Files
mpd/src/event/InotifyEvent.cxx

107 lines
2.3 KiB
C++

// SPDX-License-Identifier: BSD-2-Clause
// Copyright CM4all GmbH
// author: Max Kellermann <mk@cm4all.com>
#include "InotifyEvent.hxx"
#include "lib/fmt/SystemError.hxx"
#include "io/UniqueFileDescriptor.hxx"
#include <array>
#include <limits.h>
#include <sys/inotify.h>
static UniqueFileDescriptor
CreateInotify()
{
int fd = inotify_init1(IN_CLOEXEC|IN_NONBLOCK);
if (fd < 0)
throw MakeErrno("inotify_init1() failed");
return UniqueFileDescriptor(AdoptTag{}, fd);
}
InotifyEvent::InotifyEvent(EventLoop &event_loop, InotifyHandler &_handler)
:event(event_loop, BIND_THIS_METHOD(OnInotifyReady),
CreateInotify().Release()),
handler(_handler)
{
Enable();
}
InotifyEvent::~InotifyEvent() noexcept
{
Close();
}
int
InotifyEvent::TryAddWatch(const char *pathname, uint32_t mask) noexcept
{
return inotify_add_watch(event.GetFileDescriptor().Get(),
pathname, mask);
}
int
InotifyEvent::AddWatch(const char *pathname, uint32_t mask)
{
int wd = TryAddWatch(pathname, mask);
if (wd < 0)
throw FmtErrno("inotify_add_watch({:?}) failed", pathname);
return wd;
}
int
InotifyEvent::AddModifyWatch(const char *pathname)
{
return AddWatch(pathname, IN_MODIFY);
}
void
InotifyEvent::RemoveWatch(int wd) noexcept
{
inotify_rm_watch(event.GetFileDescriptor().Get(), wd);
}
inline void
InotifyEvent::OnInotifyReady(unsigned) noexcept
try {
std::array<std::byte, 4096> buffer;
static_assert(sizeof(buffer) >= sizeof(struct inotify_event) + NAME_MAX + 1,
"inotify buffer too small");
ssize_t nbytes = event.GetFileDescriptor().Read(buffer);
if (nbytes <= 0) [[unlikely]] {
if (nbytes == 0)
throw std::runtime_error{"EOF from inotify"};
const int e = errno;
if (e == EAGAIN)
return;
throw MakeErrno(e, "Reading inotify failed");
}
const std::byte *p = buffer.data(), *const end = p + nbytes;
while (true) {
const size_t remaining = end - p;
const auto &ie = *(const struct inotify_event *)(const void *)p;
if (remaining < sizeof(ie) ||
remaining < sizeof(ie) + ie.len)
break;
const char *name;
if (ie.len > 0 && ie.name[ie.len - 1] == 0)
name = ie.name;
else
name = nullptr;
handler.OnInotify(ie.wd, ie.mask, name);
p += sizeof(ie) + ie.len;
}
} catch (...) {
Close();
handler.OnInotifyError(std::current_exception());
}