2005-02-23 Andrew J. Schorr <ajschorr@alumni.princeton.edu>

	* buffer.h: Make the struct buffer and struct buffer_data structures
	  private by moving them inside buffer.c.  Add comments for all
	  functions.  Rename buffer_write as buffer_put (to be more consistent
	  with the buffer_putc and buffer_putstr functions).  Declare a new
	  buffer_write function that is used to write data to a file descriptor
	  and/or add it to the buffer queue.  Remove unused function
	  buffer_flush_vty_all.  Create a new enum typedef buffer_status_t
	  to be used as the return code for all buffer_flush* functions
	  and buffer_write.
	* buffer.c: The struct buffer and struct buffer_data declarations
	  are now private to this file.  In conjunction with that, remove
	  some unnecessary fields: struct buffer (alloc, unused_head,
	  unused_tail, length), struct buffer_data (prev).
	  (buffer_data_new) Removed: functionality incorporated into buffer_add.
	  (buffer_data_free) Removed: use a macro BUFFER_DATA_FREE instead.
	  (buffer_new) Use calloc instead of malloc + memset(zero).
	  Supply an appropriate default size if the specified size is 0.
	  (buffer_free) Eliminate code duplication by calling buffer_reset to
	  free the contents of the buffer (and remove unused code related
	  to unused_head).
	  (buffer_empty,buffer_putc,buffer_putstr) Aesthetic change (make more
	  compact).
	  (buffer_reset) Use macro BUFFER_DATA_FREE.  No need to set
	  alloc and length to 0 (these fields have been removed).
	  (buffer_add) Fix scope to be static.  Call XMALLOC directly instead
	  of calling removed buffer_data_new function.  Simplify the logic
	  (since it's now a singly-linked list instead of doubly-linked).
	  (buffer_write) Renamed to buffer_put.  Change to void, since return
	  code of 1 was meaningless.  No need to adjust length field, since
	  it has been removed.
	  (buffer_putw,buffer_flush,buffer_flush_vty_all,buffer_flush_vty)
	  Remove unused functions.
	  (buffer_flush_all) Rewrite using buffer_flush_available to eliminate
	  a possible failure mode if IOV_MAX is less than the number of buffers
	  on the queue.
	  (buffer_flush_window) Incorporate logic from buffer_flush_vty.
	  Log an error message if there is a writev error.
	  (buffer_flush_available) Be more paranoid: check for case where
	  buffer is already empty.  Use new ERRNO_IO_RETRY macro, and use
	  new enum for return codes.  Simplify deletion logic (since it's
	  now a singly-linked list).
	  (buffer_write) New function for use with non-blocking I/O.
	* vty.h: Replace the struct vty sb_buffer field with a fixed-size
	  (5-character) sb_buf field and an sb_len field, since using
	  a struct buffer was inappropriate for this task.  Add some useful
	  comments about telnet window size negotiation.
	* vty.c: Include <arpa/telnet.h> (no longer included by zebra.h).
	  Remove VTY_OBUF_SIZE (instead use buffer_new default size).
	  Make telnet_backward_char and telnet_space_char static const.
	  (vty_out) Replace buffer_write with buffer_put.
	  (vty_log_out) Check for I/O errors.  If fatal, close the vty session.
	  Consolidate 3 separate writes into a single write call.
	  (vty_will_echo,vty_command,vty_next_line,vty_previous_line,
	  vty_end_config,vty_describe_fold,vty_clear_buf,vty_serv_sock_addrinfo,
	  vty_serv_sock_family,vty_serv_un,vty_use_backup_config,exec_timeout,
	  vty_config_write,vty_save_cwd) Fix scope to static.
	  (vty_new) Let buffer_new use its default buffer size.
	  (vty_write) Fix signature: 2nd arg should be const char *.
	  Replaced buffer_write with buffer_put.
	  (vty_telnet_option) Fix minor bug (window height or width greater than
	  255 was broken).  Use sb_buf and sb_len instead of removed sb_buffer
	  (which was being used improperly).
	  (vty_read) On error, use ERRNO_IO_RETRY to decide whether it's fatal.
	  If the error is fatal, call buffer_reset so vty_close does not attempt
	  to flush the data.  Use new sb_buf and sb_len instead of sb_buffer
	  to store the SB negotiation string.
	  (vty_flush) When vty->lines is 0, call buffer_flush_available instead
	  of buffer_flush_window.  Look at the return code from buffer_flush
	  to detect I/O errors (and in that case, log an error message and
	  close the vty).
	  (vty_create) Fix scope to static.  Initialize sb_len to 0 instead
	  of creating sb_buffer.
	  (vty_accept) Set socket nonblocking.
	  (vtysh_accept) Use new set_nonblocking function instead of calling
	  fcntl directly.
	  (vtysh_flush) New function called from vtysh_read (after command
	  execution) and from vtysh_write.  This flushes the buffer
	  and reacts appropriately to the return code (by closing the vty
	  or scheduling further flushes).
	  (vtysh_read) Check whether error is fatal using ERRNO_IO_RETRY.
	  If not, just try again later.  Otherwise, call buffer_reset before
	  calling vty_close (to avoid trying to flush the buffer in vty_close).
	  Fix logic to allow case where a command does not arrive atomically
	  in a single read call by checking for the terminating NUL char.
	  (vtysh_write) Use new vtysh_flush helper function.
	  (vty_close) No need to call buffer_empty, just call buffer_flush_all
	  in any case (it will check whether the buffer is empty).
	  Do not free sb_buffer (since it has been removed).
	  (vty_log_fixed) Use writev instead of write.
	* zebra.h: Do not include <arpa/telnet.h>, since this is used only
	  by lib/vty.c.

1 files changed, 64 insertions, 52 deletions

diff --git a/lib/buffer.h b/lib/buffer.h
index c0245a7f..249354cb 100644
--- a/lib/buffer.h
+++ b/lib/buffer.h
@@ -23,68 +23,80 @@
 #ifndef _ZEBRA_BUFFER_H
 #define _ZEBRA_BUFFER_H
 
-/* Buffer master. */
-struct buffer
-{
-  /* Data list. */
-  struct buffer_data *head;
-  struct buffer_data *tail;
-  
-  /* XXX: These unsigned longs should be size_t's */
-  /* Current allocated data. */
-  unsigned long alloc;
-
-  /* Size of each buffer_data chunk. */
-  unsigned long size;
-
-  /* For allocation. */
-  struct buffer_data *unused_head;
-  struct buffer_data *unused_tail;
-
-  /* Current total length of this buffer. */
-  unsigned long length;
-};
-
-/* Data container. */
-struct buffer_data
-{
-  struct buffer_data *next;
-  struct buffer_data *prev;
-
-  /* Current pointer. */
-  unsigned long cp;
-
-  /* Start pointer. */
-  unsigned long sp;
-
-  /* Actual data stream (variable length). */
-  unsigned char data[0];  /* real dimension is buffer->size */
-};
-
-/* Buffer prototypes. */
+
+/* Create a new buffer.  Memory will be allocated in chunks of the given
+   size.  If the argument is 0, the library will supply a reasonable
+   default size suitable for buffering socket I/O. */
 struct buffer *buffer_new (size_t);
-int buffer_write (struct buffer *, const void *, size_t);
+
+/* Free all data in the buffer. */
+void buffer_reset (struct buffer *);
+
+/* This function first calls buffer_reset to release all buffered data.
+   Then it frees the struct buffer itself. */
 void buffer_free (struct buffer *);
 
+/* Add the given data to the end of the buffer. */
+extern void buffer_put (struct buffer *, const void *, size_t);
+/* Add a single character to the end of the buffer. */
+extern void buffer_putc (struct buffer *, u_char);
+/* Add a NUL-terminated string to the end of the buffer. */
+extern void buffer_putstr (struct buffer *, const char *);
+
 /* Combine all accumulated (and unflushed) data inside the buffer into a
    single NUL-terminated string allocated using XMALLOC(MTYPE_TMP).  Note
    that this function does not alter the state of the buffer, so the data
    is still inside waiting to be flushed. */
 char *buffer_getstr (struct buffer *);
 
-int buffer_putc (struct buffer *, u_char);
-int buffer_putstr (struct buffer *, const char *);
-void buffer_reset (struct buffer *);
-int buffer_flush_all (struct buffer *, int);
-int buffer_flush_vty_all (struct buffer *, int, int, int);
-int buffer_flush_window (struct buffer *, int, int, int, int, int);
+/* Returns 1 if there is no pending data in the buffer.  Otherwise returns 0. */
 int buffer_empty (struct buffer *);
 
-/* buffer_flush_available attempts to flush the queued data to the given
-   file descriptor.  It returns 0 if the buffers are now empty (after
-   flushing), or 1 if more data remains on the buffer queue (must be flushed
-   later).  This function (unlike the other buffer_flush* functions) is
-   designed to work with non-blocking file descriptors. */
-int buffer_flush_available(struct buffer *, int fd);
+typedef enum
+  {
+    /* An I/O error occurred.  The buffer should be destroyed and the
+       file descriptor should be closed. */
+    BUFFER_ERROR = -1,
+
+    /* The data was written successfully, and the buffer is now empty
+       (there is no pending data waiting to be flushed). */
+    BUFFER_EMPTY = 0,
+
+    /* There is pending data in the buffer waiting to be flushed.  Please
+       try flushing the buffer when select indicates that the file descriptor
+       is writeable. */
+    BUFFER_PENDING = 1
+  } buffer_status_t;
+
+/* Try to write this data to the file descriptor.  Any data that cannot
+   be written immediately is added to the buffer queue. */
+extern buffer_status_t buffer_write(struct buffer *, int fd,
+				    const void *, size_t);
+
+/* This function attempts to flush some (but perhaps not all) of 
+   the queued data to the given file descriptor. */
+extern buffer_status_t buffer_flush_available(struct buffer *, int fd);
+
+/* The following 2 functions (buffer_flush_all and buffer_flush_window)
+   are for use in lib/vty.c only.  They should not be used elsewhere. */
+
+/* Call buffer_flush_available repeatedly until either all data has been
+   flushed, or an I/O error has been encountered, or the operation would
+   block. */
+extern buffer_status_t buffer_flush_all (struct buffer *, int fd);
+
+/* Attempt to write enough data to the given fd to fill a window of the
+   given width and height (and remove the data written from the buffer).
+
+   If !no_more, then a message saying " --More-- " is appended. 
+   If erase is true, then first overwrite the previous " --More-- " message
+   with spaces.
+
+   Any write error (including EAGAIN or EINTR) will cause this function
+   to return -1 (because the logic for handling the erase and more features
+   is too complicated to retry the write later).
+*/
+extern buffer_status_t buffer_flush_window (struct buffer *, int fd, int width,
+					    int height, int erase, int no_more);
 
 #endif /* _ZEBRA_BUFFER_H */