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blame.c
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blame.c
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#include "cache.h"
#include "refs.h"
#include "object-store.h"
#include "cache-tree.h"
#include "mergesort.h"
#include "diff.h"
#include "diffcore.h"
#include "tag.h"
#include "blame.h"
#include "alloc.h"
#include "commit-slab.h"
define_commit_slab(blame_suspects, struct blame_origin *);
static struct blame_suspects blame_suspects;
struct blame_origin *get_blame_suspects(struct commit *commit)
{
struct blame_origin **result;
result = blame_suspects_peek(&blame_suspects, commit);
return result ? *result : NULL;
}
static void set_blame_suspects(struct commit *commit, struct blame_origin *origin)
{
*blame_suspects_at(&blame_suspects, commit) = origin;
}
void blame_origin_decref(struct blame_origin *o)
{
if (o && --o->refcnt <= 0) {
struct blame_origin *p, *l = NULL;
if (o->previous)
blame_origin_decref(o->previous);
free(o->file.ptr);
/* Should be present exactly once in commit chain */
for (p = get_blame_suspects(o->commit); p; l = p, p = p->next) {
if (p == o) {
if (l)
l->next = p->next;
else
set_blame_suspects(o->commit, p->next);
free(o);
return;
}
}
die("internal error in blame_origin_decref");
}
}
/*
* Given a commit and a path in it, create a new origin structure.
* The callers that add blame to the scoreboard should use
* get_origin() to obtain shared, refcounted copy instead of calling
* this function directly.
*/
static struct blame_origin *make_origin(struct commit *commit, const char *path)
{
struct blame_origin *o;
FLEX_ALLOC_STR(o, path, path);
o->commit = commit;
o->refcnt = 1;
o->next = get_blame_suspects(commit);
set_blame_suspects(commit, o);
return o;
}
/*
* Locate an existing origin or create a new one.
* This moves the origin to front position in the commit util list.
*/
static struct blame_origin *get_origin(struct commit *commit, const char *path)
{
struct blame_origin *o, *l;
for (o = get_blame_suspects(commit), l = NULL; o; l = o, o = o->next) {
if (!strcmp(o->path, path)) {
/* bump to front */
if (l) {
l->next = o->next;
o->next = get_blame_suspects(commit);
set_blame_suspects(commit, o);
}
return blame_origin_incref(o);
}
}
return make_origin(commit, path);
}
static void verify_working_tree_path(struct repository *repo,
struct commit *work_tree, const char *path)
{
struct commit_list *parents;
int pos;
for (parents = work_tree->parents; parents; parents = parents->next) {
const struct object_id *commit_oid = &parents->item->object.oid;
struct object_id blob_oid;
unsigned mode;
if (!get_tree_entry(commit_oid, path, &blob_oid, &mode) &&
oid_object_info(repo, &blob_oid, NULL) == OBJ_BLOB)
return;
}
pos = index_name_pos(repo->index, path, strlen(path));
if (pos >= 0)
; /* path is in the index */
else if (-1 - pos < repo->index->cache_nr &&
!strcmp(repo->index->cache[-1 - pos]->name, path))
; /* path is in the index, unmerged */
else
die("no such path '%s' in HEAD", path);
}
static struct commit_list **append_parent(struct commit_list **tail, const struct object_id *oid)
{
struct commit *parent;
parent = lookup_commit_reference(the_repository, oid);
if (!parent)
die("no such commit %s", oid_to_hex(oid));
return &commit_list_insert(parent, tail)->next;
}
static void append_merge_parents(struct commit_list **tail)
{
int merge_head;
struct strbuf line = STRBUF_INIT;
merge_head = open(git_path_merge_head(the_repository), O_RDONLY);
if (merge_head < 0) {
if (errno == ENOENT)
return;
die("cannot open '%s' for reading",
git_path_merge_head(the_repository));
}
while (!strbuf_getwholeline_fd(&line, merge_head, '\n')) {
struct object_id oid;
if (line.len < GIT_SHA1_HEXSZ || get_oid_hex(line.buf, &oid))
die("unknown line in '%s': %s",
git_path_merge_head(the_repository), line.buf);
tail = append_parent(tail, &oid);
}
close(merge_head);
strbuf_release(&line);
}
/*
* This isn't as simple as passing sb->buf and sb->len, because we
* want to transfer ownership of the buffer to the commit (so we
* must use detach).
*/
static void set_commit_buffer_from_strbuf(struct commit *c, struct strbuf *sb)
{
size_t len;
void *buf = strbuf_detach(sb, &len);
set_commit_buffer(the_repository, c, buf, len);
}
/*
* Prepare a dummy commit that represents the work tree (or staged) item.
* Note that annotating work tree item never works in the reverse.
*/
static struct commit *fake_working_tree_commit(struct repository *repo,
struct diff_options *opt,
const char *path,
const char *contents_from)
{
struct commit *commit;
struct blame_origin *origin;
struct commit_list **parent_tail, *parent;
struct object_id head_oid;
struct strbuf buf = STRBUF_INIT;
const char *ident;
time_t now;
int len;
struct cache_entry *ce;
unsigned mode;
struct strbuf msg = STRBUF_INIT;
read_index(repo->index);
time(&now);
commit = alloc_commit_node(the_repository);
commit->object.parsed = 1;
commit->date = now;
parent_tail = &commit->parents;
if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL))
die("no such ref: HEAD");
parent_tail = append_parent(parent_tail, &head_oid);
append_merge_parents(parent_tail);
verify_working_tree_path(repo, commit, path);
origin = make_origin(commit, path);
ident = fmt_ident("Not Committed Yet", "not.committed.yet", NULL, 0);
strbuf_addstr(&msg, "tree 0000000000000000000000000000000000000000\n");
for (parent = commit->parents; parent; parent = parent->next)
strbuf_addf(&msg, "parent %s\n",
oid_to_hex(&parent->item->object.oid));
strbuf_addf(&msg,
"author %s\n"
"committer %s\n\n"
"Version of %s from %s\n",
ident, ident, path,
(!contents_from ? path :
(!strcmp(contents_from, "-") ? "standard input" : contents_from)));
set_commit_buffer_from_strbuf(commit, &msg);
if (!contents_from || strcmp("-", contents_from)) {
struct stat st;
const char *read_from;
char *buf_ptr;
unsigned long buf_len;
if (contents_from) {
if (stat(contents_from, &st) < 0)
die_errno("Cannot stat '%s'", contents_from);
read_from = contents_from;
}
else {
if (lstat(path, &st) < 0)
die_errno("Cannot lstat '%s'", path);
read_from = path;
}
mode = canon_mode(st.st_mode);
switch (st.st_mode & S_IFMT) {
case S_IFREG:
if (opt->flags.allow_textconv &&
textconv_object(read_from, mode, &null_oid, 0, &buf_ptr, &buf_len))
strbuf_attach(&buf, buf_ptr, buf_len, buf_len + 1);
else if (strbuf_read_file(&buf, read_from, st.st_size) != st.st_size)
die_errno("cannot open or read '%s'", read_from);
break;
case S_IFLNK:
if (strbuf_readlink(&buf, read_from, st.st_size) < 0)
die_errno("cannot readlink '%s'", read_from);
break;
default:
die("unsupported file type %s", read_from);
}
}
else {
/* Reading from stdin */
mode = 0;
if (strbuf_read(&buf, 0, 0) < 0)
die_errno("failed to read from stdin");
}
convert_to_git(repo->index, path, buf.buf, buf.len, &buf, 0);
origin->file.ptr = buf.buf;
origin->file.size = buf.len;
pretend_object_file(buf.buf, buf.len, OBJ_BLOB, &origin->blob_oid);
/*
* Read the current index, replace the path entry with
* origin->blob_sha1 without mucking with its mode or type
* bits; we are not going to write this index out -- we just
* want to run "diff-index --cached".
*/
discard_index(repo->index);
read_index(repo->index);
len = strlen(path);
if (!mode) {
int pos = index_name_pos(repo->index, path, len);
if (0 <= pos)
mode = repo->index->cache[pos]->ce_mode;
else
/* Let's not bother reading from HEAD tree */
mode = S_IFREG | 0644;
}
ce = make_empty_cache_entry(repo->index, len);
oidcpy(&ce->oid, &origin->blob_oid);
memcpy(ce->name, path, len);
ce->ce_flags = create_ce_flags(0);
ce->ce_namelen = len;
ce->ce_mode = create_ce_mode(mode);
add_index_entry(repo->index, ce,
ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE);
cache_tree_invalidate_path(repo->index, path);
return commit;
}
static int diff_hunks(mmfile_t *file_a, mmfile_t *file_b,
xdl_emit_hunk_consume_func_t hunk_func, void *cb_data, int xdl_opts)
{
xpparam_t xpp = {0};
xdemitconf_t xecfg = {0};
xdemitcb_t ecb = {NULL};
xpp.flags = xdl_opts;
xecfg.hunk_func = hunk_func;
ecb.priv = cb_data;
return xdi_diff(file_a, file_b, &xpp, &xecfg, &ecb);
}
/*
* Given an origin, prepare mmfile_t structure to be used by the
* diff machinery
*/
static void fill_origin_blob(struct diff_options *opt,
struct blame_origin *o, mmfile_t *file, int *num_read_blob)
{
if (!o->file.ptr) {
enum object_type type;
unsigned long file_size;
(*num_read_blob)++;
if (opt->flags.allow_textconv &&
textconv_object(o->path, o->mode, &o->blob_oid, 1, &file->ptr, &file_size))
;
else
file->ptr = read_object_file(&o->blob_oid, &type,
&file_size);
file->size = file_size;
if (!file->ptr)
die("Cannot read blob %s for path %s",
oid_to_hex(&o->blob_oid),
o->path);
o->file = *file;
}
else
*file = o->file;
}
static void drop_origin_blob(struct blame_origin *o)
{
if (o->file.ptr) {
FREE_AND_NULL(o->file.ptr);
}
}
/*
* Any merge of blames happens on lists of blames that arrived via
* different parents in a single suspect. In this case, we want to
* sort according to the suspect line numbers as opposed to the final
* image line numbers. The function body is somewhat longish because
* it avoids unnecessary writes.
*/
static struct blame_entry *blame_merge(struct blame_entry *list1,
struct blame_entry *list2)
{
struct blame_entry *p1 = list1, *p2 = list2,
**tail = &list1;
if (!p1)
return p2;
if (!p2)
return p1;
if (p1->s_lno <= p2->s_lno) {
do {
tail = &p1->next;
if ((p1 = *tail) == NULL) {
*tail = p2;
return list1;
}
} while (p1->s_lno <= p2->s_lno);
}
for (;;) {
*tail = p2;
do {
tail = &p2->next;
if ((p2 = *tail) == NULL) {
*tail = p1;
return list1;
}
} while (p1->s_lno > p2->s_lno);
*tail = p1;
do {
tail = &p1->next;
if ((p1 = *tail) == NULL) {
*tail = p2;
return list1;
}
} while (p1->s_lno <= p2->s_lno);
}
}
static void *get_next_blame(const void *p)
{
return ((struct blame_entry *)p)->next;
}
static void set_next_blame(void *p1, void *p2)
{
((struct blame_entry *)p1)->next = p2;
}
/*
* Final image line numbers are all different, so we don't need a
* three-way comparison here.
*/
static int compare_blame_final(const void *p1, const void *p2)
{
return ((struct blame_entry *)p1)->lno > ((struct blame_entry *)p2)->lno
? 1 : -1;
}
static int compare_blame_suspect(const void *p1, const void *p2)
{
const struct blame_entry *s1 = p1, *s2 = p2;
/*
* to allow for collating suspects, we sort according to the
* respective pointer value as the primary sorting criterion.
* The actual relation is pretty unimportant as long as it
* establishes a total order. Comparing as integers gives us
* that.
*/
if (s1->suspect != s2->suspect)
return (intptr_t)s1->suspect > (intptr_t)s2->suspect ? 1 : -1;
if (s1->s_lno == s2->s_lno)
return 0;
return s1->s_lno > s2->s_lno ? 1 : -1;
}
void blame_sort_final(struct blame_scoreboard *sb)
{
sb->ent = llist_mergesort(sb->ent, get_next_blame, set_next_blame,
compare_blame_final);
}
static int compare_commits_by_reverse_commit_date(const void *a,
const void *b,
void *c)
{
return -compare_commits_by_commit_date(a, b, c);
}
/*
* For debugging -- origin is refcounted, and this asserts that
* we do not underflow.
*/
static void sanity_check_refcnt(struct blame_scoreboard *sb)
{
int baa = 0;
struct blame_entry *ent;
for (ent = sb->ent; ent; ent = ent->next) {
/* Nobody should have zero or negative refcnt */
if (ent->suspect->refcnt <= 0) {
fprintf(stderr, "%s in %s has negative refcnt %d\n",
ent->suspect->path,
oid_to_hex(&ent->suspect->commit->object.oid),
ent->suspect->refcnt);
baa = 1;
}
}
if (baa)
sb->on_sanity_fail(sb, baa);
}
/*
* 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.
*/
void blame_coalesce(struct blame_scoreboard *sb)
{
struct blame_entry *ent, *next;
for (ent = sb->ent; ent && (next = ent->next); ent = next) {
if (ent->suspect == next->suspect &&
ent->s_lno + ent->num_lines == next->s_lno) {
ent->num_lines += next->num_lines;
ent->next = next->next;
blame_origin_decref(next->suspect);
free(next);
ent->score = 0;
next = ent; /* again */
}
}
if (sb->debug) /* sanity */
sanity_check_refcnt(sb);
}
/*
* Merge the given sorted list of blames into a preexisting origin.
* If there were no previous blames to that commit, it is entered into
* the commit priority queue of the score board.
*/
static void queue_blames(struct blame_scoreboard *sb, struct blame_origin *porigin,
struct blame_entry *sorted)
{
if (porigin->suspects)
porigin->suspects = blame_merge(porigin->suspects, sorted);
else {
struct blame_origin *o;
for (o = get_blame_suspects(porigin->commit); o; o = o->next) {
if (o->suspects) {
porigin->suspects = sorted;
return;
}
}
porigin->suspects = sorted;
prio_queue_put(&sb->commits, porigin->commit);
}
}
/*
* Fill the blob_sha1 field of an origin if it hasn't, so that later
* call to fill_origin_blob() can use it to locate the data. blob_sha1
* for an origin is also used to pass the blame for the entire file to
* the parent to detect the case where a child's blob is identical to
* that of its parent's.
*
* This also fills origin->mode for corresponding tree path.
*/
static int fill_blob_sha1_and_mode(struct repository *repo,
struct blame_origin *origin)
{
if (!is_null_oid(&origin->blob_oid))
return 0;
if (get_tree_entry(&origin->commit->object.oid, origin->path, &origin->blob_oid, &origin->mode))
goto error_out;
if (oid_object_info(repo, &origin->blob_oid, NULL) != OBJ_BLOB)
goto error_out;
return 0;
error_out:
oidclr(&origin->blob_oid);
origin->mode = S_IFINVALID;
return -1;
}
/*
* We have an origin -- check if the same path exists in the
* parent and return an origin structure to represent it.
*/
static struct blame_origin *find_origin(struct commit *parent,
struct blame_origin *origin)
{
struct blame_origin *porigin;
struct diff_options diff_opts;
const char *paths[2];
/* First check any existing origins */
for (porigin = get_blame_suspects(parent); porigin; porigin = porigin->next)
if (!strcmp(porigin->path, origin->path)) {
/*
* The same path between origin and its parent
* without renaming -- the most common case.
*/
return blame_origin_incref (porigin);
}
/* See if the origin->path is different between parent
* and origin first. Most of the time they are the
* same and diff-tree is fairly efficient about this.
*/
diff_setup(&diff_opts);
diff_opts.flags.recursive = 1;
diff_opts.detect_rename = 0;
diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
paths[0] = origin->path;
paths[1] = NULL;
parse_pathspec(&diff_opts.pathspec,
PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
PATHSPEC_LITERAL_PATH, "", paths);
diff_setup_done(&diff_opts);
if (is_null_oid(&origin->commit->object.oid))
do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
else
diff_tree_oid(get_commit_tree_oid(parent),
get_commit_tree_oid(origin->commit),
"", &diff_opts);
diffcore_std(&diff_opts);
if (!diff_queued_diff.nr) {
/* The path is the same as parent */
porigin = get_origin(parent, origin->path);
oidcpy(&porigin->blob_oid, &origin->blob_oid);
porigin->mode = origin->mode;
} else {
/*
* Since origin->path is a pathspec, if the parent
* commit had it as a directory, we will see a whole
* bunch of deletion of files in the directory that we
* do not care about.
*/
int i;
struct diff_filepair *p = NULL;
for (i = 0; i < diff_queued_diff.nr; i++) {
const char *name;
p = diff_queued_diff.queue[i];
name = p->one->path ? p->one->path : p->two->path;
if (!strcmp(name, origin->path))
break;
}
if (!p)
die("internal error in blame::find_origin");
switch (p->status) {
default:
die("internal error in blame::find_origin (%c)",
p->status);
case 'M':
porigin = get_origin(parent, origin->path);
oidcpy(&porigin->blob_oid, &p->one->oid);
porigin->mode = p->one->mode;
break;
case 'A':
case 'T':
/* Did not exist in parent, or type changed */
break;
}
}
diff_flush(&diff_opts);
clear_pathspec(&diff_opts.pathspec);
return porigin;
}
/*
* We have an origin -- find the path that corresponds to it in its
* parent and return an origin structure to represent it.
*/
static struct blame_origin *find_rename(struct commit *parent,
struct blame_origin *origin)
{
struct blame_origin *porigin = NULL;
struct diff_options diff_opts;
int i;
diff_setup(&diff_opts);
diff_opts.flags.recursive = 1;
diff_opts.detect_rename = DIFF_DETECT_RENAME;
diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
diff_opts.single_follow = origin->path;
diff_setup_done(&diff_opts);
if (is_null_oid(&origin->commit->object.oid))
do_diff_cache(get_commit_tree_oid(parent), &diff_opts);
else
diff_tree_oid(get_commit_tree_oid(parent),
get_commit_tree_oid(origin->commit),
"", &diff_opts);
diffcore_std(&diff_opts);
for (i = 0; i < diff_queued_diff.nr; i++) {
struct diff_filepair *p = diff_queued_diff.queue[i];
if ((p->status == 'R' || p->status == 'C') &&
!strcmp(p->two->path, origin->path)) {
porigin = get_origin(parent, p->one->path);
oidcpy(&porigin->blob_oid, &p->one->oid);
porigin->mode = p->one->mode;
break;
}
}
diff_flush(&diff_opts);
clear_pathspec(&diff_opts.pathspec);
return porigin;
}
/*
* Append a new blame entry to a given output queue.
*/
static void add_blame_entry(struct blame_entry ***queue,
const struct blame_entry *src)
{
struct blame_entry *e = xmalloc(sizeof(*e));
memcpy(e, src, sizeof(*e));
blame_origin_incref(e->suspect);
e->next = **queue;
**queue = e;
*queue = &e->next;
}
/*
* src typically is on-stack; we want to copy the information in it to
* a malloced blame_entry that gets added to the given queue. The
* origin of dst loses a refcnt.
*/
static void dup_entry(struct blame_entry ***queue,
struct blame_entry *dst, struct blame_entry *src)
{
blame_origin_incref(src->suspect);
blame_origin_decref(dst->suspect);
memcpy(dst, src, sizeof(*src));
dst->next = **queue;
**queue = dst;
*queue = &dst->next;
}
const char *blame_nth_line(struct blame_scoreboard *sb, long lno)
{
return sb->final_buf + sb->lineno[lno];
}
/*
* 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 ----->
* <------>
* <------------>
* <------------>
* <------------------>
*
* 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(struct blame_entry *split,
struct blame_entry *e,
int tlno, int plno, int same,
struct blame_origin *parent)
{
int chunk_end_lno;
memset(split, 0, sizeof(struct blame_entry [3]));
if (e->s_lno < tlno) {
/* there is a pre-chunk part not blamed on parent */
split[0].suspect = blame_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 = blame_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 = blame_origin_incref(parent);
}
/*
* split_overlap() divided an existing blame e into up to three parts
* in split. Any assigned blame is moved to queue to
* reflect the split.
*/
static void split_blame(struct blame_entry ***blamed,
struct blame_entry ***unblamed,
struct blame_entry *split,
struct blame_entry *e)
{
if (split[0].suspect && split[2].suspect) {
/* The first part (reuse storage for the existing entry e) */
dup_entry(unblamed, e, &split[0]);
/* The last part -- me */
add_blame_entry(unblamed, &split[2]);
/* ... and the middle part -- parent */
add_blame_entry(blamed, &split[1]);
}
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(blamed, e, &split[1]);
else if (split[0].suspect) {
/* me and then parent */
dup_entry(unblamed, e, &split[0]);
add_blame_entry(blamed, &split[1]);
}
else {
/* parent and then me */
dup_entry(blamed, e, &split[1]);
add_blame_entry(unblamed, &split[2]);
}
}
/*
* After splitting the blame, the origins used by the
* on-stack blame_entry should lose one refcnt each.
*/
static void decref_split(struct blame_entry *split)
{
int i;
for (i = 0; i < 3; i++)
blame_origin_decref(split[i].suspect);
}
/*
* reverse_blame reverses the list given in head, appending tail.
* That allows us to build lists in reverse order, then reverse them
* afterwards. This can be faster than building the list in proper
* order right away. The reason is that building in proper order
* requires writing a link in the _previous_ element, while building
* in reverse order just requires placing the list head into the
* _current_ element.
*/
static struct blame_entry *reverse_blame(struct blame_entry *head,
struct blame_entry *tail)
{
while (head) {
struct blame_entry *next = head->next;
head->next = tail;
tail = head;
head = next;
}
return tail;
}
/*
* Process one hunk from the patch between the current suspect for
* blame_entry e and its parent. This first blames any unfinished
* entries before the chunk (which is where target and parent start
* differing) on the parent, and then splits blame entries at the
* start and at the end of the difference region. Since use of -M and
* -C options may lead to overlapping/duplicate source line number
* ranges, all we can rely on from sorting/merging is the order of the
* first suspect line number.
*/
static void blame_chunk(struct blame_entry ***dstq, struct blame_entry ***srcq,
int tlno, int offset, int same,
struct blame_origin *parent)
{
struct blame_entry *e = **srcq;
struct blame_entry *samep = NULL, *diffp = NULL;
while (e && e->s_lno < tlno) {
struct blame_entry *next = e->next;
/*
* current record starts before differing portion. If
* it reaches into it, we need to split it up and
* examine the second part separately.
*/
if (e->s_lno + e->num_lines > tlno) {
/* Move second half to a new record */
int len = tlno - e->s_lno;
struct blame_entry *n = xcalloc(1, sizeof (struct blame_entry));
n->suspect = e->suspect;
n->lno = e->lno + len;
n->s_lno = e->s_lno + len;
n->num_lines = e->num_lines - len;
e->num_lines = len;
e->score = 0;
/* Push new record to diffp */
n->next = diffp;
diffp = n;
} else
blame_origin_decref(e->suspect);
/* Pass blame for everything before the differing
* chunk to the parent */
e->suspect = blame_origin_incref(parent);
e->s_lno += offset;
e->next = samep;
samep = e;
e = next;
}
/*
* As we don't know how much of a common stretch after this
* diff will occur, the currently blamed parts are all that we
* can assign to the parent for now.
*/
if (samep) {
**dstq = reverse_blame(samep, **dstq);
*dstq = &samep->next;
}
/*
* Prepend the split off portions: everything after e starts
* after the blameable portion.
*/
e = reverse_blame(diffp, e);
/*
* Now retain records on the target while parts are different
* from the parent.
*/
samep = NULL;
diffp = NULL;
while (e && e->s_lno < same) {
struct blame_entry *next = e->next;
/*
* If current record extends into sameness, need to split.
*/
if (e->s_lno + e->num_lines > same) {
/*
* Move second half to a new record to be
* processed by later chunks
*/
int len = same - e->s_lno;
struct blame_entry *n = xcalloc(1, sizeof (struct blame_entry));
n->suspect = blame_origin_incref(e->suspect);
n->lno = e->lno + len;
n->s_lno = e->s_lno + len;
n->num_lines = e->num_lines - len;
e->num_lines = len;
e->score = 0;
/* Push new record to samep */
n->next = samep;
samep = n;
}
e->next = diffp;
diffp = e;
e = next;
}
**srcq = reverse_blame(diffp, reverse_blame(samep, e));
/* Move across elements that are in the unblamable portion */
if (diffp)
*srcq = &diffp->next;
}
struct blame_chunk_cb_data {
struct blame_origin *parent;
long offset;
struct blame_entry **dstq;
struct blame_entry **srcq;
};
/* diff chunks are from parent to target */
static int blame_chunk_cb(long start_a, long count_a,
long start_b, long count_b, void *data)
{
struct blame_chunk_cb_data *d = data;
if (start_a - start_b != d->offset)
die("internal error in blame::blame_chunk_cb");
blame_chunk(&d->dstq, &d->srcq, start_b, start_a - start_b,
start_b + count_b, d->parent);
d->offset = start_a + count_a - (start_b + count_b);
return 0;
}
/*
* We are looking at the origin 'target' and aiming to pass blame
* for the lines it is suspected to its parent. Run diff to find
* which lines came from parent and pass blame for them.
*/
static void pass_blame_to_parent(struct blame_scoreboard *sb,
struct blame_origin *target,
struct blame_origin *parent)
{
mmfile_t file_p, file_o;
struct blame_chunk_cb_data d;
struct blame_entry *newdest = NULL;
if (!target->suspects)
return; /* nothing remains for this target */
d.parent = parent;
d.offset = 0;
d.dstq = &newdest; d.srcq = &target->suspects;
fill_origin_blob(&sb->revs->diffopt, parent, &file_p, &sb->num_read_blob);
fill_origin_blob(&sb->revs->diffopt, target, &file_o, &sb->num_read_blob);
sb->num_get_patch++;
if (diff_hunks(&file_p, &file_o, blame_chunk_cb, &d, sb->xdl_opts))
die("unable to generate diff (%s -> %s)",
oid_to_hex(&parent->commit->object.oid),
oid_to_hex(&target->commit->object.oid));
/* The rest are the same as the parent */
blame_chunk(&d.dstq, &d.srcq, INT_MAX, d.offset, INT_MAX, parent);
*d.dstq = NULL;
queue_blames(sb, parent, newdest);
return;
}
/*
* The lines in blame_entry after splitting blames many times can become
* very small and trivial, and at some point it becomes pointless to
* blame the parents. E.g. "\t\t}\n\t}\n\n" appears everywhere in any
* ordinary C program, and it is not worth to say it was copied from
* totally unrelated file in the parent.
*
* Compute how trivial the lines in the blame_entry are.