[LTP] [PATCH v3 2/2] lib/tst_kconfig: Make use of boolean expression eval

Cyril Hrubis chrubis@suse.cz
Tue Nov 3 12:38:21 CET 2020


Now each string in the kconfig[] array in tst_test structure is an
boolean expression which is evaluated. All expressions has to be true in
order for the test to continue.

This also makes the parser for the kernel config a bit more robust as it
was pointed out that there may have been cases where it could be mislead
by hand edited config files.

+ Update the docs.

Signed-off-by: Cyril Hrubis <chrubis@suse.cz>
CC: Pengfei Xu <pengfei.xu@intel.com>
---

 v3:
     - fix segfaults caused by off-by-one in the map() function
     - fix the acct02 test, that uses the kconfig loader in setup()

 doc/test-writing-guidelines.txt         |  21 +-
 include/tst_kconfig.h                   |  34 +--
 lib/newlib_tests/.gitignore             |   1 +
 lib/newlib_tests/config06               |   1 +
 lib/newlib_tests/test_kconfig.c         |   2 +
 lib/newlib_tests/test_kconfig01.c       |  23 ++
 lib/tst_kconfig.c                       | 366 ++++++++++++++++--------
 testcases/kernel/syscalls/acct/acct02.c |  14 +-
 8 files changed, 307 insertions(+), 155 deletions(-)
 create mode 100644 lib/newlib_tests/config06
 create mode 100644 lib/newlib_tests/test_kconfig01.c

diff --git a/doc/test-writing-guidelines.txt b/doc/test-writing-guidelines.txt
index 1a51ef7c7..3c2ab7166 100644
--- a/doc/test-writing-guidelines.txt
+++ b/doc/test-writing-guidelines.txt
@@ -1643,21 +1643,26 @@ on the system, disabled syscalls can be detected by checking for 'ENOSYS'
 errno etc.
 
 However in rare cases core kernel features couldn't be detected based on the
-kernel userspace API and we have to resort to kernel .config parsing.
+kernel userspace API and we have to resort to parse the kernel .config.
 
-For this cases the test should set the 'NULL' terminated '.needs_kconfigs' array
-of kernel config options required for the test. The config option can be
-specified either as plain "CONFIG_FOO" in which case it's sufficient for the
-test continue if it's set to any value (typically =y or =m). Or with a value
-as "CONFIG_FOO=bar" in which case the value has to match as well. The test is
-aborted with 'TCONF' if any of the required options were not set.
+For this cases the test should set the 'NULL' terminated '.needs_kconfigs'
+array of boolean expressions with constraints on the kconfig variables. The
+boolean expression consits of variables, two binary operations '&' and '|',
+negation '!' and correct sequence of parentesis '()'. Variables are expected
+to be in a form of "CONFIG_FOO[=bar]".
+
+The test will continue to run if all expressions are evaluated to 'True'.
+Missing variable is mapped to 'False' as well as variable with different than
+specified value, e.g. 'CONFIG_FOO=bar' will evaluate to 'False' if the value
+is anything else but 'bar'. If config variable is specified as plain
+'CONFIG_FOO' it's evaluated to true it's set to any value (typically =y or =m).
 
 [source,c]
 -------------------------------------------------------------------------------
 #include "tst_test.h"
 
 static const char *kconfigs[] = {
-	"CONFIG_X86_INTEL_UMIP",
+	"CONFIG_X86_INTEL_UMIP | CONFIG_X86_UMIP",
 	NULL
 };
 
diff --git a/include/tst_kconfig.h b/include/tst_kconfig.h
index 2d2cfd782..1bb21fea8 100644
--- a/include/tst_kconfig.h
+++ b/include/tst_kconfig.h
@@ -6,27 +6,27 @@
 #ifndef TST_KCONFIG_H__
 #define TST_KCONFIG_H__
 
-struct tst_kconfig_res {
-	char match;
-	char *value;
+struct tst_kconfig_var {
+	char id[64];
+	unsigned int id_len;
+	char choice;
+	char *val;
 };
 
 /**
- * Reads a kernel config and parses it for values defined in kconfigs array.
+ *
+ * Reads a kernel config, parses it and writes results into an array of
+ * tst_kconfig_var structures.
  *
  * The path to the kernel config should be autodetected in most of the cases as
  * the code looks for know locations. It can be explicitely set/overrided with
  * the KCONFIG_PATH environment variable as well.
  *
- * The kcofings array is expected to contain strings in a format "CONFIG_FOO"
- * or "CONFIG_FOO=bar". The result array has to be suitably sized to fit the
- * results.
- *
- * @param kconfigs array of config strings to look for
- * @param results array to store results to
- * @param cnt size of the arrays
+ * The caller has to initialize the tst_kconfig_var structure. The id has to be
+ * filled with config variable name such as 'CONFIG_FOO', the id_len should
+ * hold the id string length and the choice and val has to be zeroed.
  *
- * The match in the tst_kconfig_res structure is set as follows:
+ * After a call to this function each choice be set as follows:
  *
  *  'm' - config option set to m
  *  'y' - config option set to y
@@ -34,11 +34,13 @@ struct tst_kconfig_res {
  *  'n' - config option is not set
  *   0  - config option not found
  *
- * In the case that match is set to 'v' the value points to a newly allocated
- * string that holds the value.
+ * In the case that match is set to 'v' the val pointer points to a newly
+ * allocated string that holds the value.
+ *
+ * @param vars An array of caller initalized tst_kconfig_var structures.
+ * @param vars_len Length of the vars array.
  */
-void tst_kconfig_read(const char *const kconfigs[],
-		      struct tst_kconfig_res results[], size_t cnt);
+void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len);
 
 /**
  * Checks if required kernel configuration options are set in the kernel
diff --git a/lib/newlib_tests/.gitignore b/lib/newlib_tests/.gitignore
index 1e96db1da..89de61cf7 100644
--- a/lib/newlib_tests/.gitignore
+++ b/lib/newlib_tests/.gitignore
@@ -31,6 +31,7 @@ test_timer
 test_exec
 test_exec_child
 test_kconfig
+test_kconfig01
 variant
 test_guarded_buf
 tst_bool_expr
diff --git a/lib/newlib_tests/config06 b/lib/newlib_tests/config06
new file mode 100644
index 000000000..b7db25411
--- /dev/null
+++ b/lib/newlib_tests/config06
@@ -0,0 +1 @@
+# Empty
diff --git a/lib/newlib_tests/test_kconfig.c b/lib/newlib_tests/test_kconfig.c
index d9c662fc5..1f659b95a 100644
--- a/lib/newlib_tests/test_kconfig.c
+++ b/lib/newlib_tests/test_kconfig.c
@@ -14,6 +14,8 @@ static const char *kconfigs[] = {
 	"CONFIG_MMU",
 	"CONFIG_EXT4_FS=m",
 	"CONFIG_PGTABLE_LEVELS=4",
+	"CONFIG_MMU & CONFIG_EXT4_FS=m",
+	"CONFIG_EXT4_FS=m | CONFIG_MMU",
 	NULL
 };
 
diff --git a/lib/newlib_tests/test_kconfig01.c b/lib/newlib_tests/test_kconfig01.c
new file mode 100644
index 000000000..ee919dcac
--- /dev/null
+++ b/lib/newlib_tests/test_kconfig01.c
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2020 Cyril Hrubis <chrubis@suse.cz>
+ *
+ * Invalid boolean expression test.
+ */
+
+#include "tst_test.h"
+
+static void do_test(void)
+{
+	tst_res(TPASS, "Test passed!");
+}
+
+static const char *kconfigs[] = {
+	"CONFIG_EXT4_FS=m | CONFIG_MMU)",
+	NULL
+};
+
+static struct tst_test test = {
+	.test_all = do_test,
+	.needs_kconfigs = kconfigs,
+};
diff --git a/lib/tst_kconfig.c b/lib/tst_kconfig.c
index d49187b6f..cf257843f 100644
--- a/lib/tst_kconfig.c
+++ b/lib/tst_kconfig.c
@@ -12,6 +12,7 @@
 #define TST_NO_DEFAULT_MAIN
 #include "tst_test.h"
 #include "tst_kconfig.h"
+#include "tst_bool_expr.h"
 
 static const char *kconfig_path(char *path_buf, size_t path_buf_len)
 {
@@ -84,126 +85,108 @@ static void close_kconfig(FILE *fp)
 		fclose(fp);
 }
 
-struct match {
-	/* match len, string length up to \0 or = */
-	size_t len;
-	/* if set part of conf string after = */
-	const char *val;
-	/* if set the config option was matched already */
-	int match;
-};
-
-static int is_set(const char *str, const char *val)
+static inline int kconfig_parse_line(const char *line,
+                                     struct tst_kconfig_var *vars,
+                                     unsigned int vars_len)
 {
-	size_t vlen = strlen(val);
+	unsigned int i, var_len = 0;
+	const char *var;
+	int is_not_set = 0;
 
-	while (isspace(*str))
-		str++;
+	while (isspace(*line))
+		line++;
 
-	if (strncmp(str, val, vlen))
-		return 0;
+	if (*line == '#') {
+		if (!strstr(line, "is not set"))
+			return 0;
 
-	switch (str[vlen]) {
-	case ' ':
-	case '\n':
-	case '\0':
-		return 1;
-	break;
-	default:
-		return 0;
+		is_not_set = 1;
 	}
-}
-
-static inline int match(struct match *match, const char *conf,
-                        struct tst_kconfig_res *result, const char *line)
-{
-	if (match->match)
-		return 0;
 
-	const char *cfg = strstr(line, "CONFIG_");
+	var = strstr(line, "CONFIG_");
 
-	if (!cfg)
+	if (!var)
 		return 0;
 
-	if (strncmp(cfg, conf, match->len))
-		return 0;
-
-	const char *val = &cfg[match->len];
-
-	switch (cfg[match->len]) {
-	case '=':
+	for (;;) {
+		switch (var[var_len]) {
+		case 'A' ... 'Z':
+		case '0' ... '9':
+		case '_':
+			var_len++;
+		break;
+		default:
+			goto out;
 		break;
-	case ' ':
-		if (is_set(val, "is not set")) {
-			result->match = 'n';
-			goto match;
 		}
-	/* fall through */
-	default:
-		return 0;
 	}
 
-	if (is_set(val, "=y")) {
-		result->match = 'y';
-		goto match;
-	}
+out:
 
-	if (is_set(val, "=m")) {
-		result->match = 'm';
-		goto match;
-	}
+	for (i = 0; i < vars_len; i++) {
+		const char *val;
+		unsigned int val_len = 0;
 
-	result->match = 'v';
-	result->value = strndup(val+1, strlen(val)-2);
+		if (vars[i].id_len != var_len)
+			continue;
 
-match:
-	match->match = 1;
-	return 1;
-}
+		if (strncmp(vars[i].id, var, var_len))
+			continue;
 
-void tst_kconfig_read(const char *const *kconfigs,
-                      struct tst_kconfig_res results[], size_t cnt)
-{
-	struct match matches[cnt];
-	FILE *fp;
-	unsigned int i, j;
-	char buf[1024];
+		if (is_not_set) {
+			vars[i].choice = 'n';
+			return 1;
+		}
 
-	for (i = 0; i < cnt; i++) {
-		const char *val = strchr(kconfigs[i], '=');
+		val = var + var_len;
 
-		if (strncmp("CONFIG_", kconfigs[i], 7))
-			tst_brk(TBROK, "Invalid config string '%s'", kconfigs[i]);
+		while (isspace(*val))
+			val++;
 
-		matches[i].match = 0;
-		matches[i].len = strlen(kconfigs[i]);
+		if (*val != '=')
+			return 0;
 
-		if (val) {
-			matches[i].val = val + 1;
-			matches[i].len -= strlen(val);
+		val++;
+
+		while (isspace(*val))
+			val++;
+
+		while (!isspace(val[val_len]))
+			val_len++;
+
+		if (val_len == 1) {
+			switch (val[0]) {
+			case 'y':
+				vars[i].choice = 'y';
+				return 1;
+			case 'm':
+				vars[i].choice = 'm';
+				return 1;
+			}
 		}
 
-		results[i].match = 0;
-		results[i].value = NULL;
+		vars[i].choice = 'v';
+		vars[i].val = strndup(val, val_len);
 	}
 
-	fp = open_kconfig();
+	return 0;
+}
+
+void tst_kconfig_read(struct tst_kconfig_var vars[], size_t vars_len)
+{
+	char line[128];
+	unsigned int vars_found = 0;
+
+	FILE *fp = open_kconfig();
 	if (!fp)
 		tst_brk(TBROK, "Cannot parse kernel .config");
 
-	while (fgets(buf, sizeof(buf), fp)) {
-		for (i = 0; i < cnt; i++) {
-			if (match(&matches[i], kconfigs[i], &results[i], buf)) {
-				for (j = 0; j < cnt; j++) {
-					if (matches[j].match)
-						break;
-				}
-
-				if (j == cnt)
-					goto exit;
-			}
-		}
+	while (fgets(line, sizeof(line), fp)) {
+		if (kconfig_parse_line(line, vars, vars_len))
+			vars_found++;
 
+		if (vars_found == vars_len)
+			goto exit;
 	}
 
 exit:
@@ -219,65 +202,198 @@ static size_t array_len(const char *const kconfigs[])
 	return i;
 }
 
-static int compare_res(struct tst_kconfig_res *res, const char *kconfig,
-                       char match, const char *val)
+static const char *strnchr(const char *s, int c, unsigned int len)
 {
-	if (res->match != match) {
-		tst_res(TINFO, "Needs kernel %s, have %c", kconfig, res->match);
-		return 1;
+	unsigned int i;
+
+	for (i = 0; i < len; i++) {
+		if (s[i] == c)
+			return s + i;
 	}
 
-	if (match != 'v')
-		return 0;
+	return NULL;
+}
+
+static inline unsigned int get_len(const char* kconfig, unsigned int len)
+{
+	const char *sep = strnchr(kconfig, '=', len);
+
+	if (!sep)
+		return len;
 
-	if (strcmp(res->value, val)) {
-		tst_res(TINFO, "Needs kernel %s, have %s", kconfig, res->value);
-		return 1;
+	return sep - kconfig;
+}
+
+static inline unsigned int get_var_cnt(struct tst_expr *const exprs[],
+                                       unsigned int expr_cnt)
+{
+	unsigned int i;
+	const struct tst_expr_tok *j;
+	unsigned int cnt = 0;
+
+	for (i = 0; i < expr_cnt; i++) {
+		for (j = exprs[i]->expr; j; j = j->next) {
+			if (j->op == TST_OP_VAR)
+				cnt++;
+		}
 	}
 
-	return 0;
+	return cnt;
 }
 
-void tst_kconfig_check(const char *const kconfigs[])
+static const struct tst_kconfig_var *find_var(const struct tst_kconfig_var vars[],
+                                        unsigned int var_cnt,
+                                        const char *var)
 {
-	size_t cnt = array_len(kconfigs);
-	struct tst_kconfig_res results[cnt];
 	unsigned int i;
-	int abort_test = 0;
 
-	tst_kconfig_read(kconfigs, results, cnt);
+	for (i = 0; i < var_cnt; i++) {
+		if (!strcmp(vars[i].id, var))
+			return &vars[i];
+	}
 
-	for (i = 0; i < cnt; i++) {
-		if (results[i].match == 0) {
-			tst_res(TINFO, "Missing kernel %s", kconfigs[i]);
-			abort_test = 1;
+	return NULL;
+}
+
+/*
+ * Fill in the kconfig variables array from the expressions. Also makes sure
+ * that each variable is copied to the array exaclty once.
+ */
+static inline unsigned int populate_vars(struct tst_expr *exprs[],
+                                         unsigned int expr_cnt,
+                                    struct tst_kconfig_var vars[])
+{
+	unsigned int i;
+	struct tst_expr_tok *j;
+	unsigned int cnt = 0;
+
+	for (i = 0; i < expr_cnt; i++) {
+		for (j = exprs[i]->expr; j; j = j->next) {
+			const struct tst_kconfig_var *var;
+
+			if (j->op != TST_OP_VAR)
+				continue;
+
+			vars[cnt].id_len = get_len(j->tok, j->tok_len);
+
+			if (vars[cnt].id_len + 1 >= sizeof(vars[cnt].id))
+				tst_brk(TBROK, "kconfig var id too long!");
+
+			strncpy(vars[cnt].id, j->tok, vars[cnt].id_len);
+			vars[cnt].id[vars[cnt].id_len] = 0;
+			vars[cnt].choice = 0;
+
+			var = find_var(vars, cnt, vars[cnt].id);
+
+			if (var)
+				j->priv = var;
+			else
+				j->priv = &vars[cnt++];
+		}
+	}
+
+	return cnt;
+}
+
+static int map(struct tst_expr_tok *expr)
+{
+	const struct tst_kconfig_var *var = expr->priv;
+
+	if (var->choice == 0)
+		return 0;
+
+	const char *val = strnchr(expr->tok, '=', expr->tok_len);
+
+	/* CONFIG_FOO evaluates to true if y or m */
+	if (!val)
+		return var->choice == 'y' || var->choice == 'm';
+
+	val++;
+
+	unsigned int len = expr->tok_len - (val - expr->tok);
+	char choice = 'v';
+
+	if (!strncmp(val, "n", len))
+		choice = 'n';
+
+	if (!strncmp(val, "y", len))
+		choice = 'y';
+
+	if (!strncmp(val, "m", len))
+		choice = 'm';
+
+	if (choice != 'v')
+		return var->choice == choice;
+
+	if (strlen(var->val) != len)
+		return 0;
+
+	return !strncmp(val, var->val, len);
+}
+
+static void dump_vars(const struct tst_expr *expr)
+{
+	const struct tst_expr_tok *i;
+	const struct tst_kconfig_var *var;
+
+	tst_res(TINFO, "Variables:");
+
+	for (i = expr->expr; i; i = i->next) {
+		if (i->op != TST_OP_VAR)
+			continue;
+
+		var = i->priv;
+
+		if (!var->choice) {
+			tst_res(TINFO, " %s Undefined", var->id);
 			continue;
 		}
 
-		if (results[i].match == 'n') {
-			tst_res(TINFO, "Kernel %s is not set", kconfigs[i]);
-			abort_test = 1;
+		if (var->choice == 'v') {
+			tst_res(TINFO, " %s=%s", var->id, var->val);
 			continue;
 		}
 
-		const char *val = strchr(kconfigs[i], '=');
+		tst_res(TINFO, " %s=%c", var->id, var->choice);
+	}
+}
 
-		if (val) {
-			char match = 'v';
-			val++;
+void tst_kconfig_check(const char *const kconfigs[])
+{
+	size_t expr_cnt = array_len(kconfigs);
+	struct tst_expr *exprs[expr_cnt];
+	unsigned int i, var_cnt;
+	int abort_test = 0;
 
-			if (!strcmp(val, "y"))
-				match = 'y';
+	for (i = 0; i < expr_cnt; i++) {
+		exprs[i] = tst_bool_expr_parse(kconfigs[i]);
 
-			if (!strcmp(val, "m"))
-				match = 'm';
+		if (!exprs[i])
+			tst_brk(TBROK, "Invalid kconfig expression!");
+	}
 
-			if (compare_res(&results[i], kconfigs[i], match, val))
-				abort_test = 1;
+	var_cnt = get_var_cnt(exprs, expr_cnt);
+	struct tst_kconfig_var vars[var_cnt];
 
+	var_cnt = populate_vars(exprs, expr_cnt, vars);
+
+	tst_kconfig_read(vars, var_cnt);
+
+	for (i = 0; i < expr_cnt; i++) {
+		int val = tst_bool_expr_eval(exprs[i], map);
+
+		if (val != 1) {
+			abort_test = 1;
+			tst_res(TINFO, "Constrain '%s' not satisfied!", kconfigs[i]);
+			dump_vars(exprs[i]);
 		}
 
-		free(results[i].value);
+		tst_bool_expr_free(exprs[i]);
+	}
+
+	for (i = 0; i < var_cnt; i++) {
+		if (vars[i].choice == 'v')
+			free(vars[i].val);
 	}
 
 	if (abort_test)
diff --git a/testcases/kernel/syscalls/acct/acct02.c b/testcases/kernel/syscalls/acct/acct02.c
index 8ee1bfcf8..1bf6378db 100644
--- a/testcases/kernel/syscalls/acct/acct02.c
+++ b/testcases/kernel/syscalls/acct/acct02.c
@@ -49,18 +49,20 @@ static union acct_union {
 	struct acct_v3	v3;
 } acct_struct;
 
+#define ACCT_V3 "CONFIG_BSD_PROCESS_ACCT_V3"
+
 static int acct_version_is_3(void)
 {
-	const char *kconfig_acct_v3[] = {
-		"CONFIG_BSD_PROCESS_ACCT_V3",
-		NULL
+	struct tst_kconfig_var kconfig = {
+		.id = ACCT_V3,
+		.id_len = sizeof(ACCT_V3)-1,
 	};
 
-	struct tst_kconfig_res results[1];
+	tst_kconfig_read(&kconfig, 1);
 
-	tst_kconfig_read(kconfig_acct_v3, results, 1);
+	tst_res(TINFO, ACCT_V3 "=%c", kconfig.choice);
 
-	return results[0].match == 'y';
+	return kconfig.choice == 'y';
 }
 
 static void run_command(void)
-- 
2.26.2



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