crtl: `strtok` not implemented (undeclared function)

Type: feature (crtl coverage gap)
Track: B — lib/crtl/src/string.c (crtl function-body impl is Track B per [[feedback_crtl_impl_is_track_b]] file-ownership convention)
Status: backlog
Opened: 2026-07-02
Found while: Track B probing string.h crtl coverage.

Problem

#include <string.h>
char src[] = "hello,world,foo";
char *tok = strtok(src, ",");

fails with call to undeclared function: strtok. lib/crtl/src/string.c has strcat/strchr/strcpy/strerror/strncat/strncpy/strpbrk/strrchr/strstr/memcmp/ strcmp/strcoll/strncmp/strcspn/strlen/strspn/strxfrm/memchr/memcpy/memmove/ memset — strtok (and strtok_r) are the only common string.h functions missing from that set.

Why it matters

strtok is one of the most commonly reached-for string.h functions for tokenizing (config parsing, CSV-ish splitting, simple protocol lines). Its absence will silently wall off any C program that uses it, with no earlier warning since everything else in string.h works.

Scope

Implement strtok (classic non-reentrant version, static internal save-pointer) and ideally strtok_r (explicit save-pointer, reentrant — needed for any threadsafe caller) in lib/crtl/src/string.c, matching standard semantics (delimiter set as second arg, NULL first-arg to continue from the saved position, consecutive delimiters collapsed, returns NULL when exhausted).

Acceptance

char src[] = "hello,world,foo";
char *tok = strtok(src, ",");
while (tok) { printf("[%s]", tok); tok = strtok(NULL, ","); }

prints [hello][world][foo].

Log

2026-07-02 — Filed by Track B while probing string.h coverage; rest of string.h (strcpy/strcmp/strstr/etc.) and qsort/snprintf all verified correct in the same session. No code touched — test/repro only.

RESOLVED 2026-07-07 (Track B)

Implemented strtok + strtok_r in lib/crtl/src/string.c (decls in string.h), built on the existing strspn/strcspn: strtok_r skips leading delimiters, NUL-terminates the token in place, advances the save-pointer; strtok wraps it over a static save-pointer. Standard semantics (empty fields between adjacent delimiters skipped; NULL first arg continues). Regression b181 (comma/space/ adjacent-delimiter tokenizing + in-place NUL). make test + lua green.