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 along
  18  * with this program; see the file COPYING; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #ifndef _ZEBRA_BUFFER_H
  23 #define _ZEBRA_BUFFER_H
  24
  25
  26 /* Create a new buffer.  Memory will be allocated in chunks of the given
  27    size.  If the argument is 0, the library will supply a reasonable
  28    default size suitable for buffering socket I/O. */
  29 extern struct buffer *buffer_new (size_t);
  30
  31 /* Free all data in the buffer. */
  32 extern void buffer_reset (struct buffer *);
  33
  34 /* This function first calls buffer_reset to release all buffered data.
  35    Then it frees the struct buffer itself. */
  36 extern void buffer_free (struct buffer *);
  37
  38 /* Add the given data to the end of the buffer. */
  39 extern void buffer_put (struct buffer *, const void *, size_t);
  40 /* Add a single character to the end of the buffer. */
  41 extern void buffer_putc (struct buffer *, u_char);
  42 /* Add a NUL-terminated string to the end of the buffer. */
  43 extern void buffer_putstr (struct buffer *, const char *);
  44
  45 /* Combine all accumulated (and unflushed) data inside the buffer into a
  46    single NUL-terminated string allocated using XMALLOC(MTYPE_TMP).  Note
  47    that this function does not alter the state of the buffer, so the data
  48    is still inside waiting to be flushed. */
  49 char *buffer_getstr (struct buffer *);
  50
  51 /* Returns 1 if there is no pending data in the buffer.  Otherwise returns 0. */
  52 int buffer_empty (struct buffer *);
  53
  54 typedef enum
  55   {
  56     /* An I/O error occurred.  The buffer should be destroyed and the
  57        file descriptor should be closed. */
  58     BUFFER_ERROR = -1,
  59
  60     /* The data was written successfully, and the buffer is now empty
  61        (there is no pending data waiting to be flushed). */
  62     BUFFER_EMPTY = 0,
  63
  64     /* There is pending data in the buffer waiting to be flushed.  Please
  65        try flushing the buffer when select indicates that the file descriptor
  66        is writeable. */
  67     BUFFER_PENDING = 1
  68   } buffer_status_t;
  69
  70 /* Try to write this data to the file descriptor.  Any data that cannot
  71    be written immediately is added to the buffer queue. */
  72 extern buffer_status_t buffer_write(struct buffer *, int fd,
  73                                     const void *, size_t);
  74
  75 /* This function attempts to flush some (but perhaps not all) of
  76    the queued data to the given file descriptor. */
  77 extern buffer_status_t buffer_flush_available(struct buffer *, int fd);
  78
  79 /* The following 2 functions (buffer_flush_all and buffer_flush_window)
  80    are for use in lib/vty.c only.  They should not be used elsewhere. */
  81
  82 /* Call buffer_flush_available repeatedly until either all data has been
  83    flushed, or an I/O error has been encountered, or the operation would
  84    block. */
  85 extern buffer_status_t buffer_flush_all (struct buffer *, int fd);
  86
  87 /* Attempt to write enough data to the given fd to fill a window of the
  88    given width and height (and remove the data written from the buffer).
  89
  90    If !no_more, then a message saying " --More-- " is appended.
  91    If erase is true, then first overwrite the previous " --More-- " message
  92    with spaces.
  93
  94    Any write error (including EAGAIN or EINTR) will cause this function
  95    to return -1 (because the logic for handling the erase and more features
  96    is too complicated to retry the write later).
  97 */
  98 extern buffer_status_t buffer_flush_window (struct buffer *, int fd, int width,
  99                                             int height, int erase, int no_more);
 100
 101 #endif /* _ZEBRA_BUFFER_H */