[PATCH v4 2/2] Add API to iterate over inodes in EROFS
Kelvin Zhang
zhangkelvin at google.com
Tue Dec 14 14:32:39 AEDT 2021
Change-Id: Ia35708080a72ee204eaaddfc670d3cb8023a078c
Signed-off-by: Kelvin Zhang <zhangkelvin at google.com>
---
include/erofs/iterate.h | 46 ++++++++++++
include/erofs_fs.h | 4 +-
lib/Makefile.am | 2 +-
lib/iterate.c | 154 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 203 insertions(+), 3 deletions(-)
create mode 100644 include/erofs/iterate.h
create mode 100644 lib/iterate.c
diff --git a/include/erofs/iterate.h b/include/erofs/iterate.h
new file mode 100644
index 0000000..4e2c783
--- /dev/null
+++ b/include/erofs/iterate.h
@@ -0,0 +1,46 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef ITERATE_ITERATE
+#define ITERATE_ITERATE
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+
+#include "erofs/io.h"
+#include "erofs/print.h"
+
+
+struct erofs_inode_info {
+ const char* name;
+ enum erofs_ftype ftype;
+ struct erofs_inode* inode;
+ void* arg;
+};
+// Callback function for iterating over inodes of EROFS
+
+typedef bool (*erofs_readdir_cb)(struct erofs_inode_info*);
+
+// Iterate over inodes that are in directory specified by |nid|.
+// |parent_nid| is optional, if specified, additional sanity checks will
+// be performed.
+// |cb| will be called for every inode, regardless of type of inode.
+// |arg| will be passed to the callback in |erofs_readdir_cb| struct's
+// |arg| field.
+int erofs_iterate_dir(const struct erofs_sb_info* sbi,
+ erofs_nid_t nid,
+ erofs_nid_t parent_nid,
+ erofs_readdir_cb cb,
+ void* arg);
+int erofs_iterate_root_dir(const struct erofs_sb_info* sbi,
+ erofs_readdir_cb cbg,
+ void* arg);
+int erofs_get_occupied_size(const struct erofs_inode* inode, erofs_off_t* size);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // ITERATE_ITERATE
diff --git a/include/erofs_fs.h b/include/erofs_fs.h
index 9a91877..7ee8251 100644
--- a/include/erofs_fs.h
+++ b/include/erofs_fs.h
@@ -389,8 +389,8 @@ struct erofs_dirent {
} __packed;
/* file types used in inode_info->flags */
-enum {
- EROFS_FT_UNKNOWN,
+enum erofs_ftype {
+ EROFS_FT_UNKNOWN = 0,
EROFS_FT_REG_FILE,
EROFS_FT_DIR,
EROFS_FT_CHRDEV,
diff --git a/lib/Makefile.am b/lib/Makefile.am
index 67ba798..20c0e4f 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -27,7 +27,7 @@ noinst_HEADERS = $(top_srcdir)/include/erofs_fs.h \
noinst_HEADERS += compressor.h
liberofs_la_SOURCES = config.c io.c cache.c super.c inode.c xattr.c exclude.c \
namei.c data.c compress.c compressor.c zmap.c decompress.c \
- compress_hints.c hashmap.c sha256.c blobchunk.c
+ compress_hints.c hashmap.c sha256.c blobchunk.c iterate.c
liberofs_la_CFLAGS = -Wall -Werror -I$(top_srcdir)/include
if ENABLE_LZ4
liberofs_la_CFLAGS += ${LZ4_CFLAGS}
diff --git a/lib/iterate.c b/lib/iterate.c
new file mode 100644
index 0000000..e01eadf
--- /dev/null
+++ b/lib/iterate.c
@@ -0,0 +1,154 @@
+// SPDX-License-Identifier: Apache-2.0
+
+#include "erofs/internal.h"
+#include "erofs_fs.h"
+#include "erofs/print.h"
+#include "erofs/iterate.h"
+
+static int erofs_read_dirent(const struct erofs_sb_info* sbi,
+ const struct erofs_dirent* de,
+ erofs_nid_t nid,
+ erofs_nid_t parent_nid,
+ const char* dname,
+ erofs_readdir_cb cb,
+ void* arg) {
+ int err;
+ struct erofs_inode inode = {.nid = de->nid};
+ err = erofs_read_inode_from_disk(&inode);
+ if (err) {
+ erofs_err("read file inode from disk failed!");
+ return err;
+ }
+ char buf[PATH_MAX + 1];
+ erofs_get_inode_name(sbi, de->nid, buf, PATH_MAX + 1);
+ struct erofs_inode_info info = {
+ .name = buf,
+ .ftype = de->file_type,
+ .inode = &inode,
+ .arg = arg};
+ cb(&info);
+ if ((de->file_type == EROFS_FT_DIR) && de->nid != nid &&
+ de->nid != parent_nid) {
+ err = erofs_iterate_dir(sbi, de->nid, nid, cb, arg);
+ if (err) {
+ erofs_err("parse dir nid %u error occurred\n",
+ (unsigned int)(de->nid));
+ return err;
+ }
+ }
+ return 0;
+}
+
+static inline int erofs_checkdirent(const struct erofs_dirent* de,
+ const struct erofs_dirent* last_de,
+ u32 maxsize,
+ const char* dname) {
+ int dname_len;
+ unsigned int 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, de->nid | 0ULL);
+ return -EFSCORRUPTED;
+ }
+ dname_len = (de + 1 >= last_de) ? strnlen(dname, maxsize - nameoff)
+ : le16_to_cpu(de[1].nameoff) - nameoff;
+ /* a corrupted entry is found */
+ if (nameoff + dname_len > maxsize || dname_len > EROFS_NAME_LEN) {
+ erofs_err("bogus dirent @ nid %llu", le64_to_cpu(de->nid) | 0ULL);
+ DBG_BUGON(1);
+ return -EFSCORRUPTED;
+ }
+ if (de->file_type >= EROFS_FT_MAX) {
+ erofs_err("invalid file type %u", (unsigned int)(de->nid));
+ return -EFSCORRUPTED;
+ }
+ return dname_len;
+}
+
+int erofs_iterate_dir(const struct erofs_sb_info* sbi,
+ erofs_nid_t nid,
+ erofs_nid_t parent_nid,
+ erofs_readdir_cb cb,
+ void* arg) {
+ int err;
+ erofs_off_t offset;
+ char buf[EROFS_BLKSIZ];
+ struct erofs_inode vi = {.nid = nid};
+ err = erofs_read_inode_from_disk(&vi);
+ if (err)
+ return err;
+ struct erofs_inode_info inode_info = {
+ .name = buf,
+ .ftype = EROFS_FT_DIR,
+ .inode = &vi,
+ .arg = arg,
+ };
+ err = erofs_get_inode_name(sbi, nid, buf, EROFS_BLKSIZ);
+ cb(&inode_info);
+ if (err) {
+ return err;
+ }
+ offset = 0;
+ while (offset < vi.i_size) {
+ erofs_off_t maxsize = min_t(erofs_off_t, vi.i_size - offset, EROFS_BLKSIZ);
+ const struct erofs_dirent* de = (const struct erofs_dirent*)(buf);
+ struct erofs_dirent* end;
+ unsigned int nameoff;
+ err = erofs_pread(&vi, buf, maxsize, offset);
+ if (err)
+ return err;
+ nameoff = le16_to_cpu(de->nameoff);
+ end = (struct erofs_dirent*)(buf + nameoff);
+ while (de < end) {
+ const char * const dname = (char*)buf + nameoff;
+ int ret;
+ /* skip "." and ".." dentry */
+ if (is_dot_dotdot(dname)) {
+ if (dname[1] == '.' && parent_nid > 0) {
+ // Directory ".." should have nid == parent_nid.
+ // But parent_nid parameter is optional, so only perform the check
+ // if parent_nid is specified.
+ if (parent_nid != de->nid) {
+ return EFSCORRUPTED;
+ }
+ }
+ de++;
+ continue;
+ }
+ ret = erofs_checkdirent(de, end, maxsize, dname);
+ if (ret < 0)
+ return ret;
+ ret = erofs_read_dirent(sbi, de, nid, parent_nid, dname, cb, arg);
+ if (ret < 0)
+ return ret;
+ ++de;
+ }
+ offset += maxsize;
+ }
+ return 0;
+}
+
+int erofs_get_occupied_size(const struct erofs_inode* inode, erofs_off_t* size) {
+ *size = 0;
+ switch (inode->datalayout) {
+ case EROFS_INODE_FLAT_INLINE:
+ case EROFS_INODE_FLAT_PLAIN:
+ case EROFS_INODE_CHUNK_BASED:
+ *size = inode->i_size;
+ break;
+ case EROFS_INODE_FLAT_COMPRESSION_LEGACY:
+ case EROFS_INODE_FLAT_COMPRESSION:
+ *size = inode->u.i_blocks * EROFS_BLKSIZ;
+ break;
+ default:
+ erofs_err("unknown datalayout");
+ return -1;
+ }
+ return 0;
+}
+
+int erofs_iterate_root_dir(const struct erofs_sb_info* sbi,
+ erofs_readdir_cb cb,
+ void* arg) {
+ return erofs_iterate_dir(sbi, sbi->root_nid, sbi->root_nid, cb, arg);
+}
+
--
2.34.1.173.g76aa8bc2d0-goog
More information about the Linux-erofs
mailing list