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Message-ID: <20260106133655.249887-6-wander@redhat.com>
Date: Tue, 6 Jan 2026 08:49:41 -0300
From: Wander Lairson Costa <wander@...hat.com>
To: Steven Rostedt <rostedt@...dmis.org>,
Tomas Glozar <tglozar@...hat.com>,
Wander Lairson Costa <wander@...hat.com>,
Ivan Pravdin <ipravdin.official@...il.com>,
Crystal Wood <crwood@...hat.com>,
Costa Shulyupin <costa.shul@...hat.com>,
John Kacur <jkacur@...hat.com>,
Tiezhu Yang <yangtiezhu@...ngson.cn>,
linux-trace-kernel@...r.kernel.org (open list:Real-time Linux Analysis (RTLA) tools),
linux-kernel@...r.kernel.org (open list:Real-time Linux Analysis (RTLA) tools),
bpf@...r.kernel.org (open list:BPF [MISC]:Keyword:(?:\b|_)bpf(?:\b|_))
Subject: [PATCH v2 05/18] rtla: Simplify argument parsing
The actions_parse() function uses open-coded logic to extract arguments
from a string. This includes manual length checks and strncmp() calls,
which can be verbose and error-prone.
To simplify and improve the robustness of argument parsing, introduce a
new extract_arg() helper macro. This macro extracts the value from a
"key=value" pair, making the code more concise and readable.
Also, introduce STRING_LENGTH() and strncmp_static() macros to
perform compile-time calculations of string lengths and safer string
comparisons.
Refactor actions_parse() to use these new helpers, resulting in
cleaner and more maintainable code.
Signed-off-by: Wander Lairson Costa <wander@...hat.com>
---
tools/tracing/rtla/src/actions.c | 57 +++++++++++++++++++++++---------
tools/tracing/rtla/src/utils.h | 14 ++++++--
2 files changed, 54 insertions(+), 17 deletions(-)
diff --git a/tools/tracing/rtla/src/actions.c b/tools/tracing/rtla/src/actions.c
index e933c2c68b208..b50bf9f9adf28 100644
--- a/tools/tracing/rtla/src/actions.c
+++ b/tools/tracing/rtla/src/actions.c
@@ -113,6 +113,29 @@ actions_add_continue(struct actions *self)
action->type = ACTION_CONTINUE;
}
+static inline const char *__extract_arg(const char *token, const char *opt, size_t opt_len)
+{
+ const size_t tok_len = strlen(token);
+
+ if (tok_len <= opt_len)
+ return NULL;
+
+ if (strncmp(token, opt, opt_len))
+ return NULL;
+
+ return token + opt_len;
+}
+
+/*
+ * extract_arg - extract argument value from option token
+ * @token: option token (e.g., "file=trace.txt")
+ * @opt: option name to match (e.g., "file")
+ *
+ * Returns pointer to argument value after "=" if token matches "opt=",
+ * otherwise returns NULL.
+ */
+#define extract_arg(token, opt) __extract_arg(token, opt "=", STRING_LENGTH(opt "="))
+
/*
* actions_parse - add an action based on text specification
*/
@@ -122,6 +145,7 @@ actions_parse(struct actions *self, const char *trigger, const char *tracefn)
enum action_type type = ACTION_NONE;
const char *token;
char trigger_c[strlen(trigger) + 1];
+ const char *arg_value;
/* For ACTION_SIGNAL */
int signal = 0, pid = 0;
@@ -152,12 +176,10 @@ actions_parse(struct actions *self, const char *trigger, const char *tracefn)
if (token == NULL)
trace_output = tracefn;
else {
- if (strlen(token) > 5 && strncmp(token, "file=", 5) == 0) {
- trace_output = token + 5;
- } else {
+ trace_output = extract_arg(token, "file");
+ if (!trace_output)
/* Invalid argument */
return -1;
- }
token = strtok(NULL, ",");
if (token != NULL)
@@ -169,17 +191,21 @@ actions_parse(struct actions *self, const char *trigger, const char *tracefn)
case ACTION_SIGNAL:
/* Takes two arguments, num (signal) and pid */
while (token != NULL) {
- if (strlen(token) > 4 && strncmp(token, "num=", 4) == 0) {
- if (strtoi(token + 4, &signal))
- return -1;
- } else if (strlen(token) > 4 && strncmp(token, "pid=", 4) == 0) {
- if (strncmp(token + 4, "parent", 7) == 0)
- pid = -1;
- else if (strtoi(token + 4, &pid))
+ arg_value = extract_arg(token, "num");
+ if (arg_value) {
+ if (strtoi(arg_value, &signal))
return -1;
} else {
- /* Invalid argument */
- return -1;
+ arg_value = extract_arg(token, "pid");
+ if (arg_value) {
+ if (strncmp_static(arg_value, "parent") == 0)
+ pid = -1;
+ else if (strtoi(arg_value, &pid))
+ return -1;
+ } else {
+ /* Invalid argument */
+ return -1;
+ }
}
token = strtok(NULL, ",");
@@ -194,9 +220,10 @@ actions_parse(struct actions *self, const char *trigger, const char *tracefn)
case ACTION_SHELL:
if (token == NULL)
return -1;
- if (strlen(token) > 8 && strncmp(token, "command=", 8))
+ arg_value = extract_arg(token, "command");
+ if (!arg_value)
return -1;
- actions_add_shell(self, token + 8);
+ actions_add_shell(self, arg_value);
break;
case ACTION_CONTINUE:
/* Takes no argument */
diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
index efbf798650306..7fa3ac5e0bfb6 100644
--- a/tools/tracing/rtla/src/utils.h
+++ b/tools/tracing/rtla/src/utils.h
@@ -13,8 +13,18 @@
#define MAX_NICE 20
#define MIN_NICE -19
-#define container_of(ptr, type, member)({ \
- const typeof(((type *)0)->member) *__mptr = (ptr); \
+#ifndef ARRAY_SIZE
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof(*(x)))
+#endif
+
+/* Calculate string length at compile time (excluding null terminator) */
+#define STRING_LENGTH(s) (ARRAY_SIZE(s) - sizeof(*(s)))
+
+/* Compare string with static string, length determined at compile time */
+#define strncmp_static(s1, s2) strncmp(s1, s2, STRING_LENGTH(s2))
+
+#define container_of(ptr, type, member)({ \
+ const typeof(((type *)0)->member) * __mptr = (ptr); \
(type *)((char *)__mptr - offsetof(type, member)) ; })
extern int config_debug;
--
2.52.0
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