[ltt-dev] [PATCH take2 06/13] introduce ltt_serialize_printf()
Mathieu Desnoyers
compudj at krystal.dyndns.org
Mon Feb 23 13:15:31 EST 2009
* Lai Jiangshan (laijs at cn.fujitsu.com) wrote:
> introduce ltt_serialize_printf() for format binary data which is in
> ltt-relay buffer to human readable text string.
>
> Signed-off-by: Lai Jiangshan <laijs at cn.fujitsu.com>
> ---
> diff --git a/include/linux/ltt-tracer.h b/include/linux/ltt-tracer.h
> index 42fc47d..7cb8f14 100644
> --- a/include/linux/ltt-tracer.h
> +++ b/include/linux/ltt-tracer.h
> @@ -118,6 +118,9 @@ extern void ltt_vtrace(const struct marker *mdata, void *probe_data,
> extern void ltt_trace(const struct marker *mdata, void *probe_data,
> void *call_data, const char *fmt, ...);
>
> +size_t ltt_serialize_printf(struct rchan_buf *buf, size_t buf_offset,
> + u32 *msg_size, char *output, size_t outlen, const char *fmt);
> +
> /*
> * Unique ID assigned to each registered probe.
> */
> diff --git a/ltt/ltt-serialize.c b/ltt/ltt-serialize.c
> index 0ca6683..b1e9f7e 100644
> --- a/ltt/ltt-serialize.c
> +++ b/ltt/ltt-serialize.c
> @@ -227,7 +227,7 @@ parse_end:
> * %n not supported.
> */
> static inline const char *parse_c_type(const char *fmt,
> - char *c_size, enum ltt_type *c_type)
> + char *c_size, enum ltt_type *c_type, char *outfmt)
> {
> int qualifier; /* 'h', 'l', or 'L' for integer fields */
> /* 'z' support added 23/7/1999 S.H. */
> @@ -259,6 +259,13 @@ repeat:
> }
> }
>
> + if (outfmt) {
> + if (qualifier != -1)
> + *outfmt++ = (char)qualifier;
> + *outfmt++ = *fmt;
> + *outfmt = 0;
> + }
> +
> switch (*fmt) {
> case 'c':
> *c_type = LTT_TYPE_UNSIGNED_INT;
> @@ -502,7 +509,7 @@ notrace size_t ltt_serialize_data(struct rchan_buf *buf, size_t buf_offset,
> ++fmt; /* skip first '%' */
> if (*fmt == '%') /* Escaped %% */
> break;
> - fmt = parse_c_type(fmt, &c_size, &c_type);
> + fmt = parse_c_type(fmt, &c_size, &c_type, NULL);
> /*
> * Output c types if no trace types has been
> * specified.
> @@ -573,6 +580,118 @@ static inline uint64_t unserialize_base_type(struct rchan_buf *buf,
> return 0;
> }
>
> +static inline int serialize_printf_data(struct rchan_buf *buf, size_t *ppos,
> + char trace_size, enum ltt_type trace_type,
> + char c_size, enum ltt_type c_type,
> + char *output, size_t outlen, const char *outfmt)
> +{
> + u64 value;
> + outlen = (ssize_t)outlen < 0 ? 0 : outlen;
> +
> + if (trace_type == LTT_TYPE_STRING) {
> + size_t len = ltt_relay_read_cstr(buf, *ppos, output, outlen);
> + *ppos += len + 1;
> + return len;
> + }
> +
> + value = unserialize_base_type(buf, ppos, trace_size, trace_type);
> +
> + if (c_size == 8)
> + return snprintf(output, outlen, outfmt, value);
> + else
> + return snprintf(output, outlen, outfmt, (unsigned int)value);
> +}
> +
> +/**
> + * ltt_serialize_printf - Format a string and place it in a buffer
> + * @buf: The ltt-relay buffer that store binary data
> + * @buf_offset: binary data's offset in @buf
> + * @msg_size: return message's length
> + * @output: The buffer to place the result into
> + * @outlen: The size of the buffer, including the trailing null space
Maybe this header should describe that outlen can have a negative ssize_t
value ? And then what does that mean ? Why are we doing a max_t at the
beginning of ltt_serialize_printf ?
> + * @fmt: The format string to use
> + *
> + * The return value is the number of characters which would
> + * be generated for the given input, excluding the trailing
> + * '\0', as per ISO C99. If the return is greater than or equal to @size,
Do you mean @outlen ?
> + * the resulting string is truncated.
> + */
> +size_t ltt_serialize_printf(struct rchan_buf *buf, size_t buf_offset,
> + u32 *msg_size, char *output, size_t outlen, const char *fmt)
> +{
> + char trace_size = 0, c_size = 0; /*
> + * 0 (unset), 1, 2, 4, 8 bytes.
> + */
> + enum ltt_type trace_type = LTT_TYPE_NONE, c_type = LTT_TYPE_NONE;
> + unsigned long attributes = 0;
> + char outfmt[4] = "%";
> + size_t outpos = 0;
> + size_t len;
> + size_t msgpos = buf_offset;
> + outlen = max_t(ssize_t, 0, outlen);
> +
> + for (; *fmt ; ++fmt) {
> + switch (*fmt) {
> + case '#':
> + /* tracetypes (#) */
> + ++fmt; /* skip first '#' */
> + if (*fmt == '#') { /* Escaped ## */
> + if (outpos < outlen)
> + output[outpos] = '#';
Does outlen contain the final \0 ? Where is this \0 written to the
output ? And I worry about off-by-one here.
Mathieu
> + outpos++;
> + break;
> + }
> + attributes = 0;
> + fmt = parse_trace_type(fmt, &trace_size, &trace_type,
> + &attributes);
> + break;
> + case '%':
> + /* c types (%) */
> + ++fmt; /* skip first '%' */
> + if (*fmt == '%') { /* Escaped %% */
> + if (outpos < outlen)
> + output[outpos] = '%';
> + outpos++;
> + break;
> + }
> + fmt = parse_c_type(fmt, &c_size, &c_type, outfmt + 1);
> + /*
> + * Output c types if no trace types has been
> + * specified.
> + */
> + if (!trace_size)
> + trace_size = c_size;
> + if (trace_type == LTT_TYPE_NONE)
> + trace_type = c_type;
> + if (c_type == LTT_TYPE_STRING)
> + trace_type = LTT_TYPE_STRING;
> +
> + /* perform trace printf */
> + len = serialize_printf_data(buf, &msgpos, trace_size,
> + trace_type, c_size, c_type,
> + output + outpos, outlen - outpos,
> + outfmt);
> + outpos += len;
> + trace_size = 0;
> + c_size = 0;
> + trace_type = LTT_TYPE_NONE;
> + c_size = LTT_TYPE_NONE;
> + attributes = 0;
> + break;
> + default:
> + if (outpos < outlen)
> + output[outpos] = *fmt;
> + outpos++;
> + break;
> + }
> + }
> + if (msg_size)
> + *msg_size = msgpos - buf_offset;
> +
> + return outpos;
> +}
> +EXPORT_SYMBOL_GPL(ltt_serialize_printf);
> +
> /*
> * Calculate data size
> * Assume that the padding for alignment starts at a sizeof(void *) address.
>
>
>
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>
--
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68
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