third_party/ulib/musl/src/stdio/ftell.c

#include "stdio_impl.h"
#include <errno.h>
#include <limits.h>

off_t __ftello_unlocked(FILE* f) {
    off_t pos = f->seek(f, 0, (f->flags & F_APP) && f->wpos > f->wbase ? SEEK_END : SEEK_CUR);
    if (pos < 0)
        return pos;

    /* Adjust for data in buffer. */
    return pos - (f->rend - f->rpos) + (f->wpos - f->wbase);
}

off_t __ftello(FILE* f) {
    off_t pos;
    FLOCK(f);
    pos = __ftello_unlocked(f);
    FUNLOCK(f);
    return pos;
}

long ftell(FILE* f) {
    off_t pos = __ftello(f);
    if (pos > LONG_MAX) {
        errno = EOVERFLOW;
        return -1;
    }
    return pos;
}

weak_alias(__ftello, ftello);