[LTP] [PATCH v3 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             | 29 ++++++++++++++
 lib/newlib_tests/test_kconfig03.c | 40 +++++++++++++++++++
 lib/tst_kconfig.c                 | 66 +++++++++++++++++++++++++++++++
 3 files changed, 135 insertions(+)
 create mode 100644 lib/newlib_tests/test_kconfig03.c

diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
index 8b24a8380..bbb899784 100644
--- a/include/tst_kconfig.h
+++ b/include/tst_kconfig.h
@@ -6,6 +6,8 @@
 #ifndef TST_KCONFIG_H__
 #define TST_KCONFIG_H__
 
+#include <stdbool.h>
+
 /**
  * Initialization helper macro for struct tst_kconfig_var. Requires <string.h>
  */
@@ -64,4 +66,31 @@ 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 = "", \
+	.found = false \
+}
+
+/**
+ * Structure for storing command-line parameter key and its corresponding value
+ */
+struct tst_kcmdline_var {
+	const char *key;
+	char value[128];
+	bool found;
+};
+
+/**
+ * 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/newlib_tests/test_kconfig03.c b/lib/newlib_tests/test_kconfig03.c
new file mode 100644
index 000000000..937c2b29c
--- /dev/null
+++ b/lib/newlib_tests/test_kconfig03.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2024 Li Wang <liwang@redhat.com>
+ */
+
+#include "tst_test.h"
+#include "tst_kconfig.h"
+
+static struct tst_kcmdline_var params[] = {
+	TST_KCMDLINE_INIT("BOOT_IMAGE"),
+	TST_KCMDLINE_INIT("root"),
+	TST_KCMDLINE_INIT("foo")
+};
+
+static void do_test(void)
+{
+	int i, N;
+
+	N = (int) ARRAY_SIZE(params);
+
+	tst_kcmdline_parse(params, N);
+
+	for (i = 0; i < N; i++) {
+		if (params[i].found) {
+			if (params[i].value)
+				tst_res(TPASS, "params[%d] = {%s, %s}", i, params[i].key, params[i].value);
+			else
+				tst_res(TPASS, "params[%d] = {%s, no value}", i, params[i].key);
+		} else {
+			if (!strcmp(params[i].key, "foo"))
+				tst_res(TPASS, "%s is not found in /proc/cmdline", params[i].key);
+			else
+				tst_res(TFAIL, "%s is not found in /proc/cmdline", params[i].key);
+		}
+	}
+}
+
+static struct tst_test test = {
+	.test_all = do_test,
+};
diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index 595ea4b09..e16ca1400 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 +566,68 @@ 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], line[512];
+	size_t b_pos = 0,l_pos =0, i;
+	int var_id = -1;
+
+	FILE *f = SAFE_FOPEN("/proc/cmdline", "r");
+
+	if (fgets(line, sizeof(line), f) == NULL) {
+		SAFE_FCLOSE(f);
+		tst_brk(TBROK, "Failed to read /proc/cmdline");
+	}
+
+	for (l_pos = 0; line[l_pos] != '\0'; l_pos++) {
+		char c = line[l_pos];
+
+		switch (c) {
+		case '=':
+			buf[b_pos] = '\0';
+			for (i = 0; i < params_len; i++) {
+				if (strcmp(buf, params[i].key) == 0) {
+					var_id = (int)i;
+					params[i].found = true;
+				}
+			}
+
+			b_pos = 0;
+		break;
+		case ' ':
+		case '\n':
+			buf[b_pos] = '\0';
+			if (var_id >= 0 && var_id < (int)params_len)
+				strcpy(params[var_id].value, buf);
+
+			var_id = -1;
+			b_pos = 0;
+		break;
+		default:
+			if (b_pos + 1 >= sizeof(buf)) {
+				tst_res(TWARN, "Buffer overflowed while parsing /proc/cmdline");
+				while (line[l_pos] != '\0' && line[l_pos] != ' ' && line[l_pos] != '\n')
+					l_pos++;
+
+				var_id = -1;
+				b_pos = 0;
+
+				if (line[l_pos] != '\0')
+					l_pos--;
+			} else {
+				buf[b_pos++] = c;
+			}
+		break;
+		}
+	}
+
+	for (i = 0; i < params_len; i++) {
+		if (params[i].found)
+			tst_res(TINFO, "%s is found in /proc/cmdline", params[i].key);
+		else
+			tst_res(TINFO, "%s is not found in /proc/cmdline", params[i].key);
+	}
+
+	SAFE_FCLOSE(f);
+}
-- 
2.40.1