transmission/libtransmission/watchdir-inotify.cc

230 lines
6.5 KiB
C++

// This file Copyright © 2015-2022 Mnemosyne LLC.
// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
// or any future license endorsed by Mnemosyne LLC.
// License text can be found in the licenses/ folder.
#include <cerrno>
#include <climits> /* NAME_MAX */
#include <string_view>
#include <unistd.h> /* close() */
#include <sys/inotify.h>
#include <event2/bufferevent.h>
#include <event2/event.h>
#include <fmt/core.h>
#define LIBTRANSMISSION_WATCHDIR_MODULE
#include "transmission.h"
#include "log.h"
#include "tr-assert.h"
#include "utils.h"
#include "watchdir.h"
#include "watchdir-common.h"
/***
****
***/
struct tr_watchdir_inotify
{
tr_watchdir_backend base;
int infd;
int inwd;
struct bufferevent* event;
};
#define BACKEND_UPCAST(b) ((tr_watchdir_inotify*)(b))
#define INOTIFY_WATCH_MASK (IN_CLOSE_WRITE | IN_MOVED_TO | IN_CREATE)
/***
****
***/
static void tr_watchdir_inotify_on_first_scan(evutil_socket_t /*fd*/, short /*type*/, void* context)
{
auto const handle = static_cast<tr_watchdir_t>(context);
tr_watchdir_scan(handle, nullptr);
}
static void tr_watchdir_inotify_on_event(struct bufferevent* event, void* context)
{
TR_ASSERT(context != nullptr);
auto const handle = static_cast<tr_watchdir_t>(context);
#ifdef TR_ENABLE_ASSERTS
tr_watchdir_inotify const* const backend = BACKEND_UPCAST(tr_watchdir_get_backend(handle));
#endif
struct inotify_event ev;
size_t name_size = NAME_MAX + 1;
auto* name = tr_new(char, name_size);
/* Read the size of the struct excluding name into buf. Guaranteed to have at
least sizeof(ev) available */
auto nread = size_t{};
while ((nread = bufferevent_read(event, &ev, sizeof(ev))) != 0)
{
if (nread == (size_t)-1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't read event: {error} ({error_code})"),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
break;
}
if (nread != sizeof(ev))
{
tr_logAddError(fmt::format(
_("Couldn't read event: expected {expected_size}, got {actual_size}"),
fmt::arg("expected_size", sizeof(ev)),
fmt::arg("actual_size", nread)));
break;
}
TR_ASSERT(ev.wd == backend->inwd);
TR_ASSERT((ev.mask & INOTIFY_WATCH_MASK) != 0);
TR_ASSERT(ev.len > 0);
if (ev.len > name_size)
{
name_size = ev.len;
name = tr_renew(char, name, name_size);
}
/* Consume entire name into buffer */
if ((nread = bufferevent_read(event, name, ev.len)) == (size_t)-1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't read filename: {error} ({error_code})"),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
break;
}
if (nread != ev.len)
{
tr_logAddError(fmt::format(
_("Couldn't read filename: expected {expected_size}, got {actual_size}"),
fmt::arg("expected_size", sizeof(ev)),
fmt::arg("actual_size", nread)));
break;
}
tr_watchdir_process(handle, name);
}
tr_free(name);
}
static void tr_watchdir_inotify_free(tr_watchdir_backend* backend_base)
{
auto* const backend = BACKEND_UPCAST(backend_base);
if (backend == nullptr)
{
return;
}
TR_ASSERT(backend->base.free_func == &tr_watchdir_inotify_free);
if (backend->event != nullptr)
{
bufferevent_disable(backend->event, EV_READ);
bufferevent_free(backend->event);
}
if (backend->infd != -1)
{
if (backend->inwd != -1)
{
inotify_rm_watch(backend->infd, backend->inwd);
}
close(backend->infd);
}
tr_free(backend);
}
tr_watchdir_backend* tr_watchdir_inotify_new(tr_watchdir_t handle)
{
char const* const path = tr_watchdir_get_path(handle);
auto* const backend = tr_new0(tr_watchdir_inotify, 1);
backend->base.free_func = &tr_watchdir_inotify_free;
backend->infd = inotify_init();
if (backend->infd == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't watch '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto FAIL;
}
backend->inwd = inotify_add_watch(backend->infd, path, INOTIFY_WATCH_MASK | IN_ONLYDIR);
if (backend->inwd == -1)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't watch '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto FAIL;
}
backend->event = bufferevent_socket_new(tr_watchdir_get_event_base(handle), backend->infd, 0);
if (backend->event == nullptr)
{
auto const error_code = errno;
tr_logAddError(fmt::format(
_("Couldn't watch '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
goto FAIL;
}
/* Guarantees at least the sizeof an inotify event will be available in the
event buffer */
bufferevent_setwatermark(backend->event, EV_READ, sizeof(struct inotify_event), 0);
bufferevent_setcb(backend->event, &tr_watchdir_inotify_on_event, nullptr, nullptr, handle);
bufferevent_enable(backend->event, EV_READ);
/* Perform an initial scan on the directory */
if (event_base_once(
tr_watchdir_get_event_base(handle),
-1,
EV_TIMEOUT,
&tr_watchdir_inotify_on_first_scan,
handle,
nullptr) == -1)
{
auto const error_code = errno;
tr_logAddWarn(fmt::format(
_("Couldn't scan '{path}': {error} ({error_code})"),
fmt::arg("path", path),
fmt::arg("error", tr_strerror(error_code)),
fmt::arg("error_code", error_code)));
}
return BACKEND_DOWNCAST(backend);
FAIL:
tr_watchdir_inotify_free(BACKEND_DOWNCAST(backend));
return nullptr;
}