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-rw-r--r--fs/erofs/namei.c252
1 files changed, 252 insertions, 0 deletions
diff --git a/fs/erofs/namei.c b/fs/erofs/namei.c
new file mode 100644
index 0000000000..f1195a09ea
--- /dev/null
+++ b/fs/erofs/namei.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0+
+#include "internal.h"
+
+int erofs_read_inode_from_disk(struct erofs_inode *vi)
+{
+ int ret, ifmt;
+ char buf[sizeof(struct erofs_inode_extended)];
+ struct erofs_inode_compact *dic;
+ struct erofs_inode_extended *die;
+ const erofs_off_t inode_loc = iloc(vi->nid);
+
+ ret = erofs_dev_read(0, buf, inode_loc, sizeof(*dic));
+ if (ret < 0)
+ return -EIO;
+
+ dic = (struct erofs_inode_compact *)buf;
+ ifmt = le16_to_cpu(dic->i_format);
+
+ vi->datalayout = erofs_inode_datalayout(ifmt);
+ if (vi->datalayout >= EROFS_INODE_DATALAYOUT_MAX) {
+ erofs_err("unsupported datalayout %u of nid %llu",
+ vi->datalayout, vi->nid | 0ULL);
+ return -EOPNOTSUPP;
+ }
+ switch (erofs_inode_version(ifmt)) {
+ case EROFS_INODE_LAYOUT_EXTENDED:
+ vi->inode_isize = sizeof(struct erofs_inode_extended);
+
+ ret = erofs_dev_read(0, buf + sizeof(*dic), inode_loc + sizeof(*dic),
+ sizeof(*die) - sizeof(*dic));
+ if (ret < 0)
+ return -EIO;
+
+ die = (struct erofs_inode_extended *)buf;
+ vi->xattr_isize = erofs_xattr_ibody_size(die->i_xattr_icount);
+ vi->i_mode = le16_to_cpu(die->i_mode);
+
+ switch (vi->i_mode & S_IFMT) {
+ case S_IFREG:
+ case S_IFDIR:
+ case S_IFLNK:
+ vi->u.i_blkaddr = le32_to_cpu(die->i_u.raw_blkaddr);
+ break;
+ case S_IFCHR:
+ case S_IFBLK:
+ vi->u.i_rdev = 0;
+ break;
+ case S_IFIFO:
+ case S_IFSOCK:
+ vi->u.i_rdev = 0;
+ break;
+ default:
+ goto bogusimode;
+ }
+
+ vi->i_uid = le32_to_cpu(die->i_uid);
+ vi->i_gid = le32_to_cpu(die->i_gid);
+ vi->i_nlink = le32_to_cpu(die->i_nlink);
+
+ vi->i_ctime = le64_to_cpu(die->i_ctime);
+ vi->i_ctime_nsec = le64_to_cpu(die->i_ctime_nsec);
+ vi->i_size = le64_to_cpu(die->i_size);
+ if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
+ /* fill chunked inode summary info */
+ vi->u.chunkformat = le16_to_cpu(die->i_u.c.format);
+ break;
+ case EROFS_INODE_LAYOUT_COMPACT:
+ vi->inode_isize = sizeof(struct erofs_inode_compact);
+ vi->xattr_isize = erofs_xattr_ibody_size(dic->i_xattr_icount);
+ vi->i_mode = le16_to_cpu(dic->i_mode);
+
+ switch (vi->i_mode & S_IFMT) {
+ case S_IFREG:
+ case S_IFDIR:
+ case S_IFLNK:
+ vi->u.i_blkaddr = le32_to_cpu(dic->i_u.raw_blkaddr);
+ break;
+ case S_IFCHR:
+ case S_IFBLK:
+ vi->u.i_rdev = 0;
+ break;
+ case S_IFIFO:
+ case S_IFSOCK:
+ vi->u.i_rdev = 0;
+ break;
+ default:
+ goto bogusimode;
+ }
+
+ vi->i_uid = le16_to_cpu(dic->i_uid);
+ vi->i_gid = le16_to_cpu(dic->i_gid);
+ vi->i_nlink = le16_to_cpu(dic->i_nlink);
+
+ vi->i_ctime = sbi.build_time;
+ vi->i_ctime_nsec = sbi.build_time_nsec;
+
+ vi->i_size = le32_to_cpu(dic->i_size);
+ if (vi->datalayout == EROFS_INODE_CHUNK_BASED)
+ vi->u.chunkformat = le16_to_cpu(dic->i_u.c.format);
+ break;
+ default:
+ erofs_err("unsupported on-disk inode version %u of nid %llu",
+ erofs_inode_version(ifmt), vi->nid | 0ULL);
+ return -EOPNOTSUPP;
+ }
+
+ vi->flags = 0;
+ if (vi->datalayout == EROFS_INODE_CHUNK_BASED) {
+ if (vi->u.chunkformat & ~EROFS_CHUNK_FORMAT_ALL) {
+ erofs_err("unsupported chunk format %x of nid %llu",
+ vi->u.chunkformat, vi->nid | 0ULL);
+ return -EOPNOTSUPP;
+ }
+ vi->u.chunkbits = LOG_BLOCK_SIZE +
+ (vi->u.chunkformat & EROFS_CHUNK_FORMAT_BLKBITS_MASK);
+ } else if (erofs_inode_is_data_compressed(vi->datalayout))
+ return -EOPNOTSUPP;
+ return 0;
+bogusimode:
+ erofs_err("bogus i_mode (%o) @ nid %llu", vi->i_mode, vi->nid | 0ULL);
+ return -EFSCORRUPTED;
+}
+
+struct erofs_dirent *find_target_dirent(erofs_nid_t pnid,
+ void *dentry_blk,
+ const char *name, unsigned int len,
+ unsigned int nameoff,
+ unsigned int maxsize)
+{
+ struct erofs_dirent *de = dentry_blk;
+ const struct erofs_dirent *end = dentry_blk + nameoff;
+
+ while (de < end) {
+ const char *de_name;
+ unsigned int de_namelen;
+
+ nameoff = le16_to_cpu(de->nameoff);
+ de_name = (char *)dentry_blk + nameoff;
+
+ /* the last dirent in the block? */
+ if (de + 1 >= end)
+ de_namelen = strnlen(de_name, maxsize - nameoff);
+ else
+ de_namelen = le16_to_cpu(de[1].nameoff) - nameoff;
+
+ /* a corrupted entry is found */
+ if (nameoff + de_namelen > maxsize ||
+ de_namelen > EROFS_NAME_LEN) {
+ erofs_err("bogus dirent @ nid %llu", pnid | 0ULL);
+ DBG_BUGON(1);
+ return ERR_PTR(-EFSCORRUPTED);
+ }
+
+ if (len == de_namelen && !memcmp(de_name, name, de_namelen))
+ return de;
+ ++de;
+ }
+ return NULL;
+}
+
+struct nameidata {
+ erofs_nid_t nid;
+ unsigned int ftype;
+};
+
+int erofs_namei(struct nameidata *nd,
+ const char *name, unsigned int len)
+{
+ erofs_nid_t nid = nd->nid;
+ int ret;
+ char buf[EROFS_BLKSIZ];
+ struct erofs_inode vi = { .nid = nid };
+ erofs_off_t offset;
+
+ ret = erofs_read_inode_from_disk(&vi);
+ if (ret)
+ return ret;
+
+ offset = 0;
+ while (offset < vi.i_size) {
+ erofs_off_t maxsize = min_t(erofs_off_t,
+ vi.i_size - offset, EROFS_BLKSIZ);
+ struct erofs_dirent *de = (void *)buf;
+ unsigned int nameoff;
+
+ ret = erofs_pread(&vi, buf, maxsize, offset);
+ if (ret)
+ return ret;
+
+ nameoff = le16_to_cpu(de->nameoff);
+ if (nameoff < sizeof(struct erofs_dirent) ||
+ nameoff >= PAGE_SIZE) {
+ erofs_err("invalid de[0].nameoff %u @ nid %llu",
+ nameoff, nid | 0ULL);
+ return -EFSCORRUPTED;
+ }
+
+ de = find_target_dirent(nid, buf, name, len,
+ nameoff, maxsize);
+ if (IS_ERR(de))
+ return PTR_ERR(de);
+
+ if (de) {
+ nd->nid = le64_to_cpu(de->nid);
+ return 0;
+ }
+ offset += maxsize;
+ }
+ return -ENOENT;
+}
+
+static int link_path_walk(const char *name, struct nameidata *nd)
+{
+ nd->nid = sbi.root_nid;
+
+ while (*name == '/')
+ name++;
+
+ /* At this point we know we have a real path component. */
+ while (*name != '\0') {
+ const char *p = name;
+ int ret;
+
+ do {
+ ++p;
+ } while (*p != '\0' && *p != '/');
+
+ DBG_BUGON(p <= name);
+ ret = erofs_namei(nd, name, p - name);
+ if (ret)
+ return ret;
+
+ name = p;
+ /* Skip until no more slashes. */
+ for (name = p; *name == '/'; ++name)
+ ;
+ }
+ return 0;
+}
+
+int erofs_ilookup(const char *path, struct erofs_inode *vi)
+{
+ int ret;
+ struct nameidata nd;
+
+ ret = link_path_walk(path, &nd);
+ if (ret)
+ return ret;
+
+ vi->nid = nd.nid;
+ return erofs_read_inode_from_disk(vi);
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-12 04:13:09 +0000