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vfs: handle root directory explicitly

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This makes '/' and the actual root of VFS distinguishable. A VFS root
may contain one ore more '/' entries for each file system. 'opendir' for
the VFS root opens all file systems via 'open_composite_dir', while
'opendir' for '/' only returns a VFS handle.

Fixes #2569
This commit is contained in:
Sebastian Sumpf 2017-11-20 10:21:38 +01:00 committed by Christian Helmuth
parent 66d5954fc5
commit 9c852c750a
7 changed files with 68 additions and 29 deletions
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2
repos/libports/src/lib/libc/task.cc
View File

@ -97,7 +97,7 @@ class Libc::Env_implementation : public Libc::Env
:
_env(env), _file_system_factory(alloc),
_vfs(_env, alloc, _vfs_config(), io_response_handler,
_file_system_factory)
_file_system_factory, Vfs::Dir_file_system::Root())
{ }

72
repos/os/include/vfs/dir_file_system.h
View File

@ -30,8 +30,17 @@ class Vfs::Dir_file_system : public File_system
enum { MAX_NAME_LEN = 128 };
struct Root { };
private:
/**
* This instance is the root of VFS
*
* Additionally, the root has an empty _name.
*/
bool _vfs_root;
struct Dir_vfs_handle : Vfs_handle
{
struct Subdir_handle_element;
@ -92,7 +101,10 @@ class Vfs::Dir_file_system : public File_system
*/
char _name[MAX_NAME_LEN];
bool _root() const { return _name[0] == 0; }
/**
* Returns if path corresponds to top directory of file system
*/
bool _top_dir(char const *path) const { return strcmp(path, "/") == 0; }
/**
* Perform operation on a file system
@ -165,10 +177,10 @@ class Vfs::Dir_file_system : public File_system
char const *_sub_path(char const *path) const
{
/* do not strip anything from the path when we are root */
if (_root())
if (_vfs_root)
return path;
if (strcmp(path, "/") == 0)
if (_top_dir(path))
return path;
/* skip heading slash in path if present */
@ -248,6 +260,9 @@ class Vfs::Dir_file_system : public File_system
result = vfs_handle.fs().queue_read(&vfs_handle, sizeof(Dirent));
}
/* adjust base index for next file system */
base += fs_num_dirent;
};
dir_vfs_handle->subdir_handle_registry.for_each(f);
@ -297,6 +312,7 @@ class Vfs::Dir_file_system : public File_system
Io_response_handler &io_handler,
File_system_factory &fs_factory)
:
_vfs_root(false),
_first_file_system(0)
{
using namespace Genode;
@ -337,6 +353,15 @@ class Vfs::Dir_file_system : public File_system
}
}
Dir_file_system(Genode::Env &env,
Genode::Allocator &alloc,
Genode::Xml_node node,
Io_response_handler &io_handler,
File_system_factory &fs_factory,
Dir_file_system::Root)
:
Dir_file_system(env, alloc, node, io_handler, fs_factory)
{ _vfs_root = true; }
/*********************************
** Directory-service interface **
@ -384,7 +409,7 @@ class Vfs::Dir_file_system : public File_system
* If path equals directory name, return information about the
* current directory.
*/
if (strlen(path) == 0 || (strcmp(path, "/") == 0)) {
if (strlen(path) == 0 || _top_dir(path)) {
out.size = 0;
out.mode = STAT_MODE_DIRECTORY | 0755;
out.uid = 0;
@ -415,12 +440,12 @@ class Vfs::Dir_file_system : public File_system
file_size num_dirent(char const *path) override
{
if (_root()) {
if (_vfs_root) {
return _sum_dirents_of_file_systems(path);
} else {
if (strcmp(path, "/") == 0)
if (_top_dir(path))
return 1;
/*
@ -444,7 +469,7 @@ class Vfs::Dir_file_system : public File_system
*/
bool directory(char const *path) override
{
if (strcmp(path, "/") == 0)
if (_top_dir(path))
return true;
path = _sub_path(path);
@ -544,9 +569,8 @@ class Vfs::Dir_file_system : public File_system
Opendir_result open_composite_dirs(char const *sub_path,
Dir_vfs_handle &dir_vfs_handle)
{
Opendir_result result = OPENDIR_OK;
try {
for (File_system *fs = _first_file_system; (fs && result == OPENDIR_OK); fs = fs->next) {
for (File_system *fs = _first_file_system; fs; fs = fs->next) {
Vfs_handle *sub_dir_handle = nullptr;
Opendir_result r = fs->opendir(
@ -556,9 +580,7 @@ class Vfs::Dir_file_system : public File_system
case OPENDIR_OK:
break;
case OPENDIR_ERR_LOOKUP_FAILED:
continue;
default:
result = r; /* loop will break */
continue;
}
@ -569,7 +591,8 @@ class Vfs::Dir_file_system : public File_system
}
catch (Genode::Out_of_ram) { return OPENDIR_ERR_OUT_OF_RAM; }
catch (Genode::Out_of_caps) { return OPENDIR_ERR_OUT_OF_CAPS; }
return result;
return OPENDIR_OK;
}
Opendir_result opendir(char const *path, bool create,
@ -577,13 +600,22 @@ class Vfs::Dir_file_system : public File_system
{
Opendir_result result = OPENDIR_OK;
/* path equals "/" (for reading the name of this directory) */
if (strcmp(path, "/") == 0) {
if (_top_dir(path)) {
if (create)
return OPENDIR_ERR_PERMISSION_DENIED;
/*
* opendir with '/' (called from 'open_composite_dirs' returns handle
* only, VFS root additionally calls 'open_composite_dirs' in order to
* open its file systems
*/
Dir_vfs_handle *root_handle = new (alloc)
Dir_vfs_handle(*this, *this, alloc, path);
/* the VFS root may contain more file systems */
if (_vfs_root)
result = open_composite_dirs("/", *root_handle);
if (result == OPENDIR_OK) {
*out_handle = root_handle;
} else {
@ -622,6 +654,10 @@ class Vfs::Dir_file_system : public File_system
Dir_vfs_handle *dir_vfs_handle = new (alloc)
Dir_vfs_handle(*this, *this, alloc, path);
/* path equals "/" (for reading the name of this directory) */
if (strlen(sub_path) == 0)
sub_path = "/";
result = open_composite_dirs(sub_path, *dir_vfs_handle);
if (result == OPENDIR_OK) {
*out_handle = dir_vfs_handle;
@ -740,10 +776,10 @@ class Vfs::Dir_file_system : public File_system
Dir_vfs_handle *dir_vfs_handle =
static_cast<Dir_vfs_handle*>(vfs_handle);
if (_root())
if (_vfs_root)
return _queue_read_of_file_systems(dir_vfs_handle);
if (strcmp(dir_vfs_handle->path.base(), "/") == 0)
if (_top_dir(dir_vfs_handle->path.base()))
return true;
return _queue_read_of_file_systems(dir_vfs_handle);
@ -761,10 +797,10 @@ class Vfs::Dir_file_system : public File_system
Dir_vfs_handle *dir_vfs_handle =
static_cast<Dir_vfs_handle*>(vfs_handle);
if (_root())
if (_vfs_root)
return _complete_read_of_file_systems(dir_vfs_handle, dst, count, out_count);
if (strcmp(dir_vfs_handle->path.base(), "/") == 0) {
if (_top_dir(dir_vfs_handle->path.base())) {
Dirent *dirent = (Dirent*)dst;
file_offset index = vfs_handle->seek() / sizeof(Dirent);

2
repos/os/src/app/cli_monitor/main.cc
View File

@ -157,7 +157,7 @@ struct Cli_monitor::Main
/* initialize virtual file system */
Vfs::Dir_file_system _root_dir { _env, _heap, _vfs_config(), io_response_handler,
_global_file_system_factory };
_global_file_system_factory, Vfs::Dir_file_system::Root() };
Subsystem_config_registry _subsystem_config_registry { _root_dir, _heap, _env.ep() };

3
repos/os/src/server/fs_report/main.cc
View File

@ -202,7 +202,8 @@ class Fs_report::Root : public Genode::Root_component<Session_component>
Vfs::Dir_file_system _vfs {
_env, _heap, vfs_config(),
_io_response_handler,
_global_file_system_factory };
_global_file_system_factory,
Vfs::Dir_file_system::Root() };
Genode::Signal_handler<Root> _config_dispatcher {
_env.ep(), *this, &Root::_config_update };

2
repos/os/src/server/vfs/main.cc
View File

@ -678,7 +678,7 @@ class Vfs_server::Root :
Vfs::Dir_file_system _vfs {
_env, _vfs_heap, vfs_config(), _io_response_handler,
_global_file_system_factory };
_global_file_system_factory, Vfs::Dir_file_system::Root() };
Genode::Signal_handler<Root> _config_handler {
_env.ep(), *this, &Root::_config_update };

3
repos/os/src/test/vfs_stress/main.cc
View File

@ -533,7 +533,8 @@ void Component::construct(Genode::Env &env)
Vfs::Dir_file_system vfs_root(env, heap, config_xml.sub_node("vfs"),
io_response_handler,
global_file_system_factory);
global_file_system_factory,
Vfs::Dir_file_system::Root());
Vfs::Vfs_handle *vfs_root_handle;
vfs_root.opendir("/", false, &vfs_root_handle, heap);

3
repos/ports/src/noux/main.cc
View File

@ -237,7 +237,8 @@ struct Noux::Main
Vfs::Dir_file_system _root_dir { _env, _heap, _config.xml().sub_node("fstab"),
_io_response_handler,
_global_file_system_factory };
_global_file_system_factory,
Vfs::Dir_file_system::Root() };
Vfs_handle_context _vfs_handle_context;