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3.1.9 Stream

#include <mailutils/stream.h>

These generic flags are interpreted as appropriate to the specific streams.

MU_STREAM_READ

The stream is open read only.

MU_STREAM_WRITE

The stream is open write only.

MU_STREAM_RDWR

The stream is open read and write.

MU_STREAM_APPEND

The stream is open in append mode for writing.

MU_STREAM_CREAT

The stream open will create the underlying resource (such as a file) if it doesn't exist already.

MU_STREAM_NONBLOCK

The stream is set non blocking.

MU_STREAM_NO_CHECK

Stream is destroyed without checking for the owner.

MU_STREAM_SEEKABLE

MU_STREAM_NO_CLOSE

Stream doesn't close it's underlying resource when it is closed or destroyed.

MU_STREAM_ALLOW_LINKS

Function: int mu_file_stream_create (mu_stream_t *stream, const char *filename, int flags)

Function: int mu_tcp_stream_create (mu_stream_t *stream, const char *host, int port, int flags)

Function: int mu_mapfile_stream_create (mu_stream_t *stream, const char *filename, int flags)

Function: int mu_memory_stream_create (mu_stream_t *stream, const char *filename, int flags)

Function: int mu_encoder_stream_create (mu_stream_t *stream, mu_stream_t iostream, const char *encoding)

Function: int mu_decoder_stream_create (mu_stream_t *stream, mu_stream_t iostream, const char *encoding)

Function: int mu_stdio_stream_create (mu_stream_t *stream, FILE *stdio, int flags)

If MU_STREAM_NO_CLOSE is specified, fclose() will not be called on stdio when the stream is closed.

Function: int mu_prog_stream_create (mu_stream_t *stream, const char *progname, int flags)

Function: int mu_filter_prog_stream_create (mu_stream_t *stream, const char *progname, mu_stream_t input)

Function: void mu_stream_destroy (mu_stream_t *stream, void *owner)

Function: int mu_stream_open (mu_stream_t stream)

Function: int mu_stream_close (mu_stream_t stream)

Function: int mu_stream_is_seekable (mu_stream_t stream)

Function: int mu_stream_get_fd (mu_stream_t stream, int *fd)

Function: int mu_stream_get_fd2 (mu_stream_t stream, int *fd1, int *fd2)

Function: int mu_stream_read (mu_stream_t stream, char *buffer, size_t buflen, mu_off_t offset, size_t *writen)

Function: int mu_stream_readline (mu_stream_t stream, char *buffer, size_t buflen, mu_off_t offset, size_t *writen)

Function: int mu_stream_size (mu_stream_t stream, mu_off_t *size)

Function: n int mu_stream_truncate (mu_stream_t stream, mu_off_t size)

Function: int mu_stream_write (mu_stream_t stream, const char *buffer, size_t buflen, mu_off_t offset, size_t *writen)

Function: int mu_stream_setbufsiz (mu_stream_t stream, size_t size)

Function: int mu_stream_flush (mu_stream_t stream)

Function: int mu_stream_create (mu_stream_t *stream, int flags, void *owner)

Used to implement a new kind of stream.

Function: void* mu_stream_get_owner (mu_stream_t stream)

Function: void mu_stream_set_owner (mu_stream_t stream, void *owner)

Function: int mu_stream_get_flags (mu_stream_t stream, int *flags)

Function: int mu_stream_set_flags (mu_stream_t stream, int flags)

Function: int mu_stream_get_property (mu_stream_t stream, property_t *)

Function: int mu_stream_set_property (mu_stream_t stream, property_t, void *)

Function: int mu_stream_get_state (mu_stream_t stream, int *state)

MU_STREAM_STATE_OPEN

Last action was mu_stream_open.

MU_STREAM_STATE_READ

Last action was mu_stream_read or mu_stream_readline.

MU_STREAM_STATE_WRITE

Last action was mu_stream_write.

MU_STREAM_STATE_CLOSE

Last action was mu_stream_close.

Function: int mu_stream_set_destroy (mu_stream_t stream, void (*_destroy) (mu_stream_t), void *owner)

Function: int mu_stream_set_open (mu_stream_t stream, int (*_open) (mu_stream_t), void *owner)

Function: int mu_stream_set_close (mu_stream_t stream, int (*_close) (mu_stream_t), void *owner)

Function: int mu_stream_set_fd (mu_stream_t stream, int (*_get_fd) (mu_stream_t, int *, int *), void *owner)

Function: int mu_stream_set_read (mu_stream_t stream, int (*_read) (mu_stream_t, char *, size_t, mu_off_t, size_t *), void *owner)

Function: int mu_stream_set_readline (mu_stream_t stream, int (*_readline) (mu_stream_t, char *, size_t, mu_off_t, size_t *), void *owner)

Function: int mu_stream_set_size (mu_stream_t stream, int (*_size) (mu_stream_t, mu_off_t *), void *owner)

Function: int mu_stream_set_truncate (mu_stream_t stream, int (*_truncate) (mu_stream_t, mu_off_t), void *owner)

Function: int mu_stream_set_write (mu_stream_t stream, int (*_write) (mu_stream_t, const char *, size_t, mu_off_t, size_t *), void *owner)

Function: int mu_stream_set_flush (mu_stream_t stream, int (*_flush) (mu_stream_t), void *owner)

Function: int mu_stream_set_strerror (mu_stream_t stream, int (*_fp) (mu_stream_t, char **), void *owner)

Function: int mu_stream_sequential_readline (mu_stream_ts stream, char *buf, size_t size, size_t *nbytes)

Function: int mu_stream_sequential_write (mu_stream_t stream, char *buf, size_t size)

Function: int mu_stream_seek (mu_stream_t stream, mu_off_t off, int whence)

Function: int mu_stream_strerror (mu_stream_t stream, char **p)

An example using mu_tcp_stream_create() to make a simple web client:

/* This is an example program to illustrate the use of stream functions.
   It connects to a remote HTTP server and prints the contents of its
   index page */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/time.h>

#include <mailutils/mailutils.h>

char wbuf[1024];
char rbuf[1024];

size_t io_timeout = 3;
size_t io_attempts = 3;

int
http_stream_wait (mu_stream_t stream, int flags, size_t *attempt)
{
  int rc;
  int oflags = flags;
  struct timeval tv;

  while (*attempt < io_attempts)
    {
      tv.tv_sec = io_timeout;
      tv.tv_usec = 0;
      rc = mu_stream_wait (stream, &oflags, &tv);
      switch (rc) {
      case 0:
	if (flags & oflags)
	  return 0;
	/* FALLTHROUGH */
      case EAGAIN:
      case EINPROGRESS:
	++*attempt;
	continue;
	
      default:
	return rc;
      }
    }
  return ETIMEDOUT;
}

int
main (int argc, char **argv)
{
  int ret, off = 0;
  mu_stream_t stream;
  size_t nb, size;
  size_t attempt;
  char *url = "www.gnu.org";

  if (argc > 3)
    {
      fprintf (stderr, "usage: %s [hostname [url]]\n", argv[0]);
      exit (1);
    }
  
  if (argc > 1)
    url = argv[1];
  
  snprintf (wbuf, sizeof wbuf, "GET %s HTTP/1.0\r\n\r\n",
	    argc == 3 ? argv[2] : "/");

  ret = mu_tcp_stream_create (&stream, url, 80, MU_STREAM_NONBLOCK);
  if (ret != 0)
    {
      mu_error ("mu_tcp_stream_create: %s", mu_strerror (ret));
      exit (EXIT_FAILURE);
    }

  for (attempt = 0; (ret = mu_stream_open (stream)); )
    {
      if ((ret == EAGAIN || ret == EINPROGRESS) && attempt < io_attempts)
	{
	  ret = http_stream_wait(stream, MU_STREAM_READY_WR, &attempt);
	  if (ret == 0)
	    continue;
	}
      mu_error ("mu_stream_open: %s", mu_strerror (ret));
      exit (EXIT_FAILURE);
    }

  for (attempt = 0, size = strlen (wbuf); size > 0; )
    {
      ret = mu_stream_write (stream, wbuf + off, strlen (wbuf), 0, &nb);
      if (ret == 0)
	{
	  if (nb == 0)
	    {
	      mu_error("mu_stream_write: wrote 0 bytes");
	      exit (EXIT_FAILURE);
	    }
	  off += nb;
	  size -= nb;
	}
      else if (ret == EAGAIN)
        {
	  if (attempt < io_attempts)
	    {
	      ret = http_stream_wait (stream, MU_STREAM_READY_WR, &attempt);
	      if (ret)
		{
		  mu_error ("http_wait failed: %s", mu_strerror (ret));
		  return -1;
		}
	      continue;
	    }
	  else
	    {
	      mu_error ("mu_stream_write timed out");
	      exit (EXIT_FAILURE);
	    }
	}
      else
	{
	  mu_error ("mu_stream_write: %s", mu_strerror (ret));
	  exit (EXIT_FAILURE);
	}
    }

  attempt = 0;
  for (;;)
    {
      ret = mu_stream_read (stream, rbuf, sizeof (rbuf), 0, &nb);
      if (ret == 0)
	{
	  if (nb == 0)
	    break;
	  write (1, rbuf, nb);
	}
      else if (ret == EAGAIN)
	{
	  if (attempt < io_attempts)
	    {
	      ret = http_stream_wait (stream, MU_STREAM_READY_RD, &attempt);
	      if (ret)
		{
		  mu_error ("http_stream_wait failed: %s", mu_strerror (ret));
		  exit (EXIT_FAILURE);
		}
	    }
	  else
	    {
	      mu_error ("mu_stream_read: %s", mu_strerror (ret));
	      exit (EXIT_FAILURE);
	    }
	}
    }

  ret = mu_stream_close (stream);
  if (ret != 0)
    {
      mu_error ("mu_stream_close: %s", mu_strerror (ret));
      exit (EXIT_FAILURE);
    }

  mu_stream_destroy (&stream, NULL);
  exit (EXIT_SUCCESS);
}

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