[LTP] [Patch v2 1/4] lib: add module is loaded check

[Li Wang]

Add a helper that checks whether a kernel module is loaded by
looking it up in /proc/modules. Module names are normalized so that
hyphens match the underscores used by the kernel.

Signed-off-by: Li Wang <li.wang@linux.dev>
---
 include/tst_module.h |  1 +
 lib/tst_module.c     | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/include/tst_module.h b/include/tst_module.h
index e55321d19..9b789e289 100644
--- a/include/tst_module.h
+++ b/include/tst_module.h
@@ -49,5 +49,6 @@ static inline void tst_requires_module_signature_disabled(void)
 
 void tst_modprobe(const char *mod_name, char *const argv[]);
 void tst_module_reload(const char *mod_name, char *const argv[]);
+bool tst_module_is_loaded(const char *mod_name);
 
 #endif /* TST_MODULE_H */
diff --git a/lib/tst_module.c b/lib/tst_module.c
index cbd2415d5..db341ec57 100644
--- a/lib/tst_module.c
+++ b/lib/tst_module.c
@@ -21,6 +21,7 @@
  */
 
 #define _GNU_SOURCE
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <unistd.h>
@@ -174,3 +175,41 @@ void tst_module_reload(const char *mod_name, char *const argv[])
 	tst_module_unload_(NULL, mod_name);
 	tst_modprobe(mod_name, argv);
 }
+
+bool tst_module_is_loaded(const char *mod_name)
+{
+	char line[4096];
+	size_t mod_len = strlen(mod_name);
+	FILE *file;
+
+	file = fopen("/proc/modules", "r");
+	if (!file)
+		return false;
+
+	while (fgets(line, sizeof(line), file)) {
+		char *p = line;
+		size_t i;
+
+		while (*p && !isspace(*p))
+			p++;
+
+		if ((size_t)(p - line) != mod_len)
+			continue;
+
+		for (i = 0; i < mod_len; i++) {
+			char a = (line[i] == '-') ? '_' : line[i];
+			char b = (mod_name[i] == '-') ? '_' : mod_name[i];
+
+			if (a != b)
+				break;
+		}
+
+		if (i == mod_len) {
+			fclose(file);
+			return true;
+		}
+	}
+
+	fclose(file);
+	return false;
+}
-- 
2.56.0