Changeset a8e1aae in mainline for uspace/lib/ext2/libext2_directory.c

Timestamp:

2011-02-24T21:03:42Z (14 years ago)

Author:

Martin Sucha <sucha14@…>

Branches:

lfn, master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

9ffbdf1

Parents:

102d400

Message:

Add support for reading directories to libext2

File:

• uspace/lib/ext2/libext2_directory.c (modified) (2 diffs)

uspace/lib/ext2/libext2_directory.c

@@ -37 +37 @@
 #include "libext2_directory.h"
 #include <byteorder.h>
+#include <errno.h>
+#include <assert.h>
 
 /**
@@ -75 +77 @@
 }
 
+/**
+ * Initialize a directory iterator
+ * 
+ * @param it pointer to iterator to initialize
+ * @param fs pointer to filesystem structure
+ * @param inode pointer to inode reference structure
+ * @return EOK on success or negative error code on failure
+ */
+int ext2_directory_iterator_init(ext2_directory_iterator_t *it,
+    ext2_filesystem_t *fs, ext2_inode_ref_t *inode_ref)
+{
+        int rc;
+        uint32_t block_id;
+        it->inode_ref = inode_ref;
+        it->fs = fs;
+        
+        // Get the first data block, so we can get first entry
+        rc = ext2_filesystem_get_inode_data_block_index(fs, inode_ref->inode, 0, 
+            &block_id);
+        if (rc != EOK) {
+                return rc;
+        }
+        
+        rc = block_get(&it->current_block, fs->device, block_id, 0);
+        if (rc != EOK) {
+                return rc;
+        }
+        
+        it->current = it->current_block->data;
+        it->current_offset = 0;
+        
+        return EOK;
+}
+
+/**
+ * Advance the directory iterator to the next entry
+ * 
+ * @param it pointer to iterator to initialize
+ * @return EOK on success or negative error code on failure
+ */
+int ext2_directory_iterator_next(ext2_directory_iterator_t *it)
+{
+        int rc;
+        uint16_t skip;
+        uint64_t size;
+        aoff64_t current_block_idx;
+        aoff64_t next_block_idx;
+        uint32_t next_block_phys_idx;
+        uint32_t block_size;
+        uint32_t offset_in_block;
+        
+        assert(it->current != NULL);
+        
+        skip = ext2_directory_entry_ll_get_entry_length(it->current);
+        size = ext2_inode_get_size(it->fs->superblock, it->inode_ref->inode);
+        
+        // Are we at the end?
+        if (it->current_offset + skip >= size) {
+                rc = block_put(it->current_block);
+                it->current_block = NULL;
+                it->current = NULL;
+                if (rc != EOK) {
+                        return rc;
+                }
+                
+                it->current_offset += skip;
+                return EOK;
+        }
+        
+        block_size = ext2_superblock_get_block_size(it->fs->superblock);
+        current_block_idx = it->current_offset / block_size;
+        next_block_idx = (it->current_offset + skip) / block_size;
+        
+        // If we are moving accross block boundary,
+        // we need to get another block
+        if (current_block_idx != next_block_idx) {
+                rc = block_put(it->current_block);
+                it->current_block = NULL;
+                it->current = NULL;
+                if (rc != EOK) {
+                        return rc;
+                }
+                
+                rc = ext2_filesystem_get_inode_data_block_index(it->fs,
+                    it->inode_ref->inode, next_block_idx, &next_block_phys_idx);
+                if (rc != EOK) {
+                        return rc;
+                }
+                
+                rc = block_get(&it->current_block, it->fs->device, next_block_phys_idx,
+                    BLOCK_FLAGS_NONE);
+                if (rc != EOK) {
+                        it->current_block = NULL;
+                        return rc;
+                }
+        }
+        
+        offset_in_block = (it->current_offset + skip) % block_size;
+        
+        // Ensure proper alignment
+        if ((offset_in_block % 4) != 0) {
+                it->current = NULL;
+                return EIO;
+        }
+        
+        // Ensure that the core of the entry does not overflow the block
+        if (offset_in_block > block_size - 8) {
+                it->current = NULL;
+                return EIO;
+        }
+                
+        it->current = it->current_block->data + offset_in_block;
+        it->current_offset += skip;
+        
+        // Ensure that the whole entry does not overflow the block
+        skip = ext2_directory_entry_ll_get_entry_length(it->current);
+        if (offset_in_block + skip > block_size) {
+                it->current = NULL;
+                return EIO;
+        }
+        
+        // Ensure the name length is not too large
+        if (ext2_directory_entry_ll_get_name_length(it->fs->superblock, 
+            it->current) > skip-8) {
+                it->current = NULL;
+                return EIO;
+        }
+        
+        return EOK;
+}
+
+/**
+ * Release all resources asociated with the directory iterator
+ * 
+ * @param it pointer to iterator to initialize
+ * @return EOK on success or negative error code on failure
+ */
+int ext2_directory_iterator_fini(ext2_directory_iterator_t *it)
+{
+        int rc;
+        
+        it->fs = NULL;
+        it->inode_ref = NULL;
+        it->current = NULL;
+        
+        if (it->current_block) {
+                rc = block_put(it->current_block);
+                if (rc != EOK) {
+                        return rc;
+                }
+        }
+        
+        return EOK;
+}
+
 /** @}
  */