lib/buffer.h

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Buffering to output and input.
   4  * Copyright (C) 1998 Kunihiro Ishiguro
   5  */
   6
   7 #ifndef _ZEBRA_BUFFER_H
   8 #define _ZEBRA_BUFFER_H
   9
  10 #ifdef __cplusplus
  11 extern "C" {
  12 #endif
  13
  14 /* Create a new buffer.  Memory will be allocated in chunks of the given
  15    size.  If the argument is 0, the library will supply a reasonable
  16    default size suitable for buffering socket I/O. */
  17 extern struct buffer *buffer_new(size_t);
  18
  19 /* Free all data in the buffer. */
  20 extern void buffer_reset(struct buffer *);
  21
  22 /* This function first calls buffer_reset to release all buffered data.
  23    Then it frees the struct buffer itself. */
  24 extern void buffer_free(struct buffer *);
  25
  26 /* Add the given data to the end of the buffer. */
  27 extern void buffer_put(struct buffer *, const void *, size_t);
  28 /* Add a single character to the end of the buffer. */
  29 extern void buffer_putc(struct buffer *, uint8_t);
  30 /* Add a NUL-terminated string to the end of the buffer. */
  31 extern void buffer_putstr(struct buffer *, const char *);
  32 /* Add given data, inline-expanding \n to \r\n */
  33 extern void buffer_put_crlf(struct buffer *b, const void *p, size_t size);
  34
  35 /* Combine all accumulated (and unflushed) data inside the buffer into a
  36    single NUL-terminated string allocated using XMALLOC(MTYPE_TMP).  Note
  37    that this function does not alter the state of the buffer, so the data
  38    is still inside waiting to be flushed. */
  39 char *buffer_getstr(struct buffer *);
  40
  41 /* Returns 1 if there is no pending data in the buffer.  Otherwise returns 0. */
  42 int buffer_empty(struct buffer *);
  43
  44 typedef enum {
  45         /* An I/O error occurred.  The buffer should be destroyed and the
  46            file descriptor should be closed. */
  47         BUFFER_ERROR = -1,
  48
  49         /* The data was written successfully, and the buffer is now empty
  50            (there is no pending data waiting to be flushed). */
  51         BUFFER_EMPTY = 0,
  52
  53         /* There is pending data in the buffer waiting to be flushed.  Please
  54            try flushing the buffer when select indicates that the file
  55            descriptor
  56            is writeable. */
  57         BUFFER_PENDING = 1
  58 } buffer_status_t;
  59
  60 /* Try to write this data to the file descriptor.  Any data that cannot
  61    be written immediately is added to the buffer queue. */
  62 extern buffer_status_t buffer_write(struct buffer *, int fd, const void *,
  63                                     size_t);
  64
  65 /* This function attempts to flush some (but perhaps not all) of
  66    the queued data to the given file descriptor. */
  67 extern buffer_status_t buffer_flush_available(struct buffer *, int fd);
  68
  69 /* The following 2 functions (buffer_flush_all and buffer_flush_window)
  70    are for use in lib/vty.c only.  They should not be used elsewhere. */
  71
  72 /* Call buffer_flush_available repeatedly until either all data has been
  73    flushed, or an I/O error has been encountered, or the operation would
  74    block. */
  75 extern buffer_status_t buffer_flush_all(struct buffer *, int fd);
  76
  77 /* Attempt to write enough data to the given fd to fill a window of the
  78    given width and height (and remove the data written from the buffer).
  79
  80    If !no_more, then a message saying " --More-- " is appended.
  81    If erase is true, then first overwrite the previous " --More-- " message
  82    with spaces.
  83
  84    Any write error (including EAGAIN or EINTR) will cause this function
  85    to return -1 (because the logic for handling the erase and more features
  86    is too complicated to retry the write later).
  87 */
  88 extern buffer_status_t buffer_flush_window(struct buffer *, int fd, int width,
  89                                            int height, int erase, int no_more);
  90
  91 #ifdef __cplusplus
  92 }
  93 #endif
  94
  95 #endif /* _ZEBRA_BUFFER_H */