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-rw-r--r--tree-diff.c721
1 files changed, 721 insertions, 0 deletions
diff --git a/tree-diff.c b/tree-diff.c
new file mode 100644
index 0000000..69031d7
--- /dev/null
+++ b/tree-diff.c
@@ -0,0 +1,721 @@
+/*
+ * Helper functions for tree diff generation
+ */
+#include "cache.h"
+#include "diff.h"
+#include "diffcore.h"
+#include "tree.h"
+
+/*
+ * internal mode marker, saying a tree entry != entry of tp[imin]
+ * (see ll_diff_tree_paths for what it means there)
+ *
+ * we will update/use/emit entry for diff only with it unset.
+ */
+#define S_IFXMIN_NEQ S_DIFFTREE_IFXMIN_NEQ
+
+#define FAST_ARRAY_ALLOC(x, nr) do { \
+ if ((nr) <= 2) \
+ (x) = xalloca((nr) * sizeof(*(x))); \
+ else \
+ ALLOC_ARRAY((x), nr); \
+} while(0)
+#define FAST_ARRAY_FREE(x, nr) do { \
+ if ((nr) <= 2) \
+ xalloca_free((x)); \
+ else \
+ free((x)); \
+} while(0)
+
+static struct combine_diff_path *ll_diff_tree_paths(
+ struct combine_diff_path *p, const struct object_id *oid,
+ const struct object_id **parents_oid, int nparent,
+ struct strbuf *base, struct diff_options *opt);
+static void ll_diff_tree_oid(const struct object_id *old_oid,
+ const struct object_id *new_oid,
+ struct strbuf *base, struct diff_options *opt);
+
+/*
+ * Compare two tree entries, taking into account only path/S_ISDIR(mode),
+ * but not their sha1's.
+ *
+ * NOTE files and directories *always* compare differently, even when having
+ * the same name - thanks to base_name_compare().
+ *
+ * NOTE empty (=invalid) descriptor(s) take part in comparison as +infty,
+ * so that they sort *after* valid tree entries.
+ *
+ * Due to this convention, if trees are scanned in sorted order, all
+ * non-empty descriptors will be processed first.
+ */
+static int tree_entry_pathcmp(struct tree_desc *t1, struct tree_desc *t2)
+{
+ struct name_entry *e1, *e2;
+ int cmp;
+
+ /* empty descriptors sort after valid tree entries */
+ if (!t1->size)
+ return t2->size ? 1 : 0;
+ else if (!t2->size)
+ return -1;
+
+ e1 = &t1->entry;
+ e2 = &t2->entry;
+ cmp = base_name_compare(e1->path, tree_entry_len(e1), e1->mode,
+ e2->path, tree_entry_len(e2), e2->mode);
+ return cmp;
+}
+
+
+/*
+ * convert path -> opt->diff_*() callbacks
+ *
+ * emits diff to first parent only, and tells diff tree-walker that we are done
+ * with p and it can be freed.
+ */
+static int emit_diff_first_parent_only(struct diff_options *opt, struct combine_diff_path *p)
+{
+ struct combine_diff_parent *p0 = &p->parent[0];
+ if (p->mode && p0->mode) {
+ opt->change(opt, p0->mode, p->mode, &p0->oid, &p->oid,
+ 1, 1, p->path, 0, 0);
+ }
+ else {
+ const struct object_id *oid;
+ unsigned int mode;
+ int addremove;
+
+ if (p->mode) {
+ addremove = '+';
+ oid = &p->oid;
+ mode = p->mode;
+ } else {
+ addremove = '-';
+ oid = &p0->oid;
+ mode = p0->mode;
+ }
+
+ opt->add_remove(opt, addremove, mode, oid, 1, p->path, 0);
+ }
+
+ return 0; /* we are done with p */
+}
+
+
+/*
+ * Make a new combine_diff_path from path/mode/sha1
+ * and append it to paths list tail.
+ *
+ * Memory for created elements could be reused:
+ *
+ * - if last->next == NULL, the memory is allocated;
+ *
+ * - if last->next != NULL, it is assumed that p=last->next was returned
+ * earlier by this function, and p->next was *not* modified.
+ * The memory is then reused from p.
+ *
+ * so for clients,
+ *
+ * - if you do need to keep the element
+ *
+ * p = path_appendnew(p, ...);
+ * process(p);
+ * p->next = NULL;
+ *
+ * - if you don't need to keep the element after processing
+ *
+ * pprev = p;
+ * p = path_appendnew(p, ...);
+ * process(p);
+ * p = pprev;
+ * ; don't forget to free tail->next in the end
+ *
+ * p->parent[] remains uninitialized.
+ */
+static struct combine_diff_path *path_appendnew(struct combine_diff_path *last,
+ int nparent, const struct strbuf *base, const char *path, int pathlen,
+ unsigned mode, const struct object_id *oid)
+{
+ struct combine_diff_path *p;
+ size_t len = st_add(base->len, pathlen);
+ size_t alloclen = combine_diff_path_size(nparent, len);
+
+ /* if last->next is !NULL - it is a pre-allocated memory, we can reuse */
+ p = last->next;
+ if (p && (alloclen > (intptr_t)p->next)) {
+ FREE_AND_NULL(p);
+ }
+
+ if (!p) {
+ p = xmalloc(alloclen);
+
+ /*
+ * until we go to it next round, .next holds how many bytes we
+ * allocated (for faster realloc - we don't need copying old data).
+ */
+ p->next = (struct combine_diff_path *)(intptr_t)alloclen;
+ }
+
+ last->next = p;
+
+ p->path = (char *)&(p->parent[nparent]);
+ memcpy(p->path, base->buf, base->len);
+ memcpy(p->path + base->len, path, pathlen);
+ p->path[len] = 0;
+ p->mode = mode;
+ oidcpy(&p->oid, oid ? oid : null_oid());
+
+ return p;
+}
+
+/*
+ * new path should be added to combine diff
+ *
+ * 3 cases on how/when it should be called and behaves:
+ *
+ * t, !tp -> path added, all parents lack it
+ * !t, tp -> path removed from all parents
+ * t, tp -> path modified/added
+ * (M for tp[i]=tp[imin], A otherwise)
+ */
+static struct combine_diff_path *emit_path(struct combine_diff_path *p,
+ struct strbuf *base, struct diff_options *opt, int nparent,
+ struct tree_desc *t, struct tree_desc *tp,
+ int imin)
+{
+ unsigned short mode;
+ const char *path;
+ const struct object_id *oid;
+ int pathlen;
+ int old_baselen = base->len;
+ int i, isdir, recurse = 0, emitthis = 1;
+
+ /* at least something has to be valid */
+ assert(t || tp);
+
+ if (t) {
+ /* path present in resulting tree */
+ oid = tree_entry_extract(t, &path, &mode);
+ pathlen = tree_entry_len(&t->entry);
+ isdir = S_ISDIR(mode);
+ } else {
+ /*
+ * a path was removed - take path from imin parent. Also take
+ * mode from that parent, to decide on recursion(1).
+ *
+ * 1) all modes for tp[i]=tp[imin] should be the same wrt
+ * S_ISDIR, thanks to base_name_compare().
+ */
+ tree_entry_extract(&tp[imin], &path, &mode);
+ pathlen = tree_entry_len(&tp[imin].entry);
+
+ isdir = S_ISDIR(mode);
+ oid = NULL;
+ mode = 0;
+ }
+
+ if (opt->flags.recursive && isdir) {
+ recurse = 1;
+ emitthis = opt->flags.tree_in_recursive;
+ }
+
+ if (emitthis) {
+ int keep;
+ struct combine_diff_path *pprev = p;
+ p = path_appendnew(p, nparent, base, path, pathlen, mode, oid);
+
+ for (i = 0; i < nparent; ++i) {
+ /*
+ * tp[i] is valid, if present and if tp[i]==tp[imin] -
+ * otherwise, we should ignore it.
+ */
+ int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
+
+ const struct object_id *oid_i;
+ unsigned mode_i;
+
+ p->parent[i].status =
+ !t ? DIFF_STATUS_DELETED :
+ tpi_valid ?
+ DIFF_STATUS_MODIFIED :
+ DIFF_STATUS_ADDED;
+
+ if (tpi_valid) {
+ oid_i = &tp[i].entry.oid;
+ mode_i = tp[i].entry.mode;
+ }
+ else {
+ oid_i = null_oid();
+ mode_i = 0;
+ }
+
+ p->parent[i].mode = mode_i;
+ oidcpy(&p->parent[i].oid, oid_i);
+ }
+
+ keep = 1;
+ if (opt->pathchange)
+ keep = opt->pathchange(opt, p);
+
+ /*
+ * If a path was filtered or consumed - we don't need to add it
+ * to the list and can reuse its memory, leaving it as
+ * pre-allocated element on the tail.
+ *
+ * On the other hand, if path needs to be kept, we need to
+ * correct its .next to NULL, as it was pre-initialized to how
+ * much memory was allocated.
+ *
+ * see path_appendnew() for details.
+ */
+ if (!keep)
+ p = pprev;
+ else
+ p->next = NULL;
+ }
+
+ if (recurse) {
+ const struct object_id **parents_oid;
+
+ FAST_ARRAY_ALLOC(parents_oid, nparent);
+ for (i = 0; i < nparent; ++i) {
+ /* same rule as in emitthis */
+ int tpi_valid = tp && !(tp[i].entry.mode & S_IFXMIN_NEQ);
+
+ parents_oid[i] = tpi_valid ? &tp[i].entry.oid : NULL;
+ }
+
+ strbuf_add(base, path, pathlen);
+ strbuf_addch(base, '/');
+ p = ll_diff_tree_paths(p, oid, parents_oid, nparent, base, opt);
+ FAST_ARRAY_FREE(parents_oid, nparent);
+ }
+
+ strbuf_setlen(base, old_baselen);
+ return p;
+}
+
+static void skip_uninteresting(struct tree_desc *t, struct strbuf *base,
+ struct diff_options *opt)
+{
+ enum interesting match;
+
+ while (t->size) {
+ match = tree_entry_interesting(opt->repo->index, &t->entry,
+ base, 0, &opt->pathspec);
+ if (match) {
+ if (match == all_entries_not_interesting)
+ t->size = 0;
+ break;
+ }
+ update_tree_entry(t);
+ }
+}
+
+
+/*
+ * generate paths for combined diff D(sha1,parents_oid[])
+ *
+ * Resulting paths are appended to combine_diff_path linked list, and also, are
+ * emitted on the go via opt->pathchange() callback, so it is possible to
+ * process the result as batch or incrementally.
+ *
+ * The paths are generated scanning new tree and all parents trees
+ * simultaneously, similarly to what diff_tree() was doing for 2 trees.
+ * The theory behind such scan is as follows:
+ *
+ *
+ * D(T,P1...Pn) calculation scheme
+ * -------------------------------
+ *
+ * D(T,P1...Pn) = D(T,P1) ^ ... ^ D(T,Pn) (regarding resulting paths set)
+ *
+ * D(T,Pj) - diff between T..Pj
+ * D(T,P1...Pn) - combined diff from T to parents P1,...,Pn
+ *
+ *
+ * We start from all trees, which are sorted, and compare their entries in
+ * lock-step:
+ *
+ * T P1 Pn
+ * - - -
+ * |t| |p1| |pn|
+ * |-| |--| ... |--| imin = argmin(p1...pn)
+ * | | | | | |
+ * |-| |--| |--|
+ * |.| |. | |. |
+ * . . .
+ * . . .
+ *
+ * at any time there could be 3 cases:
+ *
+ * 1) t < p[imin];
+ * 2) t > p[imin];
+ * 3) t = p[imin].
+ *
+ * Schematic deduction of what every case means, and what to do, follows:
+ *
+ * 1) t < p[imin] -> ∀j t ∉ Pj -> "+t" ∈ D(T,Pj) -> D += "+t"; t↓
+ *
+ * 2) t > p[imin]
+ *
+ * 2.1) ∃j: pj > p[imin] -> "-p[imin]" ∉ D(T,Pj) -> D += ø; ∀ pi=p[imin] pi↓
+ * 2.2) ∀i pi = p[imin] -> pi ∉ T -> "-pi" ∈ D(T,Pi) -> D += "-p[imin]"; ∀i pi↓
+ *
+ * 3) t = p[imin]
+ *
+ * 3.1) ∃j: pj > p[imin] -> "+t" ∈ D(T,Pj) -> only pi=p[imin] remains to investigate
+ * 3.2) pi = p[imin] -> investigate δ(t,pi)
+ * |
+ * |
+ * v
+ *
+ * 3.1+3.2) looking at δ(t,pi) ∀i: pi=p[imin] - if all != ø ->
+ *
+ * ⎧δ(t,pi) - if pi=p[imin]
+ * -> D += ⎨
+ * ⎩"+t" - if pi>p[imin]
+ *
+ *
+ * in any case t↓ ∀ pi=p[imin] pi↓
+ *
+ *
+ * ~~~~~~~~
+ *
+ * NOTE
+ *
+ * Usual diff D(A,B) is by definition the same as combined diff D(A,[B]),
+ * so this diff paths generator can, and is used, for plain diffs
+ * generation too.
+ *
+ * Please keep attention to the common D(A,[B]) case when working on the
+ * code, in order not to slow it down.
+ *
+ * NOTE
+ * nparent must be > 0.
+ */
+
+
+/* ∀ pi=p[imin] pi↓ */
+static inline void update_tp_entries(struct tree_desc *tp, int nparent)
+{
+ int i;
+ for (i = 0; i < nparent; ++i)
+ if (!(tp[i].entry.mode & S_IFXMIN_NEQ))
+ update_tree_entry(&tp[i]);
+}
+
+static struct combine_diff_path *ll_diff_tree_paths(
+ struct combine_diff_path *p, const struct object_id *oid,
+ const struct object_id **parents_oid, int nparent,
+ struct strbuf *base, struct diff_options *opt)
+{
+ struct tree_desc t, *tp;
+ void *ttree, **tptree;
+ int i;
+
+ FAST_ARRAY_ALLOC(tp, nparent);
+ FAST_ARRAY_ALLOC(tptree, nparent);
+
+ /*
+ * load parents first, as they are probably already cached.
+ *
+ * ( log_tree_diff() parses commit->parent before calling here via
+ * diff_tree_oid(parent, commit) )
+ */
+ for (i = 0; i < nparent; ++i)
+ tptree[i] = fill_tree_descriptor(opt->repo, &tp[i], parents_oid[i]);
+ ttree = fill_tree_descriptor(opt->repo, &t, oid);
+
+ /* Enable recursion indefinitely */
+ opt->pathspec.recursive = opt->flags.recursive;
+
+ for (;;) {
+ int imin, cmp;
+
+ if (diff_can_quit_early(opt))
+ break;
+
+ if (opt->max_changes && diff_queued_diff.nr > opt->max_changes)
+ break;
+
+ if (opt->pathspec.nr) {
+ skip_uninteresting(&t, base, opt);
+ for (i = 0; i < nparent; i++)
+ skip_uninteresting(&tp[i], base, opt);
+ }
+
+ /* comparing is finished when all trees are done */
+ if (!t.size) {
+ int done = 1;
+ for (i = 0; i < nparent; ++i)
+ if (tp[i].size) {
+ done = 0;
+ break;
+ }
+ if (done)
+ break;
+ }
+
+ /*
+ * lookup imin = argmin(p1...pn),
+ * mark entries whether they =p[imin] along the way
+ */
+ imin = 0;
+ tp[0].entry.mode &= ~S_IFXMIN_NEQ;
+
+ for (i = 1; i < nparent; ++i) {
+ cmp = tree_entry_pathcmp(&tp[i], &tp[imin]);
+ if (cmp < 0) {
+ imin = i;
+ tp[i].entry.mode &= ~S_IFXMIN_NEQ;
+ }
+ else if (cmp == 0) {
+ tp[i].entry.mode &= ~S_IFXMIN_NEQ;
+ }
+ else {
+ tp[i].entry.mode |= S_IFXMIN_NEQ;
+ }
+ }
+
+ /* fixup markings for entries before imin */
+ for (i = 0; i < imin; ++i)
+ tp[i].entry.mode |= S_IFXMIN_NEQ; /* pi > p[imin] */
+
+
+
+ /* compare t vs p[imin] */
+ cmp = tree_entry_pathcmp(&t, &tp[imin]);
+
+ /* t = p[imin] */
+ if (cmp == 0) {
+ /* are either pi > p[imin] or diff(t,pi) != ø ? */
+ if (!opt->flags.find_copies_harder) {
+ for (i = 0; i < nparent; ++i) {
+ /* p[i] > p[imin] */
+ if (tp[i].entry.mode & S_IFXMIN_NEQ)
+ continue;
+
+ /* diff(t,pi) != ø */
+ if (!oideq(&t.entry.oid, &tp[i].entry.oid) ||
+ (t.entry.mode != tp[i].entry.mode))
+ continue;
+
+ goto skip_emit_t_tp;
+ }
+ }
+
+ /* D += {δ(t,pi) if pi=p[imin]; "+a" if pi > p[imin]} */
+ p = emit_path(p, base, opt, nparent,
+ &t, tp, imin);
+
+ skip_emit_t_tp:
+ /* t↓, ∀ pi=p[imin] pi↓ */
+ update_tree_entry(&t);
+ update_tp_entries(tp, nparent);
+ }
+
+ /* t < p[imin] */
+ else if (cmp < 0) {
+ /* D += "+t" */
+ p = emit_path(p, base, opt, nparent,
+ &t, /*tp=*/NULL, -1);
+
+ /* t↓ */
+ update_tree_entry(&t);
+ }
+
+ /* t > p[imin] */
+ else {
+ /* ∀i pi=p[imin] -> D += "-p[imin]" */
+ if (!opt->flags.find_copies_harder) {
+ for (i = 0; i < nparent; ++i)
+ if (tp[i].entry.mode & S_IFXMIN_NEQ)
+ goto skip_emit_tp;
+ }
+
+ p = emit_path(p, base, opt, nparent,
+ /*t=*/NULL, tp, imin);
+
+ skip_emit_tp:
+ /* ∀ pi=p[imin] pi↓ */
+ update_tp_entries(tp, nparent);
+ }
+ }
+
+ free(ttree);
+ for (i = nparent-1; i >= 0; i--)
+ free(tptree[i]);
+ FAST_ARRAY_FREE(tptree, nparent);
+ FAST_ARRAY_FREE(tp, nparent);
+
+ return p;
+}
+
+struct combine_diff_path *diff_tree_paths(
+ struct combine_diff_path *p, const struct object_id *oid,
+ const struct object_id **parents_oid, int nparent,
+ struct strbuf *base, struct diff_options *opt)
+{
+ p = ll_diff_tree_paths(p, oid, parents_oid, nparent, base, opt);
+
+ /*
+ * free pre-allocated last element, if any
+ * (see path_appendnew() for details about why)
+ */
+ FREE_AND_NULL(p->next);
+
+ return p;
+}
+
+/*
+ * Does it look like the resulting diff might be due to a rename?
+ * - single entry
+ * - not a valid previous file
+ */
+static inline int diff_might_be_rename(void)
+{
+ return diff_queued_diff.nr == 1 &&
+ !DIFF_FILE_VALID(diff_queued_diff.queue[0]->one);
+}
+
+static void try_to_follow_renames(const struct object_id *old_oid,
+ const struct object_id *new_oid,
+ struct strbuf *base, struct diff_options *opt)
+{
+ struct diff_options diff_opts;
+ struct diff_queue_struct *q = &diff_queued_diff;
+ struct diff_filepair *choice;
+ int i;
+
+ /*
+ * follow-rename code is very specific, we need exactly one
+ * path. Magic that matches more than one path is not
+ * supported.
+ */
+ GUARD_PATHSPEC(&opt->pathspec, PATHSPEC_FROMTOP | PATHSPEC_LITERAL);
+#if 0
+ /*
+ * We should reject wildcards as well. Unfortunately we
+ * haven't got a reliable way to detect that 'foo\*bar' in
+ * fact has no wildcards. nowildcard_len is merely a hint for
+ * optimization. Let it slip for now until wildmatch is taught
+ * about dry-run mode and returns wildcard info.
+ */
+ if (opt->pathspec.has_wildcard)
+ BUG("wildcards are not supported");
+#endif
+
+ /* Remove the file creation entry from the diff queue, and remember it */
+ choice = q->queue[0];
+ q->nr = 0;
+
+ repo_diff_setup(opt->repo, &diff_opts);
+ diff_opts.flags.recursive = 1;
+ diff_opts.flags.find_copies_harder = 1;
+ diff_opts.output_format = DIFF_FORMAT_NO_OUTPUT;
+ diff_opts.single_follow = opt->pathspec.items[0].match;
+ diff_opts.break_opt = opt->break_opt;
+ diff_opts.rename_score = opt->rename_score;
+ diff_setup_done(&diff_opts);
+ ll_diff_tree_oid(old_oid, new_oid, base, &diff_opts);
+ diffcore_std(&diff_opts);
+ clear_pathspec(&diff_opts.pathspec);
+
+ /* Go through the new set of filepairing, and see if we find a more interesting one */
+ opt->found_follow = 0;
+ for (i = 0; i < q->nr; i++) {
+ struct diff_filepair *p = q->queue[i];
+
+ /*
+ * Found a source? Not only do we use that for the new
+ * diff_queued_diff, we will also use that as the path in
+ * the future!
+ */
+ if ((p->status == 'R' || p->status == 'C') &&
+ !strcmp(p->two->path, opt->pathspec.items[0].match)) {
+ const char *path[2];
+
+ /* Switch the file-pairs around */
+ q->queue[i] = choice;
+ choice = p;
+
+ /* Update the path we use from now on.. */
+ path[0] = p->one->path;
+ path[1] = NULL;
+ clear_pathspec(&opt->pathspec);
+ parse_pathspec(&opt->pathspec,
+ PATHSPEC_ALL_MAGIC & ~PATHSPEC_LITERAL,
+ PATHSPEC_LITERAL_PATH, "", path);
+
+ /*
+ * The caller expects us to return a set of vanilla
+ * filepairs to let a later call to diffcore_std()
+ * it makes to sort the renames out (among other
+ * things), but we already have found renames
+ * ourselves; signal diffcore_std() not to muck with
+ * rename information.
+ */
+ opt->found_follow = 1;
+ break;
+ }
+ }
+
+ /*
+ * Then, discard all the non-relevant file pairs...
+ */
+ for (i = 0; i < q->nr; i++) {
+ struct diff_filepair *p = q->queue[i];
+ diff_free_filepair(p);
+ }
+
+ /*
+ * .. and re-instate the one we want (which might be either the
+ * original one, or the rename/copy we found)
+ */
+ q->queue[0] = choice;
+ q->nr = 1;
+}
+
+static void ll_diff_tree_oid(const struct object_id *old_oid,
+ const struct object_id *new_oid,
+ struct strbuf *base, struct diff_options *opt)
+{
+ struct combine_diff_path phead, *p;
+ pathchange_fn_t pathchange_old = opt->pathchange;
+
+ phead.next = NULL;
+ opt->pathchange = emit_diff_first_parent_only;
+ diff_tree_paths(&phead, new_oid, &old_oid, 1, base, opt);
+
+ for (p = phead.next; p;) {
+ struct combine_diff_path *pprev = p;
+ p = p->next;
+ free(pprev);
+ }
+
+ opt->pathchange = pathchange_old;
+}
+
+void diff_tree_oid(const struct object_id *old_oid,
+ const struct object_id *new_oid,
+ const char *base_str, struct diff_options *opt)
+{
+ struct strbuf base;
+
+ strbuf_init(&base, PATH_MAX);
+ strbuf_addstr(&base, base_str);
+
+ ll_diff_tree_oid(old_oid, new_oid, &base, opt);
+ if (!*base_str && opt->flags.follow_renames && diff_might_be_rename())
+ try_to_follow_renames(old_oid, new_oid, &base, opt);
+
+ strbuf_release(&base);
+}
+
+void diff_root_tree_oid(const struct object_id *new_oid,
+ const char *base,
+ struct diff_options *opt)
+{
+ diff_tree_oid(NULL, new_oid, base, opt);
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-02 14:54:14 +0000