mpd/src/db/update/InotifyUpdate.cxx

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/*
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* Copyright 2003-2017 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
#include "config.h" /* must be first for large file support */
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#include "InotifyUpdate.hxx"
#include "InotifySource.hxx"
#include "InotifyQueue.hxx"
#include "InotifyDomain.hxx"
#include "storage/StorageInterface.hxx"
#include "fs/AllocatedPath.hxx"
#include "fs/FileInfo.hxx"
#include "Log.hxx"
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#include <string>
#include <map>
#include <forward_list>
#include <assert.h>
#include <sys/inotify.h>
#include <string.h>
#include <dirent.h>
static constexpr unsigned IN_MASK =
#ifdef IN_ONLYDIR
IN_ONLYDIR|
#endif
IN_ATTRIB|IN_CLOSE_WRITE|IN_CREATE|IN_DELETE|IN_DELETE_SELF
|IN_MOVE|IN_MOVE_SELF;
struct WatchDirectory {
WatchDirectory *parent;
AllocatedPath name;
int descriptor;
std::forward_list<WatchDirectory> children;
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template<typename N>
WatchDirectory(WatchDirectory *_parent, N &&_name,
int _descriptor)
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:parent(_parent), name(std::forward<N>(_name)),
descriptor(_descriptor) {}
WatchDirectory(const WatchDirectory &) = delete;
WatchDirectory &operator=(const WatchDirectory &) = delete;
gcc_pure
unsigned GetDepth() const noexcept;
gcc_pure
AllocatedPath GetUriFS() const noexcept;
};
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static InotifySource *inotify_source;
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static InotifyQueue *inotify_queue;
static unsigned inotify_max_depth;
static WatchDirectory *inotify_root;
static std::map<int, WatchDirectory *> inotify_directories;
static void
tree_add_watch_directory(WatchDirectory *directory)
{
inotify_directories.insert(std::make_pair(directory->descriptor,
directory));
}
static void
tree_remove_watch_directory(WatchDirectory *directory)
{
auto i = inotify_directories.find(directory->descriptor);
assert(i != inotify_directories.end());
inotify_directories.erase(i);
}
static WatchDirectory *
tree_find_watch_directory(int wd)
{
auto i = inotify_directories.find(wd);
if (i == inotify_directories.end())
return nullptr;
return i->second;
}
static void
disable_watch_directory(WatchDirectory &directory)
{
tree_remove_watch_directory(&directory);
for (WatchDirectory &child : directory.children)
disable_watch_directory(child);
inotify_source->Remove(directory.descriptor);
}
static void
remove_watch_directory(WatchDirectory *directory)
{
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assert(directory != nullptr);
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if (directory->parent == nullptr) {
LogWarning(inotify_domain,
"music directory was removed - "
"cannot continue to watch it");
return;
}
disable_watch_directory(*directory);
/* remove it from the parent, which effectively deletes it */
directory->parent->children.remove_if([directory](const WatchDirectory &child){
return &child == directory;
});
}
AllocatedPath
WatchDirectory::GetUriFS() const noexcept
{
if (parent == nullptr)
return nullptr;
const auto uri = parent->GetUriFS();
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if (uri.IsNull())
return name;
return AllocatedPath::Build(uri, name);
}
/* we don't look at "." / ".." nor files with newlines in their name */
static bool skip_path(const char *path)
{
return (path[0] == '.' && path[1] == 0) ||
(path[0] == '.' && path[1] == '.' && path[2] == 0) ||
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strchr(path, '\n') != nullptr;
}
static void
recursive_watch_subdirectories(WatchDirectory *directory,
const AllocatedPath &path_fs, unsigned depth)
{
DIR *dir;
struct dirent *ent;
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assert(directory != nullptr);
assert(depth <= inotify_max_depth);
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assert(!path_fs.IsNull());
++depth;
if (depth > inotify_max_depth)
return;
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dir = opendir(path_fs.c_str());
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if (dir == nullptr) {
FormatErrno(inotify_domain,
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"Failed to open directory %s", path_fs.c_str());
return;
}
while ((ent = readdir(dir))) {
int ret;
if (skip_path(ent->d_name))
continue;
const auto child_path_fs =
AllocatedPath::Build(path_fs, ent->d_name);
FileInfo fi;
try {
fi = FileInfo(child_path_fs);
} catch (...) {
LogError(std::current_exception());
continue;
}
if (!fi.IsDirectory())
continue;
try {
ret = inotify_source->Add(child_path_fs.c_str(),
IN_MASK);
} catch (...) {
FormatError(std::current_exception(),
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"Failed to register %s",
child_path_fs.c_str());
continue;
}
WatchDirectory *child = tree_find_watch_directory(ret);
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if (child != nullptr)
/* already being watched */
continue;
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directory->children.emplace_front(directory,
AllocatedPath::FromFS(ent->d_name),
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ret);
child = &directory->children.front();
tree_add_watch_directory(child);
recursive_watch_subdirectories(child, child_path_fs, depth);
}
closedir(dir);
}
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gcc_pure
unsigned
WatchDirectory::GetDepth() const noexcept
{
const WatchDirectory *d = this;
unsigned depth = 0;
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while ((d = d->parent) != nullptr)
++depth;
return depth;
}
static void
mpd_inotify_callback(int wd, unsigned mask,
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gcc_unused const char *name, gcc_unused void *ctx)
{
WatchDirectory *directory;
/*FormatDebug(inotify_domain, "wd=%d mask=0x%x name='%s'", wd, mask, name);*/
directory = tree_find_watch_directory(wd);
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if (directory == nullptr)
return;
const auto uri_fs = directory->GetUriFS();
if ((mask & (IN_DELETE_SELF|IN_MOVE_SELF)) != 0) {
remove_watch_directory(directory);
return;
}
if ((mask & (IN_ATTRIB|IN_CREATE|IN_MOVE)) != 0 &&
(mask & IN_ISDIR) != 0) {
/* a sub directory was changed: register those in
inotify */
const auto &root = inotify_root->name;
const auto path_fs = uri_fs.IsNull()
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? root
: AllocatedPath::Build(root, uri_fs.c_str());
recursive_watch_subdirectories(directory, path_fs,
directory->GetDepth());
}
if ((mask & (IN_CLOSE_WRITE|IN_MOVE|IN_DELETE)) != 0 ||
/* at the maximum depth, we watch out for newly created
directories */
(directory->GetDepth() == inotify_max_depth &&
(mask & (IN_CREATE|IN_ISDIR)) == (IN_CREATE|IN_ISDIR))) {
/* a file was changed, or a directory was
moved/deleted: queue a database update */
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if (!uri_fs.IsNull()) {
const std::string uri_utf8 = uri_fs.ToUTF8();
if (!uri_utf8.empty())
inotify_queue->Enqueue(uri_utf8.c_str());
}
else
inotify_queue->Enqueue("");
}
}
void
mpd_inotify_init(EventLoop &loop, Storage &storage, UpdateService &update,
unsigned max_depth)
{
LogDebug(inotify_domain, "initializing inotify");
const auto path = storage.MapFS("");
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if (path.IsNull()) {
LogDebug(inotify_domain, "no music directory configured");
return;
}
try {
inotify_source = new InotifySource(loop,
mpd_inotify_callback,
nullptr);
} catch (...) {
LogError(std::current_exception());
return;
}
inotify_max_depth = max_depth;
int descriptor;
try {
descriptor = inotify_source->Add(path.c_str(), IN_MASK);
} catch (...) {
LogError(std::current_exception());
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delete inotify_source;
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inotify_source = nullptr;
return;
}
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inotify_root = new WatchDirectory(nullptr, path, descriptor);
tree_add_watch_directory(inotify_root);
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recursive_watch_subdirectories(inotify_root, path, 0);
inotify_queue = new InotifyQueue(loop, update);
LogDebug(inotify_domain, "watching music directory");
}
void
mpd_inotify_finish(void) noexcept
{
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if (inotify_source == nullptr)
return;
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delete inotify_queue;
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delete inotify_source;
delete inotify_root;
inotify_directories.clear();
}