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643 lines (556 loc) · 16.1 KB
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/*
* Copyright (C) the libgit2 contributors. All rights reserved.
*
* This file is part of libgit2, distributed under the GNU GPL v2 with
* a Linking Exception. For full terms see the included COPYING file.
*/
#include "blame_git.h"
#include "commit.h"
#include "blob.h"
#include "xdiff/xinclude.h"
#include "diff_xdiff.h"
/*
* Origin is refcounted and usually we keep the blob contents to be
* reused.
*/
static git_blame__origin *origin_incref(git_blame__origin *o)
{
if (o)
o->refcnt++;
return o;
}
static void origin_decref(git_blame__origin *o)
{
if (o && --o->refcnt <= 0) {
if (o->previous)
origin_decref(o->previous);
git_blob_free(o->blob);
git_commit_free(o->commit);
git__free(o);
}
}
/* Given a commit and a path in it, create a new origin structure. */
static int make_origin(git_blame__origin **out, git_commit *commit, const char *path)
{
git_blame__origin *o;
size_t path_len = strlen(path), alloc_len;
int error = 0;
GITERR_CHECK_ALLOC_ADD(&alloc_len, sizeof(*o), path_len);
GITERR_CHECK_ALLOC_ADD(&alloc_len, alloc_len, 1);
o = git__calloc(1, alloc_len);
GITERR_CHECK_ALLOC(o);
o->commit = commit;
o->refcnt = 1;
strcpy(o->path, path);
if (!(error = git_object_lookup_bypath((git_object**)&o->blob, (git_object*)commit,
path, GIT_OBJ_BLOB))) {
*out = o;
} else {
origin_decref(o);
}
return error;
}
/* Locate an existing origin or create a new one. */
int git_blame__get_origin(
git_blame__origin **out,
git_blame *blame,
git_commit *commit,
const char *path)
{
git_blame__entry *e;
for (e = blame->ent; e; e = e->next) {
if (e->suspect->commit == commit && !strcmp(e->suspect->path, path)) {
*out = origin_incref(e->suspect);
}
}
return make_origin(out, commit, path);
}
typedef struct blame_chunk_cb_data {
git_blame *blame;
git_blame__origin *target;
git_blame__origin *parent;
long tlno;
long plno;
}blame_chunk_cb_data;
static bool same_suspect(git_blame__origin *a, git_blame__origin *b)
{
if (a == b)
return true;
if (git_oid_cmp(git_commit_id(a->commit), git_commit_id(b->commit)))
return false;
return 0 == strcmp(a->path, b->path);
}
/* find the line number of the last line the target is suspected for */
static int find_last_in_target(git_blame *blame, git_blame__origin *target)
{
git_blame__entry *e;
int last_in_target = -1;
for (e=blame->ent; e; e=e->next) {
if (e->guilty || !same_suspect(e->suspect, target))
continue;
if (last_in_target < e->s_lno + e->num_lines)
last_in_target = e->s_lno + e->num_lines;
}
return last_in_target;
}
/*
* It is known that lines between tlno to same came from parent, and e
* has an overlap with that range. it also is known that parent's
* line plno corresponds to e's line tlno.
*
* <---- e ----->
* <------> (entirely within)
* <------------> (extends past)
* <------------> (starts before)
* <------------------> (entirely encloses)
*
* Split e into potentially three parts; before this chunk, the chunk
* to be blamed for the parent, and after that portion.
*/
static void split_overlap(git_blame__entry *split, git_blame__entry *e,
int tlno, int plno, int same, git_blame__origin *parent)
{
int chunk_end_lno;
if (e->s_lno < tlno) {
/* there is a pre-chunk part not blamed on the parent */
split[0].suspect = origin_incref(e->suspect);
split[0].lno = e->lno;
split[0].s_lno = e->s_lno;
split[0].num_lines = tlno - e->s_lno;
split[1].lno = e->lno + tlno - e->s_lno;
split[1].s_lno = plno;
} else {
split[1].lno = e->lno;
split[1].s_lno = plno + (e->s_lno - tlno);
}
if (same < e->s_lno + e->num_lines) {
/* there is a post-chunk part not blamed on parent */
split[2].suspect = origin_incref(e->suspect);
split[2].lno = e->lno + (same - e->s_lno);
split[2].s_lno = e->s_lno + (same - e->s_lno);
split[2].num_lines = e->s_lno + e->num_lines - same;
chunk_end_lno = split[2].lno;
} else {
chunk_end_lno = e->lno + e->num_lines;
}
split[1].num_lines = chunk_end_lno - split[1].lno;
/*
* if it turns out there is nothing to blame the parent for, forget about
* the splitting. !split[1].suspect signals this.
*/
if (split[1].num_lines < 1)
return;
split[1].suspect = origin_incref(parent);
}
/*
* Link in a new blame entry to the scoreboard. Entries that cover the same
* line range have been removed from the scoreboard previously.
*/
static void add_blame_entry(git_blame *blame, git_blame__entry *e)
{
git_blame__entry *ent, *prev = NULL;
origin_incref(e->suspect);
for (ent = blame->ent; ent && ent->lno < e->lno; ent = ent->next)
prev = ent;
/* prev, if not NULL, is the last one that is below e */
e->prev = prev;
if (prev) {
e->next = prev->next;
prev->next = e;
} else {
e->next = blame->ent;
blame->ent = e;
}
if (e->next)
e->next->prev = e;
}
/*
* src typically is on-stack; we want to copy the information in it to
* a malloced blame_entry that is already on the linked list of the scoreboard.
* The origin of dst loses a refcnt while the origin of src gains one.
*/
static void dup_entry(git_blame__entry *dst, git_blame__entry *src)
{
git_blame__entry *p, *n;
p = dst->prev;
n = dst->next;
origin_incref(src->suspect);
origin_decref(dst->suspect);
memcpy(dst, src, sizeof(*src));
dst->prev = p;
dst->next = n;
dst->score = 0;
}
/*
* split_overlap() divided an existing blame e into up to three parts in split.
* Adjust the linked list of blames in the scoreboard to reflect the split.
*/
static void split_blame(git_blame *blame, git_blame__entry *split, git_blame__entry *e)
{
git_blame__entry *new_entry;
if (split[0].suspect && split[2].suspect) {
/* The first part (reuse storage for the existing entry e */
dup_entry(e, &split[0]);
/* The last part -- me */
new_entry = git__malloc(sizeof(*new_entry));
memcpy(new_entry, &(split[2]), sizeof(git_blame__entry));
add_blame_entry(blame, new_entry);
/* ... and the middle part -- parent */
new_entry = git__malloc(sizeof(*new_entry));
memcpy(new_entry, &(split[1]), sizeof(git_blame__entry));
add_blame_entry(blame, new_entry);
} else if (!split[0].suspect && !split[2].suspect) {
/*
* The parent covers the entire area; reuse storage for e and replace it
* with the parent
*/
dup_entry(e, &split[1]);
} else if (split[0].suspect) {
/* me and then parent */
dup_entry(e, &split[0]);
new_entry = git__malloc(sizeof(*new_entry));
memcpy(new_entry, &(split[1]), sizeof(git_blame__entry));
add_blame_entry(blame, new_entry);
} else {
/* parent and then me */
dup_entry(e, &split[1]);
new_entry = git__malloc(sizeof(*new_entry));
memcpy(new_entry, &(split[2]), sizeof(git_blame__entry));
add_blame_entry(blame, new_entry);
}
}
/*
* After splitting the blame, the origins used by the on-stack blame_entry
* should lose one refcnt each.
*/
static void decref_split(git_blame__entry *split)
{
int i;
for (i=0; i<3; i++)
origin_decref(split[i].suspect);
}
/*
* Helper for blame_chunk(). blame_entry e is known to overlap with the patch
* hunk; split it and pass blame to the parent.
*/
static void blame_overlap(
git_blame *blame,
git_blame__entry *e,
int tlno,
int plno,
int same,
git_blame__origin *parent)
{
git_blame__entry split[3] = {{0}};
split_overlap(split, e, tlno, plno, same, parent);
if (split[1].suspect)
split_blame(blame, split, e);
decref_split(split);
}
/*
* Process one hunk from the patch between the current suspect for blame_entry
* e and its parent. Find and split the overlap, and pass blame to the
* overlapping part to the parent.
*/
static void blame_chunk(
git_blame *blame,
int tlno,
int plno,
int same,
git_blame__origin *target,
git_blame__origin *parent)
{
git_blame__entry *e;
for (e = blame->ent; e; e = e->next) {
if (e->guilty || !same_suspect(e->suspect, target))
continue;
if (same <= e->s_lno)
continue;
if (tlno < e->s_lno + e->num_lines) {
blame_overlap(blame, e, tlno, plno, same, parent);
}
}
}
static int my_emit(
long start_a, long count_a,
long start_b, long count_b,
void *cb_data)
{
blame_chunk_cb_data *d = (blame_chunk_cb_data *)cb_data;
blame_chunk(d->blame, d->tlno, d->plno, start_b, d->target, d->parent);
d->plno = start_a + count_a;
d->tlno = start_b + count_b;
return 0;
}
static void trim_common_tail(mmfile_t *a, mmfile_t *b, long ctx)
{
const int blk = 1024;
long trimmed = 0, recovered = 0;
char *ap = a->ptr + a->size;
char *bp = b->ptr + b->size;
long smaller = (long)((a->size < b->size) ? a->size : b->size);
if (ctx)
return;
while (blk + trimmed <= smaller && !memcmp(ap - blk, bp - blk, blk)) {
trimmed += blk;
ap -= blk;
bp -= blk;
}
while (recovered < trimmed)
if (ap[recovered++] == '\n')
break;
a->size -= trimmed - recovered;
b->size -= trimmed - recovered;
}
static int diff_hunks(mmfile_t file_a, mmfile_t file_b, void *cb_data)
{
xpparam_t xpp = {0};
xdemitconf_t xecfg = {0};
xdemitcb_t ecb = {0};
xecfg.hunk_func = my_emit;
ecb.priv = cb_data;
trim_common_tail(&file_a, &file_b, 0);
if (file_a.size > GIT_XDIFF_MAX_SIZE ||
file_b.size > GIT_XDIFF_MAX_SIZE) {
giterr_set(GITERR_INVALID, "file too large to blame");
return -1;
}
return xdl_diff(&file_a, &file_b, &xpp, &xecfg, &ecb);
}
static void fill_origin_blob(git_blame__origin *o, mmfile_t *file)
{
memset(file, 0, sizeof(*file));
if (o->blob) {
file->ptr = (char*)git_blob_rawcontent(o->blob);
file->size = (size_t)git_blob_rawsize(o->blob);
}
}
static int pass_blame_to_parent(
git_blame *blame,
git_blame__origin *target,
git_blame__origin *parent)
{
int last_in_target;
mmfile_t file_p, file_o;
blame_chunk_cb_data d = { blame, target, parent, 0, 0 };
last_in_target = find_last_in_target(blame, target);
if (last_in_target < 0)
return 1; /* nothing remains for this target */
fill_origin_blob(parent, &file_p);
fill_origin_blob(target, &file_o);
if (diff_hunks(file_p, file_o, &d) < 0)
return -1;
/* The reset (i.e. anything after tlno) are the same as the parent */
blame_chunk(blame, d.tlno, d.plno, last_in_target, target, parent);
return 0;
}
static int paths_on_dup(void **old, void *new)
{
GIT_UNUSED(old);
git__free(new);
return -1;
}
static git_blame__origin* find_origin(
git_blame *blame,
git_commit *parent,
git_blame__origin *origin)
{
git_blame__origin *porigin = NULL;
git_diff *difflist = NULL;
git_diff_options diffopts = GIT_DIFF_OPTIONS_INIT;
git_tree *otree=NULL, *ptree=NULL;
/* Get the trees from this commit and its parent */
if (0 != git_commit_tree(&otree, origin->commit) ||
0 != git_commit_tree(&ptree, parent))
goto cleanup;
/* Configure the diff */
diffopts.context_lines = 0;
diffopts.flags = GIT_DIFF_SKIP_BINARY_CHECK;
/* Check to see if files we're interested have changed */
diffopts.pathspec.count = blame->paths.length;
diffopts.pathspec.strings = (char**)blame->paths.contents;
if (0 != git_diff_tree_to_tree(&difflist, blame->repository, ptree, otree, &diffopts))
goto cleanup;
if (!git_diff_num_deltas(difflist)) {
/* No changes; copy data */
git_blame__get_origin(&porigin, blame, parent, origin->path);
} else {
git_diff_find_options findopts = GIT_DIFF_FIND_OPTIONS_INIT;
int i;
/* Generate a full diff between the two trees */
git_diff_free(difflist);
diffopts.pathspec.count = 0;
if (0 != git_diff_tree_to_tree(&difflist, blame->repository, ptree, otree, &diffopts))
goto cleanup;
/* Let diff find renames */
findopts.flags = GIT_DIFF_FIND_RENAMES;
if (0 != git_diff_find_similar(difflist, &findopts))
goto cleanup;
/* Find one that matches */
for (i=0; i<(int)git_diff_num_deltas(difflist); i++) {
const git_diff_delta *delta = git_diff_get_delta(difflist, i);
if (!git_vector_bsearch(NULL, &blame->paths, delta->new_file.path))
{
git_vector_insert_sorted(&blame->paths, (void*)git__strdup(delta->old_file.path),
paths_on_dup);
make_origin(&porigin, parent, delta->old_file.path);
}
}
}
cleanup:
git_diff_free(difflist);
git_tree_free(otree);
git_tree_free(ptree);
return porigin;
}
/*
* The blobs of origin and porigin exactly match, so everything origin is
* suspected for can be blamed on the parent.
*/
static void pass_whole_blame(git_blame *blame,
git_blame__origin *origin, git_blame__origin *porigin)
{
git_blame__entry *e;
if (!porigin->blob)
git_object_lookup((git_object**)&porigin->blob, blame->repository,
git_blob_id(origin->blob), GIT_OBJ_BLOB);
for (e=blame->ent; e; e=e->next) {
if (!same_suspect(e->suspect, origin))
continue;
origin_incref(porigin);
origin_decref(e->suspect);
e->suspect = porigin;
}
}
static int pass_blame(git_blame *blame, git_blame__origin *origin, uint32_t opt)
{
git_commit *commit = origin->commit;
int i, num_parents;
git_blame__origin *sg_buf[16];
git_blame__origin *porigin, **sg_origin = sg_buf;
int ret, error = 0;
num_parents = git_commit_parentcount(commit);
if (!git_oid_cmp(git_commit_id(commit), &blame->options.oldest_commit))
/* Stop at oldest specified commit */
num_parents = 0;
else if (opt & GIT_BLAME_FIRST_PARENT && num_parents > 1)
/* Limit search to the first parent */
num_parents = 1;
if (!num_parents) {
git_oid_cpy(&blame->options.oldest_commit, git_commit_id(commit));
goto finish;
}
else if (num_parents < (int)ARRAY_SIZE(sg_buf))
memset(sg_buf, 0, sizeof(sg_buf));
else
sg_origin = git__calloc(num_parents, sizeof(*sg_origin));
for (i=0; i<num_parents; i++) {
git_commit *p;
int j, same;
if (sg_origin[i])
continue;
git_commit_parent(&p, origin->commit, i);
porigin = find_origin(blame, p, origin);
if (!porigin)
continue;
if (porigin->blob && origin->blob &&
!git_oid_cmp(git_blob_id(porigin->blob), git_blob_id(origin->blob))) {
pass_whole_blame(blame, origin, porigin);
origin_decref(porigin);
goto finish;
}
for (j = same = 0; j<i; j++)
if (sg_origin[j] &&
!git_oid_cmp(git_blob_id(sg_origin[j]->blob), git_blob_id(porigin->blob))) {
same = 1;
break;
}
if (!same)
sg_origin[i] = porigin;
else
origin_decref(porigin);
}
/* Standard blame */
for (i=0; i<num_parents; i++) {
git_blame__origin *porigin = sg_origin[i];
if (!porigin)
continue;
if (!origin->previous) {
origin_incref(porigin);
origin->previous = porigin;
}
if ((ret = pass_blame_to_parent(blame, origin, porigin)) != 0) {
if (ret < 0)
error = -1;
goto finish;
}
}
/* TODO: optionally find moves in parents' files */
/* TODO: optionally find copies in parents' files */
finish:
for (i=0; i<num_parents; i++)
if (sg_origin[i])
origin_decref(sg_origin[i]);
if (sg_origin != sg_buf)
git__free(sg_origin);
return error;
}
/*
* If two blame entries that are next to each other came from
* contiguous lines in the same origin (i.e. <commit, path> pair),
* merge them together.
*/
static void coalesce(git_blame *blame)
{
git_blame__entry *ent, *next;
for (ent=blame->ent; ent && (next = ent->next); ent = next) {
if (same_suspect(ent->suspect, next->suspect) &&
ent->guilty == next->guilty &&
ent->s_lno + ent->num_lines == next->s_lno)
{
ent->num_lines += next->num_lines;
ent->next = next->next;
if (ent->next)
ent->next->prev = ent;
origin_decref(next->suspect);
git__free(next);
ent->score = 0;
next = ent; /* again */
}
}
}
int git_blame__like_git(git_blame *blame, uint32_t opt)
{
while (true) {
git_blame__entry *ent;
git_blame__origin *suspect = NULL;
/* Find a suspect to break down */
for (ent = blame->ent; !suspect && ent; ent = ent->next)
if (!ent->guilty)
suspect = ent->suspect;
if (!suspect)
return 0; /* all done */
/* We'll use this suspect later in the loop, so hold on to it for now. */
origin_incref(suspect);
if (pass_blame(blame, suspect, opt) < 0)
return -1;
/* Take responsibility for the remaining entries */
for (ent = blame->ent; ent; ent = ent->next) {
if (same_suspect(ent->suspect, suspect)) {
ent->guilty = true;
ent->is_boundary = !git_oid_cmp(
git_commit_id(suspect->commit),
&blame->options.oldest_commit);
}
}
origin_decref(suspect);
}
coalesce(blame);
return 0;
}
void git_blame__free_entry(git_blame__entry *ent)
{
if (!ent) return;
origin_decref(ent->suspect);
git__free(ent);
}
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