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-/* $NetBSD: analyze.c,v 1.1.1.1 2003/01/26 00:43:16 wiz Exp $ */
-
-/* Analyze file differences for GNU DIFF.
-
- Copyright (C) 1988, 1989, 1992, 1993, 1994, 1995, 1998, 2001, 2002
- 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,
- 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 <regex.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).
- Return the approximate edit cost; this is the total number of
- lines inserted or deleted (counting only lines before the midpoint),
- unless a heuristic is used to terminate the search prematurely.
-
- 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 lin
-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 = 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)
- {
- 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 = 1;
- fd[d] = x;
- if (odd && bmin <= d && d <= bmax && bd[d] <= x)
- {
- part->xmid = x;
- part->ymid = y;
- part->lo_minimal = part->hi_minimal = 1;
- return 2 * c - 1;
- }
- }
-
- /* 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 = 1;
- bd[d] = x;
- if (!odd && fmin <= d && d <= fmax && x <= fd[d])
- {
- part->xmid = x;
- part->ymid = y;
- part->lo_minimal = part->hi_minimal = 1;
- return 2 * c;
- }
- }
-
- 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;
-
- 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 = 1;
- part->hi_minimal = 0;
- return 2 * c - 1;
- }
-
- 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 = 0;
- part->hi_minimal = 1;
- return 2 * c - 1;
- }
- }
-
- /* 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, fxbest;
- lin bxybest, bxbest;
-
- fxbest = bxbest = 0; /* Pacify `gcc -Wall'. */
-
- /* 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 = 1;
- part->hi_minimal = 0;
- }
- else
- {
- part->xmid = bxbest;
- part->ymid = bxybest - bxbest;
- part->lo_minimal = 0;
- part->hi_minimal = 1;
- }
- return 2 * c - 1;
- }
- }
-}
-
-/* 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
- {
- lin c;
- struct partition part;
-
- /* Find a point of correspondence in the middle of the files. */
-
- c = diag (xoff, xlim, yoff, ylim, find_minimal, &part);
-
- 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 (part.xmid - part.ymid < xoff - yoff)
- files[1].changed[files[1].realindexes[part.ymid - 1]] = 1;
- else
- files[0].changed[files[0].realindexes[part.xmid]] = 1;
-#endif
- }
- else
- {
- /* 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);
- }
- }
-}
-
-/* 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]);
-}
-
-/* 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++)
- {
- bool *changed = filevec[f].changed;
- bool const *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;
- }
- }
- }
-}
-
-/* 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;
- bool *changed0 = filevec[0].changed;
- bool *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;
- bool *changed0 = filevec[0].changed;
- bool *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;
-}
-
-/* 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;
-
- if (brief)
- message ("Files %s and %s differ\n", label0, label1);
- else
- {
- message ("Binary files %s and %s differ\n", label0, label1);
- 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;
- bool *flag_space = zalloc (s * sizeof *flag_space);
- 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, 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);
- 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;
-}