linux-kernel - [PATCH v3 10/18] rtla: Add str_has

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Message-ID: <20260115163650.118910-11-wander@redhat.com>
Date: Thu, 15 Jan 2026 13:31:53 -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>,
	Crystal Wood <crwood@...hat.com>,
	Ivan Pravdin <ipravdin.official@...il.com>,
	Costa Shulyupin <costa.shul@...hat.com>,
	John Kacur <jkacur@...hat.com>,
	Tiezhu Yang <yangtiezhu@...ngson.cn>,
	Haiyong Sun <sunhaiyong@...ngson.cn>,
	Daniel Wagner <dwagner@...e.de>,
	Daniel Bristot de Oliveira <bristot@...nel.org>,
	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 v3 10/18] rtla: Add str_has_prefix() helper function

Add a str_has_prefix() helper function that tests whether a string
starts with a given prefix. This function provides a cleaner interface
for prefix matching compared to using strncmp() with strlen() directly.

The function returns a boolean value indicating whether the string
starts with the specified prefix. This helper will be used in
subsequent changes to simplify prefix matching code throughout rtla.

Also add the missing string.h include which is needed for the strlen()
and strncmp() functions used by str_has_prefix() and the existing
strncmp_static() macro.

Signed-off-by: Wander Lairson Costa <wander@...hat.com>
---
 tools/tracing/rtla/src/utils.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/tools/tracing/rtla/src/utils.h b/tools/tracing/rtla/src/utils.h
index 25b08fc5e199a..1235d0f3a7bfd 100644
--- a/tools/tracing/rtla/src/utils.h
+++ b/tools/tracing/rtla/src/utils.h
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 
 #include <stdint.h>
+#include <string.h>
 #include <time.h>
 #include <sched.h>
 #include <stdbool.h>
@@ -24,6 +25,18 @@
 /* Compare string with static string, length determined at compile time */
 #define strncmp_static(s1, s2) strncmp(s1, s2, ARRAY_SIZE(s2))
 
+/**
+ * str_has_prefix - Test if a string has a given prefix
+ * @str: The string to test
+ * @prefix: The string to see if @str starts with
+ *
+ * Returns: true if @str starts with @prefix, false otherwise
+ */
+static inline bool str_has_prefix(const char *str, const char *prefix)
+{
+	return strncmp(str, prefix, strlen(prefix)) == 0;
+}
+
 #define container_of(ptr, type, member)({				\
 	const typeof(((type *)0)->member) * __mptr = (ptr);		\
 	(type *)((char *)__mptr - offsetof(type, member)) ; })
-- 
2.52.0