rtla/actions: 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@redhat.com>
Link: https://lore.kernel.org/r/20260309195040.1019085-4-wander@redhat.com
Signed-off-by: Tomas Glozar <tglozar@redhat.com>

diff --git a/tools/tracing/rtla/src/actions.c b/tools/tracing/rtla/src/actions.c
index 0ac42ffd734a39b91002fbeba267745aec4cf09f..b0d68b5de08db21fc2978e4dc2a79a5891b1d717 100644 (file)
--- a/tools/tracing/rtla/src/actions.c
+++ b/tools/tracing/rtla/src/actions.c
@@ -111,6 +111,29 @@ 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
  */
@@ -120,6 +143,7 @@ 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 163b4ec37d3552623907ec55df6357da6d69184e..b15a1a154076120df260bc2cf18a4f3758f85080 100644 (file)
--- a/tools/tracing/rtla/src/utils.h
+++ b/tools/tracing/rtla/src/utils.h
@@ -14,6 +14,16 @@
 #define MAX_NICE               20
 #define MIN_NICE               -19
 
+#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, ARRAY_SIZE(s2))
+
 #define container_of(ptr, type, member)({                      \
        const typeof(((type *)0)->member) *__mptr = (ptr);      \
        (type *)((char *)__mptr - offsetof(type, member)) ; })