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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-09 13:34:27 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-09 13:34:27 +0000
commit4dbdc42d9e7c3968ff7f690d00680419c9b8cb0f (patch)
tree47c1d492e9c956c1cd2b74dbd3b9d8b0db44dc4e /bisect.c
parentInitial commit. (diff)
downloadgit-4dbdc42d9e7c3968ff7f690d00680419c9b8cb0f.tar.xz
git-4dbdc42d9e7c3968ff7f690d00680419c9b8cb0f.zip
Adding upstream version 1:2.43.0.upstream/1%2.43.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'bisect.c')
-rw-r--r--bisect.c1205
1 files changed, 1205 insertions, 0 deletions
diff --git a/bisect.c b/bisect.c
new file mode 100644
index 0000000..1be8e0a
--- /dev/null
+++ b/bisect.c
@@ -0,0 +1,1205 @@
+#include "git-compat-util.h"
+#include "config.h"
+#include "commit.h"
+#include "diff.h"
+#include "environment.h"
+#include "gettext.h"
+#include "hex.h"
+#include "revision.h"
+#include "refs.h"
+#include "list-objects.h"
+#include "quote.h"
+#include "hash-lookup.h"
+#include "run-command.h"
+#include "log-tree.h"
+#include "bisect.h"
+#include "oid-array.h"
+#include "strvec.h"
+#include "commit-slab.h"
+#include "commit-reach.h"
+#include "object-name.h"
+#include "object-store-ll.h"
+#include "path.h"
+#include "dir.h"
+
+static struct oid_array good_revs;
+static struct oid_array skipped_revs;
+
+static struct object_id *current_bad_oid;
+
+static const char *term_bad;
+static const char *term_good;
+
+/* Remember to update object flag allocation in object.h */
+#define COUNTED (1u<<16)
+
+/*
+ * This is a truly stupid algorithm, but it's only
+ * used for bisection, and we just don't care enough.
+ *
+ * We care just barely enough to avoid recursing for
+ * non-merge entries.
+ */
+static int count_distance(struct commit_list *entry)
+{
+ int nr = 0;
+
+ while (entry) {
+ struct commit *commit = entry->item;
+ struct commit_list *p;
+
+ if (commit->object.flags & (UNINTERESTING | COUNTED))
+ break;
+ if (!(commit->object.flags & TREESAME))
+ nr++;
+ commit->object.flags |= COUNTED;
+ p = commit->parents;
+ entry = p;
+ if (p) {
+ p = p->next;
+ while (p) {
+ nr += count_distance(p);
+ p = p->next;
+ }
+ }
+ }
+
+ return nr;
+}
+
+static void clear_distance(struct commit_list *list)
+{
+ while (list) {
+ struct commit *commit = list->item;
+ commit->object.flags &= ~COUNTED;
+ list = list->next;
+ }
+}
+
+define_commit_slab(commit_weight, int *);
+static struct commit_weight commit_weight;
+
+#define DEBUG_BISECT 0
+
+static inline int weight(struct commit_list *elem)
+{
+ return **commit_weight_at(&commit_weight, elem->item);
+}
+
+static inline void weight_set(struct commit_list *elem, int weight)
+{
+ **commit_weight_at(&commit_weight, elem->item) = weight;
+}
+
+static int count_interesting_parents(struct commit *commit, unsigned bisect_flags)
+{
+ struct commit_list *p;
+ int count;
+
+ for (count = 0, p = commit->parents; p; p = p->next) {
+ if (!(p->item->object.flags & UNINTERESTING))
+ count++;
+ if (bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY)
+ break;
+ }
+ return count;
+}
+
+static inline int approx_halfway(struct commit_list *p, int nr)
+{
+ int diff;
+
+ /*
+ * Don't short-cut something we are not going to return!
+ */
+ if (p->item->object.flags & TREESAME)
+ return 0;
+ if (DEBUG_BISECT)
+ return 0;
+ /*
+ * For small number of commits 2 and 3 are halfway of 5, and
+ * 3 is halfway of 6 but 2 and 4 are not.
+ */
+ diff = 2 * weight(p) - nr;
+ switch (diff) {
+ case -1: case 0: case 1:
+ return 1;
+ default:
+ /*
+ * For large number of commits we are not so strict, it's
+ * good enough if it's within ~0.1% of the halfway point,
+ * e.g. 5000 is exactly halfway of 10000, but we consider
+ * the values [4996, 5004] as halfway as well.
+ */
+ if (abs(diff) < nr / 1024)
+ return 1;
+ return 0;
+ }
+}
+
+static void show_list(const char *debug, int counted, int nr,
+ struct commit_list *list)
+{
+ struct commit_list *p;
+
+ if (!DEBUG_BISECT)
+ return;
+
+ fprintf(stderr, "%s (%d/%d)\n", debug, counted, nr);
+
+ for (p = list; p; p = p->next) {
+ struct commit_list *pp;
+ struct commit *commit = p->item;
+ unsigned commit_flags = commit->object.flags;
+ enum object_type type;
+ unsigned long size;
+ char *buf = repo_read_object_file(the_repository,
+ &commit->object.oid, &type,
+ &size);
+ const char *subject_start;
+ int subject_len;
+
+ fprintf(stderr, "%c%c%c ",
+ (commit_flags & TREESAME) ? ' ' : 'T',
+ (commit_flags & UNINTERESTING) ? 'U' : ' ',
+ (commit_flags & COUNTED) ? 'C' : ' ');
+ if (*commit_weight_at(&commit_weight, p->item))
+ fprintf(stderr, "%3d", weight(p));
+ else
+ fprintf(stderr, "---");
+ fprintf(stderr, " %.*s", 8, oid_to_hex(&commit->object.oid));
+ for (pp = commit->parents; pp; pp = pp->next)
+ fprintf(stderr, " %.*s", 8,
+ oid_to_hex(&pp->item->object.oid));
+
+ subject_len = find_commit_subject(buf, &subject_start);
+ if (subject_len)
+ fprintf(stderr, " %.*s", subject_len, subject_start);
+ fprintf(stderr, "\n");
+ }
+}
+
+static struct commit_list *best_bisection(struct commit_list *list, int nr)
+{
+ struct commit_list *p, *best;
+ int best_distance = -1;
+
+ best = list;
+ for (p = list; p; p = p->next) {
+ int distance;
+ unsigned commit_flags = p->item->object.flags;
+
+ if (commit_flags & TREESAME)
+ continue;
+ distance = weight(p);
+ if (nr - distance < distance)
+ distance = nr - distance;
+ if (distance > best_distance) {
+ best = p;
+ best_distance = distance;
+ }
+ }
+
+ return best;
+}
+
+struct commit_dist {
+ struct commit *commit;
+ int distance;
+};
+
+static int compare_commit_dist(const void *a_, const void *b_)
+{
+ struct commit_dist *a, *b;
+
+ a = (struct commit_dist *)a_;
+ b = (struct commit_dist *)b_;
+ if (a->distance != b->distance)
+ return b->distance - a->distance; /* desc sort */
+ return oidcmp(&a->commit->object.oid, &b->commit->object.oid);
+}
+
+static struct commit_list *best_bisection_sorted(struct commit_list *list, int nr)
+{
+ struct commit_list *p;
+ struct commit_dist *array = xcalloc(nr, sizeof(*array));
+ struct strbuf buf = STRBUF_INIT;
+ int cnt, i;
+
+ for (p = list, cnt = 0; p; p = p->next) {
+ int distance;
+ unsigned commit_flags = p->item->object.flags;
+
+ if (commit_flags & TREESAME)
+ continue;
+ distance = weight(p);
+ if (nr - distance < distance)
+ distance = nr - distance;
+ array[cnt].commit = p->item;
+ array[cnt].distance = distance;
+ cnt++;
+ }
+ QSORT(array, cnt, compare_commit_dist);
+ for (p = list, i = 0; i < cnt; i++) {
+ struct object *obj = &(array[i].commit->object);
+
+ strbuf_reset(&buf);
+ strbuf_addf(&buf, "dist=%d", array[i].distance);
+ add_name_decoration(DECORATION_NONE, buf.buf, obj);
+
+ p->item = array[i].commit;
+ if (i < cnt - 1)
+ p = p->next;
+ }
+ if (p) {
+ free_commit_list(p->next);
+ p->next = NULL;
+ }
+ strbuf_release(&buf);
+ free(array);
+ return list;
+}
+
+/*
+ * zero or positive weight is the number of interesting commits it can
+ * reach, including itself. Especially, weight = 0 means it does not
+ * reach any tree-changing commits (e.g. just above uninteresting one
+ * but traversal is with pathspec).
+ *
+ * weight = -1 means it has one parent and its distance is yet to
+ * be computed.
+ *
+ * weight = -2 means it has more than one parent and its distance is
+ * unknown. After running count_distance() first, they will get zero
+ * or positive distance.
+ */
+static struct commit_list *do_find_bisection(struct commit_list *list,
+ int nr, int *weights,
+ unsigned bisect_flags)
+{
+ int n, counted;
+ struct commit_list *p;
+
+ counted = 0;
+
+ for (n = 0, p = list; p; p = p->next) {
+ struct commit *commit = p->item;
+ unsigned commit_flags = commit->object.flags;
+
+ *commit_weight_at(&commit_weight, p->item) = &weights[n++];
+ switch (count_interesting_parents(commit, bisect_flags)) {
+ case 0:
+ if (!(commit_flags & TREESAME)) {
+ weight_set(p, 1);
+ counted++;
+ show_list("bisection 2 count one",
+ counted, nr, list);
+ }
+ /*
+ * otherwise, it is known not to reach any
+ * tree-changing commit and gets weight 0.
+ */
+ break;
+ case 1:
+ weight_set(p, -1);
+ break;
+ default:
+ weight_set(p, -2);
+ break;
+ }
+ }
+
+ show_list("bisection 2 initialize", counted, nr, list);
+
+ /*
+ * If you have only one parent in the resulting set
+ * then you can reach one commit more than that parent
+ * can reach. So we do not have to run the expensive
+ * count_distance() for single strand of pearls.
+ *
+ * However, if you have more than one parents, you cannot
+ * just add their distance and one for yourself, since
+ * they usually reach the same ancestor and you would
+ * end up counting them twice that way.
+ *
+ * So we will first count distance of merges the usual
+ * way, and then fill the blanks using cheaper algorithm.
+ */
+ for (p = list; p; p = p->next) {
+ if (p->item->object.flags & UNINTERESTING)
+ continue;
+ if (weight(p) != -2)
+ continue;
+ if (bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY)
+ BUG("shouldn't be calling count-distance in fp mode");
+ weight_set(p, count_distance(p));
+ clear_distance(list);
+
+ /* Does it happen to be at half-way? */
+ if (!(bisect_flags & FIND_BISECTION_ALL) &&
+ approx_halfway(p, nr))
+ return p;
+ counted++;
+ }
+
+ show_list("bisection 2 count_distance", counted, nr, list);
+
+ while (counted < nr) {
+ for (p = list; p; p = p->next) {
+ struct commit_list *q;
+ unsigned commit_flags = p->item->object.flags;
+
+ if (0 <= weight(p))
+ continue;
+
+ for (q = p->item->parents;
+ q;
+ q = bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY ? NULL : q->next) {
+ if (q->item->object.flags & UNINTERESTING)
+ continue;
+ if (0 <= weight(q))
+ break;
+ }
+ if (!q)
+ continue;
+
+ /*
+ * weight for p is unknown but q is known.
+ * add one for p itself if p is to be counted,
+ * otherwise inherit it from q directly.
+ */
+ if (!(commit_flags & TREESAME)) {
+ weight_set(p, weight(q)+1);
+ counted++;
+ show_list("bisection 2 count one",
+ counted, nr, list);
+ }
+ else
+ weight_set(p, weight(q));
+
+ /* Does it happen to be at half-way? */
+ if (!(bisect_flags & FIND_BISECTION_ALL) &&
+ approx_halfway(p, nr))
+ return p;
+ }
+ }
+
+ show_list("bisection 2 counted all", counted, nr, list);
+
+ if (!(bisect_flags & FIND_BISECTION_ALL))
+ return best_bisection(list, nr);
+ else
+ return best_bisection_sorted(list, nr);
+}
+
+void find_bisection(struct commit_list **commit_list, int *reaches,
+ int *all, unsigned bisect_flags)
+{
+ int nr, on_list;
+ struct commit_list *list, *p, *best, *next, *last;
+ int *weights;
+
+ show_list("bisection 2 entry", 0, 0, *commit_list);
+ init_commit_weight(&commit_weight);
+
+ /*
+ * Count the number of total and tree-changing items on the
+ * list, while reversing the list.
+ */
+ for (nr = on_list = 0, last = NULL, p = *commit_list;
+ p;
+ p = next) {
+ unsigned commit_flags = p->item->object.flags;
+
+ next = p->next;
+ if (commit_flags & UNINTERESTING) {
+ free(p);
+ continue;
+ }
+ p->next = last;
+ last = p;
+ if (!(commit_flags & TREESAME))
+ nr++;
+ on_list++;
+ }
+ list = last;
+ show_list("bisection 2 sorted", 0, nr, list);
+
+ *all = nr;
+ CALLOC_ARRAY(weights, on_list);
+
+ /* Do the real work of finding bisection commit. */
+ best = do_find_bisection(list, nr, weights, bisect_flags);
+ if (best) {
+ if (!(bisect_flags & FIND_BISECTION_ALL)) {
+ list->item = best->item;
+ free_commit_list(list->next);
+ best = list;
+ best->next = NULL;
+ }
+ *reaches = weight(best);
+ }
+ free(weights);
+ *commit_list = best;
+ clear_commit_weight(&commit_weight);
+}
+
+static int register_ref(const char *refname, const struct object_id *oid,
+ int flags UNUSED, void *cb_data UNUSED)
+{
+ struct strbuf good_prefix = STRBUF_INIT;
+ strbuf_addstr(&good_prefix, term_good);
+ strbuf_addstr(&good_prefix, "-");
+
+ if (!strcmp(refname, term_bad)) {
+ current_bad_oid = xmalloc(sizeof(*current_bad_oid));
+ oidcpy(current_bad_oid, oid);
+ } else if (starts_with(refname, good_prefix.buf)) {
+ oid_array_append(&good_revs, oid);
+ } else if (starts_with(refname, "skip-")) {
+ oid_array_append(&skipped_revs, oid);
+ }
+
+ strbuf_release(&good_prefix);
+
+ return 0;
+}
+
+static int read_bisect_refs(void)
+{
+ return for_each_ref_in("refs/bisect/", register_ref, NULL);
+}
+
+static GIT_PATH_FUNC(git_path_bisect_names, "BISECT_NAMES")
+static GIT_PATH_FUNC(git_path_bisect_expected_rev, "BISECT_EXPECTED_REV")
+static GIT_PATH_FUNC(git_path_bisect_ancestors_ok, "BISECT_ANCESTORS_OK")
+static GIT_PATH_FUNC(git_path_bisect_run, "BISECT_RUN")
+static GIT_PATH_FUNC(git_path_bisect_start, "BISECT_START")
+static GIT_PATH_FUNC(git_path_bisect_log, "BISECT_LOG")
+static GIT_PATH_FUNC(git_path_bisect_terms, "BISECT_TERMS")
+static GIT_PATH_FUNC(git_path_bisect_first_parent, "BISECT_FIRST_PARENT")
+
+static void read_bisect_paths(struct strvec *array)
+{
+ struct strbuf str = STRBUF_INIT;
+ const char *filename = git_path_bisect_names();
+ FILE *fp = xfopen(filename, "r");
+
+ while (strbuf_getline_lf(&str, fp) != EOF) {
+ strbuf_trim(&str);
+ if (sq_dequote_to_strvec(str.buf, array))
+ die(_("Badly quoted content in file '%s': %s"),
+ filename, str.buf);
+ }
+
+ strbuf_release(&str);
+ fclose(fp);
+}
+
+static char *join_oid_array_hex(struct oid_array *array, char delim)
+{
+ struct strbuf joined_hexs = STRBUF_INIT;
+ int i;
+
+ for (i = 0; i < array->nr; i++) {
+ strbuf_addstr(&joined_hexs, oid_to_hex(array->oid + i));
+ if (i + 1 < array->nr)
+ strbuf_addch(&joined_hexs, delim);
+ }
+
+ return strbuf_detach(&joined_hexs, NULL);
+}
+
+/*
+ * In this function, passing a not NULL skipped_first is very special.
+ * It means that we want to know if the first commit in the list is
+ * skipped because we will want to test a commit away from it if it is
+ * indeed skipped.
+ * So if the first commit is skipped, we cannot take the shortcut to
+ * just "return list" when we find the first non skipped commit, we
+ * have to return a fully filtered list.
+ *
+ * We use (*skipped_first == -1) to mean "it has been found that the
+ * first commit is not skipped". In this case *skipped_first is set back
+ * to 0 just before the function returns.
+ */
+struct commit_list *filter_skipped(struct commit_list *list,
+ struct commit_list **tried,
+ int show_all,
+ int *count,
+ int *skipped_first)
+{
+ struct commit_list *filtered = NULL, **f = &filtered;
+
+ *tried = NULL;
+
+ if (skipped_first)
+ *skipped_first = 0;
+ if (count)
+ *count = 0;
+
+ if (!skipped_revs.nr)
+ return list;
+
+ while (list) {
+ struct commit_list *next = list->next;
+ list->next = NULL;
+ if (0 <= oid_array_lookup(&skipped_revs, &list->item->object.oid)) {
+ if (skipped_first && !*skipped_first)
+ *skipped_first = 1;
+ /* Move current to tried list */
+ *tried = list;
+ tried = &list->next;
+ } else {
+ if (!show_all) {
+ if (!skipped_first || !*skipped_first)
+ return list;
+ } else if (skipped_first && !*skipped_first) {
+ /* This means we know it's not skipped */
+ *skipped_first = -1;
+ }
+ /* Move current to filtered list */
+ *f = list;
+ f = &list->next;
+ if (count)
+ (*count)++;
+ }
+ list = next;
+ }
+
+ if (skipped_first && *skipped_first == -1)
+ *skipped_first = 0;
+
+ return filtered;
+}
+
+#define PRN_MODULO 32768
+
+/*
+ * This is a pseudo random number generator based on "man 3 rand".
+ * It is not used properly because the seed is the argument and it
+ * is increased by one between each call, but that should not matter
+ * for this application.
+ */
+static unsigned get_prn(unsigned count)
+{
+ count = count * 1103515245 + 12345;
+ return (count/65536) % PRN_MODULO;
+}
+
+/*
+ * Custom integer square root from
+ * https://en.wikipedia.org/wiki/Integer_square_root
+ */
+static int sqrti(int val)
+{
+ float d, x = val;
+
+ if (!val)
+ return 0;
+
+ do {
+ float y = (x + (float)val / x) / 2;
+ d = (y > x) ? y - x : x - y;
+ x = y;
+ } while (d >= 0.5);
+
+ return (int)x;
+}
+
+static struct commit_list *skip_away(struct commit_list *list, int count)
+{
+ struct commit_list *cur, *previous;
+ int prn, index, i;
+
+ prn = get_prn(count);
+ index = (count * prn / PRN_MODULO) * sqrti(prn) / sqrti(PRN_MODULO);
+
+ cur = list;
+ previous = NULL;
+
+ for (i = 0; cur; cur = cur->next, i++) {
+ if (i == index) {
+ if (!oideq(&cur->item->object.oid, current_bad_oid))
+ return cur;
+ if (previous)
+ return previous;
+ return list;
+ }
+ previous = cur;
+ }
+
+ return list;
+}
+
+static struct commit_list *managed_skipped(struct commit_list *list,
+ struct commit_list **tried)
+{
+ int count, skipped_first;
+
+ *tried = NULL;
+
+ if (!skipped_revs.nr)
+ return list;
+
+ list = filter_skipped(list, tried, 0, &count, &skipped_first);
+
+ if (!skipped_first)
+ return list;
+
+ return skip_away(list, count);
+}
+
+static void bisect_rev_setup(struct repository *r, struct rev_info *revs,
+ struct strvec *rev_argv,
+ const char *prefix,
+ const char *bad_format, const char *good_format,
+ int read_paths)
+{
+ struct setup_revision_opt opt = {
+ .free_removed_argv_elements = 1,
+ };
+ int i;
+
+ repo_init_revisions(r, revs, prefix);
+ revs->abbrev = 0;
+ revs->commit_format = CMIT_FMT_UNSPECIFIED;
+
+ /* rev_argv.argv[0] will be ignored by setup_revisions */
+ strvec_push(rev_argv, "bisect_rev_setup");
+ strvec_pushf(rev_argv, bad_format, oid_to_hex(current_bad_oid));
+ for (i = 0; i < good_revs.nr; i++)
+ strvec_pushf(rev_argv, good_format,
+ oid_to_hex(good_revs.oid + i));
+ strvec_push(rev_argv, "--");
+ if (read_paths)
+ read_bisect_paths(rev_argv);
+
+ setup_revisions(rev_argv->nr, rev_argv->v, revs, &opt);
+}
+
+static void bisect_common(struct rev_info *revs)
+{
+ if (prepare_revision_walk(revs))
+ die("revision walk setup failed");
+ if (revs->tree_objects)
+ mark_edges_uninteresting(revs, NULL, 0);
+}
+
+static enum bisect_error error_if_skipped_commits(struct commit_list *tried,
+ const struct object_id *bad)
+{
+ if (!tried)
+ return BISECT_OK;
+
+ printf("There are only 'skip'ped commits left to test.\n"
+ "The first %s commit could be any of:\n", term_bad);
+
+ for ( ; tried; tried = tried->next)
+ printf("%s\n", oid_to_hex(&tried->item->object.oid));
+
+ if (bad)
+ printf("%s\n", oid_to_hex(bad));
+ printf(_("We cannot bisect more!\n"));
+
+ return BISECT_ONLY_SKIPPED_LEFT;
+}
+
+static int is_expected_rev(const struct object_id *oid)
+{
+ const char *filename = git_path_bisect_expected_rev();
+ struct stat st;
+ struct strbuf str = STRBUF_INIT;
+ FILE *fp;
+ int res = 0;
+
+ if (stat(filename, &st) || !S_ISREG(st.st_mode))
+ return 0;
+
+ fp = fopen_or_warn(filename, "r");
+ if (!fp)
+ return 0;
+
+ if (strbuf_getline_lf(&str, fp) != EOF)
+ res = !strcmp(str.buf, oid_to_hex(oid));
+
+ strbuf_release(&str);
+ fclose(fp);
+
+ return res;
+}
+
+enum bisect_error bisect_checkout(const struct object_id *bisect_rev,
+ int no_checkout)
+{
+ struct commit *commit;
+ struct pretty_print_context pp = {0};
+ struct strbuf commit_msg = STRBUF_INIT;
+
+ update_ref(NULL, "BISECT_EXPECTED_REV", bisect_rev, NULL, 0, UPDATE_REFS_DIE_ON_ERR);
+
+ if (no_checkout) {
+ update_ref(NULL, "BISECT_HEAD", bisect_rev, NULL, 0,
+ UPDATE_REFS_DIE_ON_ERR);
+ } else {
+ struct child_process cmd = CHILD_PROCESS_INIT;
+
+ cmd.git_cmd = 1;
+ strvec_pushl(&cmd.args, "checkout", "-q",
+ oid_to_hex(bisect_rev), "--", NULL);
+ if (run_command(&cmd))
+ /*
+ * Errors in `run_command()` itself, signaled by res < 0,
+ * and errors in the child process, signaled by res > 0
+ * can both be treated as regular BISECT_FAILED (-1).
+ */
+ return BISECT_FAILED;
+ }
+
+ commit = lookup_commit_reference(the_repository, bisect_rev);
+ repo_format_commit_message(the_repository, commit, "[%H] %s%n",
+ &commit_msg, &pp);
+ fputs(commit_msg.buf, stdout);
+ strbuf_release(&commit_msg);
+
+ return BISECT_OK;
+}
+
+static struct commit *get_commit_reference(struct repository *r,
+ const struct object_id *oid)
+{
+ struct commit *c = lookup_commit_reference(r, oid);
+ if (!c)
+ die(_("Not a valid commit name %s"), oid_to_hex(oid));
+ return c;
+}
+
+static struct commit **get_bad_and_good_commits(struct repository *r,
+ int *rev_nr)
+{
+ struct commit **rev;
+ int i, n = 0;
+
+ ALLOC_ARRAY(rev, 1 + good_revs.nr);
+ rev[n++] = get_commit_reference(r, current_bad_oid);
+ for (i = 0; i < good_revs.nr; i++)
+ rev[n++] = get_commit_reference(r, good_revs.oid + i);
+ *rev_nr = n;
+
+ return rev;
+}
+
+static enum bisect_error handle_bad_merge_base(void)
+{
+ if (is_expected_rev(current_bad_oid)) {
+ char *bad_hex = oid_to_hex(current_bad_oid);
+ char *good_hex = join_oid_array_hex(&good_revs, ' ');
+ if (!strcmp(term_bad, "bad") && !strcmp(term_good, "good")) {
+ fprintf(stderr, _("The merge base %s is bad.\n"
+ "This means the bug has been fixed "
+ "between %s and [%s].\n"),
+ bad_hex, bad_hex, good_hex);
+ } else if (!strcmp(term_bad, "new") && !strcmp(term_good, "old")) {
+ fprintf(stderr, _("The merge base %s is new.\n"
+ "The property has changed "
+ "between %s and [%s].\n"),
+ bad_hex, bad_hex, good_hex);
+ } else {
+ fprintf(stderr, _("The merge base %s is %s.\n"
+ "This means the first '%s' commit is "
+ "between %s and [%s].\n"),
+ bad_hex, term_bad, term_good, bad_hex, good_hex);
+ }
+ return BISECT_MERGE_BASE_CHECK;
+ }
+
+ fprintf(stderr, _("Some %s revs are not ancestors of the %s rev.\n"
+ "git bisect cannot work properly in this case.\n"
+ "Maybe you mistook %s and %s revs?\n"),
+ term_good, term_bad, term_good, term_bad);
+ return BISECT_FAILED;
+}
+
+static void handle_skipped_merge_base(const struct object_id *mb)
+{
+ char *mb_hex = oid_to_hex(mb);
+ char *bad_hex = oid_to_hex(current_bad_oid);
+ char *good_hex = join_oid_array_hex(&good_revs, ' ');
+
+ warning(_("the merge base between %s and [%s] "
+ "must be skipped.\n"
+ "So we cannot be sure the first %s commit is "
+ "between %s and %s.\n"
+ "We continue anyway."),
+ bad_hex, good_hex, term_bad, mb_hex, bad_hex);
+ free(good_hex);
+}
+
+/*
+ * "check_merge_bases" checks that merge bases are not "bad" (or "new").
+ *
+ * - If one is "bad" (or "new"), it means the user assumed something wrong
+ * and we must return error with a non 0 error code.
+ * - If one is "good" (or "old"), that's good, we have nothing to do.
+ * - If one is "skipped", we can't know but we should warn.
+ * - If we don't know, we should check it out and ask the user to test.
+ * - If a merge base must be tested, on success return
+ * BISECT_INTERNAL_SUCCESS_MERGE_BASE (-11) a special condition
+ * for early success, this will be converted back to 0 in
+ * check_good_are_ancestors_of_bad().
+ */
+static enum bisect_error check_merge_bases(int rev_nr, struct commit **rev, int no_checkout)
+{
+ enum bisect_error res = BISECT_OK;
+ struct commit_list *result;
+
+ result = repo_get_merge_bases_many(the_repository, rev[0], rev_nr - 1,
+ rev + 1);
+
+ for (; result; result = result->next) {
+ const struct object_id *mb = &result->item->object.oid;
+ if (oideq(mb, current_bad_oid)) {
+ res = handle_bad_merge_base();
+ break;
+ } else if (0 <= oid_array_lookup(&good_revs, mb)) {
+ continue;
+ } else if (0 <= oid_array_lookup(&skipped_revs, mb)) {
+ handle_skipped_merge_base(mb);
+ } else {
+ printf(_("Bisecting: a merge base must be tested\n"));
+ res = bisect_checkout(mb, no_checkout);
+ if (!res)
+ /* indicate early success */
+ res = BISECT_INTERNAL_SUCCESS_MERGE_BASE;
+ break;
+ }
+ }
+
+ free_commit_list(result);
+ return res;
+}
+
+static int check_ancestors(struct repository *r, int rev_nr,
+ struct commit **rev, const char *prefix)
+{
+ struct strvec rev_argv = STRVEC_INIT;
+ struct rev_info revs;
+ int res;
+
+ bisect_rev_setup(r, &revs, &rev_argv, prefix, "^%s", "%s", 0);
+
+ bisect_common(&revs);
+ res = (revs.commits != NULL);
+
+ /* Clean up objects used, as they will be reused. */
+ clear_commit_marks_many(rev_nr, rev, ALL_REV_FLAGS);
+
+ release_revisions(&revs);
+ strvec_clear(&rev_argv);
+ return res;
+}
+
+/*
+ * "check_good_are_ancestors_of_bad" checks that all "good" revs are
+ * ancestor of the "bad" rev.
+ *
+ * If that's not the case, we need to check the merge bases.
+ * If a merge base must be tested by the user, its source code will be
+ * checked out to be tested by the user and we will return.
+ */
+
+static enum bisect_error check_good_are_ancestors_of_bad(struct repository *r,
+ const char *prefix,
+ int no_checkout)
+{
+ char *filename;
+ struct stat st;
+ int fd, rev_nr;
+ enum bisect_error res = BISECT_OK;
+ struct commit **rev;
+
+ if (!current_bad_oid)
+ return error(_("a %s revision is needed"), term_bad);
+
+ filename = git_pathdup("BISECT_ANCESTORS_OK");
+
+ /* Check if file BISECT_ANCESTORS_OK exists. */
+ if (!stat(filename, &st) && S_ISREG(st.st_mode))
+ goto done;
+
+ /* Bisecting with no good rev is ok. */
+ if (!good_revs.nr)
+ goto done;
+
+ /* Check if all good revs are ancestor of the bad rev. */
+
+ rev = get_bad_and_good_commits(r, &rev_nr);
+ if (check_ancestors(r, rev_nr, rev, prefix))
+ res = check_merge_bases(rev_nr, rev, no_checkout);
+ free(rev);
+
+ if (!res) {
+ /* Create file BISECT_ANCESTORS_OK. */
+ fd = open(filename, O_CREAT | O_TRUNC | O_WRONLY, 0600);
+ if (fd < 0)
+ /*
+ * BISECT_ANCESTORS_OK file is not absolutely necessary,
+ * the bisection process will continue at the next
+ * bisection step.
+ * So, just signal with a warning that something
+ * might be wrong.
+ */
+ warning_errno(_("could not create file '%s'"),
+ filename);
+ else
+ close(fd);
+ }
+ done:
+ free(filename);
+ return res;
+}
+
+/*
+ * This does "git diff-tree --pretty COMMIT" without one fork+exec.
+ */
+static void show_diff_tree(struct repository *r,
+ const char *prefix,
+ struct commit *commit)
+{
+ const char *argv[] = {
+ "diff-tree", "--pretty", "--stat", "--summary", "--cc", NULL
+ };
+ struct rev_info opt;
+
+ git_config(git_diff_ui_config, NULL);
+ repo_init_revisions(r, &opt, prefix);
+
+ setup_revisions(ARRAY_SIZE(argv) - 1, argv, &opt, NULL);
+ log_tree_commit(&opt, commit);
+ release_revisions(&opt);
+}
+
+/*
+ * The terms used for this bisect session are stored in BISECT_TERMS.
+ * We read them and store them to adapt the messages accordingly.
+ * Default is bad/good.
+ */
+void read_bisect_terms(const char **read_bad, const char **read_good)
+{
+ struct strbuf str = STRBUF_INIT;
+ const char *filename = git_path_bisect_terms();
+ FILE *fp = fopen(filename, "r");
+
+ if (!fp) {
+ if (errno == ENOENT) {
+ *read_bad = "bad";
+ *read_good = "good";
+ return;
+ } else {
+ die_errno(_("could not read file '%s'"), filename);
+ }
+ } else {
+ strbuf_getline_lf(&str, fp);
+ *read_bad = strbuf_detach(&str, NULL);
+ strbuf_getline_lf(&str, fp);
+ *read_good = strbuf_detach(&str, NULL);
+ }
+ strbuf_release(&str);
+ fclose(fp);
+}
+
+/*
+ * We use the convention that return BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10) means
+ * the bisection process finished successfully.
+ * In this case the calling function or command should not turn a
+ * BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND return code into an error or a non zero exit code.
+ *
+ * Checking BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND
+ * in bisect_helper::bisect_next() and only transforming it to 0 at
+ * the end of bisect_helper::cmd_bisect__helper() helps bypassing
+ * all the code related to finding a commit to test.
+ */
+enum bisect_error bisect_next_all(struct repository *r, const char *prefix)
+{
+ struct strvec rev_argv = STRVEC_INIT;
+ struct rev_info revs = REV_INFO_INIT;
+ struct commit_list *tried;
+ int reaches = 0, all = 0, nr, steps;
+ enum bisect_error res = BISECT_OK;
+ struct object_id *bisect_rev;
+ char *steps_msg;
+ /*
+ * If no_checkout is non-zero, the bisection process does not
+ * checkout the trial commit but instead simply updates BISECT_HEAD.
+ */
+ int no_checkout = ref_exists("BISECT_HEAD");
+ unsigned bisect_flags = 0;
+
+ read_bisect_terms(&term_bad, &term_good);
+ if (read_bisect_refs())
+ die(_("reading bisect refs failed"));
+
+ if (file_exists(git_path_bisect_first_parent()))
+ bisect_flags |= FIND_BISECTION_FIRST_PARENT_ONLY;
+
+ if (skipped_revs.nr)
+ bisect_flags |= FIND_BISECTION_ALL;
+
+ res = check_good_are_ancestors_of_bad(r, prefix, no_checkout);
+ if (res)
+ goto cleanup;
+
+ bisect_rev_setup(r, &revs, &rev_argv, prefix, "%s", "^%s", 1);
+
+ revs.first_parent_only = !!(bisect_flags & FIND_BISECTION_FIRST_PARENT_ONLY);
+ revs.limited = 1;
+
+ bisect_common(&revs);
+
+ find_bisection(&revs.commits, &reaches, &all, bisect_flags);
+ revs.commits = managed_skipped(revs.commits, &tried);
+
+ if (!revs.commits) {
+ /*
+ * We should return error here only if the "bad"
+ * commit is also a "skip" commit.
+ */
+ res = error_if_skipped_commits(tried, NULL);
+ if (res < 0)
+ goto cleanup;
+ printf(_("%s was both %s and %s\n"),
+ oid_to_hex(current_bad_oid),
+ term_good,
+ term_bad);
+
+ res = BISECT_FAILED;
+ goto cleanup;
+ }
+
+ if (!all) {
+ fprintf(stderr, _("No testable commit found.\n"
+ "Maybe you started with bad path arguments?\n"));
+
+ res = BISECT_NO_TESTABLE_COMMIT;
+ goto cleanup;
+ }
+
+ bisect_rev = &revs.commits->item->object.oid;
+
+ if (oideq(bisect_rev, current_bad_oid)) {
+ res = error_if_skipped_commits(tried, current_bad_oid);
+ if (res)
+ return res;
+ printf("%s is the first %s commit\n", oid_to_hex(bisect_rev),
+ term_bad);
+
+ show_diff_tree(r, prefix, revs.commits->item);
+ /*
+ * This means the bisection process succeeded.
+ * Using BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND (-10)
+ * so that the call chain can simply check
+ * for negative return values for early returns up
+ * until the cmd_bisect__helper() caller.
+ */
+ res = BISECT_INTERNAL_SUCCESS_1ST_BAD_FOUND;
+ goto cleanup;
+ }
+
+ nr = all - reaches - 1;
+ steps = estimate_bisect_steps(all);
+
+ steps_msg = xstrfmt(Q_("(roughly %d step)", "(roughly %d steps)",
+ steps), steps);
+ /*
+ * TRANSLATORS: the last %s will be replaced with "(roughly %d
+ * steps)" translation.
+ */
+ printf(Q_("Bisecting: %d revision left to test after this %s\n",
+ "Bisecting: %d revisions left to test after this %s\n",
+ nr), nr, steps_msg);
+ free(steps_msg);
+ /* Clean up objects used, as they will be reused. */
+ repo_clear_commit_marks(r, ALL_REV_FLAGS);
+
+ res = bisect_checkout(bisect_rev, no_checkout);
+cleanup:
+ release_revisions(&revs);
+ strvec_clear(&rev_argv);
+ return res;
+}
+
+static inline int log2i(int n)
+{
+ int log2 = 0;
+
+ for (; n > 1; n >>= 1)
+ log2++;
+
+ return log2;
+}
+
+static inline int exp2i(int n)
+{
+ return 1 << n;
+}
+
+/*
+ * Estimate the number of bisect steps left (after the current step)
+ *
+ * For any x between 0 included and 2^n excluded, the probability for
+ * n - 1 steps left looks like:
+ *
+ * P(2^n + x) == (2^n - x) / (2^n + x)
+ *
+ * and P(2^n + x) < 0.5 means 2^n < 3x
+ */
+int estimate_bisect_steps(int all)
+{
+ int n, x, e;
+
+ if (all < 3)
+ return 0;
+
+ n = log2i(all);
+ e = exp2i(n);
+ x = all - e;
+
+ return (e < 3 * x) ? n : n - 1;
+}
+
+static int mark_for_removal(const char *refname,
+ const struct object_id *oid UNUSED,
+ int flag UNUSED, void *cb_data)
+{
+ struct string_list *refs = cb_data;
+ char *ref = xstrfmt("refs/bisect%s", refname);
+ string_list_append(refs, ref);
+ return 0;
+}
+
+int bisect_clean_state(void)
+{
+ int result = 0;
+
+ /* There may be some refs packed during bisection */
+ struct string_list refs_for_removal = STRING_LIST_INIT_NODUP;
+ for_each_ref_in("refs/bisect", mark_for_removal, (void *) &refs_for_removal);
+ string_list_append(&refs_for_removal, xstrdup("BISECT_HEAD"));
+ result = delete_refs("bisect: remove", &refs_for_removal, REF_NO_DEREF);
+ refs_for_removal.strdup_strings = 1;
+ string_list_clear(&refs_for_removal, 0);
+ unlink_or_warn(git_path_bisect_expected_rev());
+ unlink_or_warn(git_path_bisect_ancestors_ok());
+ unlink_or_warn(git_path_bisect_log());
+ unlink_or_warn(git_path_bisect_names());
+ unlink_or_warn(git_path_bisect_run());
+ unlink_or_warn(git_path_bisect_terms());
+ unlink_or_warn(git_path_bisect_first_parent());
+ /*
+ * Cleanup BISECT_START last to support the --no-checkout option
+ * introduced in the commit 4796e823a.
+ */
+ unlink_or_warn(git_path_bisect_start());
+
+ return result;
+}