Changeset 4e36219 in mainline

Timestamp:

2011-06-08T19:18:52Z (13 years ago)

Author:

Martin Sucha <sucha14@…>

Branches:

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

Children:

b5085a7, c028b22

Parents:

911ee54

Message:

Allow libext2 directory iterator to seek to arbitrary position

Location:

uspace

Files:

• app/ext2info/ext2info.c (modified) (1 diff)
• lib/ext2/libext2_directory.c (modified) (5 diffs)
• lib/ext2/libext2_directory.h (modified) (1 diff)
• srv/fs/ext2fs/ext2fs_ops.c (modified) (8 diffs)

uspace/app/ext2info/ext2info.c

@@ -590 +590 @@
         printf("  Directory contents:\n");
         
-        rc = ext2_directory_iterator_init(&it, fs, inode_ref);
+        rc = ext2_directory_iterator_init(&it, fs, inode_ref, 0);
         if (rc != EOK) {
                 printf("Failed initializing directory iterator\n");

uspace/lib/ext2/libext2_directory.c

@@ -86 +86 @@
  * @param fs pointer to filesystem structure
  * @param inode pointer to inode reference structure
+ * @param pos position within inode to start at, 0 is the first entry
  * @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;
-        uint32_t block_size;
-        
+    ext2_filesystem_t *fs, ext2_inode_ref_t *inode_ref, aoff64_t pos)
+{       
         it->inode_ref = inode_ref;
         it->fs = fs;
-        
-        /* Get the first data block, so we can get the 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;
-        }
-        
-        block_size = ext2_superblock_get_block_size(fs->superblock);
-        
-        it->current_offset = 0; 
-        return ext2_directory_iterator_set(it, block_size);
+        it->current = NULL;
+        it->current_offset = 0;
+        it->current_block = NULL;
+        
+        return ext2_directory_iterator_seek(it, pos);
 }
 
@@ -124 +109 @@
 int ext2_directory_iterator_next(ext2_directory_iterator_t *it)
 {
+        uint16_t skip;
+        
+        assert(it->current != NULL);
+        
+        skip = ext2_directory_entry_ll_get_entry_length(it->current);
+        
+        return ext2_directory_iterator_seek(it, it->current_offset + skip);
+}
+
+/**
+ * Seek the directory iterator to the given byte offset within the inode.
+ * 
+ * @param it pointer to iterator to initialize
+ * @return EOK on success or negative error code on failure
+ */
+int ext2_directory_iterator_seek(ext2_directory_iterator_t *it, aoff64_t pos)
+{
         int rc;
-        uint16_t skip;
+        
         uint64_t size;
         aoff64_t current_block_idx;
@@ -132 +134 @@
         uint32_t block_size;
         
-        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);
         
+        /* The iterator is not valid until we seek to the desired position */
+        it->current = NULL;
+        
         /* 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;
+        if (pos >= size) {              
+                if (it->current_block) {
+                        rc = block_put(it->current_block);
+                        it->current_block = NULL;
+                        if (rc != EOK) {
+                                return rc;
+                        }
                 }
                 
-                it->current_offset += skip;
+                it->current_offset = pos;
                 return EOK;
         }
@@ -152 +155 @@
         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,
+        next_block_idx = pos / block_size;
+        
+        /* If we don't have a block or 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;
+        if (it->current_block == NULL || current_block_idx != next_block_idx) {         
+                if (it->current_block) {
+                        rc = block_put(it->current_block);
+                        it->current_block = NULL;
+                        if (rc != EOK) {
+                                return rc;
+                        }
                 }
                 
@@ -179 +183 @@
         }
         
-        it->current_offset += skip;
+        it->current_offset = pos;
         return ext2_directory_iterator_set(it, block_size);
 }
 
+/** Setup the entry at the current iterator offset.
+ * 
+ * This function checks the validity of the directory entry,
+ * before setting the data pointer.
+ *
+ * @return EOK on success or error code on failure 
+ */
 static int ext2_directory_iterator_set(ext2_directory_iterator_t *it,
     uint32_t block_size)

uspace/lib/ext2/libext2_directory.h

@@ -71 +71 @@
 
 extern int ext2_directory_iterator_init(ext2_directory_iterator_t *,
-    ext2_filesystem_t *, ext2_inode_ref_t *);
+    ext2_filesystem_t *, ext2_inode_ref_t *, aoff64_t);
 extern int ext2_directory_iterator_next(ext2_directory_iterator_t *);
+extern int ext2_directory_iterator_seek(ext2_directory_iterator_t *, aoff64_t pos);
 extern int ext2_directory_iterator_fini(ext2_directory_iterator_t *);
 

uspace/srv/fs/ext2fs/ext2fs_ops.c

@@ -241 +241 @@
         }
         
-        rc = ext2_directory_iterator_init(&it, fs, eparent->inode_ref);
+        rc = ext2_directory_iterator_init(&it, fs, eparent->inode_ref, 0);
         if (rc != EOK) {
                 return rc;
@@ -479 +479 @@
         }
         
-        rc = ext2_directory_iterator_init(&it, fs, enode->inode_ref);
+        rc = ext2_directory_iterator_init(&it, fs, enode->inode_ref, 0);
         if (rc != EOK) {
                 EXT2FS_DBG("error %u", rc);
@@ -819 +819 @@
 {
         ext2_directory_iterator_t it;
-        aoff64_t cur;
+        aoff64_t next;
         uint8_t *buf;
         size_t name_size;
@@ -825 +825 @@
         bool found = false;
         
-        rc = ext2_directory_iterator_init(&it, inst->filesystem, inode_ref);
+        rc = ext2_directory_iterator_init(&it, inst->filesystem, inode_ref, pos);
         if (rc != EOK) {
                 async_answer_0(callid, rc);
@@ -832 +832 @@
         }
         
-        /* Find the index we want to read
-         * Note that we need to iterate and count as
-         * the underlying structure is a linked list
-         * Moreover, we want to skip . and .. entries
+        /* Find next interesting directory entry.
+         * We want to skip . and .. entries
          * as these are not used in HelenOS
          */
-        cur = 0;
         while (it.current != NULL) {
                 if (it.current->inode == 0) {
@@ -852 +849 @@
                 }
                 
-                /* Is this the dir entry we want to read? */
-                if (cur == pos) {
-                        /* The on-disk entry does not contain \0 at the end
-                         * end of entry name, so we copy it to new buffer
-                         * and add the \0 at the end
-                         */
-                        buf = malloc(name_size+1);
-                        if (buf == NULL) {
-                                ext2_directory_iterator_fini(&it);
-                                async_answer_0(callid, ENOMEM);
-                                async_answer_0(rid, ENOMEM);
-                                return;
-                        }
-                        memcpy(buf, &it.current->name, name_size);
-                        *(buf+name_size) = 0;
-                        found = true;
-                        (void) async_data_read_finalize(callid, buf, name_size+1);
-                        free(buf);
-                        break;
-                }
-                cur++;
+                /* The on-disk entry does not contain \0 at the end
+                        * end of entry name, so we copy it to new buffer
+                        * and add the \0 at the end
+                        */
+                buf = malloc(name_size+1);
+                if (buf == NULL) {
+                        ext2_directory_iterator_fini(&it);
+                        async_answer_0(callid, ENOMEM);
+                        async_answer_0(rid, ENOMEM);
+                        return;
+                }
+                memcpy(buf, &it.current->name, name_size);
+                *(buf+name_size) = 0;
+                found = true;
+                (void) async_data_read_finalize(callid, buf, name_size+1);
+                free(buf);
+                break;
                 
 skip:
@@ -884 +877 @@
         }
         
+        if (found) {
+                rc = ext2_directory_iterator_next(&it);
+                if (rc != EOK) {
+                        async_answer_0(rid, rc);
+                        return;
+                }
+                next = it.current_offset;
+        }
+        
         rc = ext2_directory_iterator_fini(&it);
         if (rc != EOK) {
@@ -891 +893 @@
         
         if (found) {
-                async_answer_1(rid, EOK, 1);
+                async_answer_1(rid, EOK, next-pos);
         }
         else {