+ next = end->link;
+ end->link = NULL;
+
+ /* Determine whether this hunk was printed. */
+ analyze_hunk (this, &first0, &last0, &first1, &last1,
+ &deletes, &inserts);
+
+ /* Reconnect the script so it will all be freed properly. */
+ end->link = next;
+
+ if (deletes || inserts)
+ changes = 1;
+ }
+ }
+ else
+ changes = (script != 0);
+
+ free (filevec[0].undiscarded);
+
+ free (filevec[0].changed_flag - 1);
+
+ for (i = 1; i >= 0; --i)
+ free (filevec[i].equivs);
+
+ for (i = 0; i < 2; ++i)
+ free (filevec[i].linbuf + filevec[i].linbuf_base);
+
+ for (e = script; e; e = p)
+ {
+ p = e->link;
+ free (e);
+ }
+
+ if (! ROBUST_OUTPUT_STYLE (output_style))
+ for (i = 0; i < 2; ++i)
+ if (filevec[i].missing_newline)
+ {
+ error ("No newline at end of file %s", filevec[i].name, "");
+ changes = 2;
+ }
+ }
+
+ if (filevec[0].buffer != filevec[1].buffer)
+ free (filevec[0].buffer);
+ free (filevec[1].buffer);
+
+ return changes;
+}
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