| 1 | /* |
| 2 | * lttng-context-hostname.c |
| 3 | * |
| 4 | * LTTng hostname context. |
| 5 | * |
| 6 | * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 7 | * |
| 8 | * This library is free software; you can redistribute it and/or |
| 9 | * modify it under the terms of the GNU Lesser General Public |
| 10 | * License as published by the Free Software Foundation; only |
| 11 | * version 2.1 of the License. |
| 12 | * |
| 13 | * This library is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 16 | * Lesser General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU Lesser General Public |
| 19 | * License along with this library; if not, write to the Free Software |
| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 21 | */ |
| 22 | |
| 23 | #include <linux/module.h> |
| 24 | #include <linux/slab.h> |
| 25 | #include <linux/sched.h> |
| 26 | #include <linux/utsname.h> |
| 27 | #include "lttng-events.h" |
| 28 | #include "wrapper/ringbuffer/frontend_types.h" |
| 29 | #include "wrapper/vmalloc.h" |
| 30 | #include "lttng-tracer.h" |
| 31 | |
| 32 | #define LTTNG_HOSTNAME_CTX_LEN (__NEW_UTS_LEN + 1) |
| 33 | |
| 34 | static |
| 35 | size_t hostname_get_size(size_t offset) |
| 36 | { |
| 37 | size_t size = 0; |
| 38 | |
| 39 | size += LTTNG_HOSTNAME_CTX_LEN; |
| 40 | return size; |
| 41 | } |
| 42 | |
| 43 | static |
| 44 | void hostname_record(struct lttng_ctx_field *field, |
| 45 | struct lib_ring_buffer_ctx *ctx, |
| 46 | struct lttng_channel *chan) |
| 47 | { |
| 48 | struct nsproxy *nsproxy; |
| 49 | struct uts_namespace *ns; |
| 50 | char *hostname; |
| 51 | |
| 52 | /* |
| 53 | * No need to take the RCU read-side lock to read current |
| 54 | * nsproxy. (documented in nsproxy.h) |
| 55 | */ |
| 56 | nsproxy = current->nsproxy; |
| 57 | if (nsproxy) { |
| 58 | ns = nsproxy->uts_ns; |
| 59 | hostname = ns->name.nodename; |
| 60 | chan->ops->event_write(ctx, hostname, |
| 61 | LTTNG_HOSTNAME_CTX_LEN); |
| 62 | } else { |
| 63 | chan->ops->event_memset(ctx, 0, |
| 64 | LTTNG_HOSTNAME_CTX_LEN); |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | int lttng_add_hostname_to_ctx(struct lttng_ctx **ctx) |
| 69 | { |
| 70 | struct lttng_ctx_field *field; |
| 71 | |
| 72 | field = lttng_append_context(ctx); |
| 73 | if (!field) |
| 74 | return -ENOMEM; |
| 75 | if (lttng_find_context(*ctx, "hostname")) { |
| 76 | lttng_remove_context_field(ctx, field); |
| 77 | return -EEXIST; |
| 78 | } |
| 79 | field->event_field.name = "hostname"; |
| 80 | field->event_field.type.atype = atype_array; |
| 81 | field->event_field.type.u.array.elem_type.atype = atype_integer; |
| 82 | field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT; |
| 83 | field->event_field.type.u.array.elem_type.u.basic.integer.alignment = lttng_alignof(char) * CHAR_BIT; |
| 84 | field->event_field.type.u.array.elem_type.u.basic.integer.signedness = is_signed_type(char); |
| 85 | field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0; |
| 86 | field->event_field.type.u.array.elem_type.u.basic.integer.base = 10; |
| 87 | field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8; |
| 88 | field->event_field.type.u.array.length = LTTNG_HOSTNAME_CTX_LEN; |
| 89 | |
| 90 | field->get_size = hostname_get_size; |
| 91 | field->record = hostname_record; |
| 92 | wrapper_vmalloc_sync_all(); |
| 93 | return 0; |
| 94 | } |
| 95 | EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx); |
| 96 | |
| 97 | MODULE_LICENSE("GPL and additional rights"); |
| 98 | MODULE_AUTHOR("Mathieu Desnoyers"); |
| 99 | MODULE_DESCRIPTION("Linux Trace Toolkit Perf Support"); |