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TOMOYO Linux Cross Reference
Linux/tools/lib/traceevent/trace-seq.c

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  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)                                              \
 35 do {                                                                    \
 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)             \
 42 do {                                            \
 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  */
 55 void 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  */
 71 void 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  */
 86 void 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 
 95 static 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  */
123 int
124 trace_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  */
160 int
161 trace_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  */
193 int 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 
212 int 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 
226 void 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 
234 int trace_seq_do_printf(struct trace_seq *s)
235 {
236         TRACE_SEQ_CHECK(s);
237 
238         switch (s->state) {
239         case TRACE_SEQ__GOOD:
240                 return printf("%.*s", s->len, s->buffer);
241         case TRACE_SEQ__BUFFER_POISONED:
242                 puts("Usage of trace_seq after it was destroyed");
243                 break;
244         case TRACE_SEQ__MEM_ALLOC_FAILED:
245                 puts("Can't allocate trace_seq buffer memory");
246                 break;
247         }
248         return -1;
249 }
250 

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