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os/vfs.h: add support for symlink creation

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Fixes #5162
This commit is contained in:
Christian Prochaska 2024-03-22 08:32:34 +01:00 committed by Christian Helmuth
parent 7f1adbea46
commit 2eae70d3cd
1 changed files with 70 additions and 1 deletions
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71
repos/os/include/os/vfs.h
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@ -5,7 +5,7 @@
*/
/*
* Copyright (C) 2017 Genode Labs GmbH
* Copyright (C) 2017-2024 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
@ -259,6 +259,16 @@ struct Genode::Directory : Noncopyable, Interface
return stat.type == Vfs::Node_type::DIRECTORY;
}
bool symlink_exists(Path const &rel_path) const
{
Vfs::Directory_service::Stat stat { };
if (_stat(rel_path, stat) != Vfs::Directory_service::STAT_OK)
return false;
return stat.type == Vfs::Node_type::SYMLINK;
}
/**
* Return size of file at specified directory-relative path
*
@ -328,6 +338,65 @@ struct Genode::Directory : Noncopyable, Interface
return Path(Genode::Cstring(buf, (size_t)out_count));
}
/**
* Attempt to create symlink
*
* This operation may fail. Its success can be checked by calling
* 'symlink_exists'.
*/
void create_symlink(Path const &rel_path, Path const &target)
{
using namespace Vfs;
Vfs_handle *link_handle;
auto openlink_result = _nonconst_fs().openlink(
join(_path, rel_path).string(),
true, &link_handle, _alloc);
using Openlink_result = Directory_service::Openlink_result;
if (openlink_result == Openlink_result::OPENLINK_ERR_NODE_ALREADY_EXISTS)
openlink_result = _fs.openlink(
join(_path, rel_path).string(),
false, &link_handle, _alloc);
if (openlink_result != Openlink_result::OPENLINK_OK)
return;
Vfs_handle::Guard guard(link_handle);
Const_byte_range_ptr const src { target.string(), target.length() };
size_t out_count = 0;
link_handle->fs().write(link_handle, src, out_count);
if (out_count < src.num_bytes) {
unlink(rel_path);
return;
}
/* sync before the handle gets closed */
while (!link_handle->fs().queue_sync(link_handle))
_io.commit_and_wait();
File_io_service::Sync_result result;
for (;;) {
result = link_handle->fs().complete_sync(link_handle);
if (result != File_io_service::SYNC_QUEUED)
break;
_io.commit_and_wait();
};
if (result != File_io_service::SYNC_OK) {
unlink(rel_path);
return;
}
}
void unlink(Path const &rel_path)
{
_fs.unlink(join(_path, rel_path).string());