From 0637595ec5649556fd97c621868a4604e73ef49c Mon Sep 17 00:00:00 2001
From: Siddharth Chandrasekaran <siddharth@embedjournal.com>
Date: Mon, 17 Aug 2020 18:46:48 +0530
Subject: [PATCH] libc: add strtok_r implementation

This is a standard function and useful for applications.

Signed-off-by: Siddharth Chandrasekaran <siddharth@embedjournal.com>
---
 lib/libc/minimal/include/string.h       |  1 +
 lib/libc/minimal/source/string/string.c | 39 ++++++++++++++++++++++
 tests/lib/c_lib/src/main.c              | 43 ++++++++++++++++++++++++-
 3 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/lib/libc/minimal/include/string.h b/lib/libc/minimal/include/string.h
index 73a60e7218e..d2a7d6edb32 100644
--- a/lib/libc/minimal/include/string.h
+++ b/lib/libc/minimal/include/string.h
@@ -25,6 +25,7 @@ extern size_t strlen(const char *s);
 extern size_t strnlen(const char *s, size_t maxlen);
 extern int    strcmp(const char *s1, const char *s2);
 extern int    strncmp(const char *s1, const char *s2, size_t n);
+extern char  *strtok_r(char *str, const char *sep, char **state);
 extern char *strcat(char *_MLIBC_RESTRICT dest,
 		    const char *_MLIBC_RESTRICT src);
 extern char  *strncat(char *_MLIBC_RESTRICT d, const char *_MLIBC_RESTRICT s,
diff --git a/lib/libc/minimal/source/string/string.c b/lib/libc/minimal/source/string/string.c
index 4dbc32dddbf..9344f824ca8 100644
--- a/lib/libc/minimal/source/string/string.c
+++ b/lib/libc/minimal/source/string/string.c
@@ -170,6 +170,45 @@ int strncmp(const char *s1, const char *s2, size_t n)
 	return (n == 0) ? 0 : (*s1 - *s2);
 }
 
+/**
+ * @brief Separate `str` by any char in `sep` and return NULL terminated
+ * sections. Consecutive `sep` chars in `str` are treated as a single
+ * separator.
+ *
+ * @return pointer to NULL terminated string or NULL on errors.
+ */
+char *strtok_r(char *str, const char *sep, char **state)
+{
+	char *start, *end;
+
+	start = str ? str : *state;
+
+	/* skip leading delimiters */
+	while (*start && strchr(sep, *start)) {
+		start++;
+	}
+
+	if (*start == '\0') {
+		*state = start;
+		return NULL;
+	}
+
+	/* look for token chars */
+	end = start;
+	while (*end && !strchr(sep, *end)) {
+		end++;
+	}
+
+	if (*end != '\0') {
+		*end = '\0';
+		*state = end + 1;
+	} else {
+		*state = end;
+	}
+
+	return start;
+}
+
 char *strcat(char *_MLIBC_RESTRICT dest, const char *_MLIBC_RESTRICT src)
 {
 	strcpy(dest + strlen(dest), src);
diff --git a/tests/lib/c_lib/src/main.c b/tests/lib/c_lib/src/main.c
index fbe4c7d0047..306c3178116 100644
--- a/tests/lib/c_lib/src/main.c
+++ b/tests/lib/c_lib/src/main.c
@@ -558,6 +558,46 @@ void test_tolower_toupper(void)
 	zassert_equal(strcmp(lw, tolw), 0, "tolower error");
 }
 
+void test_strtok_r_do(char *str, char *sep, int tlen,
+		      const char * const *toks, bool expect)
+{
+	int len = 0;
+	char *state, *tok, buf[64+1] = {0};
+
+	strncpy(buf, str, 64);
+
+	tok = strtok_r(buf, sep, &state);
+	while (tok && len < tlen) {
+		if (strcmp(tok, toks[len]) != 0) {
+			break;
+		}
+		tok = strtok_r(NULL, sep, &state);
+		len++;
+	}
+	if (expect) {
+		zassert_equal(len, tlen,
+			      "strtok_r error '%s' / '%s'", str, sep);
+	} else {
+		zassert_not_equal(len, tlen,
+				  "strtok_r error '%s' / '%s'", str, sep);
+	}
+}
+
+void test_strtok_r(void)
+{
+	static const char * const tc01[] = { "1", "2", "3", "4", "5" };
+
+	test_strtok_r_do("1,2,3,4,5",           ",",  5, tc01, true);
+	test_strtok_r_do(",, 1 ,2  ,3   4,5  ", ", ", 5, tc01, true);
+	test_strtok_r_do("1,,,2 3,,,4 5",       ", ", 5, tc01, true);
+	test_strtok_r_do("1,2 3,,,4 5  ",       ", ", 5, tc01, true);
+	test_strtok_r_do("0,1,,,2 3,,,4 5",     ", ", 5, tc01, false);
+	test_strtok_r_do("1,,,2 3,,,4 5",       ",",  5, tc01, false);
+	test_strtok_r_do("A,,,2,3,,,4 5",       ",",  5, tc01, false);
+	test_strtok_r_do("1,,,2,3,,,",          ",",  5, tc01, false);
+	test_strtok_r_do("1|2|3,4|5",           "| ", 5, tc01, false);
+}
+
 void test_main(void)
 {
 	ztest_test_suite(test_c_lib,
@@ -580,7 +620,8 @@ void test_main(void)
 			 ztest_unit_test(test_checktype),
 			 ztest_unit_test(test_memstr),
 			 ztest_unit_test(test_str_operate),
-			 ztest_unit_test(test_tolower_toupper)
+			 ztest_unit_test(test_tolower_toupper),
+			 ztest_unit_test(test_strtok_r)
 			 );
 	ztest_run_test_suite(test_c_lib);
 }