-/*
- * SPDX-License-Identifier: LGPL-2.1-only
- *
- * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- * Copyright (C) 2019 Michael Jeanson <mjeanson@efficios.com>
- *
- * LTTng UST pid namespace context.
- */
-
-#define _LGPL_SOURCE
-#include <limits.h>
-#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-context.h>
-
-#include "context-internal.h"
-#include "ns.h"
-
-/*
- * We cache the result to ensure we don't stat(2) the proc filesystem on
- * each event. The PID namespace is global to the process.
- */
-static ino_t cached_pid_ns = NS_INO_UNINITIALIZED;
-
-static
-ino_t get_pid_ns(void)
-{
- struct stat sb;
- ino_t pid_ns;
-
- pid_ns = CMM_LOAD_SHARED(cached_pid_ns);
-
- /*
- * If the cache is populated, do nothing and return the
- * cached inode number.
- */
- if (caa_likely(pid_ns != NS_INO_UNINITIALIZED))
- return pid_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.
- */
- pid_ns = NS_INO_UNAVAILABLE;
-
- if (stat("/proc/self/ns/pid", &sb) == 0) {
- pid_ns = sb.st_ino;
- }
-
- /*
- * And finally, store the inode number in the cache.
- */
- CMM_STORE_SHARED(cached_pid_ns, pid_ns);
-
- return pid_ns;
-}
-
-/*
- * A process's PID namespace membership is determined when the process is
- * created and cannot be changed thereafter.
- *
- * The pid namespace can change only on clone(2) / fork(2) :
- * - clone(2) with the CLONE_NEWPID flag
- * - clone(2) / fork(2) after a call to unshare(2) with the CLONE_NEWPID flag
- * - clone(2) / fork(2) after a call to setns(2) with a PID namespace fd
- */
-void lttng_context_pid_ns_reset(void)
-{
- CMM_STORE_SHARED(cached_pid_ns, NS_INO_UNINITIALIZED);
-}
-
-static
-size_t pid_ns_get_size(struct lttng_ust_ctx_field *field, size_t offset)
-{
- size_t size = 0;
-
- size += lttng_ust_lib_ring_buffer_align(offset, lttng_ust_rb_alignof(ino_t));
- size += sizeof(ino_t);
- return size;
-}
-
-static
-void pid_ns_record(struct lttng_ust_ctx_field *field,
- struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct lttng_ust_channel_buffer *chan)
-{
- ino_t pid_ns;
-
- pid_ns = get_pid_ns();
- lttng_ust_lib_ring_buffer_align_ctx(ctx, lttng_ust_rb_alignof(pid_ns));
- chan->ops->event_write(ctx, &pid_ns, sizeof(pid_ns));
-}
-
-static
-void pid_ns_get_value(struct lttng_ust_ctx_field *field,
- struct lttng_ust_ctx_value *value)
-{
- value->u.s64 = get_pid_ns();
-}
-
-int lttng_add_pid_ns_to_ctx(struct lttng_ust_ctx **ctx)
-{
- struct lttng_ust_ctx_field *field;
- struct lttng_ust_type_common *type;
- int ret;
-
- type = lttng_ust_create_type_integer(sizeof(ino_t) * CHAR_BIT,
- lttng_ust_rb_alignof(ino_t) * CHAR_BIT,
- lttng_ust_is_signed_type(ino_t),
- BYTE_ORDER, 10);
- if (!type)
- return -ENOMEM;
- field = lttng_append_context(ctx);
- if (!field) {
- ret = -ENOMEM;
- goto error_context;
- }
- if (lttng_find_context(*ctx, "pid_ns")) {
- ret = -EEXIST;
- goto error_find_context;
- }
- field->event_field->name = strdup("pid_ns");
- if (!field->event_field->name) {
- ret = -ENOMEM;
- goto error_name;
- }
- field->event_field->type = type;
- field->get_size = pid_ns_get_size;
- field->record = pid_ns_record;
- field->get_value = pid_ns_get_value;
- lttng_context_update(*ctx);
- return 0;
-
-error_name:
-error_find_context:
- lttng_remove_context_field(ctx, field);
-error_context:
- lttng_ust_destroy_type(type);
- return ret;
-}