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authorDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2022-06-01 00:10:22 +0200
committerDavid Oberhollenzer <david.oberhollenzer@sigma-star.at>2022-06-02 17:26:53 +0200
commita36cf2824c74a3ba7333801268d0ba4194684423 (patch)
treef1fd950ea37bf6c91af7a154f90f5e6eb8b70e01
parentfa7110a9c4bd0ece4be33998b6f9e7d4f528acc7 (diff)
Cleanup: libsqfs: move directory iteration out of the directory reader
Add a simple directory state object to the meta data reader and use that to iterate directory entries. The code for reading the directory listing is movde to readdir.c Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>
-rw-r--r--include/sqfs/meta_reader.h83
-rw-r--r--include/sqfs/predef.h1
-rw-r--r--lib/sqfs/dir_reader/dir_reader.c123
-rw-r--r--lib/sqfs/dir_reader/internal.h10
-rw-r--r--lib/sqfs/readdir.c95
5 files changed, 204 insertions, 108 deletions
diff --git a/include/sqfs/meta_reader.h b/include/sqfs/meta_reader.h
index e0dc186..149672b 100644
--- a/include/sqfs/meta_reader.h
+++ b/include/sqfs/meta_reader.h
@@ -21,6 +21,7 @@
#define SQFS_META_READER_H
#include "sqfs/predef.h"
+#include "sqfs/super.h"
/**
* @file meta_reader.h
@@ -47,6 +48,37 @@
* from disk and reading transparently across block boarders if required.
*/
+/**
+ * @struct sqfs_readdir_state_t
+ *
+ * @brief Encapsulates state for simple directory reading
+ */
+struct sqfs_readdir_state_t {
+ struct {
+ sqfs_u64 block;
+ size_t offset;
+ size_t size;
+ } init, current;
+
+ size_t entries;
+
+ sqfs_u32 inum_base;
+ sqfs_u64 inode_block;
+};
+
+/**
+ * @brief Rewind a directory state object back to its starting location
+ *
+ * @memberof sqfs_readdir_state_t
+ *
+ * @param it A pointer to the directory state.
+ */
+static SQFS_INLINE void sqfs_readdir_state_reset(sqfs_readdir_state_t *s)
+{
+ s->current = s->init;
+ s->entries = 0;
+}
+
#ifdef __cplusplus
extern "C" {
#endif
@@ -153,6 +185,57 @@ SQFS_API int sqfs_meta_reader_read_dir_ent(sqfs_meta_reader_t *m,
sqfs_dir_entry_t **ent);
/**
+ * @brief Initialize a state object for reading a directory
+ *
+ * @memberof sqfs_readdir_state_t
+ *
+ * This function initializes a simple state object to point to the
+ * location of a directory header and store the total, uncompressed
+ * size of the directory.
+ *
+ * The state object can be passed to @ref sqfs_meta_reader_readdir
+ * to read entries one-by-one.
+ *
+ * @param s A pointer to the state object to initialize.
+ * @param super A pointer to the super block, telling us where
+ * the directory table starts.
+ * @param inode A pointer to a directory inode from which to get the
+ * directory location.
+ *
+ * @return Zero on success, an @ref SQFS_ERROR value on
+ * failure (e.g. the inode is not a directory inode).
+ */
+SQFS_API
+int sqfs_readdir_state_init(sqfs_readdir_state_t *s, const sqfs_super_t *super,
+ const sqfs_inode_generic_t *inode);
+
+/**
+ * @brief Simple directory reading interface
+ *
+ * @memberof sqfs_meta_reader_t
+ *
+ * This function successively reads directory entries, transparently
+ * parsing and skipping across headers. The state is encapsulated in
+ * an external object that is passed in and the function seeks to the
+ * location, so one can swap between multiple states and read several
+ * directories interchangeably.
+ *
+ * @param m A pointer to a meta data reader.
+ * @param s A pointer to a directory state that is used and updated.
+ * @param ent Returns a pointer to a directory entry. Can be
+ * released with a single @ref sqfs_free call.
+ * @param inum If not NULL, returns the decoded inode number.
+ * @param iref If not NULL, returns a reference to the inode.
+ *
+ * @return Zero on success, a negative @ref SQFS_ERROR number on failure,
+ * a positive number if the end of the directory is reached.
+ */
+SQFS_API int sqfs_meta_reader_readdir(sqfs_meta_reader_t *m,
+ sqfs_readdir_state_t *s,
+ sqfs_dir_entry_t **ent,
+ sqfs_u32 *inum, sqfs_u64 *iref);
+
+/**
* @brief Read and decode an inode from a meta data reader.
*
* @memberof sqfs_meta_reader_t
diff --git a/include/sqfs/predef.h b/include/sqfs/predef.h
index a976cd4..3c13ef5 100644
--- a/include/sqfs/predef.h
+++ b/include/sqfs/predef.h
@@ -94,6 +94,7 @@ typedef struct sqfs_block_writer_t sqfs_block_writer_t;
typedef struct sqfs_block_writer_stats_t sqfs_block_writer_stats_t;
typedef struct sqfs_block_processor_stats_t sqfs_block_processor_stats_t;
typedef struct sqfs_block_processor_desc_t sqfs_block_processor_desc_t;
+typedef struct sqfs_readdir_state_t sqfs_readdir_state_t;
typedef struct sqfs_fragment_t sqfs_fragment_t;
typedef struct sqfs_dir_header_t sqfs_dir_header_t;
diff --git a/lib/sqfs/dir_reader/dir_reader.c b/lib/sqfs/dir_reader/dir_reader.c
index 8a074aa..5ed0eff 100644
--- a/lib/sqfs/dir_reader/dir_reader.c
+++ b/lib/sqfs/dir_reader/dir_reader.c
@@ -105,29 +105,24 @@ int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
const sqfs_inode_generic_t *inode,
sqfs_u32 flags)
{
- sqfs_u64 block_start;
- size_t size, offset;
sqfs_u32 parent;
+ int ret;
if (flags & (~SQFS_DIR_OPEN_ALL_FLAGS))
return SQFS_ERROR_UNSUPPORTED;
- if (inode->base.type == SQFS_INODE_DIR) {
- parent = inode->data.dir.parent_inode;
- size = inode->data.dir.size;
- offset = inode->data.dir.offset;
- block_start = inode->data.dir.start_block;
- } else if (inode->base.type == SQFS_INODE_EXT_DIR) {
- parent = inode->data.dir_ext.parent_inode;
- size = inode->data.dir_ext.size;
- offset = inode->data.dir_ext.offset;
- block_start = inode->data.dir_ext.start_block;
- } else {
- return SQFS_ERROR_NOT_DIR;
- }
+ ret = sqfs_readdir_state_init(&rd->it, rd->super, inode);
+ if (ret)
+ return ret;
if ((rd->flags & SQFS_DIR_READER_DOT_ENTRIES) &&
!(flags & SQFS_DIR_OPEN_NO_DOT_ENTRIES)) {
+ if (inode->base.type == SQFS_INODE_EXT_DIR) {
+ parent = inode->data.dir_ext.parent_inode;
+ } else {
+ parent = inode->data.dir.parent_inode;
+ }
+
if (sqfs_dir_reader_dcache_find(rd, inode->base.inode_number,
&rd->cur_ref)) {
return SQFS_ERROR_NO_ENTRY;
@@ -146,21 +141,7 @@ int sqfs_dir_reader_open_dir(sqfs_dir_reader_t *rd,
}
rd->start_state = rd->state;
-
- memset(&rd->hdr, 0, sizeof(rd->hdr));
- rd->size = size;
- rd->entries = 0;
-
- block_start += rd->super->directory_table_start;
-
- rd->dir_block_start = block_start;
- rd->dir_offset = offset;
- rd->start_size = size;
-
- if (rd->size <= sizeof(rd->hdr))
- return 0;
-
- return sqfs_meta_reader_seek(rd->meta_dir, block_start, offset);
+ return 0;
}
static int mk_dummy_entry(const char *str, sqfs_dir_entry_t **out)
@@ -183,8 +164,6 @@ static int mk_dummy_entry(const char *str, sqfs_dir_entry_t **out)
int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_entry_t **out)
{
- sqfs_dir_entry_t *ent;
- size_t count;
int err;
switch (rd->state) {
@@ -207,41 +186,8 @@ int sqfs_dir_reader_read(sqfs_dir_reader_t *rd, sqfs_dir_entry_t **out)
return SQFS_ERROR_SEQUENCE;
}
- if (!rd->entries) {
- if (rd->size <= sizeof(rd->hdr))
- return 1;
-
- err = sqfs_meta_reader_read_dir_header(rd->meta_dir, &rd->hdr);
- if (err)
- return err;
-
- rd->size -= sizeof(rd->hdr);
- rd->entries = rd->hdr.count + 1;
- }
-
- if (rd->size <= sizeof(*ent)) {
- rd->size = 0;
- rd->entries = 0;
- return 1;
- }
-
- err = sqfs_meta_reader_read_dir_ent(rd->meta_dir, &ent);
- if (err)
- return err;
-
- count = sizeof(*ent) + strlen((const char *)ent->name);
-
- if (count > rd->size) {
- rd->size = 0;
- rd->entries = 0;
- } else {
- rd->size -= count;
- rd->entries -= 1;
- }
-
- rd->inode_offset = ent->offset;
- *out = ent;
- return 0;
+ return sqfs_meta_reader_readdir(rd->meta_dir, &rd->it,
+ out, NULL, &rd->ent_ref);
}
int sqfs_dir_reader_rewind(sqfs_dir_reader_t *rd)
@@ -249,16 +195,9 @@ int sqfs_dir_reader_rewind(sqfs_dir_reader_t *rd)
if (rd->state == DIR_STATE_NONE)
return SQFS_ERROR_SEQUENCE;
- memset(&rd->hdr, 0, sizeof(rd->hdr));
- rd->size = rd->start_size;
- rd->entries = 0;
+ sqfs_readdir_state_reset(&rd->it);
rd->state = rd->start_state;
-
- if (rd->size <= sizeof(rd->hdr))
- return 0;
-
- return sqfs_meta_reader_seek(rd->meta_dir, rd->dir_block_start,
- rd->dir_offset);
+ return 0;
}
int sqfs_dir_reader_find(sqfs_dir_reader_t *rd, const char *name)
@@ -266,14 +205,9 @@ int sqfs_dir_reader_find(sqfs_dir_reader_t *rd, const char *name)
sqfs_dir_entry_t *ent;
int ret;
- if (rd->state == DIR_STATE_NONE)
- return SQFS_ERROR_SEQUENCE;
-
- if (rd->size != rd->start_size || rd->state != rd->start_state) {
- ret = sqfs_dir_reader_rewind(rd);
- if (ret)
- return ret;
- }
+ ret = sqfs_dir_reader_rewind(rd);
+ if (ret != 0)
+ return ret;
do {
ret = sqfs_dir_reader_read(rd, &ent);
@@ -292,36 +226,25 @@ int sqfs_dir_reader_find(sqfs_dir_reader_t *rd, const char *name)
int sqfs_dir_reader_get_inode(sqfs_dir_reader_t *rd,
sqfs_inode_generic_t **inode)
{
- sqfs_u64 block_start;
- sqfs_u16 offset;
+ sqfs_u64 ref;
int ret;
switch (rd->state) {
- case DIR_STATE_DOT:
- block_start = rd->cur_ref >> 16;
- offset = rd->cur_ref & 0x0FFFF;
- break;
- case DIR_STATE_DOT_DOT:
- block_start = rd->parent_ref >> 16;
- offset = rd->parent_ref & 0x0FFFF;
- break;
- case DIR_STATE_ENTRIES:
- block_start = rd->hdr.start_block;
- offset = rd->inode_offset;
- break;
+ case DIR_STATE_DOT: ref = rd->cur_ref; break;
+ case DIR_STATE_DOT_DOT: ref = rd->parent_ref; break;
+ case DIR_STATE_ENTRIES: ref = rd->ent_ref; break;
default:
return SQFS_ERROR_SEQUENCE;
}
ret = sqfs_meta_reader_read_inode(rd->meta_inode, rd->super,
- block_start, offset, inode);
+ ref >> 16, ref & 0x0FFFF, inode);
if (ret != 0)
return ret;
if ((*inode)->base.type == SQFS_INODE_DIR ||
(*inode)->base.type == SQFS_INODE_EXT_DIR) {
sqfs_u32 inum = (*inode)->base.inode_number;
- sqfs_u64 ref = (block_start << 16) | rd->inode_offset;
ret = sqfs_dir_reader_dcache_add(rd, inum, ref);
if (ret != 0)
diff --git a/lib/sqfs/dir_reader/internal.h b/lib/sqfs/dir_reader/internal.h
index cd20b69..4dbe728 100644
--- a/lib/sqfs/dir_reader/internal.h
+++ b/lib/sqfs/dir_reader/internal.h
@@ -38,14 +38,7 @@ struct sqfs_dir_reader_t {
sqfs_meta_reader_t *meta_inode;
const sqfs_super_t *super;
- sqfs_dir_header_t hdr;
- sqfs_u64 dir_block_start;
- size_t entries;
- size_t size;
-
- size_t start_size;
- sqfs_u16 dir_offset;
- sqfs_u16 inode_offset;
+ sqfs_readdir_state_t it;
sqfs_u32 flags;
@@ -53,6 +46,7 @@ struct sqfs_dir_reader_t {
int state;
sqfs_u64 parent_ref;
sqfs_u64 cur_ref;
+ sqfs_u64 ent_ref;
rbtree_t dcache;
};
diff --git a/lib/sqfs/readdir.c b/lib/sqfs/readdir.c
index 8899475..e2dbcd4 100644
--- a/lib/sqfs/readdir.c
+++ b/lib/sqfs/readdir.c
@@ -9,6 +9,8 @@
#include "sqfs/meta_reader.h"
#include "sqfs/error.h"
+#include "sqfs/super.h"
+#include "sqfs/inode.h"
#include "sqfs/dir.h"
#include "compat.h"
@@ -64,3 +66,96 @@ int sqfs_meta_reader_read_dir_ent(sqfs_meta_reader_t *m,
*result = out;
return 0;
}
+
+int sqfs_readdir_state_init(sqfs_readdir_state_t *s, const sqfs_super_t *super,
+ const sqfs_inode_generic_t *inode)
+{
+ memset(s, 0, sizeof(*s));
+
+ if (inode->base.type == SQFS_INODE_DIR) {
+ s->init.block = inode->data.dir.start_block;
+ s->init.offset = inode->data.dir.offset;
+ s->init.size = inode->data.dir.size;
+ } else if (inode->base.type == SQFS_INODE_EXT_DIR) {
+ s->init.block = inode->data.dir_ext.start_block;
+ s->init.offset = inode->data.dir_ext.offset;
+ s->init.size = inode->data.dir_ext.size;
+ } else {
+ return SQFS_ERROR_NOT_DIR;
+ }
+
+ s->init.block += super->directory_table_start;
+ s->current = s->init;
+ return 0;
+}
+
+int sqfs_meta_reader_readdir(sqfs_meta_reader_t *m, sqfs_readdir_state_t *it,
+ sqfs_dir_entry_t **ent,
+ sqfs_u32 *inum, sqfs_u64 *iref)
+{
+ size_t count;
+ int ret;
+
+ if (it->entries == 0) {
+ sqfs_dir_header_t hdr;
+
+ if (it->current.size <= sizeof(hdr))
+ goto out_eof;
+
+ ret = sqfs_meta_reader_seek(m, it->current.block,
+ it->current.offset);
+ if (ret != 0)
+ return ret;
+
+ ret = sqfs_meta_reader_read_dir_header(m, &hdr);
+ if (ret != 0)
+ return ret;
+
+ sqfs_meta_reader_get_position(m, &it->current.block,
+ &it->current.offset);
+
+ it->current.size -= sizeof(hdr);
+ it->entries = hdr.count + 1;
+ it->inum_base = hdr.inode_number;
+ it->inode_block = hdr.start_block;
+ }
+
+ if (it->current.size <= sizeof(**ent))
+ goto out_eof;
+
+ ret = sqfs_meta_reader_seek(m, it->current.block, it->current.offset);
+ if (ret != 0)
+ return ret;
+
+ ret = sqfs_meta_reader_read_dir_ent(m, ent);
+ if (ret)
+ return ret;
+
+ sqfs_meta_reader_get_position(m, &it->current.block,
+ &it->current.offset);
+
+ it->current.size -= sizeof(**ent);
+ it->entries -= 1;
+
+ count = (*ent)->size + 1;
+
+ if (count >= it->current.size) {
+ it->current.size = 0;
+ } else {
+ it->current.size -= count;
+ }
+
+ if (inum != NULL)
+ *inum = it->inum_base + (*ent)->inode_diff;
+
+ if (iref != NULL) {
+ *iref = (sqfs_u64)it->inode_block << 16UL;
+ *iref |= (*ent)->offset;
+ }
+
+ return 0;
+out_eof:
+ it->current.size = 0;
+ it->entries = 0;
+ return 1;
+}