While we cannot rely on a `__typeof__' operator being portable
to use with `offsetof'; we can calculate the pointer offset
using an existing pointer and the address of a member using
pointer arithmetic for compilers without `__typeof__'.
This allows us to simplify usage of hashmap iterator macros
by not having to specify a type when a pointer of that type
is already given.
In the future, list iterator macros (e.g. list_for_each_entry)
may also be implemented using OFFSETOF_VAR to save hackers the
trouble of using container_of/list_entry macros and without
relying on non-portable `__typeof__'.
v3: use `__typeof__' to avoid clang warnings
Signed-off-by: Eric Wong <e@xxxxxxxxx>
Reviewed-by: Derrick Stolee <stolee@xxxxxxxxx>
---
attr.c | 1 -
blame.c | 2 --
builtin/describe.c | 2 +-
builtin/difftool.c | 4 +--
config.c | 1 -
diff.c | 5 ++--
diffcore-rename.c | 2 +-
git-compat-util.h | 13 +++++++++
hashmap.h | 44 ++++++++++++++++++++---------
merge-recursive.c | 5 ----
name-hash.c | 3 +-
revision.c | 8 ++----
submodule-config.c | 2 +-
t/helper/test-hashmap.c | 5 +---
t/helper/test-lazy-init-name-hash.c | 4 +--
15 files changed, 56 insertions(+), 45 deletions(-)
diff --git a/attr.c b/attr.c
index ca8be46e8e..9849106627 100644
--- a/attr.c
+++ b/attr.c
@@ -168,7 +168,6 @@ static void all_attrs_init(struct attr_hashmap *map, struct attr_check *check)
check->all_attrs_nr = size;
hashmap_for_each_entry(&map->map, &iter, e,
- struct attr_hash_entry,
ent /* member name */) {
const struct git_attr *a = e->value;
check->all_attrs[a->attr_nr].attr = a;
diff --git a/blame.c b/blame.c
index f33af0da9f..90b247abf9 100644
--- a/blame.c
+++ b/blame.c
@@ -451,7 +451,6 @@ static int fingerprint_similarity(struct fingerprint *a, struct fingerprint *b)
const struct fingerprint_entry *entry_a, *entry_b;
hashmap_for_each_entry(&b->map, &iter, entry_b,
- const struct fingerprint_entry,
entry /* member name */) {
entry_a = hashmap_get_entry(&a->map, entry_b, NULL,
struct fingerprint_entry, entry);
@@ -474,7 +473,6 @@ static void fingerprint_subtract(struct fingerprint *a, struct fingerprint *b)
hashmap_iter_init(&b->map, &iter);
hashmap_for_each_entry(&b->map, &iter, entry_b,
- const struct fingerprint_entry,
entry /* member name */) {
entry_a = hashmap_get_entry(&a->map, entry_b, NULL,
struct fingerprint_entry, entry);
diff --git a/builtin/describe.c b/builtin/describe.c
index 8cf2cd992d..1caf98f716 100644
--- a/builtin/describe.c
+++ b/builtin/describe.c
@@ -333,7 +333,7 @@ static void describe_commit(struct object_id *oid, struct strbuf *dst)
struct commit_name *n;
init_commit_names(&commit_names);
- hashmap_for_each_entry(&names, &iter, n, struct commit_name,
+ hashmap_for_each_entry(&names, &iter, n,
entry /* member name */) {
c = lookup_commit_reference_gently(the_repository,
&n->peeled, 1);
diff --git a/builtin/difftool.c b/builtin/difftool.c
index dd94179b68..f2d4d1e0f8 100644
--- a/builtin/difftool.c
+++ b/builtin/difftool.c
@@ -539,7 +539,7 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
* change in the recorded SHA1 for the submodule.
*/
hashmap_for_each_entry(&submodules, &iter, entry,
- struct pair_entry, entry /* member name */) {
+ entry /* member name */) {
if (*entry->left) {
add_path(&ldir, ldir_len, entry->path);
ensure_leading_directories(ldir.buf);
@@ -558,7 +558,7 @@ static int run_dir_diff(const char *extcmd, int symlinks, const char *prefix,
* This loop replicates that behavior.
*/
hashmap_for_each_entry(&symlinks2, &iter, entry,
- struct pair_entry, entry /* member name */) {
+ entry /* member name */) {
if (*entry->left) {
add_path(&ldir, ldir_len, entry->path);
ensure_leading_directories(ldir.buf);
diff --git a/config.c b/config.c
index 4d05dbc15a..77ed00bfbf 100644
--- a/config.c
+++ b/config.c
@@ -1943,7 +1943,6 @@ void git_configset_clear(struct config_set *cs)
return;
hashmap_for_each_entry(&cs->config_hash, &iter, entry,
- struct config_set_element,
ent /* member name */) {
free(entry->key);
string_list_clear(&entry->value_list, 1);
diff --git a/diff.c b/diff.c
index f94d9f96af..051de9832d 100644
--- a/diff.c
+++ b/diff.c
@@ -1038,7 +1038,7 @@ static void pmb_advance_or_null_multi_match(struct diff_options *o,
int i;
char *got_match = xcalloc(1, pmb_nr);
- hashmap_for_each_entry_from(hm, match, struct moved_entry, ent) {
+ hashmap_for_each_entry_from(hm, match, ent) {
for (i = 0; i < pmb_nr; i++) {
struct moved_entry *prev = pmb[i].match;
struct moved_entry *cur = (prev && prev->next_line) ?
@@ -1193,8 +1193,7 @@ static void mark_color_as_moved(struct diff_options *o,
* The current line is the start of a new block.
* Setup the set of potential blocks.
*/
- hashmap_for_each_entry_from(hm, match,
- struct moved_entry, ent) {
+ hashmap_for_each_entry_from(hm, match, ent) {
ALLOC_GROW(pmb, pmb_nr + 1, pmb_alloc);
if (o->color_moved_ws_handling &
COLOR_MOVED_WS_ALLOW_INDENTATION_CHANGE) {
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 994609ed58..9ad4dc395a 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -284,7 +284,7 @@ static int find_identical_files(struct hashmap *srcs,
*/
p = hashmap_get_entry_from_hash(srcs, hash, NULL,
struct file_similarity, entry);
- hashmap_for_each_entry_from(srcs, p, struct file_similarity, entry) {
+ hashmap_for_each_entry_from(srcs, p, entry) {
int score;
struct diff_filespec *source = p->filespec;
diff --git a/git-compat-util.h b/git-compat-util.h
index 4a23b9090b..8605cb4202 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -1337,4 +1337,17 @@ static inline void *container_of_or_null_offset(void *ptr, size_t offset)
#define container_of_or_null(ptr, type, member) \
(type *)container_of_or_null_offset(ptr, offsetof(type, member))
+/*
+ * like offsetof(), but takes a pointer to a a variable of type which
+ * contains @member, instead of a specified type.
+ * @ptr is subject to multiple evaluation since we can't rely on __typeof__
+ * everywhere.
+ */
+#if defined(__GNUC__) /* clang sets this, too */
+#define OFFSETOF_VAR(ptr, member) offsetof(__typeof__(*ptr), member)
+#else /* !__GNUC__ */
+#define OFFSETOF_VAR(ptr, member) \
+ ((uintptr_t)&(ptr)->member - (uintptr_t)(ptr))
+#endif /* !__GNUC__ */
+
#endif
diff --git a/hashmap.h b/hashmap.h
index 171d6ddb76..96786c724a 100644
--- a/hashmap.h
+++ b/hashmap.h
@@ -408,16 +408,32 @@ static inline struct hashmap_entry *hashmap_iter_first(struct hashmap *map,
return hashmap_iter_next(iter);
}
-#define hashmap_iter_next_entry(iter, type, member) \
- container_of_or_null(hashmap_iter_next(iter), type, member)
-
+/*
+ * returns the first entry in @map using @iter, where the entry is of
+ * @type (e.g. "struct foo") and @member is the name of the
+ * "struct hashmap_entry" in @type
+ */
#define hashmap_iter_first_entry(map, iter, type, member) \
container_of_or_null(hashmap_iter_first(map, iter), type, member)
-#define hashmap_for_each_entry(map, iter, var, type, member) \
- for (var = hashmap_iter_first_entry(map, iter, type, member); \
+/* internal macro for hashmap_for_each_entry */
+#define hashmap_iter_next_entry_offset(iter, offset) \
+ container_of_or_null_offset(hashmap_iter_next(iter), offset)
+
+/* internal macro for hashmap_for_each_entry */
+#define hashmap_iter_first_entry_offset(map, iter, offset) \
+ container_of_or_null_offset(hashmap_iter_first(map, iter), offset)
+
+/*
+ * iterate through @map using @iter, @var is a pointer to a type
+ * containing a @member which is a "struct hashmap_entry"
+ */
+#define hashmap_for_each_entry(map, iter, var, member) \
+ for (var = hashmap_iter_first_entry_offset(map, iter, \
+ OFFSETOF_VAR(var, member)); \
var; \
- var = hashmap_iter_next_entry(iter, type, member))
+ var = hashmap_iter_next_entry_offset(iter, \
+ OFFSETOF_VAR(var, member)))
/*
* returns a @pointer of @type matching @keyvar, or NULL if nothing found.
@@ -432,22 +448,22 @@ static inline struct hashmap_entry *hashmap_iter_first(struct hashmap *map,
container_of_or_null(hashmap_get_from_hash(map, hash, keydata), \
type, member)
/*
- * returns the next equal @type pointer to @var, or NULL if not found.
- * @var is a pointer of @type
- * @member is the name of the "struct hashmap_entry" field in @type
+ * returns the next equal pointer to @var, or NULL if not found.
+ * @var is a pointer of any type containing "struct hashmap_entry"
+ * @member is the name of the "struct hashmap_entry" field
*/
-#define hashmap_get_next_entry(map, var, type, member) \
- container_of_or_null(hashmap_get_next(map, &(var)->member), \
- type, member)
+#define hashmap_get_next_entry(map, var, member) \
+ container_of_or_null_offset(hashmap_get_next(map, &(var)->member), \
+ OFFSETOF_VAR(var, member))
/*
* iterate @map starting from @var, where @var is a pointer of @type
* and @member is the name of the "struct hashmap_entry" field in @type
*/
-#define hashmap_for_each_entry_from(map, var, type, member) \
+#define hashmap_for_each_entry_from(map, var, member) \
for (; \
var; \
- var = hashmap_get_next_entry(map, var, type, member))
+ var = hashmap_get_next_entry(map, var, member))
/*
* Disable item counting and automatic rehashing when adding/removing items.
diff --git a/merge-recursive.c b/merge-recursive.c
index 34b3d54154..3abba3a618 100644
--- a/merge-recursive.c
+++ b/merge-recursive.c
@@ -2136,7 +2136,6 @@ static void handle_directory_level_conflicts(struct merge_options *opt,
struct string_list remove_from_merge = STRING_LIST_INIT_NODUP;
hashmap_for_each_entry(dir_re_head, &iter, head_ent,
- struct dir_rename_entry,
ent /* member name */) {
merge_ent = dir_rename_find_entry(dir_re_merge, head_ent->dir);
if (merge_ent &&
@@ -2162,7 +2161,6 @@ static void handle_directory_level_conflicts(struct merge_options *opt,
remove_hashmap_entries(dir_re_merge, &remove_from_merge);
hashmap_for_each_entry(dir_re_merge, &iter, merge_ent,
- struct dir_rename_entry,
ent /* member name */) {
head_ent = dir_rename_find_entry(dir_re_head, merge_ent->dir);
if (tree_has_path(opt->repo, merge, merge_ent->dir)) {
@@ -2268,7 +2266,6 @@ static struct hashmap *get_directory_renames(struct diff_queue_struct *pairs)
* that there is no winner), we no longer need possible_new_dirs.
*/
hashmap_for_each_entry(dir_renames, &iter, entry,
- struct dir_rename_entry,
ent /* member name */) {
int max = 0;
int bad_max = 0;
@@ -2628,7 +2625,6 @@ static struct string_list *get_renames(struct merge_options *opt,
}
hashmap_for_each_entry(&collisions, &iter, e,
- struct collision_entry,
ent /* member name */) {
free(e->target_file);
string_list_clear(&e->source_files, 0);
@@ -2847,7 +2843,6 @@ static void initial_cleanup_rename(struct diff_queue_struct *pairs,
struct dir_rename_entry *e;
hashmap_for_each_entry(dir_renames, &iter, e,
- struct dir_rename_entry,
ent /* member name */) {
free(e->dir);
strbuf_release(&e->new_dir);
diff --git a/name-hash.c b/name-hash.c
index c86fe0f1df..3cda22b657 100644
--- a/name-hash.c
+++ b/name-hash.c
@@ -714,8 +714,7 @@ struct cache_entry *index_file_exists(struct index_state *istate, const char *na
ce = hashmap_get_entry_from_hash(&istate->name_hash, hash, NULL,
struct cache_entry, ent);
- hashmap_for_each_entry_from(&istate->name_hash, ce,
- struct cache_entry, ent) {
+ hashmap_for_each_entry_from(&istate->name_hash, ce, ent) {
if (same_name(ce, name, namelen, icase))
return ce;
}
diff --git a/revision.c b/revision.c
index 8a5f866ae6..5abd4a1fe7 100644
--- a/revision.c
+++ b/revision.c
@@ -129,9 +129,7 @@ static void paths_and_oids_clear(struct hashmap *map)
struct hashmap_iter iter;
struct path_and_oids_entry *entry;
- hashmap_for_each_entry(map, &iter, entry,
- struct path_and_oids_entry,
- ent /* member name */) {
+ hashmap_for_each_entry(map, &iter, entry, ent /* member name */) {
oidset_clear(&entry->trees);
free(entry->path);
}
@@ -243,9 +241,7 @@ void mark_trees_uninteresting_sparse(struct repository *r,
add_children_by_path(r, tree, &map);
}
- hashmap_for_each_entry(&map, &map_iter, entry,
- struct path_and_oids_entry,
- ent /* member name */)
+ hashmap_for_each_entry(&map, &map_iter, entry, ent /* member name */)
mark_trees_uninteresting_sparse(r, &entry->trees);
paths_and_oids_clear(&map);
diff --git a/submodule-config.c b/submodule-config.c
index 5462acc8ec..c22855cd38 100644
--- a/submodule-config.c
+++ b/submodule-config.c
@@ -100,7 +100,7 @@ static void submodule_cache_clear(struct submodule_cache *cache)
* their .gitmodules blob sha1 and submodule name.
*/
hashmap_for_each_entry(&cache->for_name, &iter, entry,
- struct submodule_entry, ent /* member name */)
+ ent /* member name */)
free_one_config(entry);
hashmap_free_entries(&cache->for_path, struct submodule_entry, ent);
diff --git a/t/helper/test-hashmap.c b/t/helper/test-hashmap.c
index 6f2530dcc8..f89d1194ef 100644
--- a/t/helper/test-hashmap.c
+++ b/t/helper/test-hashmap.c
@@ -205,10 +205,8 @@ int cmd__hashmap(int argc, const char **argv)
/* print result */
if (!entry)
puts("NULL");
- hashmap_for_each_entry_from(&map, entry,
- struct test_entry, ent) {
+ hashmap_for_each_entry_from(&map, entry, ent)
puts(get_value(entry));
- }
} else if (!strcmp("remove", cmd) && p1) {
@@ -230,7 +228,6 @@ int cmd__hashmap(int argc, const char **argv)
struct hashmap_iter iter;
hashmap_for_each_entry(&map, &iter, entry,
- struct test_entry,
ent /* member name */)
printf("%s %s\n", entry->key, get_value(entry));
diff --git a/t/helper/test-lazy-init-name-hash.c b/t/helper/test-lazy-init-name-hash.c
index 9d4664d6a4..cd1b4c9736 100644
--- a/t/helper/test-lazy-init-name-hash.c
+++ b/t/helper/test-lazy-init-name-hash.c
@@ -42,11 +42,11 @@ static void dump_run(void)
}
hashmap_for_each_entry(&the_index.dir_hash, &iter_dir, dir,
- struct dir_entry, ent /* member name */)
+ ent /* member name */)
printf("dir %08x %7d %s\n", dir->ent.hash, dir->nr, dir->name);
hashmap_for_each_entry(&the_index.name_hash, &iter_cache, ce,
- struct cache_entry, ent /* member name */)
+ ent /* member name */)
printf("name %08x %s\n", ce->ent.hash, ce->name);
discard_cache();
