transmission/libtransmission/watchdir-inotify.c

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/*
* This file Copyright (C) 2015-2016 Mnemosyne LLC
*
* It may be used under the GNU GPL versions 2 or 3
* or any future license endorsed by Mnemosyne LLC.
*
*/
#include <assert.h>
#include <errno.h>
#include <limits.h> /* NAME_MAX */
#include <stdlib.h> /* realloc () */
#include <unistd.h> /* close () */
#include <sys/inotify.h>
#include <event2/bufferevent.h>
#include <event2/event.h>
#define __LIBTRANSMISSION_WATCHDIR_MODULE__
#include "transmission.h"
#include "log.h"
#include "utils.h"
#include "watchdir.h"
#include "watchdir-common.h"
/***
****
***/
#define log_error(...) (!tr_logLevelIsActive (TR_LOG_ERROR) ? (void) 0 : \
tr_logAddMessage (__FILE__, __LINE__, TR_LOG_ERROR, "watchdir:inotify", __VA_ARGS__))
/***
****
***/
typedef struct tr_watchdir_inotify
{
tr_watchdir_backend base;
int infd;
int inwd;
struct bufferevent * event;
}
tr_watchdir_inotify;
#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 UNUSED,
short type UNUSED,
void * context)
{
const tr_watchdir_t handle = context;
tr_watchdir_scan (handle, NULL);
}
static void
tr_watchdir_inotify_on_event (struct bufferevent * event,
void * context)
{
assert (context != NULL);
const tr_watchdir_t handle = context;
tr_watchdir_inotify * const backend = BACKEND_UPCAST (tr_watchdir_get_backend (handle));
struct inotify_event ev;
size_t nread;
size_t name_size = NAME_MAX + 1;
char * name = tr_new (char, name_size);
/* Read the size of the struct excluding name into buf. Guaranteed to have at
least sizeof (ev) available */
while ((nread = bufferevent_read (event, &ev, sizeof (ev))) != 0)
{
if (nread == (size_t) -1)
{
log_error ("Failed to read inotify event: %s", tr_strerror (errno));
break;
}
if (nread != sizeof (ev))
{
log_error ("Failed to read inotify event: expected %zu, got %zu bytes.",
sizeof (ev), nread);
break;
}
assert (ev.wd == backend->inwd);
assert ((ev.mask & INOTIFY_WATCH_MASK) != 0);
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)
{
log_error ("Failed to read inotify name: %s", tr_strerror (errno));
break;
}
if (nread != ev.len)
{
log_error ("Failed to read inotify name: expected %" PRIu32 ", got %zu bytes.",
ev.len, nread);
break;
}
tr_watchdir_process (handle, name);
}
tr_free (name);
}
static void
tr_watchdir_inotify_free (tr_watchdir_backend * backend_base)
{
tr_watchdir_inotify * const backend = BACKEND_UPCAST (backend_base);
if (backend == NULL)
return;
assert (backend->base.free_func == &tr_watchdir_inotify_free);
if (backend->event != NULL)
{
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)
{
const char * const path = tr_watchdir_get_path (handle);
tr_watchdir_inotify * backend;
backend = tr_new0 (tr_watchdir_inotify, 1);
backend->base.free_func = &tr_watchdir_inotify_free;
backend->infd = -1;
backend->inwd = -1;
if ((backend->infd = inotify_init ()) == -1)
{
log_error ("Unable to inotify_init: %s", tr_strerror (errno));
goto fail;
}
if ((backend->inwd = inotify_add_watch (backend->infd, path,
INOTIFY_WATCH_MASK | IN_ONLYDIR)) == -1)
{
log_error ("Failed to setup watchdir \"%s\": %s (%d)", path,
tr_strerror (errno), errno);
goto fail;
}
if ((backend->event = bufferevent_socket_new (tr_watchdir_get_event_base (handle),
backend->infd, 0)) == NULL)
{
log_error ("Failed to create event buffer: %s", tr_strerror (errno));
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, NULL, NULL, 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, NULL) == -1)
log_error ("Failed to perform initial scan: %s", tr_strerror (errno));
return BACKEND_DOWNCAST (backend);
fail:
tr_watchdir_inotify_free (BACKEND_DOWNCAST (backend));
return NULL;
}