--- /dev/null
+/* Analyze file differences for GNU DIFF.
+
+ Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1998, 2001, 2002,
+ 2004, 2006 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 this program; see the file COPYING.
+ If not, write to the Free Software Foundation,
+ 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+
+/* The basic algorithm is described in:
+ "An O(ND) Difference Algorithm and its Variations", Eugene Myers,
+ Algorithmica Vol. 1 No. 2, 1986, pp. 251-266;
+ see especially section 4.2, which describes the variation used below.
+ Unless the --minimal option is specified, this code uses the TOO_EXPENSIVE
+ heuristic, by Paul Eggert, to limit the cost to O(N**1.5 log N)
+ at the price of producing suboptimal output for large inputs with
+ many differences.
+
+ The basic algorithm was independently discovered as described in:
+ "Algorithms for Approximate String Matching", E. Ukkonen,
+ Information and Control Vol. 64, 1985, pp. 100-118. */
+
+#include "diff.h"
+#include <cmpbuf.h>
+#include <error.h>
+#include <file-type.h>
+#include <xalloc.h>
+
+static lin *xvec, *yvec; /* Vectors being compared. */
+static lin *fdiag; /* Vector, indexed by diagonal, containing
+ 1 + the X coordinate of the point furthest
+ along the given diagonal in the forward
+ search of the edit matrix. */
+static lin *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. */
+static lin too_expensive; /* Edit scripts longer than this are too
+ expensive to compute. */
+
+#define SNAKE_LIMIT 20 /* Snakes bigger than this are considered `big'. */
+
+struct partition
+{
+ lin xmid, ymid; /* Midpoints of this partition. */
+ bool lo_minimal; /* Nonzero if low half will be analyzed minimally. */
+ bool hi_minimal; /* Likewise for high half. */
+};
+
+/* Find the midpoint of the shortest edit script for a specified
+ portion of the two files.
+
+ 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.
+
+ If FIND_MINIMAL is nonzero, find the minimal edit script regardless
+ of expense. Otherwise, if the search is too expensive, use
+ heuristics to stop the search and report a suboptimal answer.
+
+ Set PART->(xmid,ymid) to the midpoint (XMID,YMID). The diagonal number
+ XMID - YMID equals the number of inserted lines minus the number
+ of deleted lines (counting only lines before the midpoint).
+
+ Set PART->lo_minimal to true iff the minimal edit script for the
+ left half of the partition is known; similarly for PART->hi_minimal.
+
+ 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.
+
+ If we return the "wrong" partitions,
+ the worst this can do is cause suboptimal diff output.
+ It cannot cause incorrect diff output. */
+
+static void
+diag (lin xoff, lin xlim, lin yoff, lin ylim, bool find_minimal,
+ struct partition *part)
+{
+ lin *const fd = fdiag; /* Give the compiler a chance. */
+ lin *const bd = bdiag; /* Additional help for the compiler. */
+ lin const *const xv = xvec; /* Still more help for the compiler. */
+ lin const *const yv = yvec; /* And more and more . . . */
+ lin const dmin = xoff - ylim; /* Minimum valid diagonal. */
+ lin const dmax = xlim - yoff; /* Maximum valid diagonal. */
+ lin const fmid = xoff - yoff; /* Center diagonal of top-down search. */
+ lin const bmid = xlim - ylim; /* Center diagonal of bottom-up search. */
+ lin fmin = fmid, fmax = fmid; /* Limits of top-down search. */
+ lin bmin = bmid, bmax = bmid; /* Limits of bottom-up search. */
+ lin c; /* Cost. */
+ bool 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)
+ {
+ lin d; /* Active diagonal. */
+ bool big_snake = false;
+
+ /* 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)
+ {
+ lin 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 > SNAKE_LIMIT)
+ big_snake = true;
+ fd[d] = x;
+ if (odd && bmin <= d && d <= bmax && bd[d] <= x)
+ {
+ part->xmid = x;
+ part->ymid = y;
+ part->lo_minimal = part->hi_minimal = true;
+ return;
+ }
+ }
+
+ /* Similarly extend the bottom-up search. */
+ bmin > dmin ? bd[--bmin - 1] = LIN_MAX : ++bmin;
+ bmax < dmax ? bd[++bmax + 1] = LIN_MAX : --bmax;
+ for (d = bmax; d >= bmin; d -= 2)
+ {
+ lin 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 > SNAKE_LIMIT)
+ big_snake = true;
+ bd[d] = x;
+ if (!odd && fmin <= d && d <= fmax && x <= fd[d])
+ {
+ part->xmid = x;
+ part->ymid = y;
+ part->lo_minimal = part->hi_minimal = true;
+ return;
+ }
+ }
+
+ if (find_minimal)
+ continue;
+
+ /* 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 (200 < c && big_snake && speed_large_files)
+ {
+ lin best = 0;
+
+ for (d = fmax; d >= fmin; d -= 2)
+ {
+ lin dd = d - fmid;
+ lin x = fd[d];
+ lin y = x - d;
+ lin v = (x - xoff) * 2 - dd;
+ if (v > 12 * (c + (dd < 0 ? -dd : dd)))
+ {
+ if (v > best
+ && xoff + SNAKE_LIMIT <= x && x < xlim
+ && yoff + SNAKE_LIMIT <= y && y < ylim)
+ {
+ /* We have a good enough best diagonal;
+ now insist that it end with a significant snake. */
+ int k;
+
+ for (k = 1; xv[x - k] == yv[y - k]; k++)
+ if (k == SNAKE_LIMIT)
+ {
+ best = v;
+ part->xmid = x;
+ part->ymid = y;
+ break;
+ }
+ }
+ }
+ }
+ if (best > 0)
+ {
+ part->lo_minimal = true;
+ part->hi_minimal = false;
+ return;
+ }
+
+ best = 0;
+ for (d = bmax; d >= bmin; d -= 2)
+ {
+ lin dd = d - bmid;
+ lin x = bd[d];
+ lin y = x - d;
+ lin v = (xlim - x) * 2 + dd;
+ if (v > 12 * (c + (dd < 0 ? -dd : dd)))
+ {
+ if (v > best
+ && xoff < x && x <= xlim - SNAKE_LIMIT
+ && yoff < y && y <= ylim - SNAKE_LIMIT)
+ {
+ /* We have a good enough best diagonal;
+ now insist that it end with a significant snake. */
+ int k;
+
+ for (k = 0; xv[x + k] == yv[y + k]; k++)
+ if (k == SNAKE_LIMIT - 1)
+ {
+ best = v;
+ part->xmid = x;
+ part->ymid = y;
+ break;
+ }
+ }
+ }
+ }
+ if (best > 0)
+ {
+ part->lo_minimal = false;
+ part->hi_minimal = true;
+ return;
+ }
+ }
+
+ /* Heuristic: if we've gone well beyond the call of duty,
+ give up and report halfway between our best results so far. */
+ if (c >= too_expensive)
+ {
+ lin fxybest;
+ lin bxybest;
+ lin fxbest IF_LINT (= 0);
+ lin bxbest IF_LINT (= 0);
+
+ /* Find forward diagonal that maximizes X + Y. */
+ fxybest = -1;
+ for (d = fmax; d >= fmin; d -= 2)
+ {
+ lin x = MIN (fd[d], xlim);
+ lin y = x - d;
+ if (ylim < y)
+ x = ylim + d, y = ylim;
+ if (fxybest < x + y)
+ {
+ fxybest = x + y;
+ fxbest = x;
+ }
+ }
+
+ /* Find backward diagonal that minimizes X + Y. */
+ bxybest = LIN_MAX;
+ for (d = bmax; d >= bmin; d -= 2)
+ {
+ lin x = MAX (xoff, bd[d]);
+ lin y = x - d;
+ if (y < yoff)
+ x = yoff + d, y = yoff;
+ if (x + y < bxybest)
+ {
+ bxybest = x + y;
+ bxbest = x;
+ }
+ }
+
+ /* Use the better of the two diagonals. */
+ if ((xlim + ylim) - bxybest < fxybest - (xoff + yoff))
+ {
+ part->xmid = fxbest;
+ part->ymid = fxybest - fxbest;
+ part->lo_minimal = true;
+ part->hi_minimal = false;
+ }
+ else
+ {
+ part->xmid = bxbest;
+ part->ymid = bxybest - bxbest;
+ part->lo_minimal = false;
+ part->hi_minimal = true;
+ }
+ return;
+ }
+ }
+}
+\f
+/* 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, by
+ storing 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.
+
+ If FIND_MINIMAL, find a minimal difference no matter how
+ expensive it is. */
+
+static void
+compareseq (lin xoff, lin xlim, lin yoff, lin ylim, bool find_minimal)
+{
+ lin const *xv = xvec; /* Help the compiler. */
+ lin const *yv = yvec;
+
+ /* Slide down the bottom initial diagonal. */
+ while (xoff < xlim && yoff < ylim && xv[xoff] == yv[yoff])
+ ++xoff, ++yoff;
+ /* Slide up the top initial diagonal. */
+ while (xlim > xoff && ylim > yoff && xv[xlim - 1] == yv[ylim - 1])
+ --xlim, --ylim;
+
+ /* Handle simple cases. */
+ if (xoff == xlim)
+ while (yoff < ylim)
+ files[1].changed[files[1].realindexes[yoff++]] = 1;
+ else if (yoff == ylim)
+ while (xoff < xlim)
+ files[0].changed[files[0].realindexes[xoff++]] = 1;
+ else
+ {
+ struct partition part IF_LINT (= {0});
+
+ /* Find a point of correspondence in the middle of the files. */
+ diag (xoff, xlim, yoff, ylim, find_minimal, &part);
+
+ /* Use the partitions to split this problem into subproblems. */
+ compareseq (xoff, part.xmid, yoff, part.ymid, part.lo_minimal);
+ compareseq (part.xmid, xlim, part.ymid, ylim, part.hi_minimal);
+ }
+}
+\f
+/* 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. */
+
+static void
+discard_confusing_lines (struct file_data filevec[])
+{
+ int f;
+ lin i;
+ char *discarded[2];
+ lin *equiv_count[2];
+ lin *p;
+
+ /* Allocate our results. */
+ p = xmalloc ((filevec[0].buffered_lines + filevec[1].buffered_lines)
+ * (2 * sizeof *p));
+ 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 = zalloc (filevec[0].equiv_max * (2 * sizeof *p));
+ equiv_count[0] = p;
+ equiv_count[1] = p + filevec[0].equiv_max;
+
+ 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] = zalloc (filevec[0].buffered_lines
+ + filevec[1].buffered_lines);
+ discarded[1] = discarded[0] + filevec[0].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++)
+ {
+ size_t end = filevec[f].buffered_lines;
+ char *discards = discarded[f];
+ lin *counts = equiv_count[1 - f];
+ lin *equivs = filevec[f].equivs;
+ size_t many = 5;
+ size_t 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++)
+ {
+ lin 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++)
+ {
+ lin 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 lin j;
+ lin length;
+ lin 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 lin consec;
+ lin minimum = 1;
+ lin tem = length >> 2;
+
+ /* 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 (0 < (tem >>= 2))
+ minimum <<= 1;
+ 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];
+ lin end = filevec[f].buffered_lines;
+ lin j = 0;
+ for (i = 0; i < end; ++i)
+ if (minimal || discards[i] == 0)
+ {
+ filevec[f].undiscarded[j] = filevec[f].equivs[i];
+ filevec[f].realindexes[j++] = i;
+ }
+ else
+ filevec[f].changed[i] = 1;
+ filevec[f].nondiscarded_lines = j;
+ }
+
+ free (discarded[0]);
+ free (equiv_count[0]);
+}
+\f
+/* Adjust inserts/deletes of identical lines to join changes
+ as much as possible.
+
+ We do something when a run of changed lines include a
+ line at one end and have an excluded, identical line at the other.
+ We are free to choose which identical line is included.
+ `compareseq' usually chooses the one at the beginning,
+ but usually it is cleaner to consider the following identical line
+ to be the "change". */
+
+static void
+shift_boundaries (struct file_data filevec[])
+{
+ int f;
+
+ for (f = 0; f < 2; f++)
+ {
+ char *changed = filevec[f].changed;
+ char *other_changed = filevec[1 - f].changed;
+ lin const *equivs = filevec[f].equivs;
+ lin i = 0;
+ lin j = 0;
+ lin i_end = filevec[f].buffered_lines;
+
+ while (1)
+ {
+ lin runlength, start, corresponding;
+
+ /* 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])
+ {
+ while (other_changed[j++])
+ continue;
+ i++;
+ }
+
+ if (i == i_end)
+ break;
+
+ start = i;
+
+ /* Find the end of this run of changes. */
+
+ while (changed[++i])
+ continue;
+ while (other_changed[j])
+ j++;
+
+ do
+ {
+ /* Record the length of this run of changes, so that
+ we can later determine whether the run has grown. */
+ runlength = i - start;
+
+ /* Move the changed region back, so long as the
+ previous unchanged line matches the last changed one.
+ This merges with previous changed regions. */
+
+ while (start && equivs[start - 1] == equivs[i - 1])
+ {
+ changed[--start] = 1;
+ changed[--i] = 0;
+ while (changed[start - 1])
+ start--;
+ while (other_changed[--j])
+ continue;
+ }
+
+ /* Set CORRESPONDING to the end of the changed run, at the last
+ point where it corresponds to a changed run in the other file.
+ CORRESPONDING == I_END means no such point has been found. */
+ corresponding = other_changed[j - 1] ? i : i_end;
+
+ /* Move the changed region forward, so long as the
+ first changed line matches the following unchanged one.
+ This merges with following changed regions.
+ Do this second, so that if there are no merges,
+ the changed region is moved forward as far as possible. */
+
+ while (i != i_end && equivs[start] == equivs[i])
+ {
+ changed[start++] = 0;
+ changed[i++] = 1;
+ while (changed[i])
+ i++;
+ while (other_changed[++j])
+ corresponding = i;
+ }
+ }
+ while (runlength != i - start);
+
+ /* If possible, move the fully-merged run of changes
+ back to a corresponding run in the other file. */
+
+ while (corresponding < i)
+ {
+ changed[--start] = 1;
+ changed[--i] = 0;
+ while (other_changed[--j])
+ continue;
+ }
+ }
+ }
+}
+\f
+/* 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 (lin line0, lin line1, lin deleted, lin inserted,
+ struct change *old)
+{
+ struct change *new = xmalloc (sizeof *new);
+
+ 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 (struct file_data const filevec[])
+{
+ struct change *script = 0;
+ char *changed0 = filevec[0].changed;
+ char *changed1 = filevec[1].changed;
+ lin len0 = filevec[0].buffered_lines;
+ lin len1 = filevec[1].buffered_lines;
+
+ /* Note that changedN[len0] does exist, and is 0. */
+
+ lin i0 = 0, i1 = 0;
+
+ while (i0 < len0 || i1 < len1)
+ {
+ if (changed0[i0] | changed1[i1])
+ {
+ lin 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 (struct file_data const filevec[])
+{
+ struct change *script = 0;
+ char *changed0 = filevec[0].changed;
+ char *changed1 = filevec[1].changed;
+ lin i0 = filevec[0].buffered_lines, i1 = filevec[1].buffered_lines;
+
+ /* Note that changedN[-1] does exist, and is 0. */
+
+ while (i0 >= 0 || i1 >= 0)
+ {
+ if (changed0[i0 - 1] | changed1[i1 - 1])
+ {
+ lin 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;
+}
+\f
+/* If CHANGES, briefly report that two files differed.
+ Return 2 if trouble, CHANGES otherwise. */
+static int
+briefly_report (int changes, struct file_data const filevec[])
+{
+ if (changes)
+ {
+ char const *label0 = file_label[0] ? file_label[0] : filevec[0].name;
+ char const *label1 = file_label[1] ? file_label[1] : filevec[1].name;
+ message ("Files %s and %s differ\n", label0, label1);
+ if (! brief)
+ changes = 2;
+ }
+
+ return changes;
+}
+
+/* Report the differences of two files. */
+int
+diff_2_files (struct comparison *cmp)
+{
+ lin diags;
+ int f;
+ 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, --brief without any --ignore-* options means
+ we can speed things up by treating the files as binary. */
+
+ if (read_files (cmp->file, files_can_be_treated_as_binary))
+ {
+ /* Files with different lengths must be different. */
+ if (cmp->file[0].stat.st_size != cmp->file[1].stat.st_size
+ && (cmp->file[0].desc < 0 || S_ISREG (cmp->file[0].stat.st_mode))
+ && (cmp->file[1].desc < 0 || S_ISREG (cmp->file[1].stat.st_mode)))
+ changes = 1;
+
+ /* Standard input equals itself. */
+ else if (cmp->file[0].desc == cmp->file[1].desc)
+ changes = 0;
+
+ else
+ /* Scan both files, a buffer at a time, looking for a difference. */
+ {
+ /* Allocate same-sized buffers for both files. */
+ size_t lcm_max = PTRDIFF_MAX - 1;
+ size_t buffer_size =
+ buffer_lcm (sizeof (word),
+ buffer_lcm (STAT_BLOCKSIZE (cmp->file[0].stat),
+ STAT_BLOCKSIZE (cmp->file[1].stat),
+ lcm_max),
+ lcm_max);
+ for (f = 0; f < 2; f++)
+ cmp->file[f].buffer = xrealloc (cmp->file[f].buffer, buffer_size);
+
+ for (;; cmp->file[0].buffered = cmp->file[1].buffered = 0)
+ {
+ /* Read a buffer's worth from both files. */
+ for (f = 0; f < 2; f++)
+ if (0 <= cmp->file[f].desc)
+ file_block_read (&cmp->file[f],
+ buffer_size - cmp->file[f].buffered);
+
+ /* If the buffers differ, the files differ. */
+ if (cmp->file[0].buffered != cmp->file[1].buffered
+ || memcmp (cmp->file[0].buffer,
+ cmp->file[1].buffer,
+ cmp->file[0].buffered))
+ {
+ changes = 1;
+ break;
+ }
+
+ /* If we reach end of file, the files are the same. */
+ if (cmp->file[0].buffered != buffer_size)
+ {
+ changes = 0;
+ break;
+ }
+ }
+ }
+
+ changes = briefly_report (changes, cmp->file);
+ }
+ 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 0, at each end of each vector. */
+
+ size_t s = cmp->file[0].buffered_lines + cmp->file[1].buffered_lines + 4;
+ char *flag_space = zalloc (s);
+ cmp->file[0].changed = flag_space + 1;
+ cmp->file[1].changed = flag_space + cmp->file[0].buffered_lines + 3;
+
+ /* 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 (cmp->file);
+
+ /* Now do the main comparison algorithm, considering just the
+ undiscarded lines. */
+
+ xvec = cmp->file[0].undiscarded;
+ yvec = cmp->file[1].undiscarded;
+ diags = (cmp->file[0].nondiscarded_lines
+ + cmp->file[1].nondiscarded_lines + 3);
+ fdiag = xmalloc (diags * (2 * sizeof *fdiag));
+ bdiag = fdiag + diags;
+ fdiag += cmp->file[1].nondiscarded_lines + 1;
+ bdiag += cmp->file[1].nondiscarded_lines + 1;
+
+ /* Set TOO_EXPENSIVE to be approximate square root of input size,
+ bounded below by 256. */
+ too_expensive = 1;
+ for (; diags != 0; diags >>= 2)
+ too_expensive <<= 1;
+ too_expensive = MAX (256, too_expensive);
+
+ files[0] = cmp->file[0];
+ files[1] = cmp->file[1];
+
+ compareseq (0, cmp->file[0].nondiscarded_lines,
+ 0, cmp->file[1].nondiscarded_lines, minimal);
+
+ free (fdiag - (cmp->file[1].nondiscarded_lines + 1));
+
+ /* Modify the results slightly to make them prettier
+ in cases where that can validly be done. */
+
+ shift_boundaries (cmp->file);
+
+ /* 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 (cmp->file);
+ else
+ script = build_script (cmp->file);
+
+ /* Set CHANGES if we had any diffs.
+ If some changes are ignored, we must scan the script to decide. */
+ if (ignore_blank_lines || ignore_regexp.fastmap)
+ {
+ struct change *next = script;
+ changes = 0;
+
+ while (next && changes == 0)
+ {
+ struct change *this, *end;
+ lin first0, last0, first1, last1;
+
+ /* 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 = 0;
+
+ /* Determine whether this hunk is really a difference. */
+ if (analyze_hunk (this, &first0, &last0, &first1, &last1))
+ changes = 1;
+
+ /* Reconnect the script so it will all be freed properly. */
+ end->link = next;
+ }
+ }
+ else
+ changes = (script != 0);
+
+ if (brief)
+ changes = briefly_report (changes, cmp->file);
+ else
+ {
+ if (changes | !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 (file_label[0] ? file_label[0] : cmp->file[0].name,
+ file_label[1] ? file_label[1] : cmp->file[1].name,
+ cmp->parent != 0);
+
+ switch (output_style)
+ {
+ case OUTPUT_CONTEXT:
+ print_context_script (script, false);
+ break;
+
+ case OUTPUT_UNIFIED:
+ print_context_script (script, true);
+ 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);
+ break;
+
+ default:
+ abort ();
+ }
+
+ finish_output ();
+ }
+ }
+
+ free (cmp->file[0].undiscarded);
+
+ free (flag_space);
+
+ for (f = 0; f < 2; f++)
+ {
+ free (cmp->file[f].equivs);
+ free (cmp->file[f].linbuf + cmp->file[f].linbuf_base);
+ }
+
+ for (e = script; e; e = p)
+ {
+ p = e->link;
+ free (e);
+ }
+
+ if (! ROBUST_OUTPUT_STYLE (output_style))
+ for (f = 0; f < 2; ++f)
+ if (cmp->file[f].missing_newline)
+ {
+ error (0, 0, "%s: %s\n",
+ file_label[f] ? file_label[f] : cmp->file[f].name,
+ _("No newline at end of file"));
+ changes = 2;
+ }
+ }
+
+ if (cmp->file[0].buffer != cmp->file[1].buffer)
+ free (cmp->file[0].buffer);
+ free (cmp->file[1].buffer);
+
+ return changes;
+}
projects / pspp / commitdiff