[LTP] [PATCH v2 1/3] kconfig: add funtion to parse /proc/cmdline

[Li Wang]

A new structure tst_kcmdline_var is defined to hold a command-line
argument's key and a fixed-size value. Furthermore, function
tst_kcmdline_parse is added to the corresponding .c file, which
reads from /proc/cmdline, parses the command-line arguments, and
populates the tst_kcmdline_var array with the obtained key-value
pairs, ensuring safe file operations and buffer size checks.

Signed-off-by: Li Wang <liwang@redhat.com>
---
 include/tst_kconfig.h | 23 ++++++++++++++++++++++
 lib/tst_kconfig.c     | 45 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
index 8b24a8380..a8cbfb786 100644
--- a/include/tst_kconfig.h
+++ b/include/tst_kconfig.h
@@ -64,4 +64,27 @@ void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len);
  */
 int tst_kconfig_check(const char *const kconfigs[]);
 
+/**
+ * Macro to initialize a tst_kcmdline_var structure with a specified parameter
+ * name and an empty value. This is useful for setting up an array of parameter
+ * structures before parsing the actual command-line arguments.
+ */
+#define TST_KCMDLINE_INIT(paraname) { \
+	.key = paraname, \
+	.value = "" \
+}
+
+/* Structure for storing command-line parameter key and its corresponding value */
+struct tst_kcmdline_var {
+	const char *key;
+	char value[128];
+};
+
+/**
+ * Parses command-line parameters from /proc/cmdline and stores them in params array
+ * params: The array of tst_kcmdline_var structures to be filled with parsed key-value pairs
+ * params_len: The length of the params array, indicating how many parameters to parse
+ */
+void tst_kcmdline_parse(struct tst_kcmdline_var params[], size_t params_len);
+
 #endif	/* TST_KCONFIG_H__ */
diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index 595ea4b09..c200dd261 100644
--- a/lib/tst_kconfig.c
+++ b/lib/tst_kconfig.c
@@ -14,6 +14,7 @@
 #include "tst_private.h"
 #include "tst_kconfig.h"
 #include "tst_bool_expr.h"
+#include "tst_safe_stdio.h"
 
 static int kconfig_skip_check(void)
 {
@@ -565,3 +566,47 @@ char tst_kconfig_get(const char *confname)
 
 	return var.choice;
 }
+
+void tst_kcmdline_parse(struct tst_kcmdline_var params[], size_t params_len) {
+	char buf[128];
+	size_t buf_pos = 0, i;
+	int var_id = -1, c;
+
+	FILE *f = SAFE_FOPEN("/proc/cmdline", "r");
+
+	while ((c = fgetc(f)) != EOF) {
+		switch (c) {
+		case '=':
+			buf[buf_pos] = '\0';
+			for (i = 0; i < params_len; i++) {
+				if (strcmp(buf, params[i].key) == 0)
+					var_id = (int)i;
+			}
+
+			buf_pos = 0;
+		break;
+		case ' ':
+		case '\n':
+			buf[buf_pos] = '\0';
+			if (var_id >= 0 && var_id < (int)params_len)
+				strcpy(params[var_id].value, buf);
+
+			var_id = -1;
+			buf_pos = 0;
+		break;
+		default:
+			if (buf_pos + 1  >= sizeof(buf)) {
+				tst_res(TWARN, "Buffer overflowed while parsing /proc/cmdline");
+				while ((c = fgetc(f)) != EOF && c != ' ' && c != '\n');
+
+				var_id = -1;
+				buf_pos = 0;
+			}
+
+			buf[buf_pos++] = (char)c;
+		break;
+		}
+	}
+
+	SAFE_FCLOSE(f);
+}
-- 
2.40.1