2020-02-14 13:24:56

by He Zhe

Subject: [PATCH v2] tools lib traceevent: Take care of return value of asprintf

From: He Zhe <[email protected]>

According to the API, if memory allocation wasn't possible, or some other
error occurs, asprintf will return -1, and the contents of strp below are
undefined.

int asprintf(char **strp, const char *fmt, ...);

This patch takes care of return value of asprintf to make it less error
prone and prevent the following build warning.

ignoring return value of ‘asprintf’, declared with attribute warn_unused_result [-Wunused-result]

Signed-off-by: He Zhe <[email protected]>
---
v2: directly check the return value without saving to a variable

tools/lib/traceevent/parse-filter.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)

diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index 20eed71..6cd0228 100644
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -274,8 +274,7 @@ find_event(struct tep_handle *tep, struct event_list **events,
sys_name = NULL;
}

- ret = asprintf(&reg, "^%s$", event_name);
- if (ret < 0)
+ if (asprintf(&reg, "^%s$", event_name) < 0)
return TEP_ERRNO__MEM_ALLOC_FAILED;

ret = regcomp(&ereg, reg, REG_ICASE|REG_NOSUB);
@@ -285,8 +284,7 @@ find_event(struct tep_handle *tep, struct event_list **events,
return TEP_ERRNO__INVALID_EVENT_NAME;

if (sys_name) {
- ret = asprintf(&reg, "^%s$", sys_name);
- if (ret < 0) {
+ if (asprintf(&reg, "^%s$", sys_name) < 0) {
regfree(&ereg);
return TEP_ERRNO__MEM_ALLOC_FAILED;
}
@@ -1958,7 +1956,8 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
default:
break;
}
- asprintf(&str, val ? "TRUE" : "FALSE");
+ if (asprintf(&str, val ? "TRUE" : "FALSE") < 0)
+ str = NULL;
break;
}
}
@@ -1976,7 +1975,8 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
break;
}

- asprintf(&str, "(%s) %s (%s)", left, op, right);
+ if (asprintf(&str, "(%s) %s (%s)", left, op, right) < 0)
+ str = NULL;
break;

case TEP_FILTER_OP_NOT:
@@ -1992,10 +1992,12 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
right_val = 0;
if (right_val >= 0) {
/* just return the opposite */
- asprintf(&str, right_val ? "FALSE" : "TRUE");
+ if (asprintf(&str, right_val ? "FALSE" : "TRUE") < 0)
+ str = NULL;
break;
}
- asprintf(&str, "%s(%s)", op, right);
+ if (asprintf(&str, "%s(%s)", op, right) < 0)
+ str = NULL;
break;

default:
@@ -2011,7 +2013,8 @@ static char *val_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
{
char *str = NULL;

- asprintf(&str, "%lld", arg->value.val);
+ if (asprintf(&str, "%lld", arg->value.val) < 0)
+ str = NULL;

return str;
}
@@ -2069,7 +2072,8 @@ static char *exp_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
break;
}

- asprintf(&str, "%s %s %s", lstr, op, rstr);
+ if (asprintf(&str, "%s %s %s", lstr, op, rstr) < 0)
+ str = NULL;
out:
free(lstr);
free(rstr);
@@ -2113,7 +2117,8 @@ static char *num_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
if (!op)
op = "<=";

- asprintf(&str, "%s %s %s", lstr, op, rstr);
+ if (asprintf(&str, "%s %s %s", lstr, op, rstr) < 0)
+ str = NULL;
break;

default:
@@ -2148,8 +2153,9 @@ static char *str_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
if (!op)
op = "!~";

- asprintf(&str, "%s %s \"%s\"",
- arg->str.field->name, op, arg->str.val);
+ if (asprintf(&str, "%s %s \"%s\"",
+ arg->str.field->name, op, arg->str.val) < 0)
+ str = NULL;
break;

default:
@@ -2165,7 +2171,8 @@ static char *arg_to_str(struct tep_event_filter *filter, struct tep_filter_arg *

switch (arg->type) {
case TEP_FILTER_ARG_BOOLEAN:
- asprintf(&str, arg->boolean.value ? "TRUE" : "FALSE");
+ if (asprintf(&str, arg->boolean.value ? "TRUE" : "FALSE") < 0)
+ str = NULL;
return str;

case TEP_FILTER_ARG_OP:
--
2.7.4

2020-02-17 15:54:11

by Arnaldo Carvalho de Melo

Subject: Re: [PATCH v2] tools lib traceevent: Take care of return value of asprintf

Em Fri, Feb 14, 2020 at 09:21:21PM +0800, [email protected] escreveu:
> From: He Zhe <[email protected]>
>
> According to the API, if memory allocation wasn't possible, or some other
> error occurs, asprintf will return -1, and the contents of strp below are
> undefined.

Rostedt, did I miss some ack from you?

- Arnaldo

> int asprintf(char **strp, const char *fmt, ...);
>
> This patch takes care of return value of asprintf to make it less error
> prone and prevent the following build warning.
>
> ignoring return value of ‘asprintf’, declared with attribute warn_unused_result [-Wunused-result]
>
> Signed-off-by: He Zhe <[email protected]>
> ---
> v2: directly check the return value without saving to a variable
>
> tools/lib/traceevent/parse-filter.c | 35 +++++++++++++++++++++--------------
> 1 file changed, 21 insertions(+), 14 deletions(-)
>
> diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
> index 20eed71..6cd0228 100644
> --- a/tools/lib/traceevent/parse-filter.c
> +++ b/tools/lib/traceevent/parse-filter.c
> @@ -274,8 +274,7 @@ find_event(struct tep_handle *tep, struct event_list **events,
> sys_name = NULL;
> }
>
> - ret = asprintf(&reg, "^%s$", event_name);
> - if (ret < 0)
> + if (asprintf(&reg, "^%s$", event_name) < 0)
> return TEP_ERRNO__MEM_ALLOC_FAILED;
>
> ret = regcomp(&ereg, reg, REG_ICASE|REG_NOSUB);
> @@ -285,8 +284,7 @@ find_event(struct tep_handle *tep, struct event_list **events,
> return TEP_ERRNO__INVALID_EVENT_NAME;
>
> if (sys_name) {
> - ret = asprintf(&reg, "^%s$", sys_name);
> - if (ret < 0) {
> + if (asprintf(&reg, "^%s$", sys_name) < 0) {
> regfree(&ereg);
> return TEP_ERRNO__MEM_ALLOC_FAILED;
> }
> @@ -1958,7 +1956,8 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
> default:
> break;
> }
> - asprintf(&str, val ? "TRUE" : "FALSE");
> + if (asprintf(&str, val ? "TRUE" : "FALSE") < 0)
> + str = NULL;
> break;
> }
> }
> @@ -1976,7 +1975,8 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
> break;
> }
>
> - asprintf(&str, "(%s) %s (%s)", left, op, right);
> + if (asprintf(&str, "(%s) %s (%s)", left, op, right) < 0)
> + str = NULL;
> break;
>
> case TEP_FILTER_OP_NOT:
> @@ -1992,10 +1992,12 @@ static char *op_to_str(struct tep_event_filter *filter, struct tep_filter_arg *a
> right_val = 0;
> if (right_val >= 0) {
> /* just return the opposite */
> - asprintf(&str, right_val ? "FALSE" : "TRUE");
> + if (asprintf(&str, right_val ? "FALSE" : "TRUE") < 0)
> + str = NULL;
> break;
> }
> - asprintf(&str, "%s(%s)", op, right);
> + if (asprintf(&str, "%s(%s)", op, right) < 0)
> + str = NULL;
> break;
>
> default:
> @@ -2011,7 +2013,8 @@ static char *val_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> {
> char *str = NULL;
>
> - asprintf(&str, "%lld", arg->value.val);
> + if (asprintf(&str, "%lld", arg->value.val) < 0)
> + str = NULL;
>
> return str;
> }
> @@ -2069,7 +2072,8 @@ static char *exp_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> break;
> }
>
> - asprintf(&str, "%s %s %s", lstr, op, rstr);
> + if (asprintf(&str, "%s %s %s", lstr, op, rstr) < 0)
> + str = NULL;
> out:
> free(lstr);
> free(rstr);
> @@ -2113,7 +2117,8 @@ static char *num_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> if (!op)
> op = "<=";
>
> - asprintf(&str, "%s %s %s", lstr, op, rstr);
> + if (asprintf(&str, "%s %s %s", lstr, op, rstr) < 0)
> + str = NULL;
> break;
>
> default:
> @@ -2148,8 +2153,9 @@ static char *str_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
> if (!op)
> op = "!~";
>
> - asprintf(&str, "%s %s \"%s\"",
> - arg->str.field->name, op, arg->str.val);
> + if (asprintf(&str, "%s %s \"%s\"",
> + arg->str.field->name, op, arg->str.val) < 0)
> + str = NULL;
> break;
>
> default:
> @@ -2165,7 +2171,8 @@ static char *arg_to_str(struct tep_event_filter *filter, struct tep_filter_arg *
>
> switch (arg->type) {
> case TEP_FILTER_ARG_BOOLEAN:
> - asprintf(&str, arg->boolean.value ? "TRUE" : "FALSE");
> + if (asprintf(&str, arg->boolean.value ? "TRUE" : "FALSE") < 0)
> + str = NULL;
> return str;
>
> case TEP_FILTER_ARG_OP:
> --
> 2.7.4

2020-02-19 19:53:19

by Steven Rostedt

Subject: Re: [PATCH v2] tools lib traceevent: Take care of return value of asprintf

On Fri, 14 Feb 2020 21:21:21 +0800
<[email protected]> wrote:

> From: He Zhe <[email protected]>
>
> According to the API, if memory allocation wasn't possible, or some other
> error occurs, asprintf will return -1, and the contents of strp below are
> undefined.
>
> int asprintf(char **strp, const char *fmt, ...);
>
> This patch takes care of return value of asprintf to make it less error
> prone and prevent the following build warning.
>
> ignoring return value of ‘asprintf’, declared with attribute warn_unused_result [-Wunused-result]
>
> Signed-off-by: He Zhe <[email protected]>
> ---
> v2: directly check the return value without saving to a variable
>
> tools/lib/traceevent/parse-filter.c | 35 +++++++++++++++++++++--------------
> 1 file changed, 21 insertions(+), 14 deletions(-)
>
> diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
> index 20eed71..6cd0228 100644
> --- a/tools/lib/traceevent/parse-filter.c
> +++ b/tools/lib/traceevent/parse-filter.c
> @@ -274,8 +274,7 @@ find_event(struct tep_handle *tep, struct event_list **events,
> sys_name = NULL;
> }
>
> - ret = asprintf(&reg, "^%s$", event_name);
> - if (ret < 0)
> + if (asprintf(&reg, "^%s$", event_name) < 0)

I know Arnaldo said you don't need to save the return value for the
check, but let's just modify the asprintf() that needs checking, and
not remove those that already save it.

Thanks!

-- Steve