464 lines
13 KiB
C
464 lines
13 KiB
C
/*
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* Copyright (C) 2005 Junio C Hamano
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*/
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#include "cache.h"
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#include "diff.h"
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#include "diffcore.h"
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#include "delta.h"
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#include "count-delta.h"
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/* Table of rename/copy destinations */
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static struct diff_rename_dst {
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struct diff_filespec *two;
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struct diff_filepair *pair;
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} *rename_dst;
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static int rename_dst_nr, rename_dst_alloc;
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static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
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int insert_ok)
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{
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int first, last;
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first = 0;
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last = rename_dst_nr;
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while (last > first) {
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int next = (last + first) >> 1;
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struct diff_rename_dst *dst = &(rename_dst[next]);
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int cmp = strcmp(two->path, dst->two->path);
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if (!cmp)
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return dst;
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if (cmp < 0) {
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last = next;
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continue;
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}
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first = next+1;
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}
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/* not found */
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if (!insert_ok)
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return NULL;
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/* insert to make it at "first" */
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if (rename_dst_alloc <= rename_dst_nr) {
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rename_dst_alloc = alloc_nr(rename_dst_alloc);
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rename_dst = xrealloc(rename_dst,
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rename_dst_alloc * sizeof(*rename_dst));
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}
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rename_dst_nr++;
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if (first < rename_dst_nr)
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memmove(rename_dst + first + 1, rename_dst + first,
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(rename_dst_nr - first - 1) * sizeof(*rename_dst));
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rename_dst[first].two = alloc_filespec(two->path);
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fill_filespec(rename_dst[first].two, two->sha1, two->mode);
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rename_dst[first].pair = NULL;
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return &(rename_dst[first]);
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}
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/* Table of rename/copy src files */
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static struct diff_rename_src {
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struct diff_filespec *one;
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unsigned src_path_left : 1;
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} *rename_src;
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static int rename_src_nr, rename_src_alloc;
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static struct diff_rename_src *register_rename_src(struct diff_filespec *one,
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int src_path_left)
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{
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int first, last;
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first = 0;
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last = rename_src_nr;
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while (last > first) {
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int next = (last + first) >> 1;
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struct diff_rename_src *src = &(rename_src[next]);
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int cmp = strcmp(one->path, src->one->path);
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if (!cmp)
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return src;
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if (cmp < 0) {
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last = next;
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continue;
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}
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first = next+1;
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}
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/* insert to make it at "first" */
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if (rename_src_alloc <= rename_src_nr) {
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rename_src_alloc = alloc_nr(rename_src_alloc);
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rename_src = xrealloc(rename_src,
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rename_src_alloc * sizeof(*rename_src));
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}
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rename_src_nr++;
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if (first < rename_src_nr)
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memmove(rename_src + first + 1, rename_src + first,
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(rename_src_nr - first - 1) * sizeof(*rename_src));
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rename_src[first].one = one;
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rename_src[first].src_path_left = src_path_left;
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return &(rename_src[first]);
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}
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static int is_exact_match(struct diff_filespec *src, struct diff_filespec *dst)
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{
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if (src->sha1_valid && dst->sha1_valid &&
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!memcmp(src->sha1, dst->sha1, 20))
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return 1;
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if (diff_populate_filespec(src, 1) || diff_populate_filespec(dst, 1))
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return 0;
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if (src->size != dst->size)
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return 0;
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if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
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return 0;
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if (src->size == dst->size &&
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!memcmp(src->data, dst->data, src->size))
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return 1;
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return 0;
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}
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struct diff_score {
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int src; /* index in rename_src */
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int dst; /* index in rename_dst */
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int score;
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};
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static int estimate_similarity(struct diff_filespec *src,
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struct diff_filespec *dst,
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int minimum_score)
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{
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/* src points at a file that existed in the original tree (or
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* optionally a file in the destination tree) and dst points
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* at a newly created file. They may be quite similar, in which
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* case we want to say src is renamed to dst or src is copied into
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* dst, and then some edit has been applied to dst.
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*
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* Compare them and return how similar they are, representing
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* the score as an integer between 0 and MAX_SCORE.
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*
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* When there is an exact match, it is considered a better
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* match than anything else; the destination does not even
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* call into this function in that case.
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*/
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void *delta;
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unsigned long delta_size, base_size, src_copied, literal_added;
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unsigned long delta_limit;
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int score;
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/* We deal only with regular files. Symlink renames are handled
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* only when they are exact matches --- in other words, no edits
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* after renaming.
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*/
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if (!S_ISREG(src->mode) || !S_ISREG(dst->mode))
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return 0;
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delta_size = ((src->size < dst->size) ?
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(dst->size - src->size) : (src->size - dst->size));
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base_size = ((src->size < dst->size) ? src->size : dst->size);
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/* We would not consider edits that change the file size so
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* drastically. delta_size must be smaller than
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* (MAX_SCORE-minimum_score)/MAX_SCORE * min(src->size, dst->size).
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*
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* Note that base_size == 0 case is handled here already
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* and the final score computation below would not have a
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* divide-by-zero issue.
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*/
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if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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return 0;
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if (diff_populate_filespec(src, 0) || diff_populate_filespec(dst, 0))
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return 0; /* error but caught downstream */
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delta_limit = base_size * (MAX_SCORE-minimum_score) / MAX_SCORE;
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delta = diff_delta(src->data, src->size,
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dst->data, dst->size,
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&delta_size, delta_limit);
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if (!delta)
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/* If delta_limit is exceeded, we have too much differences */
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return 0;
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/* A delta that has a lot of literal additions would have
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* big delta_size no matter what else it does.
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*/
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if (base_size * (MAX_SCORE-minimum_score) < delta_size * MAX_SCORE)
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return 0;
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/* Estimate the edit size by interpreting delta. */
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if (count_delta(delta, delta_size, &src_copied, &literal_added)) {
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free(delta);
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return 0;
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}
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free(delta);
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/* Extent of damage */
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if (src->size + literal_added < src_copied)
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delta_size = 0;
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else
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delta_size = (src->size - src_copied) + literal_added;
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/*
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* Now we will give some score to it. 100% edit gets 0 points
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* and 0% edit gets MAX_SCORE points.
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*/
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score = MAX_SCORE - (MAX_SCORE * delta_size / base_size);
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if (score < 0) return 0;
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if (MAX_SCORE < score) return MAX_SCORE;
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return score;
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}
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static void record_rename_pair(int dst_index, int src_index, int score)
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{
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struct diff_filespec *one, *two, *src, *dst;
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struct diff_filepair *dp;
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if (rename_dst[dst_index].pair)
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die("internal error: dst already matched.");
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src = rename_src[src_index].one;
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one = alloc_filespec(src->path);
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fill_filespec(one, src->sha1, src->mode);
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dst = rename_dst[dst_index].two;
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two = alloc_filespec(dst->path);
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fill_filespec(two, dst->sha1, dst->mode);
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dp = diff_queue(NULL, one, two);
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dp->score = score;
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dp->source_stays = rename_src[src_index].src_path_left;
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rename_dst[dst_index].pair = dp;
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}
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/*
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* We sort the rename similarity matrix with the score, in descending
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* order (the most similar first).
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*/
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static int score_compare(const void *a_, const void *b_)
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{
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const struct diff_score *a = a_, *b = b_;
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return b->score - a->score;
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}
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static int compute_stays(struct diff_queue_struct *q,
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struct diff_filespec *one)
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{
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int i;
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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if (strcmp(one->path, p->two->path))
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continue;
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if (DIFF_PAIR_RENAME(p)) {
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return 0; /* something else is renamed into this */
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}
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}
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return 1;
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}
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void diffcore_rename(struct diff_options *options)
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{
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int detect_rename = options->detect_rename;
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int minimum_score = options->rename_score;
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int rename_limit = options->rename_limit;
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struct diff_queue_struct *q = &diff_queued_diff;
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struct diff_queue_struct outq;
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struct diff_score *mx;
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int i, j, rename_count;
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int num_create, num_src, dst_cnt;
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if (!minimum_score)
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minimum_score = DEFAULT_RENAME_SCORE;
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rename_count = 0;
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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if (!DIFF_FILE_VALID(p->one))
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if (!DIFF_FILE_VALID(p->two))
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continue; /* unmerged */
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else
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locate_rename_dst(p->two, 1);
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else if (!DIFF_FILE_VALID(p->two)) {
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/* If the source is a broken "delete", and
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* they did not really want to get broken,
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* that means the source actually stays.
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*/
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int stays = (p->broken_pair && !p->score);
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register_rename_src(p->one, stays);
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}
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else if (detect_rename == DIFF_DETECT_COPY)
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register_rename_src(p->one, 1);
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}
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if (rename_dst_nr == 0 ||
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(0 < rename_limit && rename_limit < rename_dst_nr))
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goto cleanup; /* nothing to do */
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/* We really want to cull the candidates list early
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* with cheap tests in order to avoid doing deltas.
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*/
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for (i = 0; i < rename_dst_nr; i++) {
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struct diff_filespec *two = rename_dst[i].two;
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for (j = 0; j < rename_src_nr; j++) {
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struct diff_filespec *one = rename_src[j].one;
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if (!is_exact_match(one, two))
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continue;
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record_rename_pair(i, j, MAX_SCORE);
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rename_count++;
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break; /* we are done with this entry */
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}
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}
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/* Have we run out the created file pool? If so we can avoid
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* doing the delta matrix altogether.
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*/
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if (rename_count == rename_dst_nr)
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goto cleanup;
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if (minimum_score == MAX_SCORE)
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goto cleanup;
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num_create = (rename_dst_nr - rename_count);
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num_src = rename_src_nr;
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mx = xmalloc(sizeof(*mx) * num_create * num_src);
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for (dst_cnt = i = 0; i < rename_dst_nr; i++) {
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int base = dst_cnt * num_src;
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struct diff_filespec *two = rename_dst[i].two;
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if (rename_dst[i].pair)
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continue; /* dealt with exact match already. */
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for (j = 0; j < rename_src_nr; j++) {
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struct diff_filespec *one = rename_src[j].one;
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struct diff_score *m = &mx[base+j];
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m->src = j;
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m->dst = i;
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m->score = estimate_similarity(one, two,
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minimum_score);
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}
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dst_cnt++;
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}
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/* cost matrix sorted by most to least similar pair */
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qsort(mx, num_create * num_src, sizeof(*mx), score_compare);
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for (i = 0; i < num_create * num_src; i++) {
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struct diff_rename_dst *dst = &rename_dst[mx[i].dst];
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if (dst->pair)
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continue; /* already done, either exact or fuzzy. */
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if (mx[i].score < minimum_score)
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break; /* there is no more usable pair. */
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record_rename_pair(mx[i].dst, mx[i].src, mx[i].score);
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rename_count++;
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}
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free(mx);
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cleanup:
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/* At this point, we have found some renames and copies and they
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* are recorded in rename_dst. The original list is still in *q.
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*/
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outq.queue = NULL;
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outq.nr = outq.alloc = 0;
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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struct diff_filepair *pair_to_free = NULL;
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if (!DIFF_FILE_VALID(p->one) && DIFF_FILE_VALID(p->two)) {
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/*
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* Creation
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*
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* We would output this create record if it has
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* not been turned into a rename/copy already.
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*/
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struct diff_rename_dst *dst =
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locate_rename_dst(p->two, 0);
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if (dst && dst->pair) {
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diff_q(&outq, dst->pair);
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pair_to_free = p;
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}
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else
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/* no matching rename/copy source, so
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* record this as a creation.
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*/
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diff_q(&outq, p);
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}
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else if (DIFF_FILE_VALID(p->one) && !DIFF_FILE_VALID(p->two)) {
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/*
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* Deletion
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*
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* We would output this delete record if:
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*
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* (1) this is a broken delete and the counterpart
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* broken create remains in the output; or
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* (2) this is not a broken delete, and rename_dst
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* does not have a rename/copy to move p->one->path
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* out of existence.
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*
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* Otherwise, the counterpart broken create
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* has been turned into a rename-edit; or
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* delete did not have a matching create to
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* begin with.
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*/
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if (DIFF_PAIR_BROKEN(p)) {
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/* broken delete */
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struct diff_rename_dst *dst =
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locate_rename_dst(p->one, 0);
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if (dst && dst->pair)
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/* counterpart is now rename/copy */
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pair_to_free = p;
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}
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else {
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for (j = 0; j < rename_dst_nr; j++) {
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if (!rename_dst[j].pair)
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continue;
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if (strcmp(rename_dst[j].pair->
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one->path,
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p->one->path))
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continue;
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break;
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}
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if (j < rename_dst_nr)
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/* this path remains */
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pair_to_free = p;
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}
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if (pair_to_free)
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;
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else
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diff_q(&outq, p);
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}
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else if (!diff_unmodified_pair(p))
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/* all the usual ones need to be kept */
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diff_q(&outq, p);
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else
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/* no need to keep unmodified pairs */
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pair_to_free = p;
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if (pair_to_free)
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diff_free_filepair(pair_to_free);
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}
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diff_debug_queue("done copying original", &outq);
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free(q->queue);
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*q = outq;
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diff_debug_queue("done collapsing", q);
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/* We need to see which rename source really stays here;
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* earlier we only checked if the path is left in the result,
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* but even if a path remains in the result, if that is coming
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* from copying something else on top of it, then the original
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* source is lost and does not stay.
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*/
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for (i = 0; i < q->nr; i++) {
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struct diff_filepair *p = q->queue[i];
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if (DIFF_PAIR_RENAME(p) && p->source_stays) {
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/* If one appears as the target of a rename-copy,
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* then mark p->source_stays = 0; otherwise
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* leave it as is.
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*/
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p->source_stays = compute_stays(q, p->one);
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}
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}
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for (i = 0; i < rename_dst_nr; i++) {
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diff_free_filespec_data(rename_dst[i].two);
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free(rename_dst[i].two);
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}
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free(rename_dst);
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rename_dst = NULL;
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rename_dst_nr = rename_dst_alloc = 0;
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free(rename_src);
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rename_src = NULL;
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rename_src_nr = rename_src_alloc = 0;
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return;
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}
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