From 8fb3ad76b1782a5439343b9601f73a9287a245cf Mon Sep 17 00:00:00 2001 From: Dmitry Ivankov Date: Mon, 15 Aug 2011 00:32:24 +0600 Subject: [PATCH] fast-import: prevent producing bad delta To produce deltas for tree objects fast-import tracks two versions of tree's entries - base and current one. Base version stands both for a delta base of this tree, and for a entry inside a delta base of a parent tree. So care should be taken to keep it in sync. tree_content_set cuts away a whole subtree and replaces it with a new one (or NULL for lazy load of a tree with known sha1). It keeps a base sha1 for this subtree (needed for parent tree). And here is the problem, 'subtree' tree root doesn't have the implied base version entries. Adjusting the subtree to include them would mean a deep rewrite of subtree. Invalidating the subtree base version would mean recursive invalidation of parents' base versions. So just mark this tree as do-not-delta me. Abuse setuid bit for this purpose. tree_content_replace is the same as tree_content_set except that is is used to replace the root, so just clearing base sha1 here (instead of setting the bit) is fine. [di: log message] Signed-off-by: Jonathan Nieder Signed-off-by: Dmitry Ivankov Signed-off-by: Junio C Hamano --- fast-import.c | 35 ++++++++++++++++++++++++++++++----- t/t9300-fast-import.sh | 2 +- 2 files changed, 31 insertions(+), 6 deletions(-) diff --git a/fast-import.c b/fast-import.c index 78d978684..6dad9ff4d 100644 --- a/fast-import.c +++ b/fast-import.c @@ -170,6 +170,11 @@ Format of STDIN stream: #define DEPTH_BITS 13 #define MAX_DEPTH ((1<entries[i]; if (!e->versions[v].mode) continue; - strbuf_addf(b, "%o %s%c", (unsigned int)e->versions[v].mode, - e->name->str_dat, '\0'); + strbuf_addf(b, "%o %s%c", + (unsigned int)(e->versions[v].mode & ~NO_DELTA), + e->name->str_dat, '\0'); strbuf_add(b, e->versions[v].sha1, 20); } } @@ -1425,7 +1431,7 @@ static void store_tree(struct tree_entry *root) struct tree_content *t = root->tree; unsigned int i, j, del; struct last_object lo = { STRBUF_INIT, 0, 0, /* no_swap */ 1 }; - struct object_entry *le; + struct object_entry *le = NULL; if (!is_null_sha1(root->versions[1].sha1)) return; @@ -1435,7 +1441,8 @@ static void store_tree(struct tree_entry *root) store_tree(t->entries[i]); } - le = find_object(root->versions[0].sha1); + if (!(root->versions[0].mode & NO_DELTA)) + le = find_object(root->versions[0].sha1); if (S_ISDIR(root->versions[0].mode) && le && le->pack_id == pack_id) { mktree(t, 0, &old_tree); lo.data = old_tree; @@ -1469,6 +1476,7 @@ static void tree_content_replace( { if (!S_ISDIR(mode)) die("Root cannot be a non-directory"); + hashclr(root->versions[0].sha1); hashcpy(root->versions[1].sha1, sha1); if (root->tree) release_tree_content_recursive(root->tree); @@ -1513,6 +1521,23 @@ static int tree_content_set( if (e->tree) release_tree_content_recursive(e->tree); e->tree = subtree; + + /* + * We need to leave e->versions[0].sha1 alone + * to avoid modifying the preimage tree used + * when writing out the parent directory. + * But after replacing the subdir with a + * completely different one, it's not a good + * delta base any more, and besides, we've + * thrown away the tree entries needed to + * make a delta against it. + * + * So let's just explicitly disable deltas + * for the subtree. + */ + if (S_ISDIR(e->versions[0].mode)) + e->versions[0].mode |= NO_DELTA; + hashclr(root->versions[1].sha1); return 1; } @@ -2927,7 +2952,7 @@ static void print_ls(int mode, const unsigned char *sha1, const char *path) /* mode SP type SP object_name TAB path LF */ strbuf_reset(&line); strbuf_addf(&line, "%06o %s %s\t", - mode, type, sha1_to_hex(sha1)); + mode & ~NO_DELTA, type, sha1_to_hex(sha1)); quote_c_style(path, &line, NULL, 0); strbuf_addch(&line, '\n'); } diff --git a/t/t9300-fast-import.sh b/t/t9300-fast-import.sh index c88ab467f..b33bc8246 100755 --- a/t/t9300-fast-import.sh +++ b/t/t9300-fast-import.sh @@ -765,7 +765,7 @@ g/b/f g/b/h EOF -test_expect_failure \ +test_expect_success \ 'L: nested tree copy does not corrupt deltas' \ 'git fast-import tmp && -- 2.30.2