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SubjectRe: [PATCH 1/4] perf tools: remove sscanf extension %as
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Hi Irina,

(Adding Masami to Cc)

On Fri, 14 Sep 2012 01:07:40 +0300, Irina Tirdea wrote:
> From: Irina Tirdea <irina.tirdea@intel.com>
>
> perf uses sscanf extension %as to read and allocate a
> string in the same step. This is a non-standard extension
> only present in new versions of glibc.
>
> Replacing the use of sscanf and %as with strtok_r calls
> in order to parse a given string into its components.
> This is needed in Android since bionic does not support
> %as extension for sscanf.
>
> Signed-off-by: Irina Tirdea <irina.tirdea@intel.com>
> ---
> tools/perf/util/probe-event.c | 25 ++++++++++++++++++-------
> tools/perf/util/trace-event-parse.c | 18 ++++++++----------
> 2 files changed, 26 insertions(+), 17 deletions(-)
>
> diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
> index 4ce04c2..685ddcf 100644
> --- a/tools/perf/util/probe-event.c
> +++ b/tools/perf/util/probe-event.c
> @@ -1100,6 +1100,7 @@ static int parse_probe_trace_command(const char *cmd,
> struct probe_trace_point *tp = &tev->point;
> char pr;
> char *p;
> + char *argv0_str = NULL, *fmt, *fmt1_str, *fmt2_str, *fmt3_str;
> int ret, i, argc;
> char **argv;
>
> @@ -1116,14 +1117,19 @@ static int parse_probe_trace_command(const char *cmd,
> }
>
> /* Scan event and group name. */
> - ret = sscanf(argv[0], "%c:%a[^/ \t]/%a[^ \t]",
> - &pr, (float *)(void *)&tev->group,
> - (float *)(void *)&tev->event);
> - if (ret != 3) {
> + argv0_str = strdup(argv[0]);

It seems you need to check return value of strdup.


> + fmt1_str = strtok_r(argv0_str, ":", &fmt);
> + fmt2_str = strtok_r(NULL, "/", &fmt);
> + fmt3_str = strtok_r(NULL, " \t", &fmt);
> + if (fmt1_str == NULL || strlen(fmt1_str) != 1 || fmt2_str == NULL
> + || fmt3_str == NULL) {
> semantic_error("Failed to parse event name: %s\n", argv[0]);
> ret = -EINVAL;
> goto out;
> }
> + pr = fmt1_str[0];
> + tev->group = strdup(fmt2_str);
> + tev->event = strdup(fmt3_str);
> pr_debug("Group:%s Event:%s probe:%c\n", tev->group, tev->event, pr);
>
> tp->retprobe = (pr == 'r');
> @@ -1135,10 +1141,13 @@ static int parse_probe_trace_command(const char *cmd,
> p++;
> } else
> p = argv[1];
> - ret = sscanf(p, "%a[^+]+%lu", (float *)(void *)&tp->symbol,
> - &tp->offset);
> - if (ret == 1)
> + fmt1_str = strtok_r(p, "+", &fmt);
> + tp->symbol = strdup(fmt1_str);

Probably here too - although the original code didn't but I think it's
needed.


> + fmt2_str = strtok_r(NULL, "", &fmt);
> + if (fmt2_str == NULL)
> tp->offset = 0;
> + else
> + tp->offset = strtoul(fmt2_str, NULL, 10);
>
> tev->nargs = argc - 2;
> tev->args = zalloc(sizeof(struct probe_trace_arg) * tev->nargs);
> @@ -1162,6 +1171,8 @@ static int parse_probe_trace_command(const char *cmd,
> }
> ret = 0;
> out:
> + if (argv0_str)
> + free(argv0_str);

The free() can handle a NULL pointer safely.


> argv_free(argv);
> return ret;
> }


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