lib/string/strtok/stpsep.[ch]: stpsep(): Add function

This function is somewhat simpler to use than strsep(3) in some cases.

Signed-off-by: Alejandro Colomar <alx@kernel.org>

lib/string/strtok/stpsep.c

@@ -0,0 +1,10 @@
+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#include <config.h>
+
+#include "string/strtok/stpsep.h"
+
+
+extern inline char *stpsep(char *s, const char *delim);

lib/string/strtok/stpsep.h

@@ -0,0 +1,33 @@
+// SPDX-FileCopyrightText: 2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#ifndef SHADOW_INCLUDE_LIB_STRING_STRTOK_STPSEP_H_
+#define SHADOW_INCLUDE_LIB_STRING_STRTOK_STPSEP_H_
+
+
+#include <config.h>
+
+#include <string.h>
+
+#include "attr.h"
+
+
+ATTR_STRING(1) ATTR_STRING(2)
+inline char *stpsep(char *s, const char *delim);
+
+
+// Similar to strsep(3),
+// but return the next token, and don't update the input pointer.
+// Similar to strtok(3),
+// but don't store a state, and don't skip empty fields.
+inline char *
+stpsep(char *s, const char *delim)
+{
+	strsep(&s, delim);
+
+	return s;
+}
+
+
+#endif  // include guard