+++ /dev/null
-/*
- * lttng-context-mnt-ns.c
- *
- * LTTng UST mnt namespace context.
- *
- * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * 2019 Michael Jeanson <mjeanson@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#define _LGPL_SOURCE
-#include <stddef.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <unistd.h>
-#include <lttng/ust-events.h>
-#include <lttng/ust-tracer.h>
-#include <lttng/ringbuffer-config.h>
-
-#include "ns.h"
-
-/*
- * We cache the result to ensure we don't stat(2) the proc filesystem on
- * each event. The mount namespace is global to the process.
- */
-static ino_t cached_mnt_ns = NS_INO_UNINITIALIZED;
-
-static
-ino_t get_mnt_ns(void)
-{
- struct stat sb;
- ino_t mnt_ns;
-
- mnt_ns = CMM_LOAD_SHARED(cached_mnt_ns);
-
- /*
- * If the cache is populated, do nothing and return the
- * cached inode number.
- */
- if (caa_likely(mnt_ns != NS_INO_UNINITIALIZED))
- return mnt_ns;
-
- /*
- * At this point we have to populate the cache, set the initial
- * value to NS_INO_UNAVAILABLE (0), if we fail to get the inode
- * number from the proc filesystem, this is the value we will
- * cache.
- */
- mnt_ns = NS_INO_UNAVAILABLE;
-
- if (stat("/proc/self/ns/mnt", &sb) == 0) {
- mnt_ns = sb.st_ino;
- }
-
- /*
- * And finally, store the inode number in the cache.
- */
- CMM_STORE_SHARED(cached_mnt_ns, mnt_ns);
-
- return mnt_ns;
-}
-
-/*
- * The mnt namespace can change for 3 reasons
- * * clone(2) called with CLONE_NEWNS
- * * setns(2) called with the fd of a different mnt ns
- * * unshare(2) called with CLONE_NEWNS
- */
-void lttng_context_mnt_ns_reset(void)
-{
- CMM_STORE_SHARED(cached_mnt_ns, NS_INO_UNINITIALIZED);
-}
-
-static
-size_t mnt_ns_get_size(struct lttng_ctx_field *field, size_t offset)
-{
- size_t size = 0;
-
- size += lib_ring_buffer_align(offset, lttng_alignof(ino_t));
- size += sizeof(ino_t);
- return size;
-}
-
-static
-void mnt_ns_record(struct lttng_ctx_field *field,
- struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct lttng_channel *chan)
-{
- ino_t mnt_ns;
-
- mnt_ns = get_mnt_ns();
- lib_ring_buffer_align_ctx(ctx, lttng_alignof(mnt_ns));
- chan->ops->event_write(ctx, &mnt_ns, sizeof(mnt_ns));
-}
-
-static
-void mnt_ns_get_value(struct lttng_ctx_field *field,
- struct lttng_ctx_value *value)
-{
- value->u.s64 = get_mnt_ns();
-}
-
-int lttng_add_mnt_ns_to_ctx(struct lttng_ctx **ctx)
-{
- struct lttng_ctx_field *field;
-
- field = lttng_append_context(ctx);
- if (!field)
- return -ENOMEM;
- if (lttng_find_context(*ctx, "mnt_ns")) {
- lttng_remove_context_field(ctx, field);
- return -EEXIST;
- }
- field->event_field.name = "mnt_ns";
- field->event_field.type.atype = atype_integer;
- field->event_field.type.u.integer.size = sizeof(ino_t) * CHAR_BIT;
- field->event_field.type.u.integer.alignment = lttng_alignof(ino_t) * CHAR_BIT;
- field->event_field.type.u.integer.signedness = lttng_is_signed_type(ino_t);
- field->event_field.type.u.integer.reverse_byte_order = 0;
- field->event_field.type.u.integer.base = 10;
- field->event_field.type.u.integer.encoding = lttng_encode_none;
- field->get_size = mnt_ns_get_size;
- field->record = mnt_ns_record;
- field->get_value = mnt_ns_get_value;
- lttng_context_update(*ctx);
- return 0;
-}