From 9fc7ebf10b7bb638ddf6d1b4b2d562dd417866fc Mon Sep 17 00:00:00 2001 From: ajs Date: Wed, 23 Feb 2005 15:12:34 +0000 Subject: 2005-02-23 Andrew J. Schorr * 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 (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 , since this is used only by lib/vty.c. --- lib/buffer.h | 116 ++++++++++++++++++++++++++++++++--------------------------- 1 file changed, 64 insertions(+), 52 deletions(-) (limited to 'lib/buffer.h') 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 */ -- cgit v1.2.1