Re: [PATCH 1/4] tools lib traceevent: Add state member to struct trace_seq

[Namhyung Kim]

Ping!

On Thu, 19 Dec 2013 18:34:23 +0900, Namhyung Kim wrote:
> From: Namhyung Kim <namhyung.kim@xxxxxxx>
>
> The trace_seq->state is for tracking errors during the use of
> trace_seq APIs and getting rid of die() in it.
>
> Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> ---
>  tools/lib/traceevent/event-parse.h |  7 +++++++
>  tools/lib/traceevent/trace-seq.c   | 41 ++++++++++++++++++++++++++++++++++----
>  2 files changed, 44 insertions(+), 4 deletions(-)
>
> diff --git a/tools/lib/traceevent/event-parse.h b/tools/lib/traceevent/event-parse.h
> index cf5db9013f2c..3c890cb28db7 100644
> --- a/tools/lib/traceevent/event-parse.h
> +++ b/tools/lib/traceevent/event-parse.h
> @@ -58,6 +58,12 @@ struct pevent_record {
>  #endif
>  };
>  
> +enum trace_seq_fail {
> +	TRACE_SEQ__GOOD,
> +	TRACE_SEQ__BUFFER_POISONED,
> +	TRACE_SEQ__MEM_ALLOC_FAILED,
> +};
> +
>  /*
>   * Trace sequences are used to allow a function to call several other functions
>   * to create a string of data to use (up to a max of PAGE_SIZE).
> @@ -68,6 +74,7 @@ struct trace_seq {
>  	unsigned int		buffer_size;
>  	unsigned int		len;
>  	unsigned int		readpos;
> +	enum trace_seq_fail	state;
>  };
>  
>  void trace_seq_init(struct trace_seq *s);
> diff --git a/tools/lib/traceevent/trace-seq.c b/tools/lib/traceevent/trace-seq.c
> index d7f2e68bc5b9..976ad2a146b3 100644
> --- a/tools/lib/traceevent/trace-seq.c
> +++ b/tools/lib/traceevent/trace-seq.c
> @@ -32,8 +32,8 @@
>  #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");	\
> +	if ((s)->buffer == TRACE_SEQ_POISON)				\
> +		(s)->state = TRACE_SEQ__BUFFER_POISONED;		\
>  } while (0)
>  
>  /**
> @@ -46,6 +46,7 @@ void trace_seq_init(struct trace_seq *s)
>  	s->readpos = 0;
>  	s->buffer_size = TRACE_SEQ_BUF_SIZE;
>  	s->buffer = malloc_or_die(s->buffer_size);
> +	s->state = TRACE_SEQ__GOOD;
>  }
>  
>  /**
> @@ -81,7 +82,7 @@ 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");
> +		s->state = TRACE_SEQ__MEM_ALLOC_FAILED;
>  }
>  
>  /**
> @@ -108,6 +109,9 @@ trace_seq_printf(struct trace_seq *s, const char *fmt, ...)
>  	TRACE_SEQ_CHECK(s);
>  
>   try_again:
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return 0;
> +
>  	len = (s->buffer_size - 1) - s->len;
>  
>  	va_start(ap, fmt);
> @@ -144,6 +148,9 @@ trace_seq_vprintf(struct trace_seq *s, const char *fmt, va_list args)
>  	TRACE_SEQ_CHECK(s);
>  
>   try_again:
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return 0;
> +
>  	len = (s->buffer_size - 1) - s->len;
>  
>  	ret = vsnprintf(s->buffer + s->len, len, fmt, args);
> @@ -174,11 +181,17 @@ int trace_seq_puts(struct trace_seq *s, const char *str)
>  
>  	TRACE_SEQ_CHECK(s);
>  
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return 0;
> +
>  	len = strlen(str);
>  
>  	while (len > ((s->buffer_size - 1) - s->len))
>  		expand_buffer(s);
>  
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return 0;
> +
>  	memcpy(s->buffer + s->len, str, len);
>  	s->len += len;
>  
> @@ -189,9 +202,15 @@ int trace_seq_putc(struct trace_seq *s, unsigned char c)
>  {
>  	TRACE_SEQ_CHECK(s);
>  
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return 0;
> +
>  	while (s->len >= (s->buffer_size - 1))
>  		expand_buffer(s);
>  
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return 0;
> +
>  	s->buffer[s->len++] = c;
>  
>  	return 1;
> @@ -201,6 +220,9 @@ void trace_seq_terminate(struct trace_seq *s)
>  {
>  	TRACE_SEQ_CHECK(s);
>  
> +	if (s->state != TRACE_SEQ__GOOD)
> +		return;
> +
>  	/* There's always one character left on the buffer */
>  	s->buffer[s->len] = 0;
>  }
> @@ -208,5 +230,16 @@ void trace_seq_terminate(struct trace_seq *s)
>  int trace_seq_do_printf(struct trace_seq *s)
>  {
>  	TRACE_SEQ_CHECK(s);
> -	return printf("%.*s", s->len, s->buffer);
> +
> +	switch (s->state) {
> +	case TRACE_SEQ__GOOD:
> +		return printf("%.*s", s->len, s->buffer);
> +	case TRACE_SEQ__BUFFER_POISONED:
> +		puts("Usage of trace_seq after it was destroyed");
> +		break;
> +	case TRACE_SEQ__MEM_ALLOC_FAILED:
> +		puts("Can't allocate trace_seq buffer memory");
> +		break;
> +	}
> +	return -1;
>  }
--
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