Commit | Line | Data |
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4847e9bb | 1 | /* |
e92f3e28 | 2 | * lttng-context-procname.c |
4847e9bb MD |
3 | * |
4 | * LTTng UST procname context. | |
5 | * | |
e92f3e28 MD |
6 | * Copyright (C) 2009-2011 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 | |
4847e9bb MD |
21 | */ |
22 | ||
4c1ee94e | 23 | #include <sys/prctl.h> |
4318ae1b MD |
24 | #include <lttng/ust-events.h> |
25 | #include <lttng/ust-tracer.h> | |
26 | #include <lttng/ringbuffer-config.h> | |
4847e9bb | 27 | #include <assert.h> |
4c1ee94e MD |
28 | |
29 | #define PROCNAME_LEN 17 /* includes \0 */ | |
4847e9bb MD |
30 | |
31 | /* | |
32 | * We cache the result to ensure we don't trigger a system call for | |
33 | * each event. | |
34 | * Upon exec, procname changes, but exec takes care of throwing away | |
35 | * this cached version. | |
36 | */ | |
37 | static char cached_procname[17]; | |
38 | ||
39 | static inline | |
40 | char *wrapper_getprocname(void) | |
41 | { | |
4c1ee94e MD |
42 | int ret; |
43 | ||
b5a3dfa5 | 44 | if (caa_unlikely(!cached_procname[0])) { |
4c1ee94e MD |
45 | ret = prctl(PR_GET_NAME, (unsigned long) cached_procname, |
46 | 0, 0, 0); | |
47 | assert(!ret); | |
4847e9bb MD |
48 | } |
49 | return cached_procname; | |
50 | } | |
51 | ||
52 | void lttng_context_procname_reset(void) | |
53 | { | |
54 | cached_procname[0] = '\0'; | |
55 | } | |
56 | ||
57 | static | |
58 | size_t procname_get_size(size_t offset) | |
59 | { | |
60 | size_t size = 0; | |
61 | ||
4c1ee94e | 62 | size += PROCNAME_LEN; |
4847e9bb MD |
63 | return size; |
64 | } | |
65 | ||
66 | static | |
67 | void procname_record(struct lttng_ctx_field *field, | |
4cfec15c | 68 | struct lttng_ust_lib_ring_buffer_ctx *ctx, |
4847e9bb MD |
69 | struct ltt_channel *chan) |
70 | { | |
71 | char *procname; | |
72 | ||
73 | procname = wrapper_getprocname(); | |
4c1ee94e | 74 | chan->ops->event_write(ctx, procname, PROCNAME_LEN); |
4847e9bb MD |
75 | } |
76 | ||
77 | int lttng_add_procname_to_ctx(struct lttng_ctx **ctx) | |
78 | { | |
79 | struct lttng_ctx_field *field; | |
80 | ||
81 | field = lttng_append_context(ctx); | |
82 | if (!field) | |
83 | return -ENOMEM; | |
84 | if (lttng_find_context(*ctx, "procname")) { | |
85 | lttng_remove_context_field(ctx, field); | |
86 | return -EEXIST; | |
87 | } | |
88 | field->event_field.name = "procname"; | |
89 | field->event_field.type.atype = atype_array; | |
90 | field->event_field.type.u.array.elem_type.atype = atype_integer; | |
91 | field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT; | |
92 | field->event_field.type.u.array.elem_type.u.basic.integer.alignment = lttng_alignof(char) * CHAR_BIT; | |
93 | field->event_field.type.u.array.elem_type.u.basic.integer.signedness = lttng_is_signed_type(char); | |
94 | field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0; | |
95 | field->event_field.type.u.array.elem_type.u.basic.integer.base = 10; | |
96 | field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8; | |
4c1ee94e | 97 | field->event_field.type.u.array.length = PROCNAME_LEN; |
4847e9bb MD |
98 | field->get_size = procname_get_size; |
99 | field->record = procname_record; | |
100 | return 0; | |
101 | } |