trace-seq.c

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/*
 * Copyright (C) 2009 Red Hat Inc, Steven Rostedt <[email protected]>
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation;
 * version 2.1 of the License (not later!)
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>

#include "event-parse.h"
#include "event-utils.h"

/*
 * The TRACE_SEQ_POISON is to catch the use of using
 * a trace_seq structure after it was destroyed.
 */
#define TRACE_SEQ_POISON    ((void *)0xdeadbeef)
#define TRACE_SEQ_CHECK(s)                      \
do {                                    \
    if ((s)->buffer == TRACE_SEQ_POISON)            \
        die("Usage of trace_seq after it was destroyed");   \
} while (0)

void trace_seq_init(struct trace_seq *s)
{
    s->len = 0;
    s->readpos = 0;
    s->buffer_size = TRACE_SEQ_BUF_SIZE;
    s->buffer = malloc_or_die(s->buffer_size);
}

void trace_seq_destroy(struct trace_seq *s)
{
    if (!s)
        return;
    TRACE_SEQ_CHECK(s);
    free(s->buffer);
    s->buffer = TRACE_SEQ_POISON;
}

static void expand_buffer(struct trace_seq *s)
{
    s->buffer_size += TRACE_SEQ_BUF_SIZE;
    s->buffer = realloc(s->buffer, s->buffer_size);
    if (!s->buffer)
        die("Can't allocate trace_seq buffer memory");
}

int
trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
{
    va_list ap;
    int len;
    int ret;

    TRACE_SEQ_CHECK(s);

 try_again:
    len = (s->buffer_size - 1) - s->len;

    va_start(ap, fmt);
    ret = vsnprintf(s->buffer + s->len, len, fmt, ap);
    va_end(ap);

    if (ret >= len) {
        expand_buffer(s);
        goto try_again;
    }

    s->len += ret;

    return 1;
}

int
trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
{
    int len;
    int ret;

    TRACE_SEQ_CHECK(s);

 try_again:
    len = (s->buffer_size - 1) - s->len;

    ret = vsnprintf(s->buffer + s->len, len, fmt, args);

    if (ret >= len) {
        expand_buffer(s);
        goto try_again;
    }

    s->len += ret;

    return len;
}

int trace_seq_puts(struct trace_seq *s, const char *str)
{
    int len;

    TRACE_SEQ_CHECK(s);

    len = strlen(str);

    while (len > ((s->buffer_size - 1) - s->len))
        expand_buffer(s);

    memcpy(s->buffer + s->len, str, len);
    s->len += len;

    return len;
}

int trace_seq_putc(struct trace_seq *s, unsigned char c)
{
    TRACE_SEQ_CHECK(s);

    while (s->len >= (s->buffer_size - 1))
        expand_buffer(s);

    s->buffer[s->len++] = c;

    return 1;
}

void trace_seq_terminate(struct trace_seq *s)
{
    TRACE_SEQ_CHECK(s);

    /* There's always one character left on the buffer */
    s->buffer[s->len] = 0;
}

int trace_seq_do_printf(struct trace_seq *s)
{
    TRACE_SEQ_CHECK(s);
    return printf("%.*s", s->len, s->buffer);
}