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-rw-r--r--include/fstree.h30
-rw-r--r--lib/common/serialize_fstree.c15
-rw-r--r--lib/fstree/Makemodule.am2
-rw-r--r--lib/fstree/hardlink.c65
-rw-r--r--lib/fstree/post_process.c125
-rw-r--r--mkfs/mkfs.c3
-rw-r--r--tar/tar2sqfs.c3
7 files changed, 221 insertions, 22 deletions
diff --git a/include/fstree.h b/include/fstree.h
index aff3952..7f81cf5 100644
--- a/include/fstree.h
+++ b/include/fstree.h
@@ -17,6 +17,9 @@
#include "sqfs/predef.h"
#include "compat.h"
+#define FSTREE_MODE_HARD_LINK (0)
+#define FSTREE_MODE_HARD_LINK_RESOLVED (1)
+
typedef struct tree_node_t tree_node_t;
typedef struct file_info_t file_info_t;
typedef struct dir_info_t dir_info_t;
@@ -40,6 +43,9 @@ struct dir_info_t {
/* Set to true for implicitly generated directories. */
bool created_implicitly;
+
+ /* Used by recursive tree walking code to avoid hard link loops */
+ bool visited;
};
/* A node in a file system tree */
@@ -68,12 +74,13 @@ struct tree_node_t {
Generated on the fly when writing inodes. */
sqfs_u64 inode_ref;
- /* Type specific data. Pointers are into payload area blow. */
+ /* Type specific data. "target" pointer is into payload area below. */
union {
dir_info_t dir;
file_info_t file;
char *target;
sqfs_u64 devno;
+ tree_node_t *target_node;
} data;
sqfs_u8 payload[];
@@ -156,13 +163,15 @@ int fstree_from_file(fstree_t *fs, const char *filename, FILE *fp);
/*
This function performs all the necessary post processing steps on the file
system tree, i.e. recursively sorting all directory entries by name,
- allocating inode numbers and stringing all files nodes together into a
- linked list.
+ allocating inode numbers, resolving hard links and stringing all files nodes
+ together into a linked list.
The total inode count is stored in unique_inode_count. The head of the file
list is pointed to by fs->files.
+
+ Returns 0 on success, prints to stderr on failure.
*/
-void fstree_post_process(fstree_t *fs);
+int fstree_post_process(fstree_t *fs);
/*
Generate a string holding the full path of a node. Returned
@@ -205,4 +214,17 @@ int canonicalize_name(char *filename);
*/
bool is_filename_sane(const char *name, bool check_os_specific);
+/*
+ Add a hard link node. Returns NULL on failure and sets errno.
+ */
+tree_node_t *fstree_add_hard_link(fstree_t *fs, const char *path,
+ const char *target);
+
+/*
+ Resolve a hard link node and replace it with a direct pointer to the target.
+
+ Returns 0 on success. On failure, errno is set.
+ */
+int fstree_resolve_hard_link(fstree_t *fs, tree_node_t *node);
+
#endif /* FSTREE_H */
diff --git a/lib/common/serialize_fstree.c b/lib/common/serialize_fstree.c
index 73f4e67..a5f5d71 100644
--- a/lib/common/serialize_fstree.c
+++ b/lib/common/serialize_fstree.c
@@ -64,7 +64,7 @@ static sqfs_inode_generic_t *write_dir_entries(const char *filename,
{
sqfs_u32 xattr, parent_inode;
sqfs_inode_generic_t *inode;
- tree_node_t *it;
+ tree_node_t *it, *tgt;
int ret;
ret = sqfs_dir_writer_begin(dirw, 0);
@@ -72,8 +72,14 @@ static sqfs_inode_generic_t *write_dir_entries(const char *filename,
goto fail;
for (it = node->data.dir.children; it != NULL; it = it->next) {
- ret = sqfs_dir_writer_add_entry(dirw, it->name, it->inode_num,
- it->inode_ref, it->mode);
+ if (it->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+ tgt = it->data.target_node;
+ } else {
+ tgt = it;
+ }
+
+ ret = sqfs_dir_writer_add_entry(dirw, it->name, tgt->inode_num,
+ tgt->inode_ref, tgt->mode);
if (ret)
goto fail;
}
@@ -111,6 +117,9 @@ static int serialize_tree_node(const char *filename, sqfs_writer_t *wr,
sqfs_u64 block;
int ret;
+ if (n->mode == FSTREE_MODE_HARD_LINK_RESOLVED)
+ return 0;
+
if (S_ISDIR(n->mode)) {
inode = write_dir_entries(filename, wr->dirwr, n);
ret = SQFS_ERROR_INTERNAL;
diff --git a/lib/fstree/Makemodule.am b/lib/fstree/Makemodule.am
index 751d7dc..56394a6 100644
--- a/lib/fstree/Makemodule.am
+++ b/lib/fstree/Makemodule.am
@@ -1,5 +1,5 @@
libfstree_a_SOURCES = lib/fstree/fstree.c lib/fstree/fstree_from_file.c
-libfstree_a_SOURCES += lib/fstree/fstree_sort.c
+libfstree_a_SOURCES += lib/fstree/fstree_sort.c lib/fstree/hardlink.c
libfstree_a_SOURCES += lib/fstree/post_process.c lib/fstree/get_path.c
libfstree_a_SOURCES += lib/fstree/mknode.c
libfstree_a_SOURCES += lib/fstree/add_by_path.c lib/fstree/get_by_path.c
diff --git a/lib/fstree/hardlink.c b/lib/fstree/hardlink.c
new file mode 100644
index 0000000..8a79d46
--- /dev/null
+++ b/lib/fstree/hardlink.c
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * hardlink.c
+ *
+ * Copyright (C) 2019 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+
+#include "fstree.h"
+
+#include <string.h>
+#include <stdlib.h>
+#include <errno.h>
+
+tree_node_t *fstree_add_hard_link(fstree_t *fs, const char *path,
+ const char *target)
+{
+ struct stat sb;
+ tree_node_t *n;
+
+ memset(&sb, 0, sizeof(sb));
+ sb.st_mode = S_IFLNK | 0777;
+
+ n = fstree_add_generic(fs, path, &sb, target);
+ if (n != NULL) {
+ if (canonicalize_name(n->data.target)) {
+ free(n);
+ errno = EINVAL;
+ return NULL;
+ }
+
+ n->mode = FSTREE_MODE_HARD_LINK;
+ }
+
+ return n;
+}
+
+int fstree_resolve_hard_link(fstree_t *fs, tree_node_t *node)
+{
+ tree_node_t *start = node;
+
+ while (node->mode == FSTREE_MODE_HARD_LINK ||
+ node->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+ if (node->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+ node = node->data.target_node;
+ } else {
+ node = fstree_get_node_by_path(fs, fs->root,
+ node->data.target,
+ false, false);
+ if (node == NULL)
+ return -1;
+ }
+
+ if (node == start) {
+ errno = EMLINK;
+ return -1;
+ }
+ }
+
+ start->mode = FSTREE_MODE_HARD_LINK_RESOLVED;
+ start->data.target_node = node;
+
+ node->link_count += 1;
+ return 0;
+}
diff --git a/lib/fstree/post_process.c b/lib/fstree/post_process.c
index ea52e4f..e6bcb3f 100644
--- a/lib/fstree/post_process.c
+++ b/lib/fstree/post_process.c
@@ -7,33 +7,129 @@
#include "internal.h"
#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
#include <stdio.h>
+#include <errno.h>
-static void map_child_nodes(fstree_t *fs, tree_node_t *root, size_t *counter)
+static void swap_link_with_target(tree_node_t *node)
+{
+ tree_node_t *tgt, *it;
+
+ tgt = node->data.target_node;
+
+ node->xattr_idx = tgt->xattr_idx;
+ node->uid = tgt->uid;
+ node->gid = tgt->gid;
+ node->inode_num = tgt->inode_num;
+ node->mod_time = tgt->mod_time;
+ node->mode = tgt->mode;
+ node->link_count = tgt->link_count;
+ node->inode_ref = tgt->inode_ref;
+
+ /* FIXME: data pointers now point to foreign node! */
+ node->data = tgt->data;
+
+ tgt->mode = FSTREE_MODE_HARD_LINK_RESOLVED;
+ tgt->data.target_node = node;
+
+ if (S_ISDIR(node->mode)) {
+ for (it = node->data.dir.children; it != NULL; it = it->next)
+ it->parent = node;
+ }
+}
+
+static void hard_link_snap(tree_node_t *n)
+{
+ /* XXX: the hard-link-vs-target swap may create hard links
+ pointing to hard links, making this necessary */
+ while (n->data.target_node->mode == FSTREE_MODE_HARD_LINK_RESOLVED)
+ n->data.target_node = n->data.target_node->data.target_node;
+}
+
+static int map_child_nodes(fstree_t *fs, tree_node_t *root, size_t *counter)
{
bool has_subdirs = false;
- tree_node_t *it;
+ tree_node_t *it, *tgt;
for (it = root->data.dir.children; it != NULL; it = it->next) {
- if (S_ISDIR(it->mode)) {
- has_subdirs = true;
- break;
+ if (it->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+ hard_link_snap(it);
+ tgt = it->data.target_node;
+
+ if (tgt->inode_num == 0 && tgt->parent != root)
+ swap_link_with_target(it);
}
+
+ if (S_ISDIR(it->mode))
+ has_subdirs = true;
}
if (has_subdirs) {
for (it = root->data.dir.children; it != NULL; it = it->next) {
- if (S_ISDIR(it->mode))
- map_child_nodes(fs, it, counter);
+ if (S_ISDIR(it->mode)) {
+ if (map_child_nodes(fs, it, counter))
+ return -1;
+ }
}
}
for (it = root->data.dir.children; it != NULL; it = it->next) {
- fs->unique_inode_count += 1;
+ if (it->mode == FSTREE_MODE_HARD_LINK_RESOLVED) {
+ hard_link_snap(it);
+ } else {
+ fs->unique_inode_count += 1;
- it->inode_num = *counter;
- *counter += 1;
+ it->inode_num = *counter;
+ *counter += 1;
+ }
}
+ return 0;
+}
+
+static int resolve_hard_links_dfs(fstree_t *fs, tree_node_t *n)
+{
+ tree_node_t *it;
+
+ if (n->mode == FSTREE_MODE_HARD_LINK) {
+ if (fstree_resolve_hard_link(fs, n))
+ goto fail_link;
+
+ assert(n->mode == FSTREE_MODE_HARD_LINK_RESOLVED);
+ it = n->data.target_node;
+
+ if (S_ISDIR(it->mode) && it->data.dir.visited)
+ goto fail_link_loop;
+ } else if (S_ISDIR(n->mode)) {
+ n->data.dir.visited = true;
+
+ for (it = n->data.dir.children; it != NULL; it = it->next) {
+ if (resolve_hard_links_dfs(fs, it))
+ return -1;
+ }
+
+ n->data.dir.visited = false;
+ }
+
+ return 0;
+fail_link: {
+ char *path = fstree_get_path(n);
+ fprintf(stderr, "Resolving hard link '%s' -> '%s': %s\n",
+ path == NULL ? n->name : path, n->data.target,
+ strerror(errno));
+ free(path);
+}
+ return -1;
+fail_link_loop: {
+ char *npath = fstree_get_path(n);
+ char *tpath = fstree_get_path(it);
+ fprintf(stderr, "Hard link loop detected in '%s' -> '%s'\n",
+ npath == NULL ? n->name : npath,
+ tpath == NULL ? it->name : tpath);
+ free(npath);
+ free(tpath);
+}
+ return -1;
}
static void sort_recursive(tree_node_t *n)
@@ -76,16 +172,21 @@ static file_info_t *file_list_dfs(tree_node_t *n)
return NULL;
}
-void fstree_post_process(fstree_t *fs)
+int fstree_post_process(fstree_t *fs)
{
size_t inum = 1;
sort_recursive(fs->root);
+ if (resolve_hard_links_dfs(fs, fs->root))
+ return -1;
+
fs->unique_inode_count = 0;
- map_child_nodes(fs, fs->root, &inum);
+ if (map_child_nodes(fs, fs->root, &inum))
+ return -1;
fs->root->inode_num = inum;
fs->unique_inode_count += 1;
fs->files = file_list_dfs(fs->root);
+ return 0;
}
diff --git a/mkfs/mkfs.c b/mkfs/mkfs.c
index 89215c6..213fb36 100644
--- a/mkfs/mkfs.c
+++ b/mkfs/mkfs.c
@@ -232,7 +232,8 @@ int main(int argc, char **argv)
sehnd = NULL;
}
- fstree_post_process(&sqfs.fs);
+ if (fstree_post_process(&sqfs.fs))
+ goto out;
if (pack_files(sqfs.data, &sqfs.fs, &sqfs.stats, &opt))
goto out;
diff --git a/tar/tar2sqfs.c b/tar/tar2sqfs.c
index a13b84e..63933eb 100644
--- a/tar/tar2sqfs.c
+++ b/tar/tar2sqfs.c
@@ -551,7 +551,8 @@ int main(int argc, char **argv)
if (process_tar_ball())
goto out;
- fstree_post_process(&sqfs.fs);
+ if (fstree_post_process(&sqfs.fs))
+ goto out;
if (sqfs_writer_finish(&sqfs, &cfg))
goto out;
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-28 05:12:18 +0000