[PATCH v3] tools lib traceevent: Take care of return value of asprintf

From: zhe.he
Date: Wed Feb 19 2020 - 21:01:05 EST


From: He Zhe <zhe.he@xxxxxxxxxxxxx>

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 âasprintfâ, declared with attribute warn_unused_result [-Wunused-result]

Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
---
v2: directly check the return value without saving to a variable
v3: as asked, not remove those that already save the return value

tools/lib/traceevent/parse-filter.c | 29 +++++++++++++++++++----------
1 file changed, 19 insertions(+), 10 deletions(-)

diff --git a/tools/lib/traceevent/parse-filter.c b/tools/lib/traceevent/parse-filter.c
index 20eed71..c271aee 100644
--- a/tools/lib/traceevent/parse-filter.c
+++ b/tools/lib/traceevent/parse-filter.c
@@ -1958,7 +1958,8 @@ 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 +1977,8 @@ 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 +1994,12 @@ 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 +2015,8 @@ 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 +2074,8 @@ 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 +2119,8 @@ 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 +2155,9 @@ 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 +2173,8 @@ 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