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copy: optionally, reproduce hardlinks from source in destination

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This is useful for duplicating trees that contain hardlinks: we keep
track of potential hardlinks and try to reproduce them within the
destination tree. (We do not hardlink between source and destination!).

This is useful for trees like ostree images which heavily use hardlinks
and which are otherwise exploded into separate copies of all files when
we duplicate the trees.
This commit is contained in:
Lennart Poettering
2020-09-09 20:21:29 +02:00
parent 197db625a3
commit dd480f7835
4 changed files with 274 additions and 23 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/test/test-copy.c
+34 -8
View File
@@ -81,10 +81,12 @@ static void test_copy_tree(void) {
char original_dir[] = "/tmp/test-copy_tree/";
char copy_dir[] = "/tmp/test-copy_tree-copy/";
char **files = STRV_MAKE("file", "dir1/file", "dir1/dir2/file", "dir1/dir2/dir3/dir4/dir5/file");
char **links = STRV_MAKE("link", "file",
"link2", "dir1/file");
char **symlinks = STRV_MAKE("link", "file",
"link2", "dir1/file");
char **hardlinks = STRV_MAKE("hlink", "file",
"hlink2", "dir1/file");
const char *unixsockp;
char **p, **link;
char **p, **ll;
struct stat st;
int xattr_worked = -1; /* xattr support is optional in temporary directories, hence use it if we can,
* but don't fail if we can't */
@@ -110,20 +112,30 @@ static void test_copy_tree(void) {
xattr_worked = k >= 0;
}
STRV_FOREACH_PAIR(link, p, links) {
STRV_FOREACH_PAIR(ll, p, symlinks) {
_cleanup_free_ char *f, *l;
assert_se(f = path_join(original_dir, *p));
assert_se(l = path_join(original_dir, *link));
assert_se(l = path_join(original_dir, *ll));
assert_se(mkdir_parents(l, 0755) >= 0);
assert_se(symlink(f, l) == 0);
}
STRV_FOREACH_PAIR(ll, p, hardlinks) {
_cleanup_free_ char *f, *l;
assert_se(f = path_join(original_dir, *p));
assert_se(l = path_join(original_dir, *ll));
assert_se(mkdir_parents(l, 0755) >= 0);
assert_se(link(f, l) == 0);
}
unixsockp = strjoina(original_dir, "unixsock");
assert_se(mknod(unixsockp, S_IFSOCK|0644, 0) >= 0);
assert_se(copy_tree(original_dir, copy_dir, UID_INVALID, GID_INVALID, COPY_REFLINK|COPY_MERGE) == 0);
assert_se(copy_tree(original_dir, copy_dir, UID_INVALID, GID_INVALID, COPY_REFLINK|COPY_MERGE|COPY_HARDLINKS) == 0);
STRV_FOREACH(p, files) {
_cleanup_free_ char *buf, *f, *c = NULL;
@@ -147,16 +159,30 @@ static void test_copy_tree(void) {
}
}
STRV_FOREACH_PAIR(link, p, links) {
STRV_FOREACH_PAIR(ll, p, symlinks) {
_cleanup_free_ char *target, *f, *l;
assert_se(f = strjoin(original_dir, *p));
assert_se(l = strjoin(copy_dir, *link));
assert_se(l = strjoin(copy_dir, *ll));
assert_se(chase_symlinks(l, NULL, 0, &target, NULL) == 1);
assert_se(path_equal(f, target));
}
STRV_FOREACH_PAIR(ll, p, hardlinks) {
_cleanup_free_ char *f, *l;
struct stat a, b;
assert_se(f = strjoin(copy_dir, *p));
assert_se(l = strjoin(copy_dir, *ll));
assert_se(lstat(f, &a) >= 0);
assert_se(lstat(l, &b) >= 0);
assert_se(a.st_ino == b.st_ino);
assert_se(a.st_dev == b.st_dev);
}
unixsockp = strjoina(copy_dir, "unixsock");
assert_se(stat(unixsockp, &st) >= 0);
assert_se(S_ISSOCK(st.st_mode));