rework langinfo code for ABI compat and for use by time code

[musl] / src / stdio / fgetln.c

#include "stdio_impl.h"
#include <string.h>

char *fgetln(FILE *f, size_t *plen)
{
        char *ret = 0, *z;
        ssize_t l;
        FLOCK(f);
        ungetc(getc_unlocked(f), f);
        if ((z=memchr(f->rpos, '\n', f->rend - f->rpos))) {
                ret = (char *)f->rpos;
                *plen = ++z - ret;
                f->rpos = (void *)z;
        } else if ((l = getline(&f->getln_buf, (size_t[]){0}, f)) > 0) {
                *plen = l;
                ret = f->getln_buf;
        }
        FUNLOCK(f);
        return ret;
}