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