From a133c40b23c80ed77cfe077213a45af67be28f74 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Nguy=E1=BB=85n=20Th=C3=A1i=20Ng=E1=BB=8Dc=20Duy?= Date: Tue, 16 Apr 2019 16:33:18 +0700 Subject: commit.cocci: refactor code, avoid double rewrite MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit "maybe" pointer in 'struct commit' is tricky because it can be lazily initialized to take advantage of commit-graph if available. This makes it not safe to access directly. This leads to a rule in commit.cocci to rewrite 'x->maybe_tree' to 'get_commit_tree(x)'. But that rule alone could lead to incorrectly rewrite assignments, e.g. from x->maybe_tree = yes to get_commit_tree(x) = yes Because of this we have a second rule to revert this effect. Szeder found out that we could do better by performing the assignment rewrite rule first, then the remaining is read-only access and handled by the current first rule. For this to work, we need to transform "x->maybe_tree = y" to something that does NOT contain "x->maybe_tree" to avoid the original first rule. This is where set_commit_tree() comes in. Helped-by: SZEDER Gábor Helped-by: Johannes Schindelin Signed-off-by: Nguyễn Thái Ngọc Duy Signed-off-by: Junio C Hamano diff --git a/commit-graph.c b/commit-graph.c index 47e9be0..155a270 100644 --- a/commit-graph.c +++ b/commit-graph.c @@ -343,6 +343,11 @@ static void fill_commit_graph_info(struct commit *item, struct commit_graph *g, item->generation = get_be32(commit_data + g->hash_len + 8) >> 2; } +static inline void set_commit_tree(struct commit *c, struct tree *t) +{ + c->maybe_tree = t; +} + static int fill_commit_in_graph(struct repository *r, struct commit *item, struct commit_graph *g, uint32_t pos) @@ -356,7 +361,7 @@ static int fill_commit_in_graph(struct repository *r, item->object.parsed = 1; item->graph_pos = pos; - item->maybe_tree = NULL; + set_commit_tree(item, NULL); date_high = get_be32(commit_data + g->hash_len + 8) & 0x3; date_low = get_be32(commit_data + g->hash_len + 12); @@ -442,7 +447,7 @@ static struct tree *load_tree_for_commit(struct repository *r, GRAPH_DATA_WIDTH * (c->graph_pos); hashcpy(oid.hash, commit_data); - c->maybe_tree = lookup_tree(r, &oid); + set_commit_tree(c, lookup_tree(r, &oid)); return c->maybe_tree; } diff --git a/commit.c b/commit.c index a5333c7..043ba64 100644 --- a/commit.c +++ b/commit.c @@ -340,6 +340,11 @@ void free_commit_buffer(struct parsed_object_pool *pool, struct commit *commit) } } +static inline void set_commit_tree(struct commit *c, struct tree *t) +{ + c->maybe_tree = t; +} + struct tree *get_commit_tree(const struct commit *commit) { if (commit->maybe_tree || !commit->object.parsed) @@ -358,7 +363,7 @@ struct object_id *get_commit_tree_oid(const struct commit *commit) void release_commit_memory(struct parsed_object_pool *pool, struct commit *c) { - c->maybe_tree = NULL; + set_commit_tree(c, NULL); c->index = 0; free_commit_buffer(pool, c); free_commit_list(c->parents); @@ -406,7 +411,7 @@ int parse_commit_buffer(struct repository *r, struct commit *item, const void *b if (get_oid_hex(bufptr + 5, &parent) < 0) return error("bad tree pointer in commit %s", oid_to_hex(&item->object.oid)); - item->maybe_tree = lookup_tree(r, &parent); + set_commit_tree(item, lookup_tree(r, &parent)); bufptr += tree_entry_len + 1; /* "tree " + "hex sha1" + "\n" */ pptr = &item->parents; diff --git a/contrib/coccinelle/commit.cocci b/contrib/coccinelle/commit.cocci index c49aa55..663658a 100644 --- a/contrib/coccinelle/commit.cocci +++ b/contrib/coccinelle/commit.cocci @@ -10,19 +10,25 @@ expression c; - c->maybe_tree->object.oid.hash + get_commit_tree_oid(c)->hash -// These excluded functions must access c->maybe_tree direcly. @@ -identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit)$"; +identifier f !~ "^set_commit_tree$"; expression c; +expression s; @@ f(...) {<... -- c->maybe_tree -+ get_commit_tree(c) +- c->maybe_tree = s ++ set_commit_tree(c, s) ...>} +// These excluded functions must access c->maybe_tree direcly. +// Note that if c->maybe_tree is written somewhere outside of these +// functions, then the recommended transformation will be bogus with +// get_commit_tree() on the LHS. @@ +identifier f !~ "^(get_commit_tree|get_commit_tree_in_graph_one|load_tree_for_commit|set_commit_tree)$"; expression c; -expression s; @@ -- get_commit_tree(c) = s -+ c->maybe_tree = s + f(...) {<... +- c->maybe_tree ++ get_commit_tree(c) + ...>} diff --git a/merge-recursive.c b/merge-recursive.c index 6c40c61..ca4731a 100644 --- a/merge-recursive.c +++ b/merge-recursive.c @@ -163,6 +163,11 @@ static struct tree *shift_tree_object(struct repository *repo, return lookup_tree(repo, &shifted); } +static inline void set_commit_tree(struct commit *c, struct tree *t) +{ + c->maybe_tree = t; +} + static struct commit *make_virtual_commit(struct repository *repo, struct tree *tree, const char *comment) @@ -170,7 +175,7 @@ static struct commit *make_virtual_commit(struct repository *repo, struct commit *commit = alloc_commit_node(repo); set_merge_remote_desc(commit, comment, (struct object *)commit); - commit->maybe_tree = tree; + set_commit_tree(commit, tree); commit->object.parsed = 1; return commit; } -- cgit v0.10.2-6-g49f6