#include "internal.h"

#define MAXHEADERS 20
static io·Header *tracked[MAXHEADERS];
static int doexit;

static void
untrackall(void *arg)
{
    int i;
    io·Header *it;

    for(i=0; i < MAXHEADERS; i++){
        it = tracked[i];
        if(it){
            tracked[i] = nil;
            io·flush(it);
        }
    }
}

static void
untrack(io·Header *io)
{
    int i;

    for(i=0; i<arrlen(tracked); i++){
        if(tracked[i] == io)
            tracked[i] = nil;
    }
}

static void
track(io·Header *io)
{
    int i;

    untrack(io);
    for(i=0; i<arrlen(tracked); i++){
        if(!tracked[i]){
            tracked[i] = io;
            break;
        }
    }

    if(!doexit){
        doexit = 1;
        rt·atexit(untrackall, nil);
    }
}

int
io·initcap(io·Header *io, int fd, int mode, int cap, uchar *buf)
{
    buf += io·BufUngets;
    cap += io·BufUngets;

    switch(mode & ~(sys·OCloseExec|sys·OTrunc)){
    default:
        /* fmt·fprint(2, "initcap: unknown mode %d\n" , mode); */
        return io·BufErr;
    case sys·ORead:
        io->state = io·BufRdr;
        io->olen  = 0;
        break;
    case sys·OWrite:
        track(io);
        io->state = io·BufWtr;
        io->olen  = -cap;
        break;
    }

    io->b   = buf;
    io->e   = buf+cap;
    io->g   = io->e;
    io->fd  = fd;
    io->cap = cap;
    io->pos = io->runesz = io->flag = io->ilen = io->nread = 0;
    return 0;
}

int
io·init(io·Buffer *io, int fd, int mode)
{
    return io·initcap(header(io), fd, mode, io·BufLen + io·BufUngets, io->bytes);
}

int
io·close(io·Header *io)
{
    int err;

    untrack(io);

    err = io·flush(io);
    if(io->flag == io·BufMagic){
        io->flag = 0;
        if((err=sys·close(io->fd)))
            return err;
    }
    return 0;
}