lib/buffer.h

   1 /*
   2  * Buffering to output and input.
   3  * Copyright (C) 1998 Kunihiro Ishiguro
   4  *
   5  * This file is part of GNU Zebra.
   6  *
   7  * GNU Zebra is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published
   9  * by the Free Software Foundation; either version 2, or (at your
  10  * option) any later version.
  11  *
  12  * GNU Zebra is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with GNU Zebra; see the file COPYING.  If not, write to the
  19  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20  * Boston, MA 02111-1307, USA.
  21  */
  22
  23 #ifndef _ZEBRA_BUFFER_H
  24 #define _ZEBRA_BUFFER_H
  25
  26
  27 /* Create a new buffer.  Memory will be allocated in chunks of the given
  28    size.  If the argument is 0, the library will supply a reasonable
  29    default size suitable for buffering socket I/O. */
  30 extern struct buffer *buffer_new (size_t);
  31
  32 /* Free all data in the buffer. */
  33 extern void buffer_reset (struct buffer *);
  34
  35 /* This function first calls buffer_reset to release all buffered data.
  36    Then it frees the struct buffer itself. */
  37 extern void buffer_free (struct buffer *);
  38
  39 /* Add the given data to the end of the buffer. */
  40 extern void buffer_put (struct buffer *, const void *, size_t);
  41 /* Add a single character to the end of the buffer. */
  42 extern void buffer_putc (struct buffer *, u_char);
  43 /* Add a NUL-terminated string to the end of the buffer. */
  44 extern void buffer_putstr (struct buffer *, const char *);
  45
  46 /* Combine all accumulated (and unflushed) data inside the buffer into a
  47    single NUL-terminated string allocated using XMALLOC(MTYPE_TMP).  Note
  48    that this function does not alter the state of the buffer, so the data
  49    is still inside waiting to be flushed. */
  50 char *buffer_getstr (struct buffer *);
  51
  52 /* Returns 1 if there is no pending data in the buffer.  Otherwise returns 0. */
  53 int buffer_empty (struct buffer *);
  54
  55 typedef enum
  56   {
  57     /* An I/O error occurred.  The buffer should be destroyed and the
  58        file descriptor should be closed. */
  59     BUFFER_ERROR = -1,
  60
  61     /* The data was written successfully, and the buffer is now empty
  62        (there is no pending data waiting to be flushed). */
  63     BUFFER_EMPTY = 0,
  64
  65     /* There is pending data in the buffer waiting to be flushed.  Please
  66        try flushing the buffer when select indicates that the file descriptor
  67        is writeable. */
  68     BUFFER_PENDING = 1
  69   } buffer_status_t;
  70
  71 /* Try to write this data to the file descriptor.  Any data that cannot
  72    be written immediately is added to the buffer queue. */
  73 extern buffer_status_t buffer_write(struct buffer *, int fd,
  74                                     const void *, size_t);
  75
  76 /* This function attempts to flush some (but perhaps not all) of
  77    the queued data to the given file descriptor. */
  78 extern buffer_status_t buffer_flush_available(struct buffer *, int fd);
  79
  80 /* The following 2 functions (buffer_flush_all and buffer_flush_window)
  81    are for use in lib/vty.c only.  They should not be used elsewhere. */
  82
  83 /* Call buffer_flush_available repeatedly until either all data has been
  84    flushed, or an I/O error has been encountered, or the operation would
  85    block. */
  86 extern buffer_status_t buffer_flush_all (struct buffer *, int fd);
  87
  88 /* Attempt to write enough data to the given fd to fill a window of the
  89    given width and height (and remove the data written from the buffer).
  90
  91    If !no_more, then a message saying " --More-- " is appended.
  92    If erase is true, then first overwrite the previous " --More-- " message
  93    with spaces.
  94
  95    Any write error (including EAGAIN or EINTR) will cause this function
  96    to return -1 (because the logic for handling the erase and more features
  97    is too complicated to retry the write later).
  98 */
  99 extern buffer_status_t buffer_flush_window (struct buffer *, int fd, int width,
 100                                             int height, int erase, int no_more);
 101
 102 #endif /* _ZEBRA_BUFFER_H */