Changeset ed903174 in mainline for uspace/lib/libc/generic/vfs/vfs.c

Timestamp:

2010-02-10T23:51:23Z (15 years ago)

Author:

Martin Decky <martin@…>

Branches:

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

Children:

e70edd1

Parents:

b32c604f

Message:

implement support for 64bit file offsets

• the libc API is a small deviation from standard, but we have no reason to keep a strict backward compatibility with ancient code so far
  • the basic signed 64bit offset type is called off64_t
    • lseek() and fseek() take off64_t arguments (since the argument represents a relative offset)
    • ftell() returns off64_t values (since it is a wrapper of lseek())
    • vfs_seek() implementation supports negative offsets when SEEK_CUR and SEEK_END is used
  • aoff64_t is used for internal unsigned representation of sizes (in bytes, blocks, etc.) and absolute offsets
    • mmap() and ftruncate() take aoff64_t arguments (since the full range of the absolute file offset should be used here)
    • struct stat stores the file size as aoff64_t
  • in both cases the explicit range of the types shown in the names is helpful for proper filesystem and IPC interaction
  • note: size_t should be used only for representing in-memory sizes and offsets, not device and file-related information, and vice versa
    • the code base still needs a thorough revision with respect to this rule
  • PRIdOFF64 and PRIuOFF64 can be used for printing the offsets
• VFS_OUT_LOOKUP returns the 64bit file size in two IPC arguments
  • since all 5 IPC arguments have already been taken, the fs_handle is returned as the return value (fs_handle has only 16 bits, thus the return value can be used for both indicating errors as negative values and returning positive handles)
• VFS_OUT_READ and VFS_OUT_WRITE use aoff64_t absolute offsets split into two IPC arguments

replace bn_t with aoff64_t as a generic 64bit bytes/block counter type

note: filesystem drivers need to be revised with respect to make sure that all out-of-range checks are correct (especially w.r.t. file and block offsets)

File:

• uspace/lib/libc/generic/vfs/vfs.c (modified) (4 diffs)

uspace/lib/libc/generic/vfs/vfs.c

@@ -35 +35 @@
 #include <vfs/vfs.h>
 #include <vfs/canonify.h>
+#include <macros.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -434 +435 @@
 }
 
-off_t lseek(int fildes, off_t offset, int whence)
-{
-        ipcarg_t rc;
-
-        futex_down(&vfs_phone_futex);
-        async_serialize_start();
-        vfs_connect();
-        
-        ipcarg_t newoffs;
-        rc = async_req_3_1(vfs_phone, VFS_IN_SEEK, fildes, offset, whence,
-            &newoffs);
-
-        async_serialize_end();
-        futex_up(&vfs_phone_futex);
-
+off64_t lseek(int fildes, off64_t offset, int whence)
+{
+        futex_down(&vfs_phone_futex);
+        async_serialize_start();
+        vfs_connect();
+        
+        ipcarg_t newoff_lo;
+        ipcarg_t newoff_hi;
+        ipcarg_t rc = async_req_4_2(vfs_phone, VFS_IN_SEEK, fildes,
+            LOWER32(offset), UPPER32(offset), whence,
+            &newoff_lo, &newoff_hi);
+        
+        async_serialize_end();
+        futex_up(&vfs_phone_futex);
+        
         if (rc != EOK)
-                return (off_t) -1;
-        
-        return (off_t) newoffs;
-}
-
-int ftruncate(int fildes, off_t length)
-{
-        ipcarg_t rc;
-        
-        futex_down(&vfs_phone_futex);
-        async_serialize_start();
-        vfs_connect();
-        
-        rc = async_req_2_0(vfs_phone, VFS_IN_TRUNCATE, fildes, length);
-        async_serialize_end();
-        futex_up(&vfs_phone_futex);
+                return (off64_t) -1;
+        
+        return (off64_t) MERGE_LOUP32(newoff_lo, newoff_hi);
+}
+
+int ftruncate(int fildes, aoff64_t length)
+{
+        ipcarg_t rc;
+        
+        futex_down(&vfs_phone_futex);
+        async_serialize_start();
+        vfs_connect();
+        
+        rc = async_req_3_0(vfs_phone, VFS_IN_TRUNCATE, fildes,
+            LOWER32(length), UPPER32(length));
+        async_serialize_end();
+        futex_up(&vfs_phone_futex);
+        
         return (int) rc;
 }
@@ -479 +482 @@
         
         req = async_send_1(vfs_phone, VFS_IN_FSTAT, fildes, NULL);
-        rc = async_data_read_start(vfs_phone, (void *)stat, sizeof(struct stat));
+        rc = async_data_read_start(vfs_phone, (void *) stat, sizeof(struct stat));
         if (rc != EOK) {
                 ipcarg_t rc_orig;
@@ -553 +556 @@
         if (!abs) {
                 free(dirp);
-                return ENOMEM;
+                return NULL;
         }