1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/*
* Copyright (c) 2023, Tim Flynn <trflynn89@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include "FileWatcher.h"
#include <AK/Debug.h>
#include <AK/DeprecatedString.h>
#include <AK/LexicalPath.h>
#include <LibCore/Notifier.h>
#include <errno.h>
#include <limits.h>
#include <string.h>
#include <sys/inotify.h>
#include <sys/ioctl.h>
#include <unistd.h>
#if !defined(AK_OS_LINUX)
static_assert(false, "This file must only be used for Linux");
#endif
namespace Core {
static constexpr unsigned file_watcher_flags_to_inotify_flags(FileWatcherFlags flags)
{
unsigned result = 0;
if (has_flag(flags, FileWatcherFlags::Nonblock))
result |= IN_NONBLOCK;
if (has_flag(flags, FileWatcherFlags::CloseOnExec))
result |= IN_CLOEXEC;
return result;
}
static Optional<FileWatcherEvent> get_event_from_fd(int fd, HashMap<unsigned, DeprecatedString> const& wd_to_path)
{
static constexpr auto max_event_size = sizeof(inotify_event) + NAME_MAX + 1;
// Note from INOTIFY(7) man page:
//
// Some systems cannot read integer variables if they are not properly aligned. On other
// systems, incorrect alignment may decrease performance. Hence, the buffer used for reading
// from the inotify file descriptor should have the same alignment as inotify_event.
alignas(alignof(inotify_event)) Array<u8, max_event_size> buffer;
ssize_t rc = ::read(fd, buffer.data(), buffer.size());
if (rc == 0) {
return {};
} else if (rc < 0) {
dbgln_if(FILE_WATCHER_DEBUG, "get_event_from_fd: Reading from wd {} failed: {}", fd, strerror(errno));
return {};
}
auto const* event = reinterpret_cast<inotify_event const*>(buffer.data());
FileWatcherEvent result;
auto it = wd_to_path.find(event->wd);
if (it == wd_to_path.end()) {
dbgln_if(FILE_WATCHER_DEBUG, "get_event_from_fd: Got an event for a non-existent wd {}?!", event->wd);
return {};
}
auto const& path = it->value;
if ((event->mask & IN_CREATE) != 0)
result.type |= FileWatcherEvent::Type::ChildCreated;
if ((event->mask & IN_DELETE) != 0)
result.type |= FileWatcherEvent::Type::ChildDeleted;
if ((event->mask & IN_DELETE_SELF) != 0)
result.type |= FileWatcherEvent::Type::Deleted;
if ((event->mask & IN_MODIFY) != 0)
result.type |= FileWatcherEvent::Type::ContentModified;
if ((event->mask & IN_ATTRIB) != 0)
result.type |= FileWatcherEvent::Type::MetadataModified;
if (result.type == FileWatcherEvent::Type::Invalid) {
warnln("Unknown event type {:x} returned by the watch_file descriptor for {}", event->mask, path);
return {};
}
if (event->len > 0) {
StringView child_name { event->name, strlen(event->name) };
result.event_path = LexicalPath::join(path, child_name).string();
} else {
result.event_path = path;
}
dbgln_if(FILE_WATCHER_DEBUG, "get_event_from_fd: got event from wd {} on '{}' type {}", fd, result.event_path, result.type);
return result;
}
ErrorOr<NonnullRefPtr<FileWatcher>> FileWatcher::create(FileWatcherFlags flags)
{
auto watcher_fd = ::inotify_init1(file_watcher_flags_to_inotify_flags(flags | FileWatcherFlags::CloseOnExec));
if (watcher_fd < 0)
return Error::from_errno(errno);
auto notifier = TRY(Notifier::try_create(watcher_fd, Notifier::Type::Read));
return adopt_nonnull_ref_or_enomem(new (nothrow) FileWatcher(watcher_fd, move(notifier)));
}
FileWatcher::FileWatcher(int watcher_fd, NonnullRefPtr<Notifier> notifier)
: FileWatcherBase(watcher_fd)
, m_notifier(move(notifier))
{
m_notifier->on_activation = [this] {
auto maybe_event = get_event_from_fd(m_notifier->fd(), m_wd_to_path);
if (maybe_event.has_value()) {
auto event = maybe_event.value();
on_change(event);
if (has_flag(event.type, FileWatcherEvent::Type::Deleted)) {
auto result = remove_watch(event.event_path);
if (result.is_error()) {
dbgln_if(FILE_WATCHER_DEBUG, "on_ready_to_read: {}", result.error());
}
}
}
};
}
FileWatcher::~FileWatcher() = default;
ErrorOr<bool> FileWatcherBase::add_watch(DeprecatedString path, FileWatcherEvent::Type event_mask)
{
if (m_path_to_wd.find(path) != m_path_to_wd.end()) {
dbgln_if(FILE_WATCHER_DEBUG, "add_watch: path '{}' is already being watched", path);
return false;
}
unsigned inotify_mask = 0;
if (has_flag(event_mask, FileWatcherEvent::Type::ChildCreated))
inotify_mask |= IN_CREATE;
if (has_flag(event_mask, FileWatcherEvent::Type::ChildDeleted))
inotify_mask |= IN_DELETE;
if (has_flag(event_mask, FileWatcherEvent::Type::Deleted))
inotify_mask |= IN_DELETE_SELF;
if (has_flag(event_mask, FileWatcherEvent::Type::ContentModified))
inotify_mask |= IN_MODIFY;
if (has_flag(event_mask, FileWatcherEvent::Type::MetadataModified))
inotify_mask |= IN_ATTRIB;
int watch_descriptor = ::inotify_add_watch(m_watcher_fd, path.characters(), inotify_mask);
if (watch_descriptor < 0)
return Error::from_errno(errno);
m_path_to_wd.set(path, watch_descriptor);
m_wd_to_path.set(watch_descriptor, path);
dbgln_if(FILE_WATCHER_DEBUG, "add_watch: watching path '{}' on InodeWatcher {} wd {}", path, m_watcher_fd, watch_descriptor);
return true;
}
ErrorOr<bool> FileWatcherBase::remove_watch(DeprecatedString path)
{
auto it = m_path_to_wd.find(path);
if (it == m_path_to_wd.end()) {
dbgln_if(FILE_WATCHER_DEBUG, "remove_watch: path '{}' is not being watched", path);
return false;
}
if (::inotify_rm_watch(m_watcher_fd, it->value) < 0)
return Error::from_errno(errno);
m_path_to_wd.remove(it);
m_wd_to_path.remove(it->value);
dbgln_if(FILE_WATCHER_DEBUG, "remove_watch: stopped watching path '{}' on InodeWatcher {}", path, m_watcher_fd);
return true;
}
}
|
