733 lines
16 KiB
C++
733 lines
16 KiB
C++
/*
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* \brief Embedded RAM VFS
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* \author Emery Hemingway
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* \date 2015-07-21
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*/
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/*
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* Copyright (C) 2015 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU General Public License version 2.
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*/
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#ifndef _INCLUDE__VFS__RAM_FILE_SYSTEM_H_
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#define _INCLUDE__VFS__RAM_FILE_SYSTEM_H_
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#include <ram_fs/chunk.h>
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#include <vfs/file_system.h>
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#include <dataspace/client.h>
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#include <util/avl_tree.h>
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namespace Vfs_ram {
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using namespace Genode;
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using namespace Vfs;
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class Node;
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class File;
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class Symlink;
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class Directory;
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enum { MAX_NAME_LEN = 128 };
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/**
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* Return base-name portion of null-terminated path string
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*/
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static inline char const *basename(char const *path)
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{
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char const *start = path;
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for (; *path; ++path)
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if (*path == '/')
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start = path + 1;
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return start;
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}
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}
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namespace Vfs { class Ram_file_system; }
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class Vfs_ram::Node : public Genode::Avl_node<Node>, public Genode::Lock
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{
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private:
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char _name[MAX_NAME_LEN];
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unsigned long const _inode;
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/**
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* Generate unique inode number
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*
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* XXX: these inodes could clash with other VFS plugins
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*/
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static unsigned long _unique_inode()
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{
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static unsigned long inode_count;
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return ++inode_count;
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}
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public:
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Node(char const *node_name)
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: _inode(_unique_inode()) { name(node_name); }
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virtual ~Node() { }
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unsigned long inode() const { return _inode; }
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char const *name() { return _name; }
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void name(char const *name) { strncpy(_name, name, MAX_NAME_LEN); }
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virtual Vfs::file_size length() = 0;
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/************************
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** Avl node interface **
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************************/
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bool higher(Node *c) { return (strcmp(c->_name, _name) > 0); }
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/**
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* Find index N by walking down the tree N times,
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* not the most efficient way to do this.
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*/
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Node *index(file_offset &i)
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{
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if (i-- == 0)
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return this;
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Node *n;
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n = child(LEFT);
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if (n)
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n = n->index(i);
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if (n) return n;
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n = child(RIGHT);
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if (n)
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n = n->index(i);
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return n;
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}
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Node *sibling(const char *name)
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{
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if (strcmp(name, _name) == 0) return this;
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Node *c =
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Avl_node<Node>::child(strcmp(name, _name) > 0);
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return c ? c->sibling(name) : 0;
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}
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struct Guard
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{
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Node *node;
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Guard(Node *guard_node) : node(guard_node) { node->lock(); }
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~Guard() { node->unlock(); }
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};
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};
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class Vfs_ram::File : public Vfs_ram::Node
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{
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private:
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typedef ::File_system::Chunk<4096> Chunk_level_3;
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typedef ::File_system::Chunk_index<128, Chunk_level_3> Chunk_level_2;
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typedef ::File_system::Chunk_index<64, Chunk_level_2> Chunk_level_1;
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typedef ::File_system::Chunk_index<64, Chunk_level_1> Chunk_level_0;
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Chunk_level_0 _chunk;
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file_size _length = 0;
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public:
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File(char const *name, Allocator &alloc)
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: Node(name), _chunk(alloc, 0) { }
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size_t read(char *dst, size_t len, file_size seek_offset)
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{
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file_size const chunk_used_size = _chunk.used_size();
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if (seek_offset >= _length)
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return 0;
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/*
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* Constrain read transaction to available chunk data
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*
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* Note that 'chunk_used_size' may be lower than '_length'
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* because 'Chunk' may have truncated tailing zeros.
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*/
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if (seek_offset + len >= _length)
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len = _length - seek_offset;
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file_size read_len = len;
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if (seek_offset + read_len > chunk_used_size) {
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if (chunk_used_size >= seek_offset)
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read_len = chunk_used_size - seek_offset;
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else
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read_len = 0;
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}
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_chunk.read(dst, read_len, seek_offset);
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/* add zero padding if needed */
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if (read_len < len)
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memset(dst + read_len, 0, len - read_len);
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return len;
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}
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size_t write(char const *src, size_t len, file_size seek_offset)
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{
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if (seek_offset == (file_size)(~0))
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seek_offset = _chunk.used_size();
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if (seek_offset + len >= Chunk_level_0::SIZE)
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len = Chunk_level_0::SIZE - (seek_offset + len);
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_chunk.write(src, len, (size_t)seek_offset);
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/*
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* Keep track of file length. We cannot use 'chunk.used_size()'
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* as file length because trailing zeros may by represented
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* by zero chunks, which do not contribute to 'used_size()'.
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*/
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_length = max(_length, seek_offset + len);
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return len;
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}
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file_size length() { return _length; }
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void truncate(file_size size)
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{
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if (size < _chunk.used_size())
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_chunk.truncate(size);
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_length = size;
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}
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};
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class Vfs_ram::Symlink : public Vfs_ram::Node
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{
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private:
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char _target[MAX_PATH_LEN];
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size_t _len = 0;
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public:
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Symlink(char const *name) : Node(name) { }
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file_size length() { return _len; }
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void set(char const *target, size_t len)
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{
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_len = min(len, MAX_PATH_LEN);
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memcpy(_target, target, _len);
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}
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size_t get(char *buf, size_t len)
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{
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size_t out = min(len, _len);
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memcpy(buf, _target, out);
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return out;
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}
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};
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class Vfs_ram::Directory : public Vfs_ram::Node
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{
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private:
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Avl_tree<Node> _entries;
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file_size _count = 0;
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public:
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Directory(char const *name) : Node(name) { }
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~Directory()
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{
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while (Node *node = _entries.first()) {
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_entries.remove(node);
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destroy(env()->heap(), node);
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}
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}
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void adopt(Node *node)
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{
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_entries.insert(node);
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++_count;
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}
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Node *child(char const *name)
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{
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Node *node = _entries.first();
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return node ? node->sibling(name) : 0;
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}
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void release(Node *node)
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{
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_entries.remove(node);
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--_count;
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}
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file_size length() override { return _count; }
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void dirent(file_offset index, Directory_service::Dirent &dirent)
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{
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dirent.fileno = index+1;
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dirent.type = Directory_service::DIRENT_TYPE_END;
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dirent.name[0] = '\0';
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Node *node = _entries.first();
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if (node) {
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node = node->index(index);
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if (!node) return;
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strncpy(dirent.name, node->name(), sizeof(dirent.name));
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File *file = dynamic_cast<File *>(node);
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if (file) {
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dirent.type = Directory_service::DIRENT_TYPE_FILE;
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return;
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}
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Directory *dir = dynamic_cast<Directory *>(node);
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if (dir) {
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dirent.type = Directory_service::DIRENT_TYPE_DIRECTORY;
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return;
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}
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Symlink *symlink = dynamic_cast<Symlink *>(node);
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if (symlink) {
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dirent.type = Directory_service::DIRENT_TYPE_SYMLINK;
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}
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}
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}
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};
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class Vfs::Ram_file_system : public Vfs::File_system
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{
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private:
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class Ram_vfs_handle : public Vfs_handle
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{
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private:
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Vfs_ram::File *_file;
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public:
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Ram_vfs_handle(File_system &fs, int status_flags, Vfs_ram::File *file)
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: Vfs_handle(fs, fs, status_flags), _file(file)
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{ }
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Vfs_ram::File *file() const { return _file; }
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};
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Genode::Allocator &_alloc;
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Vfs_ram::Directory _root;
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Vfs_ram::Node *lookup(char const *path, bool return_parent = false)
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{
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using namespace Vfs_ram;
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if (*path == '/') ++path;
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if (*path == '\0') return &_root;
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char buf[Vfs::MAX_PATH_LEN];
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strncpy(buf, path, Vfs::MAX_PATH_LEN);
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Directory *dir = &_root;
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char *name = &buf[0];
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for (size_t i = 0; i < MAX_PATH_LEN; ++i) {
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if (buf[i] == '/') {
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buf[i] = '\0';
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Node *node = dir->child(name);
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if (!node) return 0;
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dir = dynamic_cast<Directory *>(node);
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if (!dir) return 0;
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/* set the current name aside */
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name = &buf[i+1];
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} else if (buf[i] == '\0') {
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if (return_parent)
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return dir;
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else
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return dir->child(name);
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}
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}
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return 0;
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}
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Vfs_ram::Directory *lookup_parent(char const *path)
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{
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using namespace Vfs_ram;
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Node *node = lookup(path, true);
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if (node)
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return dynamic_cast<Directory *>(node);
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return 0;
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}
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public:
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Ram_file_system(Xml_node config)
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: _alloc(*env()->heap()), _root("") { }
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/*********************************
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** Directory service interface **
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*********************************/
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file_size num_dirent(char const *path) override
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{
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using namespace Vfs_ram;
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if (Node *node = lookup(path)) {
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Node::Guard guard(node);
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if (Directory *dir = dynamic_cast<Directory *>(node))
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return dir->length();
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}
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return 0;
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}
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bool is_directory(char const *path)
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{
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using namespace Vfs_ram;
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Node *node = lookup(path);
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return node ? dynamic_cast<Directory *>(node) : 0;
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}
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char const *leaf_path(char const *path) {
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return lookup(path) ? path : 0; }
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Mkdir_result mkdir(char const *path, unsigned mode) override
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{
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using namespace Vfs_ram;
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Directory *parent = lookup_parent(path);
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if (!parent) return MKDIR_ERR_NO_ENTRY;
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Node::Guard guard(parent);
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char const *name = basename(path);
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if (strlen(name) >= MAX_NAME_LEN)
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return MKDIR_ERR_NAME_TOO_LONG;
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if (parent->child(name)) return MKDIR_ERR_EXISTS;
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parent->adopt(new (_alloc) Directory(name));
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return MKDIR_OK;
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}
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Open_result open(char const *path, unsigned mode, Vfs_handle **handle) override
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{
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using namespace Vfs_ram;
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File *file;
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char const *name = basename(path);
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if (mode & OPEN_MODE_CREATE) {
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Directory *parent = lookup_parent(path);
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Node::Guard guard(parent);
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if (!parent) return OPEN_ERR_UNACCESSIBLE;
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if (parent->child(name)) return OPEN_ERR_EXISTS;
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if (strlen(name) >= MAX_NAME_LEN)
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return OPEN_ERR_NAME_TOO_LONG;
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file = new (_alloc) File(name, _alloc);
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parent->adopt(file);
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} else {
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Node *node = lookup(path);
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if (!node) return OPEN_ERR_UNACCESSIBLE;
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file = dynamic_cast<File *>(node);
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if (!file) return OPEN_ERR_UNACCESSIBLE;
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}
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/* allocate handle on the heap */
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*handle = new (env()->heap()) Ram_vfs_handle(*this, mode, file);
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return OPEN_OK;
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}
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Stat_result stat(char const *path, Stat &stat) override
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{
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using namespace Vfs_ram;
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Node *node = lookup(path);
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if (!node) return STAT_ERR_NO_ENTRY;
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Node::Guard guard(node);
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stat.inode = node->inode();
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stat.size = node->length();
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File *file = dynamic_cast<File *>(node);
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if (file) {
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stat.mode = STAT_MODE_FILE | 0777;
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return STAT_OK;
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}
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Directory *dir = dynamic_cast<Directory *>(node);
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if (dir) {
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stat.mode = STAT_MODE_DIRECTORY | 0777;
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return STAT_OK;
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}
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Symlink *symlink = dynamic_cast<Symlink *>(node);
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if (symlink) {
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stat.mode = STAT_MODE_SYMLINK | 0777;
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return STAT_OK;
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}
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/* this should never happen */
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return STAT_ERR_NO_ENTRY;
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}
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Dirent_result dirent(char const *path, file_offset index, Dirent &dirent) override
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{
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using namespace Vfs_ram;
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Node *node = lookup(path);
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if (!node) return DIRENT_ERR_INVALID_PATH;
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Node::Guard guard(node);
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Directory *dir = dynamic_cast<Directory *>(node);
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if (!dir) return DIRENT_ERR_INVALID_PATH;
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dir->dirent(index, dirent);
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return DIRENT_OK;
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}
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Symlink_result symlink(char const *target, char const *path) override
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{
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using namespace Vfs_ram;
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Symlink *link;
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Directory *parent = lookup_parent(path);
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if (!parent) return SYMLINK_ERR_NO_ENTRY;
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Node::Guard guard(parent);
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char const *name = basename(path);
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Node *node = parent->child(name);
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if (node) {
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node->lock();
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link = dynamic_cast<Symlink *>(node);
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if (!link) {
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node->unlock();
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return SYMLINK_ERR_EXISTS;
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}
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} else {
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if (strlen(name) >= MAX_NAME_LEN)
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return SYMLINK_ERR_NAME_TOO_LONG;
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link = new (_alloc) Symlink(name);
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link->lock();
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parent->adopt(link);
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}
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if (*target)
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link->set(target, strlen(target));
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link->unlock();
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return SYMLINK_OK;
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}
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Readlink_result readlink(char const *path, char *buf,
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file_size buf_size, file_size &out_len) override
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{
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using namespace Vfs_ram;
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Directory *parent = lookup_parent(path);
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if (!parent)
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return READLINK_ERR_NO_ENTRY;
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Node::Guard parent_guard(parent);
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Node *node = parent->child(basename(path));
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if (!node) return READLINK_ERR_NO_ENTRY;
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Node::Guard guard(node);
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Symlink *link = dynamic_cast<Symlink *>(node);
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if (!link) return READLINK_ERR_NO_ENTRY;
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out_len = link->get(buf, buf_size);
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return READLINK_OK;
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}
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Rename_result rename(char const *from, char const *to) override
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{
|
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using namespace Vfs_ram;
|
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if ((strcmp(from, to) == 0) && lookup(from))
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return RENAME_OK;
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char const *new_name = basename(to);
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if (strlen(new_name) >= MAX_NAME_LEN)
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return RENAME_ERR_NO_PERM;
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Directory *from_dir = lookup_parent(from);
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if (!from_dir) return RENAME_ERR_NO_ENTRY;
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Node::Guard from_guard(from_dir);
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Directory *to_dir = lookup_parent(to);
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if (!to_dir) return RENAME_ERR_NO_ENTRY;
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|
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/* unlock the node so a second guard can be constructed */
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if (from_dir == to_dir)
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from_dir->unlock();
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|
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Node::Guard to_guard(to_dir);
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Node *from_node = from_dir->child(basename(from));
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if (!from_node) return RENAME_ERR_NO_ENTRY;
|
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Node::Guard guard(from_node);
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|
|
Node *to_node = to_dir->child(new_name);
|
|
if (to_node) {
|
|
to_node->lock();
|
|
|
|
if (Directory *dir = dynamic_cast<Directory*>(to_node))
|
|
if (dir->length() || (!dynamic_cast<Directory*>(from_node)))
|
|
return RENAME_ERR_NO_PERM;
|
|
|
|
to_dir->release(to_node);
|
|
destroy(_alloc, to_node);
|
|
}
|
|
|
|
from_dir->release(from_node);
|
|
from_node->name(new_name);
|
|
to_dir->adopt(from_node);
|
|
|
|
return RENAME_OK;
|
|
}
|
|
|
|
Unlink_result unlink(char const *path) override
|
|
{
|
|
using namespace Vfs_ram;
|
|
|
|
Directory *parent = lookup_parent(path);
|
|
if (!parent) return UNLINK_ERR_NO_ENTRY;
|
|
Node::Guard guard(parent);
|
|
|
|
Node *node = parent->child(basename(path));
|
|
if (!node) return UNLINK_ERR_NO_ENTRY;
|
|
|
|
node->lock();
|
|
parent->release(node);
|
|
destroy(_alloc, node);
|
|
return UNLINK_OK;
|
|
}
|
|
|
|
Dataspace_capability dataspace(char const *path) override
|
|
{
|
|
using namespace Vfs_ram;
|
|
|
|
Ram_dataspace_capability ds_cap;
|
|
|
|
Node *node = lookup(path);
|
|
if (!node) return ds_cap;
|
|
Node::Guard guard(node);
|
|
|
|
File *file = dynamic_cast<File *>(node);
|
|
if (!file) return ds_cap;
|
|
|
|
size_t len = file->length();
|
|
|
|
char *local_addr = nullptr;
|
|
try {
|
|
ds_cap = env()->ram_session()->alloc(len);
|
|
|
|
local_addr = env()->rm_session()->attach(ds_cap);
|
|
file->read(local_addr, file->length(), 0);
|
|
env()->rm_session()->detach(local_addr);
|
|
|
|
} catch(...) {
|
|
env()->rm_session()->detach(local_addr);
|
|
env()->ram_session()->free(ds_cap);
|
|
return Dataspace_capability();
|
|
}
|
|
return ds_cap;
|
|
}
|
|
|
|
void release(char const *path, Dataspace_capability ds_cap) override {
|
|
env()->ram_session()->free(
|
|
static_cap_cast<Genode::Ram_dataspace>(ds_cap)); }
|
|
|
|
|
|
/************************
|
|
** File I/O interface **
|
|
************************/
|
|
|
|
Write_result write(Vfs_handle *vfs_handle,
|
|
char const *buf, file_size len,
|
|
Vfs::file_size &out) override
|
|
{
|
|
if (!(vfs_handle->status_flags() & (OPEN_MODE_WRONLY|OPEN_MODE_RDWR)))
|
|
return WRITE_ERR_INVALID;
|
|
|
|
Ram_vfs_handle const *handle =
|
|
static_cast<Ram_vfs_handle *>(vfs_handle);
|
|
|
|
Vfs_ram::Node::Guard guard(handle->file());
|
|
out = handle->file()->write(buf, len, handle->seek());
|
|
|
|
return WRITE_OK;
|
|
}
|
|
|
|
Read_result read(Vfs_handle *vfs_handle,
|
|
char *buf, file_size len,
|
|
file_size &out) override
|
|
{
|
|
if ((vfs_handle->status_flags() & OPEN_MODE_ACCMODE) == OPEN_MODE_WRONLY)
|
|
return READ_ERR_INVALID;
|
|
|
|
Ram_vfs_handle const *handle =
|
|
static_cast<Ram_vfs_handle *>(vfs_handle);
|
|
|
|
Vfs_ram::Node::Guard guard(handle->file());
|
|
|
|
out = handle->file()->read(buf, len, handle->seek());
|
|
return READ_OK;
|
|
}
|
|
|
|
Ftruncate_result ftruncate(Vfs_handle *vfs_handle, file_size len) override
|
|
{
|
|
if (!(vfs_handle->status_flags() & (OPEN_MODE_WRONLY|OPEN_MODE_RDWR)))
|
|
return FTRUNCATE_ERR_NO_PERM;
|
|
|
|
Ram_vfs_handle const *handle =
|
|
static_cast<Ram_vfs_handle *>(vfs_handle);
|
|
|
|
Vfs_ram::Node::Guard guard(handle->file());
|
|
handle->file()->truncate(len);
|
|
return FTRUNCATE_OK;
|
|
}
|
|
|
|
|
|
/***************************
|
|
** File_system interface **
|
|
***************************/
|
|
|
|
static char const *name() { return "ram"; }
|
|
};
|
|
|
|
#endif /* _INCLUDE__VFS__RAM_FILE_SYSTEM_H_ */
|