1 files changed, 237 insertions, 0 deletions
diff --git a/src/lib/ioloop-notify-inotify.c b/src/lib/ioloop-notify-inotify.c
new file mode 100644
index 0000000..796ac31
--- /dev/null
+++ b/src/lib/ioloop-notify-inotify.c
@@ -0,0 +1,237 @@
+/* Copyright (c) 2005-2018 Dovecot authors, see the included COPYING file */
+
+#define _GNU_SOURCE
+#include "lib.h"
+
+#ifdef IOLOOP_NOTIFY_INOTIFY
+
+#include "ioloop-private.h"
+#include "ioloop-notify-fd.h"
+#include "buffer.h"
+#include "net.h"
+#include "ipwd.h"
+#include "time-util.h"
+
+#include <stdio.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <sys/inotify.h>
+
+#define INOTIFY_BUFLEN (32*1024)
+
+struct ioloop_notify_handler_context {
+	struct ioloop_notify_fd_context fd_ctx;
+
+	int inotify_fd;
+	struct io *event_io;
+
+	bool disabled;
+};
+
+static struct ioloop_notify_handler_context *io_loop_notify_handler_init(void);
+
+static bool inotify_input_more(struct ioloop *ioloop)
+{
+	struct ioloop_notify_handler_context *ctx =
+		ioloop->notify_handler_context;
+        const struct inotify_event *event;
+	unsigned char event_buf[INOTIFY_BUFLEN];
+	struct io_notify *io;
+	ssize_t ret, pos;
+
+	/* read as many events as there is available and fit into our buffer.
+	   only full events are returned by the kernel. */
+	ret = read(ctx->inotify_fd, event_buf, sizeof(event_buf));
+	if (ret <= 0) {
+		if (ret == 0 || errno == EAGAIN) {
+			/* nothing more to read */
+			return FALSE;
+		}
+		i_fatal("read(inotify) failed: %m");
+	}
+
+	i_gettimeofday(&ioloop_timeval);
+	ioloop_time = ioloop_timeval.tv_sec;
+
+	for (pos = 0; pos < ret; ) {
+		if ((size_t)(ret - pos) < sizeof(*event))
+			break;
+
+		event = (struct inotify_event *)(event_buf + pos);
+		i_assert(event->len < (size_t)ret);
+		pos += sizeof(*event) + event->len;
+
+		io = io_notify_fd_find(&ctx->fd_ctx, event->wd);
+		if (io != NULL) {
+			if ((event->mask & IN_IGNORED) != 0) {
+				/* calling inotify_rm_watch() would now give
+				   EINVAL */
+				io->fd = -1;
+			}
+			io_loop_call_io(&io->io);
+		}
+	}
+	if (pos != ret)
+		i_error("read(inotify) returned partial event");
+	return (size_t)ret >= sizeof(event_buf)-512;
+}
+
+static void inotify_input(struct ioloop *ioloop)
+{
+	while (inotify_input_more(ioloop)) ;
+}
+
+#undef io_add_notify
+enum io_notify_result
+io_add_notify(const char *path, const char *source_filename,
+	      unsigned int source_linenum,
+	      io_callback_t *callback, void *context, struct io **io_r)
+{
+	struct ioloop_notify_handler_context *ctx =
+		current_ioloop->notify_handler_context;
+	int wd;
+
+	*io_r = NULL;
+
+	if (ctx == NULL)
+		ctx = io_loop_notify_handler_init();
+	if (ctx->disabled)
+		return IO_NOTIFY_NOSUPPORT;
+
+	wd = inotify_add_watch(ctx->inotify_fd, path,
+			       IN_CREATE | IN_DELETE | IN_DELETE_SELF |
+			       IN_MOVE | IN_MODIFY);
+	if (wd < 0) {
+		/* ESTALE could happen with NFS. Don't bother giving an error
+		   message then. */
+		if (errno == ENOENT || errno == ESTALE)
+			return IO_NOTIFY_NOTFOUND;
+
+		if (errno != ENOSPC)
+			i_error("inotify_add_watch(%s) failed: %m", path);
+		else {
+			i_warning("Inotify watch limit for user exceeded, "
+				  "disabling. Increase "
+				  "/proc/sys/fs/inotify/max_user_watches");
+		}
+		ctx->disabled = TRUE;
+		return IO_NOTIFY_NOSUPPORT;
+	}
+
+	if (ctx->event_io == NULL) {
+		ctx->event_io = io_add(ctx->inotify_fd, IO_READ,
+				       inotify_input, current_ioloop);
+	}
+
+	*io_r = io_notify_fd_add(&ctx->fd_ctx, wd, callback, context);
+	(*io_r)->source_filename = source_filename;
+	(*io_r)->source_linenum = source_linenum;
+	return IO_NOTIFY_ADDED;
+}
+
+void io_loop_notify_remove(struct io *_io)
+{
+	struct ioloop_notify_handler_context *ctx =
+		_io->ioloop->notify_handler_context;
+	struct io_notify *io = (struct io_notify *)_io;
+
+	if (io->fd != -1) {
+		/* ernro=EINVAL happens if the file itself is deleted and
+		   kernel has sent IN_IGNORED event which we haven't read. */
+		if (inotify_rm_watch(ctx->inotify_fd, io->fd) < 0 &&
+		    errno != EINVAL)
+			i_error("inotify_rm_watch() failed: %m");
+	}
+
+	io_notify_fd_free(&ctx->fd_ctx, io);
+
+	if (ctx->fd_ctx.notifies == NULL && ctx->event_io != NULL)
+		io_remove(&ctx->event_io);
+}
+
+static void ioloop_inotify_user_limit_exceeded(void)
+{
+	struct passwd pw;
+	const char *name;
+	uid_t uid = geteuid();
+
+	if (i_getpwuid(uid, &pw) <= 0)
+		name = t_strdup_printf("UID %s", dec2str(uid));
+	else {
+		name = t_strdup_printf("%s (UID %s)",
+				       dec2str(uid), pw.pw_name);
+	}
+	i_warning("Inotify instance limit for user %s exceeded, disabling. "
+		  "Increase /proc/sys/fs/inotify/max_user_instances", name);
+}
+
+static struct ioloop_notify_handler_context *io_loop_notify_handler_init(void)
+{
+	struct ioloop *ioloop = current_ioloop;
+	struct ioloop_notify_handler_context *ctx;
+
+	ctx = ioloop->notify_handler_context =
+		i_new(struct ioloop_notify_handler_context, 1);
+
+	ctx->inotify_fd = inotify_init();
+	if (ctx->inotify_fd == -1) {
+		if (errno != EMFILE)
+			i_error("inotify_init() failed: %m");
+		else
+			ioloop_inotify_user_limit_exceeded();
+		ctx->disabled = TRUE;
+	} else {
+		fd_close_on_exec(ctx->inotify_fd, TRUE);
+		fd_set_nonblock(ctx->inotify_fd, TRUE);
+	}
+	return ctx;
+}
+
+void io_loop_notify_handler_deinit(struct ioloop *ioloop)
+{
+	struct ioloop_notify_handler_context *ctx =
+		ioloop->notify_handler_context;
+
+	while (ctx->fd_ctx.notifies != NULL) {
+		struct io_notify *io = ctx->fd_ctx.notifies;
+		struct io *_io = &io->io;
+
+		i_warning("I/O notify leak: %p (%s:%u, fd %d)",
+			  (void *)_io->callback,
+			  _io->source_filename,
+			  _io->source_linenum, io->fd);
+		io_remove(&_io);
+	}
+
+	i_close_fd(&ctx->inotify_fd);
+	i_free(ctx);
+}
+
+int io_loop_extract_notify_fd(struct ioloop *ioloop)
+{
+	struct ioloop_notify_handler_context *ctx =
+		ioloop->notify_handler_context;
+	struct io_notify *io;
+	int fd, new_inotify_fd;
+
+	if (ctx == NULL || ctx->inotify_fd == -1)
+		return -1;
+
+	new_inotify_fd = inotify_init();
+	if (new_inotify_fd == -1) {
+		if (errno != EMFILE)
+			i_error("inotify_init() failed: %m");
+		else
+			ioloop_inotify_user_limit_exceeded();
+		return -1;
+	}
+	for (io = ctx->fd_ctx.notifies; io != NULL; io = io->next)
+		io->fd = -1;
+	io_remove(&ctx->event_io);
+	fd = ctx->inotify_fd;
+	ctx->inotify_fd = new_inotify_fd;
+	return fd;
+}
+
+#endif