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.
diff --git a/lib/buffer.h b/lib/buffer.h
index c0245a7..249354c 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 */