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, write to the Free Software
 17 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 18 *
 19 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 20 */
 21#include <stdio.h>
 22#include <stdlib.h>
 23#include <string.h>
 24#include <stdarg.h>
 25
 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 ((s)->buffer == TRACE_SEQ_POISON)			\
 37		die("Usage of trace_seq after it was destroyed");	\
 38} while (0)
 39
 40/**
 41 * trace_seq_init - initialize the trace_seq structure
 42 * @s: a pointer to the trace_seq structure to initialize
 43 */
 44void trace_seq_init(struct trace_seq *s)
 45{
 46	s->len = 0;
 47	s->readpos = 0;
 48	s->buffer_size = TRACE_SEQ_BUF_SIZE;
 49	s->buffer = malloc_or_die(s->buffer_size);
 50}
 51
 52/**
 53 * trace_seq_destroy - free up memory of a trace_seq
 54 * @s: a pointer to the trace_seq to free the buffer
 55 *
 56 * Only frees the buffer, not the trace_seq struct itself.
 57 */
 58void trace_seq_destroy(struct trace_seq *s)
 59{
 60	if (!s)
 61		return;
 62	TRACE_SEQ_CHECK(s);
 63	free(s->buffer);
 64	s->buffer = TRACE_SEQ_POISON;
 65}
 66
 67static void expand_buffer(struct trace_seq *s)
 68{
 69	s->buffer_size += TRACE_SEQ_BUF_SIZE;
 70	s->buffer = realloc(s->buffer, s->buffer_size);
 71	if (!s->buffer)
 72		die("Can't allocate trace_seq buffer memory");
 73}
 74
 75/**
 76 * trace_seq_printf - sequence printing of trace information
 77 * @s: trace sequence descriptor
 78 * @fmt: printf format string
 79 *
 80 * It returns 0 if the trace oversizes the buffer's free
 81 * space, 1 otherwise.
 82 *
 83 * The tracer may use either sequence operations or its own
 84 * copy to user routines. To simplify formating of a trace
 85 * trace_seq_printf is used to store strings into a special
 86 * buffer (@s). Then the output may be either used by
 87 * the sequencer or pulled into another buffer.
 88 */
 89int
 90trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
 91{
 92	va_list ap;
 93	int len;
 94	int ret;
 95
 96	TRACE_SEQ_CHECK(s);
 97
 98 try_again:
 99	len = (s->buffer_size - 1) - s->len;
100
101	va_start(ap, fmt);
102	ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
103	va_end(ap);
104
105	if (ret >= len) {
106		expand_buffer(s);
107		goto try_again;
108	}
109
110	s->len += ret;
111
112	return 1;
113}
114
115/**
116 * trace_seq_vprintf - sequence printing of trace information
117 * @s: trace sequence descriptor
118 * @fmt: printf format string
119 *
120 * The tracer may use either sequence operations or its own
121 * copy to user routines. To simplify formating of a trace
122 * trace_seq_printf is used to store strings into a special
123 * buffer (@s). Then the output may be either used by
124 * the sequencer or pulled into another buffer.
125 */
126int
127trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
128{
129	int len;
130	int ret;
131
132	TRACE_SEQ_CHECK(s);
133
134 try_again:
135	len = (s->buffer_size - 1) - s->len;
136
137	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
138
139	if (ret >= len) {
140		expand_buffer(s);
141		goto try_again;
142	}
143
144	s->len += ret;
145
146	return len;
147}
148
149/**
150 * trace_seq_puts - trace sequence printing of simple string
151 * @s: trace sequence descriptor
152 * @str: simple string to record
153 *
154 * The tracer may use either the sequence operations or its own
155 * copy to user routines. This function records a simple string
156 * into a special buffer (@s) for later retrieval by a sequencer
157 * or other mechanism.
158 */
159int trace_seq_puts(struct trace_seq *s, const char *str)
160{
161	int len;
162
163	TRACE_SEQ_CHECK(s);
164
165	len = strlen(str);
166
167	while (len > ((s->buffer_size - 1) - s->len))
168		expand_buffer(s);
169
170	memcpy(s->buffer + s->len, str, len);
171	s->len += len;
172
173	return len;
174}
175
176int trace_seq_putc(struct trace_seq *s, unsigned char c)
177{
178	TRACE_SEQ_CHECK(s);
179
180	while (s->len >= (s->buffer_size - 1))
181		expand_buffer(s);
182
183	s->buffer[s->len++] = c;
184
185	return 1;
186}
187
188void trace_seq_terminate(struct trace_seq *s)
189{
190	TRACE_SEQ_CHECK(s);
191
192	/* There's always one character left on the buffer */
193	s->buffer[s->len] = 0;
194}
195
196int trace_seq_do_printf(struct trace_seq *s)
197{
198	TRACE_SEQ_CHECK(s);
199	return printf("%.*s", s->len, s->buffer);
200}