/io.c

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/**********************************************************************

  io.c -

  $Author$
  created at: Fri Oct 15 18:08:59 JST 1993

  Copyright (C) 1993-2007 Yukihiro Matsumoto
  Copyright (C) 2000  Network Applied Communication Laboratory, Inc.
  Copyright (C) 2000  Information-technology Promotion Agency, Japan

**********************************************************************/

#include "ruby/ruby.h"
#include "ruby/io.h"
#include "dln.h"
#include <ctype.h>
#include <errno.h>

#define free(x) xfree(x)

#if defined(DOSISH) || defined(__CYGWIN__)
#include <io.h>
#endif

#include <sys/types.h>
#if defined HAVE_NET_SOCKET_H
# include <net/socket.h>
#elif defined HAVE_SYS_SOCKET_H
# include <sys/socket.h>
#endif

#if defined(__BOW__) || defined(__CYGWIN__) || defined(_WIN32) || defined(__EMX__) || defined(__BEOS__) || defined(__HAIKU__)
# define NO_SAFE_RENAME
#endif

#if defined(__CYGWIN__) || defined(_WIN32)
# define NO_LONG_FNAME
#endif

#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) || defined(sun) || defined(_nec_ews)
# define USE_SETVBUF
#endif

#ifdef __QNXNTO__
#include "unix.h"
#endif

#include <sys/types.h>
#if defined(HAVE_SYS_IOCTL_H) && !defined(_WIN32)
#include <sys/ioctl.h>
#endif
#if defined(HAVE_FCNTL_H) || defined(_WIN32)
#include <fcntl.h>
#elif defined(HAVE_SYS_FCNTL_H)
#include <sys/fcntl.h>
#endif

#if !HAVE_OFF_T && !defined(off_t)
# define off_t  long
#endif

#include <sys/stat.h>

/* EMX has sys/param.h, but.. */
#if defined(HAVE_SYS_PARAM_H) && !(defined(__EMX__) || defined(__HIUX_MPP__))
# include <sys/param.h>
#endif

#if !defined NOFILE
# define NOFILE 64
#endif

#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif

#ifdef HAVE_SYSCALL_H
#include <syscall.h>
#elif defined HAVE_SYS_SYSCALL_H
#include <sys/syscall.h>
#endif

extern void Init_File(void);

#if defined(__BEOS__) || defined(__HAIKU__)
# ifndef NOFILE
#  define NOFILE (OPEN_MAX)
# endif
#endif

#include "ruby/util.h"

#ifndef O_ACCMODE
#define O_ACCMODE (O_RDONLY | O_WRONLY | O_RDWR)
#endif

#if SIZEOF_OFF_T > SIZEOF_LONG && !defined(HAVE_LONG_LONG)
# error off_t is bigger than long, but you have no long long...
#endif

#ifndef PIPE_BUF
# ifdef _POSIX_PIPE_BUF
#  define PIPE_BUF _POSIX_PIPE_BUF
# else
#  define PIPE_BUF 512 /* is this ok? */
# endif
#endif

#define numberof(array) (int)(sizeof(array) / sizeof((array)[0]))

VALUE rb_cIO;
VALUE rb_eEOFError;
VALUE rb_eIOError;
VALUE rb_mWaitReadable;
VALUE rb_mWaitWritable;

VALUE rb_stdin, rb_stdout, rb_stderr;
VALUE rb_deferr;		/* rescue VIM plugin */
static VALUE orig_stdout, orig_stderr;

VALUE rb_output_fs;
VALUE rb_rs;
VALUE rb_output_rs;
VALUE rb_default_rs;

static VALUE argf;

static ID id_write, id_read, id_getc, id_flush, id_readpartial;
static VALUE sym_mode, sym_perm, sym_extenc, sym_intenc, sym_encoding, sym_open_args;
static VALUE sym_textmode, sym_binmode;

struct timeval rb_time_interval(VALUE);

struct argf {
    VALUE filename, current_file;
    int last_lineno;		/* $. */
    int lineno;
    int init_p, next_p;
    VALUE argv;
    char *inplace;
    int binmode;
    struct rb_io_enc_t encs;
};

static int max_file_descriptor = NOFILE;
#define UPDATE_MAXFD(fd) \
    do { \
        if (max_file_descriptor < (fd)) max_file_descriptor = (fd); \
    } while (0)

#define argf_of(obj) (*(struct argf *)DATA_PTR(obj))
#define ARGF argf_of(argf)

#ifdef _STDIO_USES_IOSTREAM  /* GNU libc */
#  ifdef _IO_fpos_t
#    define STDIO_READ_DATA_PENDING(fp) ((fp)->_IO_read_ptr != (fp)->_IO_read_end)
#  else
#    define STDIO_READ_DATA_PENDING(fp) ((fp)->_gptr < (fp)->_egptr)
#  endif
#elif defined(FILE_COUNT)
#  define STDIO_READ_DATA_PENDING(fp) ((fp)->FILE_COUNT > 0)
#elif defined(FILE_READEND)
#  define STDIO_READ_DATA_PENDING(fp) ((fp)->FILE_READPTR < (fp)->FILE_READEND)
#elif defined(__BEOS__) || defined(__HAIKU__)
#  define STDIO_READ_DATA_PENDING(fp) (fp->_state._eof == 0)
#else
#  define STDIO_READ_DATA_PENDING(fp) (!feof(fp))
#endif

#define GetWriteIO(io) rb_io_get_write_io(io)

#define READ_DATA_PENDING(fptr) ((fptr)->rbuf_len)
#define READ_DATA_PENDING_COUNT(fptr) ((fptr)->rbuf_len)
#define READ_DATA_PENDING_PTR(fptr) ((fptr)->rbuf+(fptr)->rbuf_off)
#define READ_DATA_BUFFERED(fptr) READ_DATA_PENDING(fptr)

#define READ_CHECK(fptr) do {\
    if (!READ_DATA_PENDING(fptr)) {\
	rb_thread_wait_fd((fptr)->fd);\
	rb_io_check_closed(fptr);\
     }\
} while(0)

#ifndef S_ISSOCK
#  ifdef _S_ISSOCK
#    define S_ISSOCK(m) _S_ISSOCK(m)
#  else
#    ifdef _S_IFSOCK
#      define S_ISSOCK(m) ((m & S_IFMT) == _S_IFSOCK)
#    else
#      ifdef S_IFSOCK
#	 define S_ISSOCK(m) ((m & S_IFMT) == S_IFSOCK)
#      endif
#    endif
#  endif
#endif

#if !defined HAVE_SHUTDOWN && !defined shutdown
#define shutdown(a,b)	0
#endif

#define rb_sys_fail_path(path) rb_sys_fail(NIL_P(path) ? 0 : RSTRING_PTR(path))

#if defined(_WIN32)
#define is_socket(fd, path)	rb_w32_is_socket(fd)
#elif !defined(S_ISSOCK)
#define is_socket(fd, path)	0
#else
static int
is_socket(int fd, VALUE path)
{
    struct stat sbuf;
    if (fstat(fd, &sbuf) < 0)
        rb_sys_fail_path(path);
    return S_ISSOCK(sbuf.st_mode);
}
#endif

void
rb_eof_error(void)
{
    rb_raise(rb_eEOFError, "end of file reached");
}

VALUE
rb_io_taint_check(VALUE io)
{
    if (!OBJ_UNTRUSTED(io) && rb_safe_level() >= 4)
	rb_raise(rb_eSecurityError, "Insecure: operation on trusted IO");
    rb_check_frozen(io);
    return io;
}

void
rb_io_check_initialized(rb_io_t *fptr)
{
    if (!fptr) {
	rb_raise(rb_eIOError, "uninitialized stream");
    }
}

void
rb_io_check_closed(rb_io_t *fptr)
{
    rb_io_check_initialized(fptr);
    if (fptr->fd < 0) {
	rb_raise(rb_eIOError, "closed stream");
    }
}

static int io_fflush(rb_io_t *);

VALUE
rb_io_get_io(VALUE io)
{
    return rb_convert_type(io, T_FILE, "IO", "to_io");
}

static VALUE
rb_io_check_io(VALUE io)
{
    return rb_check_convert_type(io, T_FILE, "IO", "to_io");
}

VALUE
rb_io_get_write_io(VALUE io)
{
    VALUE write_io;
    rb_io_check_initialized(RFILE(io)->fptr);
    write_io = RFILE(io)->fptr->tied_io_for_writing;
    if (write_io) {
        return write_io;
    }
    return io;
}

/*
 *  call-seq:
 *     IO.try_convert(obj) -> io or nil
 *
 *  Try to convert <i>obj</i> into an IO, using to_io method.
 *  Returns converted IO or nil if <i>obj</i> cannot be converted
 *  for any reason.
 *
 *     IO.try_convert(STDOUT)     # => STDOUT
 *     IO.try_convert("STDOUT")   # => nil
 *
 *     require 'zlib'
 *     f = open("/tmp/zz.gz")       # => #<File:/tmp/zz.gz>
 *     z = Zlib::GzipReader.open(f) # => #<Zlib::GzipReader:0x81d8744>
 *     IO.try_convert(z)            # => #<File:/tmp/zz.gz>
 *
 */
static VALUE
rb_io_s_try_convert(VALUE dummy, VALUE io)
{
    return rb_io_check_io(io);
}

static void
io_unread(rb_io_t *fptr)
{
    off_t r;
    rb_io_check_closed(fptr);
    if (fptr->rbuf_len == 0 || fptr->mode & FMODE_DUPLEX)
        return;
    /* xxx: target position may be negative if buffer is filled by ungetc */
    r = lseek(fptr->fd, -fptr->rbuf_len, SEEK_CUR);
    if (r < 0) {
        if (errno == ESPIPE)
            fptr->mode |= FMODE_DUPLEX;
        return;
    }
    fptr->rbuf_off = 0;
    fptr->rbuf_len = 0;
    return;
}

static rb_encoding *io_input_encoding(rb_io_t *fptr);

static void
io_ungetbyte(VALUE str, rb_io_t *fptr)
{
    long len = RSTRING_LEN(str);

    if (fptr->rbuf == NULL) {
        fptr->rbuf_off = 0;
        fptr->rbuf_len = 0;
#if SIZEOF_LONG > SIZEOF_INT
	if (len > INT_MAX)
	    rb_raise(rb_eIOError, "ungetbyte failed");
#endif
	if (len > 8192)
	    fptr->rbuf_capa = (int)len;
	else
	    fptr->rbuf_capa = 8192;
        fptr->rbuf = ALLOC_N(char, fptr->rbuf_capa);
    }
    if (fptr->rbuf_capa < len + fptr->rbuf_len) {
	rb_raise(rb_eIOError, "ungetbyte failed");
    }
    if (fptr->rbuf_off < len) {
        MEMMOVE(fptr->rbuf+fptr->rbuf_capa-fptr->rbuf_len,
                fptr->rbuf+fptr->rbuf_off,
                char, fptr->rbuf_len);
        fptr->rbuf_off = fptr->rbuf_capa-fptr->rbuf_len;
    }
    fptr->rbuf_off-=(int)len;
    fptr->rbuf_len+=(int)len;
    MEMMOVE(fptr->rbuf+fptr->rbuf_off, RSTRING_PTR(str), char, len);
}

static rb_io_t *
flush_before_seek(rb_io_t *fptr)
{
    if (io_fflush(fptr) < 0)
        rb_sys_fail(0);
    io_unread(fptr);
    errno = 0;
    return fptr;
}

#define io_set_eof(fptr) (void)(((fptr)->mode & FMODE_TTY) && ((fptr)->mode |= FMODE_EOF))
#define io_unset_eof(fptr) (fptr->mode &= ~FMODE_EOF)
#define io_seek(fptr, ofs, whence) (io_unset_eof(fptr), lseek(flush_before_seek(fptr)->fd, ofs, whence))
#define io_tell(fptr) lseek(flush_before_seek(fptr)->fd, 0, SEEK_CUR)

#ifndef SEEK_CUR
# define SEEK_SET 0
# define SEEK_CUR 1
# define SEEK_END 2
#endif

#define FMODE_SYNCWRITE (FMODE_SYNC|FMODE_WRITABLE)

void
rb_io_check_readable(rb_io_t *fptr)
{
    rb_io_check_closed(fptr);
    if (!(fptr->mode & FMODE_READABLE)) {
	rb_raise(rb_eIOError, "not opened for reading");
    }
    if (fptr->wbuf_len) {
        if (io_fflush(fptr) < 0)
            rb_sys_fail(0);
    }
    if (fptr->tied_io_for_writing) {
	rb_io_t *wfptr;
	GetOpenFile(fptr->tied_io_for_writing, wfptr);
        if (io_fflush(wfptr) < 0)
            rb_sys_fail(0);
    }
}

static rb_encoding*
io_read_encoding(rb_io_t *fptr)
{
    if (fptr->encs.enc) {
	return fptr->encs.enc;
    }
    return rb_default_external_encoding();
}

static rb_encoding*
io_input_encoding(rb_io_t *fptr)
{
    if (fptr->encs.enc2) {
	return fptr->encs.enc2;
    }
    return io_read_encoding(fptr);
}

void
rb_io_check_writable(rb_io_t *fptr)
{
    rb_io_check_closed(fptr);
    if (!(fptr->mode & FMODE_WRITABLE)) {
	rb_raise(rb_eIOError, "not opened for writing");
    }
    if (fptr->rbuf_len) {
        io_unread(fptr);
    }
}

int
rb_io_read_pending(rb_io_t *fptr)
{
    return READ_DATA_PENDING(fptr);
}

void
rb_read_check(FILE *fp)
{
    if (!STDIO_READ_DATA_PENDING(fp)) {
	rb_thread_wait_fd(fileno(fp));
    }
}

void
rb_io_read_check(rb_io_t *fptr)
{
    if (!READ_DATA_PENDING(fptr)) {
	rb_thread_wait_fd(fptr->fd);
    }
    return;
}

static int
ruby_dup(int orig)
{
    int fd;

    fd = dup(orig);
    if (fd < 0) {
	if (errno == EMFILE || errno == ENFILE || errno == ENOMEM) {
	    rb_gc();
	    fd = dup(orig);
	}
	if (fd < 0) {
	    rb_sys_fail(0);
	}
    }
    return fd;
}

static VALUE
io_alloc(VALUE klass)
{
    NEWOBJ(io, struct RFile);
    OBJSETUP(io, klass, T_FILE);

    io->fptr = 0;

    return (VALUE)io;
}

#ifndef S_ISREG
#   define S_ISREG(m) ((m & S_IFMT) == S_IFREG)
#endif

static int
wsplit_p(rb_io_t *fptr)
{
#if defined(HAVE_FCNTL) && defined(F_GETFL) && defined(O_NONBLOCK)
    int r;
#endif

    if (!(fptr->mode & FMODE_WSPLIT_INITIALIZED)) {
        struct stat buf;
        if (fstat(fptr->fd, &buf) == 0 &&
            !S_ISREG(buf.st_mode)
#if defined(HAVE_FCNTL) && defined(F_GETFL) && defined(O_NONBLOCK)
            && (r = fcntl(fptr->fd, F_GETFL)) != -1 &&
            !(r & O_NONBLOCK)
#endif
            ) {
            fptr->mode |= FMODE_WSPLIT;
        }
        fptr->mode |= FMODE_WSPLIT_INITIALIZED;
    }
    return fptr->mode & FMODE_WSPLIT;
}

struct io_internal_struct {
    int fd;
    void *buf;
    size_t capa;
};

static VALUE
internal_read_func(void *ptr)
{
    struct io_internal_struct *iis = (struct io_internal_struct*)ptr;
    return read(iis->fd, iis->buf, iis->capa);
}

static VALUE
internal_write_func(void *ptr)
{
    struct io_internal_struct *iis = (struct io_internal_struct*)ptr;
    return write(iis->fd, iis->buf, iis->capa);
}

static ssize_t
rb_read_internal(int fd, void *buf, size_t count)
{
    struct io_internal_struct iis;
    iis.fd = fd;
    iis.buf = buf;
    iis.capa = count;

    return (ssize_t)rb_thread_blocking_region(internal_read_func, &iis, RUBY_UBF_IO, 0);
}

static ssize_t
rb_write_internal(int fd, void *buf, size_t count)
{
    struct io_internal_struct iis;
    iis.fd = fd;
    iis.buf = buf;
    iis.capa = count;

    return (ssize_t)rb_thread_blocking_region(internal_write_func, &iis, RUBY_UBF_IO, 0);
}

static long
io_writable_length(rb_io_t *fptr, long l)
{
    if (PIPE_BUF < l &&
        !rb_thread_alone() &&
        wsplit_p(fptr)) {
        l = PIPE_BUF;
    }
    return l;
}

static VALUE
io_flush_buffer(VALUE arg)
{
    rb_io_t *fptr = (rb_io_t *)arg;
    long l = io_writable_length(fptr, fptr->wbuf_len);
    return rb_write_internal(fptr->fd, fptr->wbuf+fptr->wbuf_off, l);
}

static int
io_fflush(rb_io_t *fptr)
{
    long r;

    rb_io_check_closed(fptr);
    if (fptr->wbuf_len == 0)
        return 0;
    if (!rb_thread_fd_writable(fptr->fd)) {
        rb_io_check_closed(fptr);
    }
  retry:
    if (fptr->wbuf_len == 0)
        return 0;
    if (fptr->write_lock) {
	r = rb_mutex_synchronize(fptr->write_lock, io_flush_buffer, (VALUE)fptr);
    }
    else {
	long l = io_writable_length(fptr, fptr->wbuf_len);
	r = rb_write_internal(fptr->fd, fptr->wbuf+fptr->wbuf_off, l);
    }
    /* xxx: Other threads may modify wbuf.
     * A lock is required, definitely. */
    rb_io_check_closed(fptr);
    if (fptr->wbuf_len <= r) {
        fptr->wbuf_off = 0;
        fptr->wbuf_len = 0;
        return 0;
    }
    if (0 <= r) {
        fptr->wbuf_off += (int)r;
        fptr->wbuf_len -= (int)r;
        errno = EAGAIN;
    }
    if (rb_io_wait_writable(fptr->fd)) {
        rb_io_check_closed(fptr);
        goto retry;
    }
    return -1;
}

#ifdef HAVE_RB_FD_INIT
static VALUE
wait_readable(VALUE p)
{
    rb_fdset_t *rfds = (rb_fdset_t *)p;

    return rb_thread_select(rb_fd_max(rfds), rb_fd_ptr(rfds), NULL, NULL, NULL);
}
#endif

int
rb_io_wait_readable(int f)
{
    rb_fdset_t rfds;

    if (f < 0) {
	rb_raise(rb_eIOError, "closed stream");
    }
    switch (errno) {
      case EINTR:
#if defined(ERESTART)
      case ERESTART:
#endif
	rb_thread_wait_fd(f);
	return TRUE;

      case EAGAIN:
#if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
      case EWOULDBLOCK:
#endif
	rb_fd_init(&rfds);
	rb_fd_set(f, &rfds);
#ifdef HAVE_RB_FD_INIT
	rb_ensure(wait_readable, (VALUE)&rfds,
		  (VALUE (*)(VALUE))rb_fd_term, (VALUE)&rfds);
#else
	rb_thread_select(f + 1, rb_fd_ptr(&rfds), NULL, NULL, NULL);
#endif
	return TRUE;

      default:
	return FALSE;
    }
}

#ifdef HAVE_RB_FD_INIT
static VALUE
wait_writable(VALUE p)
{
    rb_fdset_t *wfds = (rb_fdset_t *)p;

    return rb_thread_select(rb_fd_max(wfds), NULL, rb_fd_ptr(wfds), NULL, NULL);
}
#endif

int
rb_io_wait_writable(int f)
{
    rb_fdset_t wfds;

    if (f < 0) {
	rb_raise(rb_eIOError, "closed stream");
    }
    switch (errno) {
      case EINTR:
#if defined(ERESTART)
      case ERESTART:
#endif
	rb_thread_fd_writable(f);
	return TRUE;

      case EAGAIN:
#if defined(EWOULDBLOCK) && EWOULDBLOCK != EAGAIN
      case EWOULDBLOCK:
#endif
	rb_fd_init(&wfds);
	rb_fd_set(f, &wfds);
#ifdef HAVE_RB_FD_INIT
	rb_ensure(wait_writable, (VALUE)&wfds,
		  (VALUE (*)(VALUE))rb_fd_term, (VALUE)&wfds);
#else
	rb_thread_select(f + 1, NULL, rb_fd_ptr(&wfds), NULL, NULL);
#endif
	return TRUE;

      default:
	return FALSE;
    }
}

#if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32)
/* Windows */
# define NEED_NEWLINE_DECORATOR_ON_READ(fptr) (!(fptr->mode & FMODE_BINMODE))
# define NEED_NEWLINE_DECORATOR_ON_WRITE(fptr) (!(fptr->mode & FMODE_BINMODE))
# define TEXTMODE_NEWLINE_DECORATOR_ON_WRITE ECONV_CRLF_NEWLINE_DECORATOR
#else
/* Unix */
# define NEED_NEWLINE_DECORATOR_ON_READ(fptr) (fptr->mode & FMODE_TEXTMODE)
# define NEED_NEWLINE_DECORATOR_ON_WRITE(fptr) 0
#endif
#define NEED_READCONV(fptr) (fptr->encs.enc2 != NULL || NEED_NEWLINE_DECORATOR_ON_READ(fptr))
#define NEED_WRITECONV(fptr) ((fptr->encs.enc != NULL && fptr->encs.enc != rb_ascii8bit_encoding()) || NEED_NEWLINE_DECORATOR_ON_WRITE(fptr) || (fptr->encs.ecflags & (ECONV_DECORATOR_MASK|ECONV_STATEFUL_DECORATOR_MASK)))

static void
make_writeconv(rb_io_t *fptr)
{
    if (!fptr->writeconv_initialized) {
        const char *senc, *denc;
        rb_encoding *enc;
        int ecflags;
        VALUE ecopts;

        fptr->writeconv_initialized = 1;

        ecflags = fptr->encs.ecflags;
        ecopts = fptr->encs.ecopts;
#ifdef TEXTMODE_NEWLINE_DECORATOR_ON_WRITE
        if (NEED_NEWLINE_DECORATOR_ON_WRITE(fptr))
            ecflags |= TEXTMODE_NEWLINE_DECORATOR_ON_WRITE;
#endif

        if (!fptr->encs.enc || (fptr->encs.enc == rb_ascii8bit_encoding() && !fptr->encs.enc2)) {
            /* no encoding conversion */
            fptr->writeconv_pre_ecflags = 0;
            fptr->writeconv_pre_ecopts = Qnil;
            fptr->writeconv = rb_econv_open_opts("", "", ecflags, ecopts);
            if (!fptr->writeconv)
                rb_exc_raise(rb_econv_open_exc("", "", ecflags));
            fptr->writeconv_asciicompat = Qnil;
        }
        else {
            enc = fptr->encs.enc2 ? fptr->encs.enc2 : fptr->encs.enc;
            senc = rb_econv_asciicompat_encoding(rb_enc_name(enc));
            if (!senc && !(fptr->encs.ecflags & ECONV_STATEFUL_DECORATOR_MASK)) {
                /* single conversion */
                fptr->writeconv_pre_ecflags = ecflags;
                fptr->writeconv_pre_ecopts = ecopts;
                fptr->writeconv = NULL;
                fptr->writeconv_asciicompat = Qnil;
            }
            else {
                /* double conversion */
                fptr->writeconv_pre_ecflags = ecflags & ~ECONV_STATEFUL_DECORATOR_MASK;
                fptr->writeconv_pre_ecopts = ecopts;
                if (senc) {
                    denc = rb_enc_name(enc);
                    fptr->writeconv_asciicompat = rb_str_new2(senc);
                }
                else {
                    senc = denc = "";
                    fptr->writeconv_asciicompat = rb_str_new2(rb_enc_name(enc));
                }
                ecflags = fptr->encs.ecflags & (ECONV_ERROR_HANDLER_MASK|ECONV_STATEFUL_DECORATOR_MASK);
                ecopts = fptr->encs.ecopts;
                fptr->writeconv = rb_econv_open_opts(senc, denc, ecflags, ecopts);
                if (!fptr->writeconv)
                    rb_exc_raise(rb_econv_open_exc(senc, denc, ecflags));
            }
        }
    }
}

/* writing functions */
struct binwrite_arg {
    rb_io_t *fptr;
    VALUE str;
    long offset;
    long length;
};

static VALUE
io_binwrite_string(VALUE arg)
{
    struct binwrite_arg *p = (struct binwrite_arg *)arg;
    long l = io_writable_length(p->fptr, p->length);
    return rb_write_internal(p->fptr->fd, RSTRING_PTR(p->str)+p->offset, l);
}

static long
io_binwrite(VALUE str, rb_io_t *fptr, int nosync)
{
    long len, n, r, offset = 0;

    len = RSTRING_LEN(str);
    if ((n = len) <= 0) return n;
    if (fptr->wbuf == NULL && !(!nosync && (fptr->mode & FMODE_SYNC))) {
        fptr->wbuf_off = 0;
        fptr->wbuf_len = 0;
        fptr->wbuf_capa = 8192;
        fptr->wbuf = ALLOC_N(char, fptr->wbuf_capa);
	fptr->write_lock = rb_mutex_new();
    }
    if ((!nosync && (fptr->mode & (FMODE_SYNC|FMODE_TTY))) ||
        (fptr->wbuf && fptr->wbuf_capa <= fptr->wbuf_len + len)) {
	struct binwrite_arg arg;

        /* xxx: use writev to avoid double write if available */
        if (fptr->wbuf_len && fptr->wbuf_len+len <= fptr->wbuf_capa) {
            if (fptr->wbuf_capa < fptr->wbuf_off+fptr->wbuf_len+len) {
                MEMMOVE(fptr->wbuf, fptr->wbuf+fptr->wbuf_off, char, fptr->wbuf_len);
                fptr->wbuf_off = 0;
            }
            MEMMOVE(fptr->wbuf+fptr->wbuf_off+fptr->wbuf_len, RSTRING_PTR(str)+offset, char, len);
            fptr->wbuf_len += (int)len;
            n = 0;
        }
        if (io_fflush(fptr) < 0)
            return -1L;
        if (n == 0)
            return len;
        /* avoid context switch between "a" and "\n" in STDERR.puts "a".
           [ruby-dev:25080] */
	if (fptr->stdio_file != stderr && !rb_thread_fd_writable(fptr->fd)) {
	    rb_io_check_closed(fptr);
	}
	arg.fptr = fptr;
	arg.str = str;
      retry:
	arg.offset = offset;
	arg.length = n;
	if (fptr->write_lock) {
	    r = rb_mutex_synchronize(fptr->write_lock, io_binwrite_string, (VALUE)&arg);
	}
	else {
	    long l = io_writable_length(fptr, n);
	    r = rb_write_internal(fptr->fd, RSTRING_PTR(str)+offset, l);
	}
	/* xxx: other threads may modify given string. */
        if (r == n) return len;
        if (0 <= r) {
            offset += r;
            n -= r;
            errno = EAGAIN;
        }
        if (rb_io_wait_writable(fptr->fd)) {
            rb_io_check_closed(fptr);
	    if (offset < RSTRING_LEN(str))
		goto retry;
        }
        return -1L;
    }

    if (fptr->wbuf_off) {
        if (fptr->wbuf_len)
            MEMMOVE(fptr->wbuf, fptr->wbuf+fptr->wbuf_off, char, fptr->wbuf_len);
        fptr->wbuf_off = 0;
    }
    MEMMOVE(fptr->wbuf+fptr->wbuf_off+fptr->wbuf_len, RSTRING_PTR(str)+offset, char, len);
    fptr->wbuf_len += (int)len;
    return len;
}

static VALUE
do_writeconv(VALUE str, rb_io_t *fptr)
{
    if (NEED_WRITECONV(fptr)) {
        VALUE common_encoding = Qnil;

        make_writeconv(fptr);

        if (fptr->writeconv) {
            if (!NIL_P(fptr->writeconv_asciicompat))
                common_encoding = fptr->writeconv_asciicompat;
            else if (!rb_enc_asciicompat(rb_enc_get(str))) {
                rb_raise(rb_eArgError, "ASCII incompatible string written for text mode IO without encoding conversion: %s",
                         rb_enc_name(rb_enc_get(str)));
            }
        }
        else {
            if (fptr->encs.enc2)
                common_encoding = rb_enc_from_encoding(fptr->encs.enc2);
            else if (fptr->encs.enc != rb_ascii8bit_encoding())
                common_encoding = rb_enc_from_encoding(fptr->encs.enc);
        }

        if (!NIL_P(common_encoding)) {
            str = rb_str_encode(str, common_encoding,
                fptr->writeconv_pre_ecflags, fptr->writeconv_pre_ecopts);
        }

        if (fptr->writeconv) {
            str = rb_econv_str_convert(fptr->writeconv, str, ECONV_PARTIAL_INPUT);
        }
    }
    return str;
}

static long
io_fwrite(VALUE str, rb_io_t *fptr, int nosync)
{
    str = do_writeconv(str, fptr);
    return io_binwrite(str, fptr, nosync);
}

static VALUE
io_write(VALUE io, VALUE str, int nosync)
{
    rb_io_t *fptr;
    long n;
    VALUE tmp;

    rb_secure(4);
    io = GetWriteIO(io);
    str = rb_obj_as_string(str);
    tmp = rb_io_check_io(io);
    if (NIL_P(tmp)) {
	/* port is not IO, call write method for it. */
	return rb_funcall(io, id_write, 1, str);
    }
    io = tmp;
    if (RSTRING_LEN(str) == 0) return INT2FIX(0);

    GetOpenFile(io, fptr);
    rb_io_check_writable(fptr);

    n = io_fwrite(str, fptr, nosync);
    if (n == -1L) rb_sys_fail_path(fptr->pathv);

    return LONG2FIX(n);
}

/*
 *  call-seq:
 *     ios.write(string)    => integer
 *
 *  Writes the given string to <em>ios</em>. The stream must be opened
 *  for writing. If the argument is not a string, it will be converted
 *  to a string using <code>to_s</code>. Returns the number of bytes
 *  written.
 *
 *     count = $stdout.write( "This is a test\n" )
 *     puts "That was #{count} bytes of data"
 *
 *  <em>produces:</em>
 *
 *     This is a test
 *     That was 15 bytes of data
 */

static VALUE
io_write_m(VALUE io, VALUE str)
{
    return io_write(io, str, 0);
}

VALUE
rb_io_write(VALUE io, VALUE str)
{
    return rb_funcall(io, id_write, 1, str);
}

/*
 *  call-seq:
 *     ios << obj     => ios
 *
 *  String Output---Writes <i>obj</i> to <em>ios</em>.
 *  <i>obj</i> will be converted to a string using
 *  <code>to_s</code>.
 *
 *     $stdout << "Hello " << "world!\n"
 *
 *  <em>produces:</em>
 *
 *     Hello world!
 */


VALUE
rb_io_addstr(VALUE io, VALUE str)
{
    rb_io_write(io, str);
    return io;
}

/*
 *  call-seq:
 *     ios.flush    => ios
 *
 *  Flushes any buffered data within <em>ios</em> to the underlying
 *  operating system (note that this is Ruby internal buffering only;
 *  the OS may buffer the data as well).
 *
 *     $stdout.print "no newline"
 *     $stdout.flush
 *
 *  <em>produces:</em>
 *
 *     no newline
 */

VALUE
rb_io_flush(VALUE io)
{
    rb_io_t *fptr;

    if (TYPE(io) != T_FILE) {
        return rb_funcall(io, id_flush, 0);
    }

    io = GetWriteIO(io);
    GetOpenFile(io, fptr);

    if (fptr->mode & FMODE_WRITABLE) {
        if (io_fflush(fptr) < 0)
            rb_sys_fail(0);
#ifdef _WIN32
	fsync(fptr->fd);
#endif
    }
    if (fptr->mode & FMODE_READABLE) {
        io_unread(fptr);
    }

    return io;
}

/*
 *  call-seq:
 *     ios.pos     => integer
 *     ios.tell    => integer
 *
 *  Returns the current offset (in bytes) of <em>ios</em>.
 *
 *     f = File.new("testfile")
 *     f.pos    #=> 0
 *     f.gets   #=> "This is line one\n"
 *     f.pos    #=> 17
 */

static VALUE
rb_io_tell(VALUE io)
{
    rb_io_t *fptr;
    off_t pos;

    GetOpenFile(io, fptr);
    pos = io_tell(fptr);
    if (pos < 0 && errno) rb_sys_fail_path(fptr->pathv);
    pos -= fptr->rbuf_len;
    return OFFT2NUM(pos);
}

static VALUE
rb_io_seek(VALUE io, VALUE offset, int whence)
{
    rb_io_t *fptr;
    off_t pos;

    pos = NUM2OFFT(offset);
    GetOpenFile(io, fptr);
    pos = io_seek(fptr, pos, whence);
    if (pos < 0 && errno) rb_sys_fail_path(fptr->pathv);

    return INT2FIX(0);
}

/*
 *  call-seq:
 *     ios.seek(amount, whence=IO::SEEK_SET) -> 0
 *
 *  Seeks to a given offset <i>anInteger</i> in the stream according to
 *  the value of <i>whence</i>:
 *
 *    IO::SEEK_CUR  | Seeks to _amount_ plus current position
 *    --------------+----------------------------------------------------
 *    IO::SEEK_END  | Seeks to _amount_ plus end of stream (you probably
 *                  | want a negative value for _amount_)
 *    --------------+----------------------------------------------------
 *    IO::SEEK_SET  | Seeks to the absolute location given by _amount_
 *
 *  Example:
 *
 *     f = File.new("testfile")
 *     f.seek(-13, IO::SEEK_END)   #=> 0
 *     f.readline                  #=> "And so on...\n"
 */

static VALUE
rb_io_seek_m(int argc, VALUE *argv, VALUE io)
{
    VALUE offset, ptrname;
    int whence = SEEK_SET;

    if (rb_scan_args(argc, argv, "11", &offset, &ptrname) == 2) {
	whence = NUM2INT(ptrname);
    }

    return rb_io_seek(io, offset, whence);
}

/*
 *  call-seq:
 *     ios.pos = integer    => integer
 *
 *  Seeks to the given position (in bytes) in <em>ios</em>.
 *
 *     f = File.new("testfile")
 *     f.pos = 17
 *     f.gets   #=> "This is line two\n"
 */

static VALUE
rb_io_set_pos(VALUE io, VALUE offset)
{
    rb_io_t *fptr;
    off_t pos;

    pos = NUM2OFFT(offset);
    GetOpenFile(io, fptr);
    pos = io_seek(fptr, pos, SEEK_SET);
    if (pos < 0) rb_sys_fail_path(fptr->pathv);

    return OFFT2NUM(pos);
}

static void clear_readconv(rb_io_t *fptr);

/*
 *  call-seq:
 *     ios.rewind    => 0
 *
 *  Positions <em>ios</em> to the beginning of input, resetting
 *  <code>lineno</code> to zero.
 *
 *     f = File.new("testfile")
 *     f.readline   #=> "This is line one\n"
 *     f.rewind     #=> 0
 *     f.lineno     #=> 0
 *     f.readline   #=> "This is line one\n"
 */

static VALUE
rb_io_rewind(VALUE io)
{
    rb_io_t *fptr;

    GetOpenFile(io, fptr);
    if (io_seek(fptr, 0L, 0) < 0) rb_sys_fail_path(fptr->pathv);
    if (io == ARGF.current_file) {
	ARGF.lineno -= fptr->lineno;
    }
    fptr->lineno = 0;
    if (fptr->readconv) {
	clear_readconv(fptr);
    }

    return INT2FIX(0);
}

static int
io_fillbuf(rb_io_t *fptr)
{
    ssize_t r;

    if (fptr->mode & FMODE_EOF) {
	return -1;
    }
    if (fptr->rbuf == NULL) {
        fptr->rbuf_off = 0;
        fptr->rbuf_len = 0;
        fptr->rbuf_capa = 8192;
        fptr->rbuf = ALLOC_N(char, fptr->rbuf_capa);
    }
    if (fptr->rbuf_len == 0) {
      retry:
	{
	    r = rb_read_internal(fptr->fd, fptr->rbuf, fptr->rbuf_capa);
	}
        if (r < 0) {
            if (rb_io_wait_readable(fptr->fd))
                goto retry;
            rb_sys_fail_path(fptr->pathv);
        }
        fptr->rbuf_off = 0;
        fptr->rbuf_len = (int)r; /* r should be <= rbuf_capa */
        if (r == 0) {
	    io_set_eof(fptr);
            return -1; /* EOF */
	}
    }
    return 0;
}

/*
 *  call-seq:
 *     ios.eof     => true or false
 *     ios.eof?    => true or false
 *
 *  Returns true if <em>ios</em> is at end of file that means
 *  there are no more data to read.
 *  The stream must be opened for reading or an <code>IOError</code> will be
 *  raised.
 *
 *     f = File.new("testfile")
 *     dummy = f.readlines
 *     f.eof   #=> true
 *
 *  If <em>ios</em> is a stream such as pipe or socket, <code>IO#eof?</code>
 *  blocks until the other end sends some data or closes it.
 *
 *     r, w = IO.pipe
 *     Thread.new { sleep 1; w.close }
 *     r.eof?  #=> true after 1 second blocking
 *
 *     r, w = IO.pipe
 *     Thread.new { sleep 1; w.puts "a" }
 *     r.eof?  #=> false after 1 second blocking
 *
 *     r, w = IO.pipe
 *     r.eof?  # blocks forever
 *
 *  Note that <code>IO#eof?</code> reads data to a input buffer.
 *  So <code>IO#sysread</code> doesn't work with <code>IO#eof?</code>.
 */

VALUE
rb_io_eof(VALUE io)
{
    rb_io_t *fptr;

    GetOpenFile(io, fptr);
    rb_io_check_readable(fptr);

    if (READ_DATA_PENDING(fptr)) return Qfalse;
    READ_CHECK(fptr);
    if (io_fillbuf(fptr) < 0) {
	return Qtrue;
    }
    return Qfalse;
}

/*
 *  call-seq:
 *     ios.sync    => true or false
 *
 *  Returns the current ``sync mode'' of <em>ios</em>. When sync mode is
 *  true, all output is immediately flushed to the underlying operating
 *  system and is not buffered by Ruby internally. See also
 *  <code>IO#fsync</code>.
 *
 *     f = File.new("testfile")
 *     f.sync   #=> false
 */

static VALUE
rb_io_sync(VALUE io)
{
    rb_io_t *fptr;

    io = GetWriteIO(io);
    GetOpenFile(io, fptr);
    return (fptr->mode & FMODE_SYNC) ? Qtrue : Qfalse;
}

/*
 *  call-seq:
 *     ios.sync = boolean   => boolean
 *
 *  Sets the ``sync mode'' to <code>true</code> or <code>false</code>.
 *  When sync mode is true, all output is immediately flushed to the
 *  underlying operating system and is not buffered internally. Returns
 *  the new state. See also <code>IO#fsync</code>.
 *
 *     f = File.new("testfile")
 *     f.sync = true
 *
 *  <em>(produces no output)</em>
 */

static VALUE
rb_io_set_sync(VALUE io, VALUE sync)
{
    rb_io_t *fptr;

    io = GetWriteIO(io);
    GetOpenFile(io, fptr);
    if (RTEST(sync)) {
	fptr->mode |= FMODE_SYNC;
    }
    else {
	fptr->mode &= ~FMODE_SYNC;
    }
    return sync;
}

#ifdef HAVE_FSYNC
/*
 *  call-seq:
 *     ios.fsync   => 0 or nil
 *
 *  Immediately writes all buffered data in <em>ios</em> to disk.
 *  Note that <code>fsync</code> differs from
 *  using <code>IO#sync=</code>. The latter ensures that data is flushed
 *  from Ruby's buffers, but doesn't not guarantee that the underlying
 *  operating system actually writes it to disk.
 *
 *  <code>NotImplementedError</code> is raised
 *  if the underlying operating system does not support <em>fsync(2)</em>.
 */

static VALUE
rb_io_fsync(VALUE io)
{
    rb_io_t *fptr;

    io = GetWriteIO(io);
    GetOpenFile(io, fptr);

    if (io_fflush(fptr) < 0)
        rb_sys_fail(0);
    if (fsync(fptr->fd) < 0)
	rb_sys_fail_path(fptr->pathv);
    return INT2FIX(0);
}
#else
#define rb_io_fsync rb_f_notimplement
#endif

#ifdef HAVE_FDATASYNC
/*
 *  call-seq:
 *     ios.fdatasync   => 0 or nil
 *
 *  Immediately writes all buffered data in <em>ios</em> to disk.
 *
 *  <code>NotImplementedError</code> is raised
 *  if the underlying operating system does not support <em>fdatasync(2)</em>.
 */

static VALUE
rb_io_fdatasync(VALUE io)
{
    rb_io_t *fptr;

    io = GetWriteIO(io);
    GetOpenFile(io, fptr);

    if (io_fflush(fptr) < 0)
        rb_sys_fail(0);
    if (fdatasync(fptr->fd) < 0)
	rb_sys_fail_path(fptr->pathv);
    return INT2FIX(0);
}
#else
#define rb_io_fdatasync rb_f_notimplement
#endif

/*
 *  call-seq:
 *     ios.fileno    => fixnum
 *     ios.to_i      => fixnum
 *
 *  Returns an integer representing the numeric file descriptor for
 *  <em>ios</em>.
 *
 *     $stdin.fileno    #=> 0
 *     $stdout.fileno   #=> 1
 */

static VALUE
rb_io_fileno(VALUE io)
{
    rb_io_t *fptr;
    int fd;

    GetOpenFile(io, fptr);
    fd = fptr->fd;
    return INT2FIX(fd);
}


/*
 *  call-seq:
 *     ios.pid    => fixnum
 *
 *  Returns the process ID of a child process associated with
 *  <em>ios</em>. This will be set by <code>IO.popen</code>.
 *
 *     pipe = IO.popen("-")
 *     if pipe
 *       $stderr.puts "In parent, child pid is #{pipe.pid}"
 *     else
 *       $stderr.puts "In child, pid is #{$$}"
 *     end
 *
 *  <em>produces:</em>
 *
 *     In child, pid is 26209
 *     In parent, child pid is 26209
 */

static VALUE
rb_io_pid(VALUE io)
{
    rb_io_t *fptr;

    GetOpenFile(io, fptr);
    if (!fptr->pid)
	return Qnil;
    return PIDT2NUM(fptr->pid);
}


/*
 * call-seq:
 *   ios.inspect   => string
 *
 * Return a string describing this IO object.
 */

static VALUE
rb_io_inspect(VALUE obj)
{
    rb_io_t *fptr;
    const char *cname;
    char fd_desc[256];
    const char *path;
    const char *st = "";

    fptr = RFILE(rb_io_taint_check(obj))->fptr;
    if (!fptr) return rb_any_to_s(obj);
    cname = rb_obj_classname(obj);
    if (NIL_P(fptr->pathv)) {
        if (fptr->fd < 0) {
            path = "";
            st = "(closed)";
        }
        else {
            snprintf(fd_desc, sizeof(fd_desc), "fd %d", fptr->fd);
            path = fd_desc;
        }
    }
    else {
        path = RSTRING_PTR(fptr->pathv);
        if (fptr->fd < 0) {
            st = " (closed)";
        }
    }
    return rb_sprintf("#<%s:%s%s>", cname, path, st);
}

/*
 *  call-seq:
 *     ios.to_io -> ios
 *
 *  Returns <em>ios</em>.
 */

static VALUE
rb_io_to_io(VALUE io)
{
    return io;
}

/* reading functions */
static long
read_buffered_data(char *ptr, long len, rb_io_t *fptr)
{
    int n;

    n = READ_DATA_PENDING_COUNT(fptr);
    if (n <= 0) return 0;
    if (n > len) n = (int)len;
    MEMMOVE(ptr, fptr->rbuf+fptr->rbuf_off, char, n);
    fptr->rbuf_off += n;
    fptr->rbuf_len -= n;
    return n;
}

static long
io_fread(VALUE str, long offset, rb_io_t *fptr)
{
    long len = RSTRING_LEN(str) - offset;
    long n = len;
    long c;

    if (READ_DATA_PENDING(fptr) == 0) {
	while (n > 0) {
          again:
	    c = rb_read_internal(fptr->fd, RSTRING_PTR(str)+offset, n);
	    if (c == 0) {
		io_set_eof(fptr);
		break;
	    }
	    if (c < 0) {
                if (rb_io_wait_readable(fptr->fd))
                    goto again;
		rb_sys_fail_path(fptr->pathv);
	    }
	    offset += c;
	    if ((n -= c) <= 0) break;
	    rb_thread_wait_fd(fptr->fd);
	}
	return len - n;
    }

    while (n > 0) {
	c = read_buffered_data(RSTRING_PTR(str)+offset, n, fptr);
	if (c > 0) {
	    offset += c;
	    if ((n -= c) <= 0) break;
	}
	rb_thread_wait_fd(fptr->fd);
	rb_io_check_closed(fptr);
	if (io_fillbuf(fptr) < 0) {
	    break;
	}
    }
    return len - n;
}

#define SMALLBUF 100

static long
remain_size(rb_io_t *fptr)
{
    struct stat st;
    off_t siz = READ_DATA_PENDING_COUNT(fptr);
    off_t pos;

    if (fstat(fptr->fd, &st) == 0  && S_ISREG(st.st_mode)
#if defined(__BEOS__) || defined(__HAIKU__)
	&& (st.st_dev > 3)
#endif
	)
    {
        if (io_fflush(fptr) < 0)
            rb_sys_fail(0);
	pos = lseek(fptr->fd, 0, SEEK_CUR);
	if (st.st_size >= pos && pos >= 0) {
	    siz += st.st_size - pos;
	    if (siz > LONG_MAX) {
		rb_raise(rb_eIOError, "file too big for single read");
	    }
	}
    }
    else {
	siz += BUFSIZ;
    }
    return (long)siz;
}

static VALUE
io_enc_str(VALUE str, rb_io_t *fptr)
{
    OBJ_TAINT(str);
    rb_enc_associate(str, io_read_encoding(fptr));
    return str;
}

static void
make_readconv(rb_io_t *fptr, int size)
{
    if (!fptr->readconv) {
        int ecflags;
        VALUE ecopts;
        const char *sname, *dname;
        ecflags = fptr->encs.ecflags;
        ecopts = fptr->encs.ecopts;
        if (NEED_NEWLINE_DECORATOR_ON_READ(fptr))
            ecflags |= ECONV_UNIVERSAL_NEWLINE_DECORATOR;
        if (fptr->encs.enc2) {
            sname = rb_enc_name(fptr->encs.enc2);
            dname = rb_enc_name(fptr->encs.enc);
        }
        else {
            sname = dname = "";
        }
        fptr->readconv = rb_econv_open_opts(sname, dname, ecflags, ecopts);
        if (!fptr->readconv)
            rb_exc_raise(rb_econv_open_exc(sname, dname, ecflags));
        fptr->cbuf_off = 0;
        fptr->cbuf_len = 0;
        fptr->cbuf_capa = size < 1024 ? 1024 : size;
        fptr->cbuf = ALLOC_N(char, fptr->cbuf_capa);
    }
}

#define MORE_CHAR_SUSPENDED Qtrue
#define MORE_CHAR_FINISHED Qnil
static VALUE
fill_cbuf(rb_io_t *fptr, int ec_flags)
{
    const unsigned char *ss, *sp, *se;
    unsigned char *ds, *dp, *de;
    rb_econv_result_t res;
    int putbackable;
    int cbuf_len0;
    VALUE exc;

    ec_flags |= ECONV_PARTIAL_INPUT;

    if (fptr->cbuf_len == fptr->cbuf_capa)
        return MORE_CHAR_SUSPENDED; /* cbuf full */
    if (fptr->cbuf_len == 0)
        fptr->cbuf_off = 0;
    else if (fptr->cbuf_off + fptr->cbuf_len == fptr->cbuf_capa) {
        memmove(fptr->cbuf, fptr->cbuf+fptr->cbuf_off, fptr->cbuf_len);
        fptr->cbuf_off = 0;
    }

    cbuf_len0 = fptr->cbuf_len;

    while (1) {
        ss = sp = (const unsigned char *)fptr->rbuf + fptr->rbuf_off;
        se = sp + fptr->rbuf_len;
        ds = dp = (unsigned char *)fptr->cbuf + fptr->cbuf_off + fptr->cbuf_len;
        de = (unsigned char *)fptr->cbuf + fptr->cbuf_capa;
        res = rb_econv_convert(fptr->readconv, &sp, se, &dp, de, ec_flags);
        fptr->rbuf_off += (int)(sp - ss);
        fptr->rbuf_len -= (int)(sp - ss);
        fptr->cbuf_len += (int)(dp - ds);

        putbackable = rb_econv_putbackable(fptr->readconv);
        if (putbackable) {
            rb_econv_putback(fptr->readconv, (unsigned char *)fptr->rbuf + fptr->rbuf_off - putbackable, putbackable);
            fptr->rbuf_off -= putbackable;
            fptr->rbuf_len += putbackable;
        }

        exc = rb_econv_make_exception(fptr->readconv);
        if (!NIL_P(exc))
            return exc;

        if (cbuf_len0 != fptr->cbuf_len)
            return MORE_CHAR_SUSPENDED;

        if (res == econv_finished) {
            return MORE_CHAR_FINISHED;
	}

        if (res == econv_source_buffer_empty) {
            if (fptr->rbuf_len == 0) {
                rb_thread_wait_fd(fptr->fd);
                rb_io_check_closed(fptr);
                if (io_fillbuf(fptr) == -1) {
                    ds = dp = (unsigned char *)fptr->cbuf + fptr->cbuf_off + fptr->cbuf_len;
                    de = (unsigned char *)fptr->cbuf + fptr->cbuf_capa;
                    res = rb_econv_convert(fptr->readconv, NULL, NULL, &dp, de, 0);
                    fptr->cbuf_len += (int)(dp - ds);
                    rb_econv_check_error(fptr->readconv);
                }
            }
        }
    }
}

static VALUE
more_char(rb_io_t *fptr)
{
    VALUE v;
    v = fill_cbuf(fptr, ECONV_AFTER_OUTPUT);
    if (v != MORE_CHAR_SUSPENDED && v != MORE_CHAR_FINISHED)
        rb_exc_raise(v);
    return v;
}

static VALUE
io_shift_cbuf(rb_io_t *fptr, int len, VALUE *strp)
{
    VALUE str;
    if (NIL_P(*strp)) {
        *strp = str = rb_str_new(fptr->cbuf+fptr->cbuf_off, len);
    }
    else {
        size_t slen;
        str = *strp;
        slen = RSTRING_LEN(str);
        rb_str_resize(str, RSTRING_LEN(str) + len);
        memcpy(RSTRING_PTR(str)+slen, fptr->cbuf+fptr->cbuf_off, len);
    }
    fptr->cbuf_off += len;
    fptr->cbuf_len -= len;
    OBJ_TAINT(str);
    rb_enc_associate(str, fptr->encs.enc);
    /* xxx: set coderange */
    if (fptr->cbuf_len == 0)
        fptr->cbuf_off = 0;
    else if (fptr->cbuf_capa/2 < fptr->cbuf_off) {
        memmove(fptr->cbuf, fptr->cbuf+fptr->cbuf_off, fptr->cbuf_len);
        fptr->cbuf_off = 0;
    }
    return str;
}

static VALUE
read_all(rb_io_t *fptr, long siz, VALUE str)
{
    long bytes;
    long n;
    long pos;
    rb_encoding *enc;
    int cr;

    if (NEED_READCONV(fptr)) {
        if (NIL_P(str)) str = rb_str_new(NULL, 0);
        else rb_str_set_len(str, 0);
        make_readconv(fptr, 0);
        while (1) {
            VALUE v;
            if (fptr->cbuf_len) {
                io_shift_cbuf(fptr, fptr->cbuf_len, &str);
            }
            v = fill_cbuf(fptr, 0);
            if (v != MORE_CHAR_SUSPENDED && v != MORE_CHAR_FINISHED) {
                if (fptr->cbuf_len) {
                    io_shift_cbuf(fptr, fptr->cbuf_len, &str);
                }
                rb_exc_raise(v);
            }
            if (v == MORE_CHAR_FINISHED) {
                clear_readconv(fptr);
                return io_enc_str(str, fptr);
            }
        }
    }

    bytes = 0;
    pos = 0;

    enc = io_read_encoding(fptr);
    cr = 0;

    if (siz == 0) siz = BUFSIZ;
    if (NIL_P(str)) {
	str = rb_str_new(0, siz);
    }
    else {
	rb_str_resize(str, siz);
    }
    for (;;) {
	READ_CHECK(fptr);
	n = io_fread(str, bytes, fptr);
	if (n == 0 && bytes == 0) {
	    break;
	}
	bytes += n;
	if (cr != ENC_CODERANGE_BROKEN)
	    pos += rb_str_coderange_scan_restartable(RSTRING_PTR(str) + pos, RSTRING_PTR(str) + bytes, enc, &cr);
	if (bytes < siz) break;
	siz += BUFSIZ;
	rb_str_resize(str, siz);
    }
    if (bytes != siz) rb_str_resize(str, bytes);
    str = io_enc_str(str, fptr);
    ENC_CODERANGE_SET(str, cr);
    return str;
}

void
rb_io_set_nonblock(rb_io_t *fptr)
{
    int oflags;
#ifdef F_GETFL
    oflags = fcntl(fptr->fd, F_GETFL);
    if (oflags == -1) {
        rb_sys_fail_path(fptr->pathv);
    }
#else
    oflags = 0;
#endif
    if ((oflags & O_NONBLOCK) == 0) {
        oflags |= O_NONBLOCK;
        if (fcntl(fptr->fd, F_SETFL, oflags) == -1) {
            rb_sys_fail_path(fptr->pathv);
        }
    }
}

static VALUE
io_getpartial(int argc, VALUE *argv, VALUE io, int nonblock)
{
    rb_io_t *fptr;
    VALUE length, str;
    long n, len;

    rb_scan_args(argc, argv, "11", &length, &str);

    if ((len = NUM2LONG(length)) < 0) {
	rb_raise(rb_eArgError, "negative length %ld given", len);
    }

    if (NIL_P(str)) {
	str = rb_str_new(0, len);
    }
    else {
	StringValue(str);
	rb_str_modify(str);
        rb_str_resize(str, len);
    }
    OBJ_TAINT(str);

    GetOpenFile(io, fptr);
    rb_io_check_readable(fptr);

    if (len == 0)
	return str;

    if (!nonblock)
        READ_CHECK(fptr);
    if (RSTRING_LEN(str) != len) {
      modified:
	rb_raise(rb_eRuntimeError, "buffer string modified");
    }
    n = read_buffered_data(RSTRING_PTR(str), len, fptr);
    if (n <= 0) {
      again:
	if (RSTRING_LEN(str) != len) goto modified;
        if (nonblock) {
            rb_io_set_nonblock(fptr);
        }
	n = rb_read_internal(fptr->fd, RSTRING_PTR(str), len);
        if (n < 0) {
            if (!nonblock && rb_io_wait_readable(fptr->fd))
                goto again;
            if (nonblock && (errno == EWOULDBLOCK || errno == EAGAIN))
                rb_mod_sys_fail(rb_mWaitReadable, "read would block");
            rb_sys_fail_path(fptr->pathv);
        }
	else if (n == 0) {
	    io_set_eof(fptr);
	}
    }
    rb_str_resize(str, n);

    if (n == 0)
        return Qnil;
    else
        return str;
}

/*
 *  call-seq:
 *     ios.readpartial(maxlen)              => string
 *     ios.readpartial(maxlen, outbuf)      => outbuf
 *
 *  Reads at most <i>maxlen</i> bytes from the I/O stream.
 *  It blocks only if <em>ios</em> has no data immediately available.
 *  It doesn't block if some data available.
 *  If the optional <i>outbuf</i> argument is present,
 *  it must reference a String, which will receive the data.
 *  It raises <code>EOFError</code> on end of file.
 *
 *  readpartial is designed for streams such as pipe, socket, tty, etc.
 *  It blocks only when no data immediately available.
 *  This means that it blocks only when following all conditions hold.
 *  * the buffer in the IO object is empty.
 *  * the content of the stream is empty.
 *  * the stream is not reached to EOF.
 *
 *  When readpartial blocks, it waits data or EOF on the stream.
 *  If some data is reached, readpartial returns with the data.
 *  If EOF is reached, readpartial raises EOFError.
 *
 *  When readpartial doesn't blocks, it returns or raises immediately.
 *  If the buffer is not empty, it returns the data in the buffer.
 *  Otherwise if the stream has some content,
 *  it returns the data in the stream.
 *  Otherwise if the stream is reached to EOF, it raises EOFError.
 *
 *     r, w = IO.pipe           #               buffer          pipe content
 *     w << "abc"               #               ""              "abc".
 *     r.readpartial(4096)      #=> "abc"       ""              ""
 *     r.readpartial(4096)      # blocks because buffer and pipe is empty.
 *
 *     r, w = IO.pipe           #               buffer          pipe content
 *     w << "abc"               #               ""              "abc"
 *     w.close                  #               ""              "abc" EOF
 *     r.readpartial(4096)      #=> "abc"       ""              EOF
 *     r.readpartial(4096)      # raises EOFError
 *
 *     r, w = IO.pipe           #               buffer          pipe content
 *     w << "abc\ndef\n"        #               ""              "abc\ndef\n"
 *     r.gets                   #=> "abc\n"     "def\n"         ""
 *     w << "ghi\n"             #               "def\n"         "ghi\n"
 *     r.readpartial(4096)      #=> "def\n"     ""              "ghi\n"
 *     r.readpartial(4096)      #=> "ghi\n"     ""              ""
 *
 *  Note that readpartial behaves similar to sysread.
 *  The differences are:
 *  * If the buffer is not empty, read from the buffer instead of "sysread for buffered IO (IOError)".
 *  * It doesn't cause Errno::EWOULDBLOCK and Errno::EINTR.  When readpartial meets EWOULDBLOCK and EINTR by read system call, readpartial retry the system call.
 *
 *  The later means that readpartial is nonblocking-flag insensitive.
 *  It blocks on the situation IO#sysread causes Errno::EWOULDBLOCK as if the fd is blocking mode.
 *
 */

static VALUE
io_readpartial(int argc, VALUE *argv, VALUE io)
{
    VALUE ret;

    ret = io_getpartial(argc, argv, io, 0);
    if (NIL_P(ret))
        rb_eof_error();
    else
        return ret;
}

/*
 *  call-seq:
 *     ios.read_nonblock(maxlen)              => string
 *     ios.read_nonblock(maxlen, outbuf)      => outbuf
 *
 *  Reads at most <i>maxlen</i> bytes from <em>ios</em> using
 *  the read(2) system call after O_NONBLOCK is set for
 *  the underlying file descriptor.
 *
 *  If the optional <i>outbuf</i> argument is present,
 *  it must reference a String, which will receive the data.
 *
 *  read_nonblock just calls the read(2) system call.
 *  It causes all errors the read(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc.
 *  The caller should care such errors.
 *
 *  If the exception is Errno::EWOULDBLOCK or Errno::AGAIN,
 *  it is extended by IO::WaitReadable.
 *  So IO::WaitReadable can be used to rescue the exceptions for retrying read_nonblock.
 *
 *  read_nonblock causes EOFError on EOF.
 *
 *  If the read buffer is not empty,
 *  read_nonblock reads from the buffer like readpartial.
 *  In this case, the read(2) system call is not called.
 *
 *  When read_nonblock raises an exception kind of IO::WaitReadable,
 *  read_nonblock should not be called
 *  until io is readable for avoiding busy loop.
 *  This can be done as follows.
 *
 *    begin
 *      result = io.read_nonblock(maxlen)
 *    rescue IO::WaitReadable, Errno::EINTR
 *      IO.select([io])
 *      retry
 *    end
 *
 *  Note that this is identical to readpartial
 *  except the non-blocking flag is set.
 */

static VALUE
io_read_nonblock(int argc, VALUE *argv, VALUE io)
{
    VALUE ret;

    ret = io_getpartial(argc, argv, io, 1);
    if (NIL_P(ret))
        rb_eof_error();
    else
        return ret;
}

/*
 *  call-seq:
 *     ios.write_nonblock(string)   => integer
 *
 *  Writes the given string to <em>ios</em> using
 *  the write(2) system call after O_NONBLOCK is set for
 *  the underlying file descriptor.
 *
 *  It returns the number of bytes written.
 *
 *  write_nonblock just calls the write(2) system call.
 *  It causes all errors the write(2) system call causes: Errno::EWOULDBLOCK, Errno::EINTR, etc.
 *  The result may also be smaller than string.length (partial write).
 *  The caller should care such errors and partial write.
 *
 *  If the exception is Errno::EWOULDBLOCK or Errno::AGAIN,
 *  it is extended by IO::WaitWritable.
 *  So IO::WaitWritable can be used to rescue the exceptions for retrying write_nonblock.
 *
 *    # Creates a pipe.
 *    r, w = IO.pipe
 *
 *    # write_nonblock writes only 65536 bytes and return 65536.
 *    # (The pipe size is 65536 bytes on this environment.)
 *    s = "a" * 100000
 *    p w.write_nonblock(s)     #=> 65536
 *
 *    # write_nonblock cannot write a byte and raise EWOULDBLOCK (EAGAIN).
 *    p w.write_nonblock("b")   # Resource temporarily unavailable (Errno::EAGAIN)
 *
 *  If the write buffer is not empty, it is flushed at first.
 *
 *  When write_nonblock raises an exception kind of IO::WaitWritable,
 *  write_nonblock should not be called
 *  until io is writable for avoiding busy loop.
 *  This can be done as follows.
 *
 *    begin
 *      result = io.write_nonblock(string)
 *    rescue IO::WaitWritable, Errno::EINTR
 *      IO.select(nil, [io])
 *      retry
 *    end
 *
 *  Note that this doesn't guarantee to write all data in string.
 *  The length written is reported as result and it should be checked later.
 *
 */

static VALUE
rb_io_write_nonblock(VALUE io, VALUE str)
{
    rb_io_t *fptr;
    long n;

    rb_secure(4);
    if (TYPE(str) != T_STRING)
	str = rb_obj_as_string(str);

    io = GetWriteIO(io);
    Get…