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feat(xattr): --fake-super for directories (#319)

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TapTap
2026-09-24 02:30:02 +02:00
parent a14fbb2c10
commit cc931790e9
7 changed files with 279 additions and 50 deletions
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tests/test_xattr.c
+110
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@@ -892,6 +892,114 @@ static void test_symlink_frame_carries_xattrs() {
EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0);
}
/* --fake-super for DIRECTORIES: rsync stores a directory's faked mode/uid/gid
* in `user.rsync.%stat` on the directory itself. fake_super_store_fd() and
* fake_super_restore_fd() operate on a directory descriptor exactly like a
* file: the full mode (with S_IFDIR + special bits) is recorded, only the
* permission bits are replayed on disk, and the owner is never real-chowned.
* Guarded on filesystem xattr support. */
static void test_fake_super_directory_fd_roundtrip() {
const char* root = "test_fake_super_dirfd_tmp";
const char* path = "test_fake_super_dirfd_tmp/subdir";
rmdir(path);
rmdir(root);
EXPECT_EQ_INT(mkdir(root, 0700), 0);
if (setxattr(root, "user.fastsync-dirprobe", "p", 1, 0) != 0) {
rmdir(root);
return; /* skip silently when the filesystem has no xattr support */
}
removexattr(root, "user.fastsync-dirprobe");
EXPECT_EQ_INT(mkdir(path, 0755), 0);
int fd = open(path, O_RDONLY | O_DIRECTORY | O_CLOEXEC);
EXPECT_TRUE(fd >= 0);
FileAttrPolicy policy = {true, true, false, false, true};
/* No record yet: restore is a silent no-op on a directory too. */
EXPECT_FALSE(fake_super_restore_fd(fd, policy));
struct stat before;
EXPECT_EQ_INT(fstat(fd, &before), 0);
fake_super_store_fd(fd, 2222, 3333, S_IFDIR | 01777, 0, 0);
char value[64];
ssize_t got = fgetxattr(fd, FAKESUPER_XATTR, value, sizeof(value));
/* S_IFDIR | 01777 == 0041777 -> "41777 0,0 2222:3333" */
EXPECT_EQ_INT((int)got, 19);
EXPECT_TRUE(got == 19 && memcmp(value, "41777 0,0 2222:3333", 19) == 0);
EXPECT_TRUE(fake_super_restore_fd(fd, policy));
struct stat after;
EXPECT_EQ_INT(fstat(fd, &after), 0);
/* The sticky bit is stored in the record but never installed on disk. */
EXPECT_EQ_INT((int)(after.st_mode & 07777), 0777);
EXPECT_EQ_INT((int)(after.st_mode & (S_ISUID | S_ISGID | S_ISVTX)), 0);
EXPECT_EQ_INT((int)after.st_uid, (int)before.st_uid);
EXPECT_EQ_INT((int)after.st_gid, (int)before.st_gid);
close(fd);
removexattr(path, FAKESUPER_XATTR);
rmdir(path);
rmdir(root);
}
/* The deferred directory-metadata pass is where a recursive -a --fake-super
* transfer stamps each directory: dir_metadata_list_apply() must park the
* directory's full stat in the reserved xattr and replay only its permission
* bits on disk. This is the recursive-path counterpart of the explicit
* --dirs store in file_save_directory_to_disk(). Guarded on xattr support. */
static void test_fake_super_directory_deferred_apply() {
const char* root = "test_fake_super_dirdir_tmp";
const char* leaf = "subdir";
const char* path = "test_fake_super_dirdir_tmp/subdir";
rmdir(path);
rmdir(root);
EXPECT_EQ_INT(mkdir(root, 0700), 0);
if (setxattr(root, "user.fastsync-dirprobe", "p", 1, 0) != 0) {
rmdir(root);
return; /* skip silently when the filesystem has no xattr support */
}
removexattr(root, "user.fastsync-dirprobe");
EXPECT_EQ_INT(mkdir(path, 0755), 0);
FileMetadata m;
memset(&m, 0, sizeof(m));
m.mode = S_IFDIR | 02751;
m.uid = 1001;
m.gid = 1002;
m.mtime_sec = 1234567890;
Config* config = config_create();
EXPECT_NOT_NULL(config);
config->use_metadata = true;
config->preserve_perms = true;
config->preserve_times = true;
config->fake_super = true;
identity_clear_active();
DirTimeList list;
dir_time_list_init(&list);
EXPECT_TRUE(dir_time_list_add(&list, leaf, &m, NULL));
dir_metadata_list_apply(&list, root, config);
dir_time_list_free(&list);
char value[64];
ssize_t got = getxattr(path, FAKESUPER_XATTR, value, sizeof(value));
/* S_IFDIR | 02751 -> "42751 0,0 1001:1002" (resolved ids == source ids). */
EXPECT_EQ_INT((int)got, 19);
EXPECT_TRUE(got == 19 && memcmp(value, "42751 0,0 1001:1002", 19) == 0);
struct stat st;
EXPECT_EQ_INT(stat(path, &st), 0);
/* Only the permission bits land on disk; setgid stays in the record. */
EXPECT_EQ_INT((int)(st.st_mode & 07777), 0751);
EXPECT_EQ_INT((int)(st.st_mode & (S_ISUID | S_ISGID | S_ISVTX)), 0);
config_delete(config);
removexattr(path, FAKESUPER_XATTR);
rmdir(path);
rmdir(root);
}
void test_xattr() {
test_xattr_list_clone();
test_xattr_capture_symlink_nofollow();
@@ -910,5 +1018,7 @@ void test_xattr() {
test_fake_super_rsync_format();
test_fake_super_no_real_chown();
test_fake_super_storage_resolution();
test_fake_super_directory_fd_roundtrip();
test_fake_super_directory_deferred_apply();
test_file_save_directory_applies_xattrs();
}