diff options
Diffstat (limited to 'blame.c')
| -rw-r--r-- | blame.c | 2811 |
1 files changed, 2811 insertions, 0 deletions
@@ -0,0 +1,2811 @@ +#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 *r, + 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 short mode; + + if (!get_tree_entry(r, commit_oid, path, &blob_oid, &mode) && + oid_object_info(r, &blob_oid, NULL) == OBJ_BLOB) + return; + } + + pos = index_name_pos(r->index, path, strlen(path)); + if (pos >= 0) + ; /* path is in the index */ + else if (-1 - pos < r->index->cache_nr && + !strcmp(r->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 repository *r, + struct commit_list **tail, + const struct object_id *oid) +{ + struct commit *parent; + + parent = lookup_commit_reference(r, 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 repository *r, + struct commit_list **tail) +{ + int merge_head; + struct strbuf line = STRBUF_INIT; + + merge_head = open(git_path_merge_head(r), O_RDONLY); + if (merge_head < 0) { + if (errno == ENOENT) + return; + die("cannot open '%s' for reading", + git_path_merge_head(r)); + } + + while (!strbuf_getwholeline_fd(&line, merge_head, '\n')) { + struct object_id oid; + if (get_oid_hex(line.buf, &oid)) + die("unknown line in '%s': %s", + git_path_merge_head(r), line.buf); + tail = append_parent(r, 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 repository *r, + struct commit *c, + struct strbuf *sb) +{ + size_t len; + void *buf = strbuf_detach(sb, &len); + set_commit_buffer(r, 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 *r, + 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; + + repo_read_index(r); + time(&now); + commit = alloc_commit_node(r); + 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(r, parent_tail, &head_oid); + append_merge_parents(r, parent_tail); + verify_working_tree_path(r, commit, path); + + origin = make_origin(commit, path); + + ident = fmt_ident("Not Committed Yet", "not.committed.yet", + WANT_BLANK_IDENT, 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(r, 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(r, 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(r->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(r->index); + repo_read_index(r); + + len = strlen(path); + if (!mode) { + int pos = index_name_pos(r->index, path, len); + if (0 <= pos) + mode = r->index->cache[pos]->ce_mode; + else + /* Let's not bother reading from HEAD tree */ + mode = S_IFREG | 0644; + } + ce = make_empty_cache_entry(r->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(r->index, ce, + ADD_CACHE_OK_TO_ADD | ADD_CACHE_OK_TO_REPLACE); + + cache_tree_invalidate_path(r->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); +} + +static const char *get_next_line(const char *start, const char *end) +{ + const char *nl = memchr(start, '\n', end - start); + + return nl ? nl + 1 : end; +} + +static int find_line_starts(int **line_starts, const char *buf, + unsigned long len) +{ + const char *end = buf + len; + const char *p; + int *lineno; + int num = 0; + + for (p = buf; p < end; p = get_next_line(p, end)) + num++; + + ALLOC_ARRAY(*line_starts, num + 1); + lineno = *line_starts; + + for (p = buf; p < end; p = get_next_line(p, end)) + *lineno++ = p - buf; + + *lineno = len; + + return num; +} + +struct fingerprint_entry; + +/* A fingerprint is intended to loosely represent a string, such that two + * fingerprints can be quickly compared to give an indication of the similarity + * of the strings that they represent. + * + * A fingerprint is represented as a multiset of the lower-cased byte pairs in + * the string that it represents. Whitespace is added at each end of the + * string. Whitespace pairs are ignored. Whitespace is converted to '\0'. + * For example, the string "Darth Radar" will be converted to the following + * fingerprint: + * {"\0d", "da", "da", "ar", "ar", "rt", "th", "h\0", "\0r", "ra", "ad", "r\0"} + * + * The similarity between two fingerprints is the size of the intersection of + * their multisets, including repeated elements. See fingerprint_similarity for + * examples. + * + * For ease of implementation, the fingerprint is implemented as a map + * of byte pairs to the count of that byte pair in the string, instead of + * allowing repeated elements in a set. + */ +struct fingerprint { + struct hashmap map; + /* As we know the maximum number of entries in advance, it's + * convenient to store the entries in a single array instead of having + * the hashmap manage the memory. + */ + struct fingerprint_entry *entries; +}; + +/* A byte pair in a fingerprint. Stores the number of times the byte pair + * occurs in the string that the fingerprint represents. + */ +struct fingerprint_entry { + /* The hashmap entry - the hash represents the byte pair in its + * entirety so we don't need to store the byte pair separately. + */ + struct hashmap_entry entry; + /* The number of times the byte pair occurs in the string that the + * fingerprint represents. + */ + int count; +}; + +/* See `struct fingerprint` for an explanation of what a fingerprint is. + * \param result the fingerprint of the string is stored here. This must be + * freed later using free_fingerprint. + * \param line_begin the start of the string + * \param line_end the end of the string + */ +static void get_fingerprint(struct fingerprint *result, + const char *line_begin, + const char *line_end) +{ + unsigned int hash, c0 = 0, c1; + const char *p; + int max_map_entry_count = 1 + line_end - line_begin; + struct fingerprint_entry *entry = xcalloc(max_map_entry_count, + sizeof(struct fingerprint_entry)); + struct fingerprint_entry *found_entry; + + hashmap_init(&result->map, NULL, NULL, max_map_entry_count); + result->entries = entry; + for (p = line_begin; p <= line_end; ++p, c0 = c1) { + /* Always terminate the string with whitespace. + * Normalise whitespace to 0, and normalise letters to + * lower case. This won't work for multibyte characters but at + * worst will match some unrelated characters. + */ + if ((p == line_end) || isspace(*p)) + c1 = 0; + else + c1 = tolower(*p); + hash = c0 | (c1 << 8); + /* Ignore whitespace pairs */ + if (hash == 0) + continue; + hashmap_entry_init(&entry->entry, hash); + + found_entry = hashmap_get_entry(&result->map, entry, + /* member name */ entry, NULL); + if (found_entry) { + found_entry->count += 1; + } else { + entry->count = 1; + hashmap_add(&result->map, &entry->entry); + ++entry; + } + } +} + +static void free_fingerprint(struct fingerprint *f) +{ + hashmap_free(&f->map); + free(f->entries); +} + +/* Calculates the similarity between two fingerprints as the size of the + * intersection of their multisets, including repeated elements. See + * `struct fingerprint` for an explanation of the fingerprint representation. + * The similarity between "cat mat" and "father rather" is 2 because "at" is + * present twice in both strings while the similarity between "tim" and "mit" + * is 0. + */ +static int fingerprint_similarity(struct fingerprint *a, struct fingerprint *b) +{ + int intersection = 0; + struct hashmap_iter iter; + const struct fingerprint_entry *entry_a, *entry_b; + + hashmap_for_each_entry(&b->map, &iter, entry_b, + entry /* member name */) { + entry_a = hashmap_get_entry(&a->map, entry_b, entry, NULL); + if (entry_a) { + intersection += entry_a->count < entry_b->count ? + entry_a->count : entry_b->count; + } + } + return intersection; +} + +/* Subtracts byte-pair elements in B from A, modifying A in place. + */ +static void fingerprint_subtract(struct fingerprint *a, struct fingerprint *b) +{ + struct hashmap_iter iter; + struct fingerprint_entry *entry_a; + const struct fingerprint_entry *entry_b; + + hashmap_iter_init(&b->map, &iter); + + hashmap_for_each_entry(&b->map, &iter, entry_b, + entry /* member name */) { + entry_a = hashmap_get_entry(&a->map, entry_b, entry, NULL); + if (entry_a) { + if (entry_a->count <= entry_b->count) + hashmap_remove(&a->map, &entry_b->entry, NULL); + else + entry_a->count -= entry_b->count; + } + } +} + +/* Calculate fingerprints for a series of lines. + * Puts the fingerprints in the fingerprints array, which must have been + * preallocated to allow storing line_count elements. + */ +static void get_line_fingerprints(struct fingerprint *fingerprints, + const char *content, const int *line_starts, + long first_line, long line_count) +{ + int i; + const char *linestart, *lineend; + + line_starts += first_line; + for (i = 0; i < line_count; ++i) { + linestart = content + line_starts[i]; + lineend = content + line_starts[i + 1]; + get_fingerprint(fingerprints + i, linestart, lineend); + } +} + +static void free_line_fingerprints(struct fingerprint *fingerprints, + int nr_fingerprints) +{ + int i; + + for (i = 0; i < nr_fingerprints; i++) + free_fingerprint(&fingerprints[i]); +} + +/* This contains the data necessary to linearly map a line number in one half + * of a diff chunk to the line in the other half of the diff chunk that is + * closest in terms of its position as a fraction of the length of the chunk. + */ +struct line_number_mapping { + int destination_start, destination_length, + source_start, source_length; +}; + +/* Given a line number in one range, offset and scale it to map it onto the + * other range. + * Essentially this mapping is a simple linear equation but the calculation is + * more complicated to allow performing it with integer operations. + * Another complication is that if a line could map onto many lines in the + * destination range then we want to choose the line at the center of those + * possibilities. + * Example: if the chunk is 2 lines long in A and 10 lines long in B then the + * first 5 lines in B will map onto the first line in the A chunk, while the + * last 5 lines will all map onto the second line in the A chunk. + * Example: if the chunk is 10 lines long in A and 2 lines long in B then line + * 0 in B will map onto line 2 in A, and line 1 in B will map onto line 7 in A. + */ +static int map_line_number(int line_number, + const struct line_number_mapping *mapping) +{ + return ((line_number - mapping->source_start) * 2 + 1) * + mapping->destination_length / + (mapping->source_length * 2) + + mapping->destination_start; +} + +/* Get a pointer to the element storing the similarity between a line in A + * and a line in B. + * + * The similarities are stored in a 2-dimensional array. Each "row" in the + * array contains the similarities for a line in B. The similarities stored in + * a row are the similarities between the line in B and the nearby lines in A. + * To keep the length of each row the same, it is padded out with values of -1 + * where the search range extends beyond the lines in A. + * For example, if max_search_distance_a is 2 and the two sides of a diff chunk + * look like this: + * a | m + * b | n + * c | o + * d | p + * e | q + * Then the similarity array will contain: + * [-1, -1, am, bm, cm, + * -1, an, bn, cn, dn, + * ao, bo, co, do, eo, + * bp, cp, dp, ep, -1, + * cq, dq, eq, -1, -1] + * Where similarities are denoted either by -1 for invalid, or the + * concatenation of the two lines in the diff being compared. + * + * \param similarities array of similarities between lines in A and B + * \param line_a the index of the line in A, in the same frame of reference as + * closest_line_a. + * \param local_line_b the index of the line in B, relative to the first line + * in B that similarities represents. + * \param closest_line_a the index of the line in A that is deemed to be + * closest to local_line_b. This must be in the same + * frame of reference as line_a. This value defines + * where similarities is centered for the line in B. + * \param max_search_distance_a maximum distance in lines from the closest line + * in A for other lines in A for which + * similarities may be calculated. + */ +static int *get_similarity(int *similarities, + int line_a, int local_line_b, + int closest_line_a, int max_search_distance_a) +{ + assert(abs(line_a - closest_line_a) <= + max_search_distance_a); + return similarities + line_a - closest_line_a + + max_search_distance_a + + local_line_b * (max_search_distance_a * 2 + 1); +} + +#define CERTAIN_NOTHING_MATCHES -2 +#define CERTAINTY_NOT_CALCULATED -1 + +/* Given a line in B, first calculate its similarities with nearby lines in A + * if not already calculated, then identify the most similar and second most + * similar lines. The "certainty" is calculated based on those two + * similarities. + * + * \param start_a the index of the first line of the chunk in A + * \param length_a the length in lines of the chunk in A + * \param local_line_b the index of the line in B, relative to the first line + * in the chunk. + * \param fingerprints_a array of fingerprints for the chunk in A + * \param fingerprints_b array of fingerprints for the chunk in B + * \param similarities 2-dimensional array of similarities between lines in A + * and B. See get_similarity() for more details. + * \param certainties array of values indicating how strongly a line in B is + * matched with some line in A. + * \param second_best_result array of absolute indices in A for the second + * closest match of a line in B. + * \param result array of absolute indices in A for the closest match of a line + * in B. + * \param max_search_distance_a maximum distance in lines from the closest line + * in A for other lines in A for which + * similarities may be calculated. + * \param map_line_number_in_b_to_a parameter to map_line_number(). + */ +static void find_best_line_matches( + int start_a, + int length_a, + int start_b, + int local_line_b, + struct fingerprint *fingerprints_a, + struct fingerprint *fingerprints_b, + int *similarities, + int *certainties, + int *second_best_result, + int *result, + const int max_search_distance_a, + const struct line_number_mapping *map_line_number_in_b_to_a) +{ + + int i, search_start, search_end, closest_local_line_a, *similarity, + best_similarity = 0, second_best_similarity = 0, + best_similarity_index = 0, second_best_similarity_index = 0; + + /* certainty has already been calculated so no need to redo the work */ + if (certainties[local_line_b] != CERTAINTY_NOT_CALCULATED) + return; + + closest_local_line_a = map_line_number( + local_line_b + start_b, map_line_number_in_b_to_a) - start_a; + + search_start = closest_local_line_a - max_search_distance_a; + if (search_start < 0) + search_start = 0; + + search_end = closest_local_line_a + max_search_distance_a + 1; + if (search_end > length_a) + search_end = length_a; + + for (i = search_start; i < search_end; ++i) { + similarity = get_similarity(similarities, + i, local_line_b, + closest_local_line_a, + max_search_distance_a); + if (*similarity == -1) { + /* This value will never exceed 10 but assert just in + * case + */ + assert(abs(i - closest_local_line_a) < 1000); + /* scale the similarity by (1000 - distance from + * closest line) to act as a tie break between lines + * that otherwise are equally similar. + */ + *similarity = fingerprint_similarity( + fingerprints_b + local_line_b, + fingerprints_a + i) * + (1000 - abs(i - closest_local_line_a)); + } + if (*similarity > best_similarity) { + second_best_similarity = best_similarity; + second_best_similarity_index = best_similarity_index; + best_similarity = *similarity; + best_similarity_index = i; + } else if (*similarity > second_best_similarity) { + second_best_similarity = *similarity; + second_best_similarity_index = i; + } + } + + if (best_similarity == 0) { + /* this line definitely doesn't match with anything. Mark it + * with this special value so it doesn't get invalidated and + * won't be recalculated. + */ + certainties[local_line_b] = CERTAIN_NOTHING_MATCHES; + result[local_line_b] = -1; + } else { + /* Calculate the certainty with which this line matches. + * If the line matches well with two lines then that reduces + * the certainty. However we still want to prioritise matching + * a line that matches very well with two lines over matching a + * line that matches poorly with one line, hence doubling + * best_similarity. + * This means that if we have + * line X that matches only one line with a score of 3, + * line Y that matches two lines equally with a score of 5, + * and line Z that matches only one line with a score or 2, + * then the lines in order of certainty are X, Y, Z. + */ + certainties[local_line_b] = best_similarity * 2 - + second_best_similarity; + + /* We keep both the best and second best results to allow us to + * check at a later stage of the matching process whether the + * result needs to be invalidated. + */ + result[local_line_b] = start_a + best_similarity_index; + second_best_result[local_line_b] = + start_a + second_best_similarity_index; + } +} + +/* + * This finds the line that we can match with the most confidence, and + * uses it as a partition. It then calls itself on the lines on either side of + * that partition. In this way we avoid lines appearing out of order, and + * retain a sensible line ordering. + * \param start_a index of the first line in A with which lines in B may be + * compared. + * \param start_b index of the first line in B for which matching should be + * done. + * \param length_a number of lines in A with which lines in B may be compared. + * \param length_b number of lines in B for which matching should be done. + * \param fingerprints_a mutable array of fingerprints in A. The first element + * corresponds to the line at start_a. + * \param fingerprints_b array of fingerprints in B. The first element + * corresponds to the line at start_b. + * \param similarities 2-dimensional array of similarities between lines in A + * and B. See get_similarity() for more details. + * \param certainties array of values indicating how strongly a line in B is + * matched with some line in A. + * \param second_best_result array of absolute indices in A for the second + * closest match of a line in B. + * \param result array of absolute indices in A for the closest match of a line + * in B. + * \param max_search_distance_a maximum distance in lines from the closest line + * in A for other lines in A for which + * similarities may be calculated. + * \param max_search_distance_b an upper bound on the greatest possible + * distance between lines in B such that they will + * both be compared with the same line in A + * according to max_search_distance_a. + * \param map_line_number_in_b_to_a parameter to map_line_number(). + */ +static void fuzzy_find_matching_lines_recurse( + int start_a, int start_b, + int length_a, int length_b, + struct fingerprint *fingerprints_a, + struct fingerprint *fingerprints_b, + int *similarities, + int *certainties, + int *second_best_result, + int *result, + int max_search_distance_a, + int max_search_distance_b, + const struct line_number_mapping *map_line_number_in_b_to_a) +{ + int i, invalidate_min, invalidate_max, offset_b, + second_half_start_a, second_half_start_b, + second_half_length_a, second_half_length_b, + most_certain_line_a, most_certain_local_line_b = -1, + most_certain_line_certainty = -1, + closest_local_line_a; + + for (i = 0; i < length_b; ++i) { + find_best_line_matches(start_a, + length_a, + start_b, + i, + fingerprints_a, + fingerprints_b, + similarities, + certainties, + second_best_result, + result, + max_search_distance_a, + map_line_number_in_b_to_a); + + if (certainties[i] > most_certain_line_certainty) { + most_certain_line_certainty = certainties[i]; + most_certain_local_line_b = i; + } + } + + /* No matches. */ + if (most_certain_local_line_b == -1) + return; + + most_certain_line_a = result[most_certain_local_line_b]; + + /* + * Subtract the most certain line's fingerprint in B from the matched + * fingerprint in A. This means that other lines in B can't also match + * the same parts of the line in A. + */ + fingerprint_subtract(fingerprints_a + most_certain_line_a - start_a, + fingerprints_b + most_certain_local_line_b); + + /* Invalidate results that may be affected by the choice of most + * certain line. + */ + invalidate_min = most_certain_local_line_b - max_search_distance_b; + invalidate_max = most_certain_local_line_b + max_search_distance_b + 1; + if (invalidate_min < 0) + invalidate_min = 0; + if (invalidate_max > length_b) + invalidate_max = length_b; + + /* As the fingerprint in A has changed, discard previously calculated + * similarity values with that fingerprint. + */ + for (i = invalidate_min; i < invalidate_max; ++i) { + closest_local_line_a = map_line_number( + i + start_b, map_line_number_in_b_to_a) - start_a; + + /* Check that the lines in A and B are close enough that there + * is a similarity value for them. + */ + if (abs(most_certain_line_a - start_a - closest_local_line_a) > + max_search_distance_a) { + continue; + } + + *get_similarity(similarities, most_certain_line_a - start_a, + i, closest_local_line_a, + max_search_distance_a) = -1; + } + + /* More invalidating of results that may be affected by the choice of + * most certain line. + * Discard the matches for lines in B that are currently matched with a + * line in A such that their ordering contradicts the ordering imposed + * by the choice of most certain line. + */ + for (i = most_certain_local_line_b - 1; i >= invalidate_min; --i) { + /* In this loop we discard results for lines in B that are + * before most-certain-line-B but are matched with a line in A + * that is after most-certain-line-A. + */ + if (certainties[i] >= 0 && + (result[i] >= most_certain_line_a || + second_best_result[i] >= most_certain_line_a)) { + certainties[i] = CERTAINTY_NOT_CALCULATED; + } + } + for (i = most_certain_local_line_b + 1; i < invalidate_max; ++i) { + /* In this loop we discard results for lines in B that are + * after most-certain-line-B but are matched with a line in A + * that is before most-certain-line-A. + */ + if (certainties[i] >= 0 && + (result[i] <= most_certain_line_a || + second_best_result[i] <= most_certain_line_a)) { + certainties[i] = CERTAINTY_NOT_CALCULATED; + } + } + + /* Repeat the matching process for lines before the most certain line. + */ + if (most_certain_local_line_b > 0) { + fuzzy_find_matching_lines_recurse( + start_a, start_b, + most_certain_line_a + 1 - start_a, + most_certain_local_line_b, + fingerprints_a, fingerprints_b, similarities, + certainties, second_best_result, result, + max_search_distance_a, + max_search_distance_b, + map_line_number_in_b_to_a); + } + /* Repeat the matching process for lines after the most certain line. + */ + if (most_certain_local_line_b + 1 < length_b) { + second_half_start_a = most_certain_line_a; + offset_b = most_certain_local_line_b + 1; + second_half_start_b = start_b + offset_b; + second_half_length_a = + length_a + start_a - second_half_start_a; + second_half_length_b = + length_b + start_b - second_half_start_b; + fuzzy_find_matching_lines_recurse( + second_half_start_a, second_half_start_b, + second_half_length_a, second_half_length_b, + fingerprints_a + second_half_start_a - start_a, + fingerprints_b + offset_b, + similarities + + offset_b * (max_search_distance_a * 2 + 1), + certainties + offset_b, + second_best_result + offset_b, result + offset_b, + max_search_distance_a, + max_search_distance_b, + map_line_number_in_b_to_a); + } +} + +/* Find the lines in the parent line range that most closely match the lines in + * the target line range. This is accomplished by matching fingerprints in each + * blame_origin, and choosing the best matches that preserve the line ordering. + * See struct fingerprint for details of fingerprint matching, and + * fuzzy_find_matching_lines_recurse for details of preserving line ordering. + * + * The performance is believed to be O(n log n) in the typical case and O(n^2) + * in a pathological case, where n is the number of lines in the target range. + */ +static int *fuzzy_find_matching_lines(struct blame_origin *parent, + struct blame_origin *target, + int tlno, int parent_slno, int same, + int parent_len) +{ + /* We use the terminology "A" for the left hand side of the diff AKA + * parent, and "B" for the right hand side of the diff AKA target. */ + int start_a = parent_slno; + int length_a = parent_len; + int start_b = tlno; + int length_b = same - tlno; + + struct line_number_mapping map_line_number_in_b_to_a = { + start_a, length_a, start_b, length_b + }; + + struct fingerprint *fingerprints_a = parent->fingerprints; + struct fingerprint *fingerprints_b = target->fingerprints; + + int i, *result, *second_best_result, + *certainties, *similarities, similarity_count; + + /* + * max_search_distance_a means that given a line in B, compare it to + * the line in A that is closest to its position, and the lines in A + * that are no greater than max_search_distance_a lines away from the + * closest line in A. + * + * max_search_distance_b is an upper bound on the greatest possible + * distance between lines in B such that they will both be compared + * with the same line in A according to max_search_distance_a. + */ + int max_search_distance_a = 10, max_search_distance_b; + + if (length_a <= 0) + return NULL; + + if (max_search_distance_a >= length_a) + max_search_distance_a = length_a ? length_a - 1 : 0; + + max_search_distance_b = ((2 * max_search_distance_a + 1) * length_b + - 1) / length_a; + + result = xcalloc(sizeof(int), length_b); + second_best_result = xcalloc(sizeof(int), length_b); + certainties = xcalloc(sizeof(int), length_b); + + /* See get_similarity() for details of similarities. */ + similarity_count = length_b * (max_search_distance_a * 2 + 1); + similarities = xcalloc(sizeof(int), similarity_count); + + for (i = 0; i < length_b; ++i) { + result[i] = -1; + second_best_result[i] = -1; + certainties[i] = CERTAINTY_NOT_CALCULATED; + } + + for (i = 0; i < similarity_count; ++i) + similarities[i] = -1; + + fuzzy_find_matching_lines_recurse(start_a, start_b, + length_a, length_b, + fingerprints_a + start_a, + fingerprints_b + start_b, + similarities, + certainties, + second_best_result, + result, + max_search_distance_a, + max_search_distance_b, + &map_line_number_in_b_to_a); + + free(similarities); + free(certainties); + free(second_best_result); + + return result; +} + +static void fill_origin_fingerprints(struct blame_origin *o) +{ + int *line_starts; + + if (o->fingerprints) + return; + o->num_lines = find_line_starts(&line_starts, o->file.ptr, + o->file.size); + o->fingerprints = xcalloc(sizeof(struct fingerprint), o->num_lines); + get_line_fingerprints(o->fingerprints, o->file.ptr, line_starts, + 0, o->num_lines); + free(line_starts); +} + +static void drop_origin_fingerprints(struct blame_origin *o) +{ + if (o->fingerprints) { + free_line_fingerprints(o->fingerprints, o->num_lines); + o->num_lines = 0; + FREE_AND_NULL(o->fingerprints); + } +} + +/* + * 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, int fill_fingerprints) +{ + if (!o->file.ptr) { + enum object_type type; + unsigned long file_size; + + (*num_read_blob)++; + if (opt->flags.allow_textconv && + textconv_object(opt->repo, 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; + if (fill_fingerprints) + fill_origin_fingerprints(o); +} + +static void drop_origin_blob(struct blame_origin *o) +{ + FREE_AND_NULL(o->file.ptr); + drop_origin_fingerprints(o); +} + +/* + * 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->ignored == next->ignored && + ent->unblamable == next->unblamable) { + 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 *r, + struct blame_origin *origin) +{ + if (!is_null_oid(&origin->blob_oid)) + return 0; + if (get_tree_entry(r, &origin->commit->object.oid, origin->path, &origin->blob_oid, &origin->mode)) + goto error_out; + if (oid_object_info(r, &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 repository *r, + 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. + */ + repo_diff_setup(r, &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 repository *r, + struct commit *parent, + struct blame_origin *origin) +{ + struct blame_origin *porigin = NULL; + struct diff_options diff_opts; + int i; + + repo_diff_setup(r, &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; + int i; + memset(split, 0, sizeof(struct blame_entry [3])); + + for (i = 0; i < 3; i++) { + split[i].ignored = e->ignored; + split[i].unblamable = e->unblamable; + } + + 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; +} + +/* + * Splits a blame entry into two entries at 'len' lines. The original 'e' + * consists of len lines, i.e. [e->lno, e->lno + len), and the second part, + * which is returned, consists of the remainder: [e->lno + len, e->lno + + * e->num_lines). The caller needs to sort out the reference counting for the + * new entry's suspect. + */ +static struct blame_entry *split_blame_at(struct blame_entry *e, int len, + struct blame_origin *new_suspect) +{ + struct blame_entry *n = xcalloc(1, sizeof(struct blame_entry)); + + n->suspect = new_suspect; + n->ignored = e->ignored; + n->unblamable = e->unblamable; + 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; + return n; +} + +struct blame_line_tracker { + int is_parent; + int s_lno; +}; + +static int are_lines_adjacent(struct blame_line_tracker *first, + struct blame_line_tracker *second) +{ + return first->is_parent == second->is_parent && + first->s_lno + 1 == second->s_lno; +} + +static int scan_parent_range(struct fingerprint *p_fps, + struct fingerprint *t_fps, int t_idx, + int from, int nr_lines) +{ + int sim, p_idx; + #define FINGERPRINT_FILE_THRESHOLD 10 + int best_sim_val = FINGERPRINT_FILE_THRESHOLD; + int best_sim_idx = -1; + + for (p_idx = from; p_idx < from + nr_lines; p_idx++) { + sim = fingerprint_similarity(&t_fps[t_idx], &p_fps[p_idx]); + if (sim < best_sim_val) + continue; + /* Break ties with the closest-to-target line number */ + if (sim == best_sim_val && best_sim_idx != -1 && + abs(best_sim_idx - t_idx) < abs(p_idx - t_idx)) + continue; + best_sim_val = sim; + best_sim_idx = p_idx; + } + return best_sim_idx; +} + +/* + * The first pass checks the blame entry (from the target) against the parent's + * diff chunk. If that fails for a line, the second pass tries to match that + * line to any part of parent file. That catches cases where a change was + * broken into two chunks by 'context.' + */ +static void guess_line_blames(struct blame_origin *parent, + struct blame_origin *target, + int tlno, int offset, int same, int parent_len, + struct blame_line_tracker *line_blames) +{ + int i, best_idx, target_idx; + int parent_slno = tlno + offset; + int *fuzzy_matches; + + fuzzy_matches = fuzzy_find_matching_lines(parent, target, + tlno, parent_slno, same, + parent_len); + for (i = 0; i < same - tlno; i++) { + target_idx = tlno + i; + if (fuzzy_matches && fuzzy_matches[i] >= 0) { + best_idx = fuzzy_matches[i]; + } else { + best_idx = scan_parent_range(parent->fingerprints, + target->fingerprints, + target_idx, 0, + parent->num_lines); + } + if (best_idx >= 0) { + line_blames[i].is_parent = 1; + line_blames[i].s_lno = best_idx; + } else { + line_blames[i].is_parent = 0; + line_blames[i].s_lno = target_idx; + } + } + free(fuzzy_matches); +} + +/* + * This decides which parts of a blame entry go to the parent (added to the + * ignoredp list) and which stay with the target (added to the diffp list). The + * actual decision was made in a separate heuristic function, and those answers + * for the lines in 'e' are in line_blames. This consumes e, essentially + * putting it on a list. + * + * Note that the blame entries on the ignoredp list are not necessarily sorted + * with respect to the parent's line numbers yet. + */ +static void ignore_blame_entry(struct blame_entry *e, + struct blame_origin *parent, + struct blame_entry **diffp, + struct blame_entry **ignoredp, + struct blame_line_tracker *line_blames) +{ + int entry_len, nr_lines, i; + + /* + * We carve new entries off the front of e. Each entry comes from a + * contiguous chunk of lines: adjacent lines from the same origin + * (either the parent or the target). + */ + entry_len = 1; + nr_lines = e->num_lines; /* e changes in the loop */ + for (i = 0; i < nr_lines; i++) { + struct blame_entry *next = NULL; + + /* + * We are often adjacent to the next line - only split the blame + * entry when we have to. + */ + if (i + 1 < nr_lines) { + if (are_lines_adjacent(&line_blames[i], + &line_blames[i + 1])) { + entry_len++; + continue; + } + next = split_blame_at(e, entry_len, + blame_origin_incref(e->suspect)); + } + if (line_blames[i].is_parent) { + e->ignored = 1; + blame_origin_decref(e->suspect); + e->suspect = blame_origin_incref(parent); + e->s_lno = line_blames[i - entry_len + 1].s_lno; + e->next = *ignoredp; + *ignoredp = e; + } else { + e->unblamable = 1; + /* e->s_lno is already in the target's address space. */ + e->next = *diffp; + *diffp = e; + } + assert(e->num_lines == entry_len); + e = next; + entry_len = 1; + } + assert(!e); +} + +/* + * 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. + * + * tlno: line number in the target where this chunk begins + * same: line number in the target where this chunk ends + * offset: add to tlno to get the chunk starting point in the parent + * parent_len: number of lines in the parent chunk + */ +static void blame_chunk(struct blame_entry ***dstq, struct blame_entry ***srcq, + int tlno, int offset, int same, int parent_len, + struct blame_origin *parent, + struct blame_origin *target, int ignore_diffs) +{ + struct blame_entry *e = **srcq; + struct blame_entry *samep = NULL, *diffp = NULL, *ignoredp = NULL; + struct blame_line_tracker *line_blames = 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 */ + struct blame_entry *n; + + n = split_blame_at(e, tlno - e->s_lno, e->suspect); + /* 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; + + if (ignore_diffs && same - tlno > 0) { + line_blames = xcalloc(sizeof(struct blame_line_tracker), + same - tlno); + guess_line_blames(parent, target, tlno, offset, same, + parent_len, line_blames); + } + + 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 + */ + struct blame_entry *n; + + n = split_blame_at(e, same - e->s_lno, + blame_origin_incref(e->suspect)); + /* Push new record to samep */ + n->next = samep; + samep = n; + } + if (ignore_diffs) { + ignore_blame_entry(e, parent, &diffp, &ignoredp, + line_blames + e->s_lno - tlno); + } else { + e->next = diffp; + diffp = e; + } + e = next; + } + free(line_blames); + if (ignoredp) { + /* + * Note ignoredp is not sorted yet, and thus neither is dstq. + * That list must be sorted before we queue_blames(). We defer + * sorting until after all diff hunks are processed, so that + * guess_line_blames() can pick *any* line in the parent. The + * slight drawback is that we end up sorting all blame entries + * passed to the parent, including those that are unrelated to + * changes made by the ignored commit. + */ + **dstq = reverse_blame(ignoredp, **dstq); + *dstq = &ignoredp->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; + struct blame_origin *target; + long offset; + int ignore_diffs; + 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, count_a, d->parent, d->target, + d->ignore_diffs); + 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, int ignore_diffs) +{ + 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.target = target; + d.offset = 0; + d.ignore_diffs = ignore_diffs; + d.dstq = &newdest; d.srcq = &target->suspects; + + fill_origin_blob(&sb->revs->diffopt, parent, &file_p, + &sb->num_read_blob, ignore_diffs); + fill_origin_blob(&sb->revs->diffopt, target, &file_o, + &sb->num_read_blob, ignore_diffs); + 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, 0, + parent, target, 0); + *d.dstq = NULL; + if (ignore_diffs) + newdest = llist_mergesort(newdest, get_next_blame, + set_next_blame, + compare_blame_suspect); + 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. + */ +unsigned blame_entry_score(struct blame_scoreboard *sb, struct blame_entry *e) +{ + unsigned score; + const char *cp, *ep; + + if (e->score) + return e->score; + + score = 1; + cp = blame_nth_line(sb, e->lno); + ep = blame_nth_line(sb, e->lno + e->num_lines); + while (cp < ep) { + unsigned ch = *((unsigned char *)cp); + if (isalnum(ch)) + score++; + cp++; + } + e->score = score; + return score; +} + +/* + * best_so_far[] and potential[] are both a split of an existing blame_entry + * that passes blame to the parent. Maintain best_so_far the best split so + * far, by comparing potential and best_so_far and copying potential into + * bst_so_far as needed. + */ +static void copy_split_if_better(struct blame_scoreboard *sb, + struct blame_entry *best_so_far, + struct blame_entry *potential) +{ + int i; + + if (!potential[1].suspect) + return; + if (best_so_far[1].suspect) { + if (blame_entry_score(sb, &potential[1]) < + blame_entry_score(sb, &best_so_far[1])) + return; + } + + for (i = 0; i < 3; i++) + blame_origin_incref(potential[i].suspect); + decref_split(best_so_far); + memcpy(best_so_far, potential, sizeof(struct blame_entry[3])); +} + +/* + * We are looking at a part of the final image represented by + * ent (tlno and same are offset by ent->s_lno). + * tlno is where we are looking at in the final image. + * up to (but not including) same match preimage. + * plno is where we are looking at in the preimage. + * + * <-------------- final image ----------------------> + * <------ent------> + * ^tlno ^same + * <---------preimage-----> + * ^plno + * + * All line numbers are 0-based. + */ +static void handle_split(struct blame_scoreboard *sb, + struct blame_entry *ent, + int tlno, int plno, int same, + struct blame_origin *parent, + struct blame_entry *split) +{ + if (ent->num_lines <= tlno) + return; + if (tlno < same) { + struct blame_entry potential[3]; + tlno += ent->s_lno; + same += ent->s_lno; + split_overlap(potential, ent, tlno, plno, same, parent); + copy_split_if_better(sb, split, potential); + decref_split(potential); + } +} + +struct handle_split_cb_data { + struct blame_scoreboard *sb; + struct blame_entry *ent; + struct blame_origin *parent; + struct blame_entry *split; + long plno; + long tlno; +}; + +static int handle_split_cb(long start_a, long count_a, + long start_b, long count_b, void *data) +{ + struct handle_split_cb_data *d = data; + handle_split(d->sb, d->ent, d->tlno, d->plno, start_b, d->parent, + d->split); + d->plno = start_a + count_a; + d->tlno = start_b + count_b; + return 0; +} + +/* + * Find the lines from parent that are the same as ent so that + * we can pass blames to it. file_p has the blob contents for + * the parent. + */ +static void find_copy_in_blob(struct blame_scoreboard *sb, + struct blame_entry *ent, + struct blame_origin *parent, + struct blame_entry *split, + mmfile_t *file_p) +{ + const char *cp; + mmfile_t file_o; + struct handle_split_cb_data d; + + memset(&d, 0, sizeof(d)); + d.sb = sb; d.ent = ent; d.parent = parent; d.split = split; + /* + * Prepare mmfile that contains only the lines in ent. + */ + cp = blame_nth_line(sb, ent->lno); + file_o.ptr = (char *) cp; + file_o.size = blame_nth_line(sb, ent->lno + ent->num_lines) - cp; + + /* + * file_o is a part of final image we are annotating. + * file_p partially may match that image. + */ + memset(split, 0, sizeof(struct blame_entry [3])); + if (diff_hunks(file_p, &file_o, handle_split_cb, &d, sb->xdl_opts)) + die("unable to generate diff (%s)", + oid_to_hex(&parent->commit->object.oid)); + /* remainder, if any, all match the preimage */ + handle_split(sb, ent, d.tlno, d.plno, ent->num_lines, parent, split); +} + +/* Move all blame entries from list *source that have a score smaller + * than score_min to the front of list *small. + * Returns a pointer to the link pointing to the old head of the small list. + */ + +static struct blame_entry **filter_small(struct blame_scoreboard *sb, + struct blame_entry **small, + struct blame_entry **source, + unsigned score_min) +{ + struct blame_entry *p = *source; + struct blame_entry *oldsmall = *small; + while (p) { + if (blame_entry_score(sb, p) <= score_min) { + *small = p; + small = &p->next; + p = *small; + } else { + *source = p; + source = &p->next; + p = *source; + } + } + *small = oldsmall; + *source = NULL; + return small; +} + +/* + * See if lines currently target is suspected for can be attributed to + * parent. + */ +static void find_move_in_parent(struct blame_scoreboard *sb, + struct blame_entry ***blamed, + struct blame_entry **toosmall, + struct blame_origin *target, + struct blame_origin *parent) +{ + struct blame_entry *e, split[3]; + struct blame_entry *unblamed = target->suspects; + struct blame_entry *leftover = NULL; + mmfile_t file_p; + + if (!unblamed) + return; /* nothing remains for this target */ + + fill_origin_blob(&sb->revs->diffopt, parent, &file_p, + &sb->num_read_blob, 0); + if (!file_p.ptr) + return; + + /* At each iteration, unblamed has a NULL-terminated list of + * entries that have not yet been tested for blame. leftover + * contains the reversed list of entries that have been tested + * without being assignable to the parent. + */ + do { + struct blame_entry **unblamedtail = &unblamed; + struct blame_entry *next; + for (e = unblamed; e; e = next) { + next = e->next; + find_copy_in_blob(sb, e, parent, split, &file_p); + if (split[1].suspect && + sb->move_score < blame_entry_score(sb, &split[1])) { + split_blame(blamed, &unblamedtail, split, e); + } else { + e->next = leftover; + leftover = e; + } + decref_split(split); + } + *unblamedtail = NULL; + toosmall = filter_small(sb, toosmall, &unblamed, sb->move_score); + } while (unblamed); + target->suspects = reverse_blame(leftover, NULL); +} + +struct blame_list { + struct blame_entry *ent; + struct blame_entry split[3]; +}; + +/* + * Count the number of entries the target is suspected for, + * and prepare a list of entry and the best split. + */ +static struct blame_list *setup_blame_list(struct blame_entry *unblamed, + int *num_ents_p) +{ + struct blame_entry *e; + int num_ents, i; + struct blame_list *blame_list = NULL; + + for (e = unblamed, num_ents = 0; e; e = e->next) + num_ents++; + if (num_ents) { + blame_list = xcalloc(num_ents, sizeof(struct blame_list)); + for (e = unblamed, i = 0; e; e = e->next) + blame_list[i++].ent = e; + } + *num_ents_p = num_ents; + return blame_list; +} + +/* + * For lines target is suspected for, see if we can find code movement + * across file boundary from the parent commit. porigin is the path + * in the parent we already tried. + */ +static void find_copy_in_parent(struct blame_scoreboard *sb, + struct blame_entry ***blamed, + struct blame_entry **toosmall, + struct blame_origin *target, + struct commit *parent, + struct blame_origin *porigin, + int opt) +{ + struct diff_options diff_opts; + int i, j; + struct blame_list *blame_list; + int num_ents; + struct blame_entry *unblamed = target->suspects; + struct blame_entry *leftover = NULL; + + if (!unblamed) + return; /* nothing remains for this target */ + + repo_diff_setup(sb->repo, &diff_opts); + diff_opts.flags.recursive = 1; + diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT; + + diff_setup_done(&diff_opts); + + /* Try "find copies harder" on new path if requested; + * we do not want to use diffcore_rename() actually to + * match things up; find_copies_harder is set only to + * force diff_tree_oid() to feed all filepairs to diff_queue, + * and this code needs to be after diff_setup_done(), which + * usually makes find-copies-harder imply copy detection. + */ + if ((opt & PICKAXE_BLAME_COPY_HARDEST) + || ((opt & PICKAXE_BLAME_COPY_HARDER) + && (!porigin || strcmp(target->path, porigin->path)))) + diff_opts.flags.find_copies_harder = 1; + + if (is_null_oid(&target->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(target->commit), + "", &diff_opts); + + if (!diff_opts.flags.find_copies_harder) + diffcore_std(&diff_opts); + + do { + struct blame_entry **unblamedtail = &unblamed; + blame_list = setup_blame_list(unblamed, &num_ents); + + for (i = 0; i < diff_queued_diff.nr; i++) { + struct diff_filepair *p = diff_queued_diff.queue[i]; + struct blame_origin *norigin; + mmfile_t file_p; + struct blame_entry potential[3]; + + if (!DIFF_FILE_VALID(p->one)) + continue; /* does not exist in parent */ + if (S_ISGITLINK(p->one->mode)) + continue; /* ignore git links */ + if (porigin && !strcmp(p->one->path, porigin->path)) + /* find_move already dealt with this path */ + continue; + + norigin = get_origin(parent, p->one->path); + oidcpy(&norigin->blob_oid, &p->one->oid); + norigin->mode = p->one->mode; + fill_origin_blob(&sb->revs->diffopt, norigin, &file_p, + &sb->num_read_blob, 0); + if (!file_p.ptr) + continue; + + for (j = 0; j < num_ents; j++) { + find_copy_in_blob(sb, blame_list[j].ent, + norigin, potential, &file_p); + copy_split_if_better(sb, blame_list[j].split, + potential); + decref_split(potential); + } + blame_origin_decref(norigin); + } + + for (j = 0; j < num_ents; j++) { + struct blame_entry *split = blame_list[j].split; + if (split[1].suspect && + sb->copy_score < blame_entry_score(sb, &split[1])) { + split_blame(blamed, &unblamedtail, split, + blame_list[j].ent); + } else { + blame_list[j].ent->next = leftover; + leftover = blame_list[j].ent; + } + decref_split(split); + } + free(blame_list); + *unblamedtail = NULL; + toosmall = filter_small(sb, toosmall, &unblamed, sb->copy_score); + } while (unblamed); + target->suspects = reverse_blame(leftover, NULL); + diff_flush(&diff_opts); + clear_pathspec(&diff_opts.pathspec); +} + +/* + * 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(struct blame_scoreboard *sb, + struct blame_origin *origin, struct blame_origin *porigin) +{ + struct blame_entry *e, *suspects; + + if (!porigin->file.ptr && origin->file.ptr) { + /* Steal its file */ + porigin->file = origin->file; + origin->file.ptr = NULL; + } + suspects = origin->suspects; + origin->suspects = NULL; + for (e = suspects; e; e = e->next) { + blame_origin_incref(porigin); + blame_origin_decref(e->suspect); + e->suspect = porigin; + } + queue_blames(sb, porigin, suspects); +} + +/* + * We pass blame from the current commit to its parents. We keep saying + * "parent" (and "porigin"), but what we mean is to find scapegoat to + * exonerate ourselves. + */ +static struct commit_list *first_scapegoat(struct rev_info *revs, struct commit *commit, + int reverse) +{ + if (!reverse) { + if (revs->first_parent_only && + commit->parents && + commit->parents->next) { + free_commit_list(commit->parents->next); + commit->parents->next = NULL; + } + return commit->parents; + } + return lookup_decoration(&revs->children, &commit->object); +} + +static int num_scapegoats(struct rev_info *revs, struct commit *commit, int reverse) +{ + struct commit_list *l = first_scapegoat(revs, commit, reverse); + return commit_list_count(l); +} + +/* Distribute collected unsorted blames to the respected sorted lists + * in the various origins. + */ +static void distribute_blame(struct blame_scoreboard *sb, struct blame_entry *blamed) +{ + blamed = llist_mergesort(blamed, get_next_blame, set_next_blame, + compare_blame_suspect); + while (blamed) + { + struct blame_origin *porigin = blamed->suspect; + struct blame_entry *suspects = NULL; + do { + struct blame_entry *next = blamed->next; + blamed->next = suspects; + suspects = blamed; + blamed = next; + } while (blamed && blamed->suspect == porigin); + suspects = reverse_blame(suspects, NULL); + queue_blames(sb, porigin, suspects); + } +} + +#define MAXSG 16 + +static void pass_blame(struct blame_scoreboard *sb, struct blame_origin *origin, int opt) +{ + struct rev_info *revs = sb->revs; + int i, pass, num_sg; + struct commit *commit = origin->commit; + struct commit_list *sg; + struct blame_origin *sg_buf[MAXSG]; + struct blame_origin *porigin, **sg_origin = sg_buf; + struct blame_entry *toosmall = NULL; + struct blame_entry *blames, **blametail = &blames; + + num_sg = num_scapegoats(revs, commit, sb->reverse); + if (!num_sg) + goto finish; + else if (num_sg < ARRAY_SIZE(sg_buf)) + memset(sg_buf, 0, sizeof(sg_buf)); + else + sg_origin = xcalloc(num_sg, sizeof(*sg_origin)); + + /* + * The first pass looks for unrenamed path to optimize for + * common cases, then we look for renames in the second pass. + */ + for (pass = 0; pass < 2 - sb->no_whole_file_rename; pass++) { + struct blame_origin *(*find)(struct repository *, struct commit *, struct blame_origin *); + find = pass ? find_rename : find_origin; + + for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse); + i < num_sg && sg; + sg = sg->next, i++) { + struct commit *p = sg->item; + int j, same; + + if (sg_origin[i]) + continue; + if (parse_commit(p)) + continue; + porigin = find(sb->repo, p, origin); + if (!porigin) + continue; + if (oideq(&porigin->blob_oid, &origin->blob_oid)) { + pass_whole_blame(sb, origin, porigin); + blame_origin_decref(porigin); + goto finish; + } + for (j = same = 0; j < i; j++) + if (sg_origin[j] && + oideq(&sg_origin[j]->blob_oid, &porigin->blob_oid)) { + same = 1; + break; + } + if (!same) + sg_origin[i] = porigin; + else + blame_origin_decref(porigin); + } + } + + sb->num_commits++; + for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse); + i < num_sg && sg; + sg = sg->next, i++) { + struct blame_origin *porigin = sg_origin[i]; + if (!porigin) + continue; + if (!origin->previous) { + blame_origin_incref(porigin); + origin->previous = porigin; + } + pass_blame_to_parent(sb, origin, porigin, 0); + if (!origin->suspects) + goto finish; + } + + /* + * Pass remaining suspects for ignored commits to their parents. + */ + if (oidset_contains(&sb->ignore_list, &commit->object.oid)) { + for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse); + i < num_sg && sg; + sg = sg->next, i++) { + struct blame_origin *porigin = sg_origin[i]; + + if (!porigin) + continue; + pass_blame_to_parent(sb, origin, porigin, 1); + /* + * Preemptively drop porigin so we can refresh the + * fingerprints if we use the parent again, which can + * occur if you ignore back-to-back commits. + */ + drop_origin_blob(porigin); + if (!origin->suspects) + goto finish; + } + } + + /* + * Optionally find moves in parents' files. + */ + if (opt & PICKAXE_BLAME_MOVE) { + filter_small(sb, &toosmall, &origin->suspects, sb->move_score); + if (origin->suspects) { + for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse); + i < num_sg && sg; + sg = sg->next, i++) { + struct blame_origin *porigin = sg_origin[i]; + if (!porigin) + continue; + find_move_in_parent(sb, &blametail, &toosmall, origin, porigin); + if (!origin->suspects) + break; + } + } + } + + /* + * Optionally find copies from parents' files. + */ + if (opt & PICKAXE_BLAME_COPY) { + if (sb->copy_score > sb->move_score) + filter_small(sb, &toosmall, &origin->suspects, sb->copy_score); + else if (sb->copy_score < sb->move_score) { + origin->suspects = blame_merge(origin->suspects, toosmall); + toosmall = NULL; + filter_small(sb, &toosmall, &origin->suspects, sb->copy_score); + } + if (!origin->suspects) + goto finish; + + for (i = 0, sg = first_scapegoat(revs, commit, sb->reverse); + i < num_sg && sg; + sg = sg->next, i++) { + struct blame_origin *porigin = sg_origin[i]; + find_copy_in_parent(sb, &blametail, &toosmall, + origin, sg->item, porigin, opt); + if (!origin->suspects) + goto finish; + } + } + +finish: + *blametail = NULL; + distribute_blame(sb, blames); + /* + * prepend toosmall to origin->suspects + * + * There is no point in sorting: this ends up on a big + * unsorted list in the caller anyway. + */ + if (toosmall) { + struct blame_entry **tail = &toosmall; + while (*tail) + tail = &(*tail)->next; + *tail = origin->suspects; + origin->suspects = toosmall; + } + for (i = 0; i < num_sg; i++) { + if (sg_origin[i]) { + if (!sg_origin[i]->suspects) + drop_origin_blob(sg_origin[i]); + blame_origin_decref(sg_origin[i]); + } + } + drop_origin_blob(origin); + if (sg_buf != sg_origin) + free(sg_origin); +} + +/* + * The main loop -- while we have blobs with lines whose true origin + * is still unknown, pick one blob, and allow its lines to pass blames + * to its parents. */ +void assign_blame(struct blame_scoreboard *sb, int opt) +{ + struct rev_info *revs = sb->revs; + struct commit *commit = prio_queue_get(&sb->commits); + + while (commit) { + struct blame_entry *ent; + struct blame_origin *suspect = get_blame_suspects(commit); + + /* find one suspect to break down */ + while (suspect && !suspect->suspects) + suspect = suspect->next; + + if (!suspect) { + commit = prio_queue_get(&sb->commits); + continue; + } + + assert(commit == suspect->commit); + + /* + * We will use this suspect later in the loop, + * so hold onto it in the meantime. + */ + blame_origin_incref(suspect); + parse_commit(commit); + if (sb->reverse || + (!(commit->object.flags & UNINTERESTING) && + !(revs->max_age != -1 && commit->date < revs->max_age))) + pass_blame(sb, suspect, opt); + else { + commit->object.flags |= UNINTERESTING; + if (commit->object.parsed) + mark_parents_uninteresting(commit); + } + /* treat root commit as boundary */ + if (!commit->parents && !sb->show_root) + commit->object.flags |= UNINTERESTING; + + /* Take responsibility for the remaining entries */ + ent = suspect->suspects; + if (ent) { + suspect->guilty = 1; + for (;;) { + struct blame_entry *next = ent->next; + if (sb->found_guilty_entry) + sb->found_guilty_entry(ent, sb->found_guilty_entry_data); + if (next) { + ent = next; + continue; + } + ent->next = sb->ent; + sb->ent = suspect->suspects; + suspect->suspects = NULL; + break; + } + } + blame_origin_decref(suspect); + + if (sb->debug) /* sanity */ + sanity_check_refcnt(sb); + } +} + +/* + * To allow quick access to the contents of nth line in the + * final image, prepare an index in the scoreboard. + */ +static int prepare_lines(struct blame_scoreboard *sb) +{ + sb->num_lines = find_line_starts(&sb->lineno, sb->final_buf, + sb->final_buf_size); + return sb->num_lines; +} + +static struct commit *find_single_final(struct rev_info *revs, + const char **name_p) +{ + int i; + struct commit *found = NULL; + const char *name = NULL; + + for (i = 0; i < revs->pending.nr; i++) { + struct object *obj = revs->pending.objects[i].item; + if (obj->flags & UNINTERESTING) + continue; + obj = deref_tag(revs->repo, obj, NULL, 0); + if (obj->type != OBJ_COMMIT) + die("Non commit %s?", revs->pending.objects[i].name); + if (found) + die("More than one commit to dig from %s and %s?", + revs->pending.objects[i].name, name); + found = (struct commit *)obj; + name = revs->pending.objects[i].name; + } + if (name_p) + *name_p = xstrdup_or_null(name); + return found; +} + +static struct commit *dwim_reverse_initial(struct rev_info *revs, + const char **name_p) +{ + /* + * DWIM "git blame --reverse ONE -- PATH" as + * "git blame --reverse ONE..HEAD -- PATH" but only do so + * when it makes sense. + */ + struct object *obj; + struct commit *head_commit; + struct object_id head_oid; + + if (revs->pending.nr != 1) + return NULL; + + /* Is that sole rev a committish? */ + obj = revs->pending.objects[0].item; + obj = deref_tag(revs->repo, obj, NULL, 0); + if (obj->type != OBJ_COMMIT) + return NULL; + + /* Do we have HEAD? */ + if (!resolve_ref_unsafe("HEAD", RESOLVE_REF_READING, &head_oid, NULL)) + return NULL; + head_commit = lookup_commit_reference_gently(revs->repo, + &head_oid, 1); + if (!head_commit) + return NULL; + + /* Turn "ONE" into "ONE..HEAD" then */ + obj->flags |= UNINTERESTING; + add_pending_object(revs, &head_commit->object, "HEAD"); + + if (name_p) + *name_p = revs->pending.objects[0].name; + return (struct commit *)obj; +} + +static struct commit *find_single_initial(struct rev_info *revs, + const char **name_p) +{ + int i; + struct commit *found = NULL; + const char *name = NULL; + + /* + * There must be one and only one negative commit, and it must be + * the boundary. + */ + for (i = 0; i < revs->pending.nr; i++) { + struct object *obj = revs->pending.objects[i].item; + if (!(obj->flags & UNINTERESTING)) + continue; + obj = deref_tag(revs->repo, obj, NULL, 0); + if (obj->type != OBJ_COMMIT) + die("Non commit %s?", revs->pending.objects[i].name); + if (found) + die("More than one commit to dig up from, %s and %s?", + revs->pending.objects[i].name, name); + found = (struct commit *) obj; + name = revs->pending.objects[i].name; + } + + if (!name) + found = dwim_reverse_initial(revs, &name); + if (!name) + die("No commit to dig up from?"); + + if (name_p) + *name_p = xstrdup(name); + return found; +} + +void init_scoreboard(struct blame_scoreboard *sb) +{ + memset(sb, 0, sizeof(struct blame_scoreboard)); + sb->move_score = BLAME_DEFAULT_MOVE_SCORE; + sb->copy_score = BLAME_DEFAULT_COPY_SCORE; +} + +void setup_scoreboard(struct blame_scoreboard *sb, + const char *path, + struct blame_origin **orig) +{ + const char *final_commit_name = NULL; + struct blame_origin *o; + struct commit *final_commit = NULL; + enum object_type type; + + init_blame_suspects(&blame_suspects); + + if (sb->reverse && sb->contents_from) + die(_("--contents and --reverse do not blend well.")); + + if (!sb->repo) + BUG("repo is NULL"); + + if (!sb->reverse) { + sb->final = find_single_final(sb->revs, &final_commit_name); + sb->commits.compare = compare_commits_by_commit_date; + } else { + sb->final = find_single_initial(sb->revs, &final_commit_name); + sb->commits.compare = compare_commits_by_reverse_commit_date; + } + + if (sb->final && sb->contents_from) + die(_("cannot use --contents with final commit object name")); + + if (sb->reverse && sb->revs->first_parent_only) + sb->revs->children.name = NULL; + + if (!sb->final) { + /* + * "--not A B -- path" without anything positive; + * do not default to HEAD, but use the working tree + * or "--contents". + */ + setup_work_tree(); + sb->final = fake_working_tree_commit(sb->repo, + &sb->revs->diffopt, + path, sb->contents_from); + add_pending_object(sb->revs, &(sb->final->object), ":"); + } + + if (sb->reverse && sb->revs->first_parent_only) { + final_commit = find_single_final(sb->revs, NULL); + if (!final_commit) + die(_("--reverse and --first-parent together require specified latest commit")); + } + + /* + * If we have bottom, this will mark the ancestors of the + * bottom commits we would reach while traversing as + * uninteresting. + */ + if (prepare_revision_walk(sb->revs)) + die(_("revision walk setup failed")); + + if (sb->reverse && sb->revs->first_parent_only) { + struct commit *c = final_commit; + + sb->revs->children.name = "children"; + while (c->parents && + !oideq(&c->object.oid, &sb->final->object.oid)) { + struct commit_list *l = xcalloc(1, sizeof(*l)); + + l->item = c; + if (add_decoration(&sb->revs->children, + &c->parents->item->object, l)) + BUG("not unique item in first-parent chain"); + c = c->parents->item; + } + + if (!oideq(&c->object.oid, &sb->final->object.oid)) + die(_("--reverse --first-parent together require range along first-parent chain")); + } + + if (is_null_oid(&sb->final->object.oid)) { + o = get_blame_suspects(sb->final); + sb->final_buf = xmemdupz(o->file.ptr, o->file.size); + sb->final_buf_size = o->file.size; + } + else { + o = get_origin(sb->final, path); + if (fill_blob_sha1_and_mode(sb->repo, o)) + die(_("no such path %s in %s"), path, final_commit_name); + + if (sb->revs->diffopt.flags.allow_textconv && + textconv_object(sb->repo, path, o->mode, &o->blob_oid, 1, (char **) &sb->final_buf, + &sb->final_buf_size)) + ; + else + sb->final_buf = read_object_file(&o->blob_oid, &type, + &sb->final_buf_size); + + if (!sb->final_buf) + die(_("cannot read blob %s for path %s"), + oid_to_hex(&o->blob_oid), + path); + } + sb->num_read_blob++; + prepare_lines(sb); + + if (orig) + *orig = o; + + free((char *)final_commit_name); +} + + + +struct blame_entry *blame_entry_prepend(struct blame_entry *head, + long start, long end, + struct blame_origin *o) +{ + struct blame_entry *new_head = xcalloc(1, sizeof(struct blame_entry)); + new_head->lno = start; + new_head->num_lines = end - start; + new_head->suspect = o; + new_head->s_lno = start; + new_head->next = head; + blame_origin_incref(o); + return new_head; +} |