Changeset 7ea69a6 in mainline for uspace/srv/fs/ext2fs/ext2fs_ops.c

Timestamp:

2011-03-23T10:40:17Z (13 years ago)

Author:

Martin Sucha <sucha14@…>

Branches:

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

Children:

6f50bb0

Parents:

f2d665b4

Message:

Support for sparse files and fixed handling of end of file

File:

• uspace/srv/fs/ext2fs/ext2fs_ops.c (modified) (5 diffs)

uspace/srv/fs/ext2fs/ext2fs_ops.c

@@ -56 +56 @@
 #include <align.h>
 #include <adt/hash_table.h>
+#include <sys/typefmt.h>
 
 #define EXT2FS_NODE(node)       ((node) ? (ext2fs_node_t *) (node)->data : NULL)
@@ -760 +761 @@
         size_t bytes;
         block_t *block;
+        uint8_t *buffer;
         
         file_size = ext2_inode_get_size(inst->filesystem->superblock,
@@ -777 +779 @@
         bytes = min(block_size - offset_in_block, size);
         
+        // Handle end of file
+        if (pos + bytes > file_size) {
+                bytes = file_size - pos;
+        }
+        
         rc = ext2_filesystem_get_inode_data_block_index(inst->filesystem,
                 inode_ref->inode, file_block, &fs_block);
@@ -785 +792 @@
         }
         
+        // Check for sparse file
+        // If ext2_filesystem_get_inode_data_block_index returned
+        // fs_block == 0, it means that the given block is not allocated for the 
+        // file and we need to return a buffer of zeros
+        if (fs_block == 0) {
+                buffer = malloc(bytes);
+                if (buffer == NULL) {
+                        async_answer_0(callid, ENOMEM);
+                        async_answer_0(rid, ENOMEM);
+                        return;
+                }
+                
+                memset(buffer, 0, bytes);
+                
+                async_data_read_finalize(callid, buffer, bytes);
+                async_answer_1(rid, EOK, bytes);
+                
+                free(buffer);
+                
+                return;
+        }
+        
+        // Usual case - we need to read a block from device
         rc = block_get(&block, inst->devmap_handle, fs_block, BLOCK_FLAGS_NONE);
         if (rc != EOK) {
@@ -792 +822 @@
         }
         
-        async_data_read_finalize(callid, block->data, bytes);
+        assert(offset_in_block + bytes <= block_size);
+        async_data_read_finalize(callid, block->data + offset_in_block, bytes);
         
         rc = block_put(block);