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 #ifdef __cplusplus
  26 extern "C" {
  27 #endif
  28
  29 /* Create a new buffer.  Memory will be allocated in chunks of the given
  30    size.  If the argument is 0, the library will supply a reasonable
  31    default size suitable for buffering socket I/O. */
  32 extern struct buffer *buffer_new(size_t);
  33
  34 /* Free all data in the buffer. */
  35 extern void buffer_reset(struct buffer *);
  36
  37 /* This function first calls buffer_reset to release all buffered data.
  38    Then it frees the struct buffer itself. */
  39 extern void buffer_free(struct buffer *);
  40
  41 /* Add the given data to the end of the buffer. */
  42 extern void buffer_put(struct buffer *, const void *, size_t);
  43 /* Add a single character to the end of the buffer. */
  44 extern void buffer_putc(struct buffer *, uint8_t);
  45 /* Add a NUL-terminated string to the end of the buffer. */
  46 extern void buffer_putstr(struct buffer *, const char *);
  47 /* Add given data, inline-expanding \n to \r\n */
  48 extern void buffer_put_crlf(struct buffer *b, const void *p, size_t size);
  49
  50 /* Combine all accumulated (and unflushed) data inside the buffer into a
  51    single NUL-terminated string allocated using XMALLOC(MTYPE_TMP).  Note
  52    that this function does not alter the state of the buffer, so the data
  53    is still inside waiting to be flushed. */
  54 char *buffer_getstr(struct buffer *);
  55
  56 /* Returns 1 if there is no pending data in the buffer.  Otherwise returns 0. */
  57 int buffer_empty(struct buffer *);
  58
  59 typedef enum {
  60         /* An I/O error occurred.  The buffer should be destroyed and the
  61            file descriptor should be closed. */
  62         BUFFER_ERROR = -1,
  63
  64         /* The data was written successfully, and the buffer is now empty
  65            (there is no pending data waiting to be flushed). */
  66         BUFFER_EMPTY = 0,
  67
  68         /* There is pending data in the buffer waiting to be flushed.  Please
  69            try flushing the buffer when select indicates that the file
  70            descriptor
  71            is writeable. */
  72         BUFFER_PENDING = 1
  73 } buffer_status_t;
  74
  75 /* Try to write this data to the file descriptor.  Any data that cannot
  76    be written immediately is added to the buffer queue. */
  77 extern buffer_status_t buffer_write(struct buffer *, int fd, const void *,
  78                                     size_t);
  79
  80 /* This function attempts to flush some (but perhaps not all) of
  81    the queued data to the given file descriptor. */
  82 extern buffer_status_t buffer_flush_available(struct buffer *, int fd);
  83
  84 /* The following 2 functions (buffer_flush_all and buffer_flush_window)
  85    are for use in lib/vty.c only.  They should not be used elsewhere. */
  86
  87 /* Call buffer_flush_available repeatedly until either all data has been
  88    flushed, or an I/O error has been encountered, or the operation would
  89    block. */
  90 extern buffer_status_t buffer_flush_all(struct buffer *, int fd);
  91
  92 /* Attempt to write enough data to the given fd to fill a window of the
  93    given width and height (and remove the data written from the buffer).
  94
  95    If !no_more, then a message saying " --More-- " is appended.
  96    If erase is true, then first overwrite the previous " --More-- " message
  97    with spaces.
  98
  99    Any write error (including EAGAIN or EINTR) will cause this function
 100    to return -1 (because the logic for handling the erase and more features
 101    is too complicated to retry the write later).
 102 */
 103 extern buffer_status_t buffer_flush_window(struct buffer *, int fd, int width,
 104                                            int height, int erase, int no_more);
 105
 106 #ifdef __cplusplus
 107 }
 108 #endif
 109
 110 #endif /* _ZEBRA_BUFFER_H */