third_party/ulib/musl/src/internal/shgetc.c

#include "shgetc.h"

void __shlim(FILE* f, off_t lim) {
    f->shlim = lim;
    f->shcnt = f->rend - f->rpos;
    if (lim && f->shcnt > lim)
        f->shend = f->rpos + lim;
    else
        f->shend = f->rend;
}

int __shgetc(FILE* f) {
    int c;
    if ((f->shlim && f->shcnt >= f->shlim) || (c = __uflow(f)) < 0) {
        f->shend = 0;
        return EOF;
    }
    if (f->shlim && f->rend - f->rpos > f->shlim - f->shcnt - 1)
        f->shend = f->rpos + (f->shlim - f->shcnt - 1);
    else
        f->shend = f->rend;
    if (f->rend)
        f->shcnt += f->rend - f->rpos + 1;
    if (f->rpos[-1] != c)
        f->rpos[-1] = c;
    return c;
}