Changeset 2b88074b in mainline for uspace/srv/vfs/vfs_file.c

Timestamp:

2009-10-29T22:06:46Z (14 years ago)

Author:

Martin Decky <martin@…>

Branches:

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

Children:

2e983c7

Parents:

14ecd6c

Message:

vfs: file descriptors housekeeping changes

• add support for allocating new file descriptors from the end of the fd range (O_DESC)
• add support for assigning of an already opened file to a free file descriptor

vfs: VFS_OUT_CLOSE is called only when the file reference count is about to drop to zero
vfs: implement VFS_IN_DUP

libc: optimize current working directory housekeeping

• using opendir() was an overkill
• allocate current working directory file descriptor from the end of the fd range using O_DESC (so it doesn't mess with the well-known descriptors 0, 1 and 2)

libc: implement dup2() (via VFS_IN_DUP)

getvc: change stdin/stdout/stderr by a slightly more elegant way (using dup2())

File:

• uspace/srv/vfs/vfs_file.c (modified) (4 diffs)

uspace/srv/vfs/vfs_file.c

@@ -76 +76 @@
 /** Allocate a file descriptor.
  *
- * @return              First available file descriptor or a negative error
- *                      code.
- */
-int vfs_fd_alloc(void)
+ * @param desc If true, look for an available file descriptor
+ *             in a descending order.
+ *
+ * @return First available file descriptor or a negative error
+ *         code.
+ */
+int vfs_fd_alloc(bool desc)
 {
         if (!vfs_files_init())
@@ -85 +88 @@
         
         unsigned int i;
-        for (i = 0; i < MAX_OPEN_FILES; i++) {
+        if (desc)
+                i = MAX_OPEN_FILES;
+        else
+                i = 0;
+        
+        while (true) {
                 if (!files[i]) {
                         files[i] = (vfs_file_t *) malloc(sizeof(vfs_file_t));
@@ -96 +104 @@
                         return (int) i;
                 }
+                
+                if (desc) {
+                        if (i == 0)
+                                break;
+                        
+                        i--;
+                } else {
+                        if (i == MAX_OPEN_FILES)
+                                break;
+                        
+                        i++;
+                }
         }
         
@@ -118 +138 @@
         vfs_file_delref(files[fd]);
         files[fd] = NULL;
+        
+        return EOK;
+}
+
+/** Assign a file to a file descriptor.
+ *
+ * @param file File to assign.
+ * @param fd   File descriptor to assign to.
+ *
+ * @return EOK on success or EINVAL if fd is an invalid or already
+ *         used file descriptor.
+ *
+ */
+int vfs_fd_assign(vfs_file_t *file, int fd)
+{
+        if (!vfs_files_init())
+                return ENOMEM;
+        
+        if ((fd < 0) || (fd >= MAX_OPEN_FILES) || (files[fd] != NULL))
+                return EINVAL;
+        
+        files[fd] = file;
+        vfs_file_addref(files[fd]);
         
         return EOK;