1/*
2 * Copyright (C) 2009 Red Hat Inc, Steven Rostedt <srostedt@redhat.com>
3 *
4 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation;
8 * version 2.1 of the License (not later!)
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 * GNU Lesser General Public License for more details.
14 *
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this program; if not,  see <http://www.gnu.org/licenses>
17 *
18 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
19 */
20#include <stdio.h>
21#include <stdlib.h>
22#include <string.h>
23#include <stdarg.h>
24
25#include <asm/bug.h>
26#include "event-parse.h"
27#include "event-utils.h"
28
29/*
30 * The TRACE_SEQ_POISON is to catch the use of using
31 * a trace_seq structure after it was destroyed.
32 */
33#define TRACE_SEQ_POISON	((void *)0xdeadbeef)
34#define TRACE_SEQ_CHECK(s)						\
35do {									\
36	if (WARN_ONCE((s)->buffer == TRACE_SEQ_POISON,			\
37		      "Usage of trace_seq after it was destroyed"))	\
38		(s)->state = TRACE_SEQ__BUFFER_POISONED;		\
39} while (0)
40
41#define TRACE_SEQ_CHECK_RET_N(s, n)		\
42do {						\
43	TRACE_SEQ_CHECK(s);			\
44	if ((s)->state != TRACE_SEQ__GOOD)	\
45		return n; 			\
46} while (0)
47
48#define TRACE_SEQ_CHECK_RET(s)   TRACE_SEQ_CHECK_RET_N(s, )
49#define TRACE_SEQ_CHECK_RET0(s)  TRACE_SEQ_CHECK_RET_N(s, 0)
50
51/**
52 * trace_seq_init - initialize the trace_seq structure
53 * @s: a pointer to the trace_seq structure to initialize
54 */
55void trace_seq_init(struct trace_seq *s)
56{
57	s->len = 0;
58	s->readpos = 0;
59	s->buffer_size = TRACE_SEQ_BUF_SIZE;
60	s->buffer = malloc(s->buffer_size);
61	if (s->buffer != NULL)
62		s->state = TRACE_SEQ__GOOD;
63	else
64		s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
65}
66
67/**
68 * trace_seq_reset - re-initialize the trace_seq structure
69 * @s: a pointer to the trace_seq structure to reset
70 */
71void trace_seq_reset(struct trace_seq *s)
72{
73	if (!s)
74		return;
75	TRACE_SEQ_CHECK(s);
76	s->len = 0;
77	s->readpos = 0;
78}
79
80/**
81 * trace_seq_destroy - free up memory of a trace_seq
82 * @s: a pointer to the trace_seq to free the buffer
83 *
84 * Only frees the buffer, not the trace_seq struct itself.
85 */
86void trace_seq_destroy(struct trace_seq *s)
87{
88	if (!s)
89		return;
90	TRACE_SEQ_CHECK_RET(s);
91	free(s->buffer);
92	s->buffer = TRACE_SEQ_POISON;
93}
94
95static void expand_buffer(struct trace_seq *s)
96{
97	char *buf;
98
99	buf = realloc(s->buffer, s->buffer_size + TRACE_SEQ_BUF_SIZE);
100	if (WARN_ONCE(!buf, "Can't allocate trace_seq buffer memory")) {
101		s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
102		return;
103	}
104
105	s->buffer = buf;
106	s->buffer_size += TRACE_SEQ_BUF_SIZE;
107}
108
109/**
110 * trace_seq_printf - sequence printing of trace information
111 * @s: trace sequence descriptor
112 * @fmt: printf format string
113 *
114 * It returns 0 if the trace oversizes the buffer's free
115 * space, 1 otherwise.
116 *
117 * The tracer may use either sequence operations or its own
118 * copy to user routines. To simplify formating of a trace
119 * trace_seq_printf is used to store strings into a special
120 * buffer (@s). Then the output may be either used by
121 * the sequencer or pulled into another buffer.
122 */
123int
124trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
125{
126	va_list ap;
127	int len;
128	int ret;
129
130 try_again:
131	TRACE_SEQ_CHECK_RET0(s);
132
133	len = (s->buffer_size - 1) - s->len;
134
135	va_start(ap, fmt);
136	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
137	va_end(ap);
138
139	if (ret >= len) {
140		expand_buffer(s);
141		goto try_again;
142	}
143
144	s->len += ret;
145
146	return 1;
147}
148
149/**
150 * trace_seq_vprintf - sequence printing of trace information
151 * @s: trace sequence descriptor
152 * @fmt: printf format string
153 *
154 * The tracer may use either sequence operations or its own
155 * copy to user routines. To simplify formating of a trace
156 * trace_seq_printf is used to store strings into a special
157 * buffer (@s). Then the output may be either used by
158 * the sequencer or pulled into another buffer.
159 */
160int
161trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
162{
163	int len;
164	int ret;
165
166 try_again:
167	TRACE_SEQ_CHECK_RET0(s);
168
169	len = (s->buffer_size - 1) - s->len;
170
171	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
172
173	if (ret >= len) {
174		expand_buffer(s);
175		goto try_again;
176	}
177
178	s->len += ret;
179
180	return len;
181}
182
183/**
184 * trace_seq_puts - trace sequence printing of simple string
185 * @s: trace sequence descriptor
186 * @str: simple string to record
187 *
188 * The tracer may use either the sequence operations or its own
189 * copy to user routines. This function records a simple string
190 * into a special buffer (@s) for later retrieval by a sequencer
191 * or other mechanism.
192 */
193int trace_seq_puts(struct trace_seq *s, const char *str)
194{
195	int len;
196
197	TRACE_SEQ_CHECK_RET0(s);
198
199	len = strlen(str);
200
201	while (len > ((s->buffer_size - 1) - s->len))
202		expand_buffer(s);
203
204	TRACE_SEQ_CHECK_RET0(s);
205
206	memcpy(s->buffer + s->len, str, len);
207	s->len += len;
208
209	return len;
210}
211
212int trace_seq_putc(struct trace_seq *s, unsigned char c)
213{
214	TRACE_SEQ_CHECK_RET0(s);
215
216	while (s->len >= (s->buffer_size - 1))
217		expand_buffer(s);
218
219	TRACE_SEQ_CHECK_RET0(s);
220
221	s->buffer[s->len++] = c;
222
223	return 1;
224}
225
226void trace_seq_terminate(struct trace_seq *s)
227{
228	TRACE_SEQ_CHECK_RET(s);
229
230	/* There's always one character left on the buffer */
231	s->buffer[s->len] = 0;
232}
233
234int trace_seq_do_fprintf(struct trace_seq *s, FILE *fp)
235{
236	TRACE_SEQ_CHECK(s);
237
238	switch (s->state) {
239	case TRACE_SEQ__GOOD:
240		return fprintf(fp, "%.*s", s->len, s->buffer);
241	case TRACE_SEQ__BUFFER_POISONED:
242		fprintf(fp, "%s\n", "Usage of trace_seq after it was destroyed");
243		break;
244	case TRACE_SEQ__MEM_ALLOC_FAILED:
245		fprintf(fp, "%s\n", "Can't allocate trace_seq buffer memory");
246		break;
247	}
248	return -1;
249}
250
251int trace_seq_do_printf(struct trace_seq *s)
252{
253	return trace_seq_do_fprintf(s, stdout);
254}
255