> From: Chengwen Feng [mailto:fengcheng...@huawei.com]
> Sent: Friday, 17 June 2022 11.46
>
> This patch supports escape special characters (including: \",\\,/,\b,
> /f,/n,/r,/t) when telemetry string.
> This patch is used to support telemetry xxx-dump commands which the
> string may include special characters.
>
> Signed-off-by: Chengwen Feng <fengcheng...@huawei.com>
> ---
> lib/telemetry/telemetry.c | 96 +++++++++++++++++++++++++++++++++++++--
> 1 file changed, 93 insertions(+), 3 deletions(-)
>
> diff --git a/lib/telemetry/telemetry.c b/lib/telemetry/telemetry.c
> index c6fd03a5ab..0f762f633e 100644
> --- a/lib/telemetry/telemetry.c
> +++ b/lib/telemetry/telemetry.c
> @@ -215,6 +215,94 @@ container_to_json(const struct rte_tel_data *d,
> char *out_buf, size_t buf_len)
> return used;
> }
>
> +static bool
> +json_is_special_char(char ch)
> +{
> + static unsigned char is_spec[256] = { 0 };
> + static bool init_once;
> +
> + if (!init_once) {
> + is_spec['\"'] = 1;
> + is_spec['\\'] = 1;
> + is_spec['/'] = 1;
> + is_spec['\b'] = 1;
> + is_spec['\f'] = 1;
> + is_spec['\n'] = 1;
> + is_spec['\r'] = 1;
> + is_spec['\t'] = 1;
> + init_once = true;
> + }
> +
> + return (bool)is_spec[(unsigned char)ch];
> +}
Here's a suggestion for simplifying the code:
Remove json_is_special_char(), and update json_escape_special_char() and
json_format_string() as follows:
> +
> +static size_t
> +json_escape_special_char(char *buf, const char ch)
Consider making this function inline.
> +{
> + size_t used = 0;
> +
> + switch (ch) {
> + case '\"':
> + buf[used++] = '\\';
> + buf[used++] = '\"';
> + break;
> + case '\\':
> + buf[used++] = '\\';
> + buf[used++] = '\\';
> + break;
> + case '/':
> + buf[used++] = '\\';
> + buf[used++] = '/';
> + break;
> + case '\b':
> + buf[used++] = '\\';
> + buf[used++] = 'b';
> + break;
> + case '\f':
> + buf[used++] = '\\';
> + buf[used++] = 'f';
> + break;
> + case '\n':
> + buf[used++] = '\\';
> + buf[used++] = 'n';
> + break;
> + case '\r':
> + buf[used++] = '\\';
> + buf[used++] = 'r';
> + break;
> + case '\t':
> + buf[used++] = '\\';
> + buf[used++] = 't';
> + break;
> + default:
Handle non-escaped characters in the default case here instead:
+ buf[used++] = ch;
> + break;
> + }
> +
> + return used;
> +}
> +
> +static size_t
> +json_format_string(char *buf, size_t len, const char *str)
> +{
> + size_t used = 0;
> +
> + while (*str) {
> + if (unlikely(len < used + 2)) {
> + TMTY_LOG(WARNING, "Insufficient buffer when json
> format string\n");
> + break;
> + }
> +
-- replace:
> + if (json_is_special_char(*str))
> + used += json_escape_special_char(buf + used, *str);
> + else
> + buf[used++] = *str;
> +
> + str++;
-- by:
+ used += json_escape_special_char(buf + used, *str++);
--
End of suggestion. Feel free to use it or not. :-)
> + }
> +
> + return used;
> +}
> +
> static void
> output_json(const char *cmd, const struct rte_tel_data *d, int s)
> {
> @@ -232,9 +320,11 @@ output_json(const char *cmd, const struct
> rte_tel_data *d, int s)
> MAX_CMD_LEN, cmd ? cmd : "none");
> break;
> case RTE_TEL_STRING:
> - used = snprintf(out_buf, sizeof(out_buf),
> "{\"%.*s\":\"%.*s\"}",
> - MAX_CMD_LEN, cmd,
> - RTE_TEL_MAX_SINGLE_STRING_LEN, d->data.str);
> + used = snprintf(out_buf, sizeof(out_buf), "{\"%.*s\":\"",
> + MAX_CMD_LEN, cmd);
> + used += json_format_string(out_buf + used,
> + sizeof(out_buf) - used - 3, d->data.str);
> + used += snprintf(out_buf + used, sizeof(out_buf) - used,
> "\"}");
I looked for missing 0-termination in json_format_string(), but that is not
required due to the immediately following snprintf().
> break;
> case RTE_TEL_DICT:
> prefix_used = snprintf(out_buf, sizeof(out_buf),
> "{\"%.*s\":",
> --
> 2.33.0
>
If you want to make it generic, these four cases in output_json() also need to
JSON encode the strings:
case RTE_TEL_DICT:
case RTE_TEL_STRING_VAL: ...
case RTE_TEL_CONTAINER: ... (strings only)
case RTE_TEL_ARRAY_STRING:
if (d->type == RTE_TEL_ARRAY_STRING) ...
else if (d->type == RTE_TEL_ARRAY_CONTAINER) ... (strings only)
However, JSON encoding of strings inside arrays and containers is not required
for the dump purposes addressed by this patch series, so I consider this patch
complete without it. No need to add "feature creep" to this series.
Reviewed-by: Morten Brørup <m...@smartsharesystems.com>
