Name
	n3667, alx-0038r1 - add strsep(), wcssep()

Principles
	-  Codify existing practice to address evident deficiencies.
	-  Enable secure programming

Category
	Standardize libc APIs

Author
	Alejandro Colomar <alx@kernel.org>

History
	<https://www.alejandro-colomar.es/src/alx/alx/wg14/alx-0038.git/>

	r0 (2025-07-01):
	-  Initial draft.

	r1 (2025-07-27; n3667):
	-  Add note about DoS.

Rationale
	strsep(3) is an API from GNU and BSD which is easier to use than
	strtok(3), as it holds no state.

	It has slightly different semantics from strtok(3), though.
	strsep(3) doesn't skip empty fields.  strtok(3) skips empty
	fields, which in some cases might be desired, but often it
	isn't.

    DoS concerns
	While one may be concerned that these APIs may promote DoS
	attacks by searching in a loop within a loop, these APIs are
	designed to be used with (short) string literals as the second
	argument.  It would only be a concern if the second argument can
	be controlled by a user, but that would be unusual.

Prior art
	This API is widely available in BSD and GNU systems, and it
	first appeared in 4.4BSD.

Proposed wording
	Based on N3550.

    7.28.5  String handling <string.h> :: Search functions
	## New subsection after 7.28.5.9 ("The strtok function")

	+7.28.5.9+1  The <b>strsep</b> function
	+
	+Synopsis
	+1
	+		#include <string.h>
	+		char *strsep(char **restrict sp, const char *restrict delim);
	+
	+Description
	+2
	+	The <b>strsep</b> function
	+	locates the first occurence
	+	in the string pointed to by <tt>*sp</tt>
	+	of any character
	+	from the string pointed to by <tt>delim</tt>.
	+	If such a character is found,
	+	the function overwrites it with a null character.
	+
	+3
	+	The value <tt>*sp</tt> is updated
	+	to point to one past the overwritten character,
	+	or set to a null pointer
	+	if no character from <tt>delim</tt> occurs in <tt>*sp</tt>.
	+
	+Returns
	+3
	+	The <b>stpsep</b> function
	+	returns <tt>*sp</tt>.

    7.33.4.6  General wide string utilities :: Wide string search functions
	## New section after 7.33.4.6.8 ("The wcstok function")

	+7.33.4.6.8+1  The <b>wcssep</b> function
	+
	+Synopsis
	+1
	+		#include <wchar.h>
	+		wchar_t *wcssep(wchar_t **restrict sp, const wchar_t *restrict delim);
	+
	+Description
	+2
	+	The <b>wcssep</b> function
	+	is equivalent to <b>strsep</b>
	+	except that it handles wide strings.