1 /* $OpenBSD: buffer.c,v 1.32 2010/02/09 03:56:28 djm Exp $ */
4 * Author: Tatu Ylonen <ylo@cs.hut.fi>
5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
7 * Functions for manipulating fifo buffers (that can grow if needed).
9 * As far as I am concerned, the code I have written for this software
10 * can be used freely for any purpose. Any derived versions of this
11 * software must be clearly marked as such, and if the derived work is
12 * incompatible with the protocol description in the RFC file, it must be
13 * called by a name other than "ssh" or "Secure Shell".
18 #include <sys/param.h>
28 #define BUFFER_MAX_CHUNK 0x100000
29 #define BUFFER_MAX_LEN 0x4000000 /* 64MB */
30 #define BUFFER_ALLOCSZ 0x008000
32 /* Initializes the buffer structure. */
35 buffer_init(Buffer *buffer)
37 const u_int len = 4096;
40 buffer->buf = xmalloc(len);
46 /* Frees any memory used for the buffer. */
49 buffer_free(Buffer *buffer)
51 if (buffer->alloc > 0) {
52 memset(buffer->buf, 0, buffer->alloc);
59 * Clears any data from the buffer, making it empty. This does not actually
64 buffer_clear(Buffer *buffer)
70 /* Appends data to the buffer, expanding it if necessary. */
73 buffer_append(Buffer *buffer, const void *data, u_int len)
76 p = buffer_append_space(buffer, len);
81 buffer_compact(Buffer *buffer)
84 * If the buffer is quite empty, but all data is at the end, move the
85 * data to the beginning.
87 if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) {
88 memmove(buffer->buf, buffer->buf + buffer->offset,
89 buffer->end - buffer->offset);
90 buffer->end -= buffer->offset;
98 * Appends space to the buffer, expanding the buffer if necessary. This does
99 * not actually copy the data into the buffer, but instead returns a pointer
100 * to the allocated region.
104 buffer_append_space(Buffer *buffer, u_int len)
109 if (len > BUFFER_MAX_CHUNK)
110 fatal("buffer_append_space: len %u not supported", len);
112 /* If the buffer is empty, start using it from the beginning. */
113 if (buffer->offset == buffer->end) {
118 /* If there is enough space to store all data, store it now. */
119 if (buffer->end + len < buffer->alloc) {
120 p = buffer->buf + buffer->end;
125 /* Compact data back to the start of the buffer if necessary */
126 if (buffer_compact(buffer))
129 /* Increase the size of the buffer and retry. */
130 newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ);
131 if (newlen > BUFFER_MAX_LEN)
132 fatal("buffer_append_space: alloc %u not supported",
134 buffer->buf = xrealloc(buffer->buf, 1, newlen);
135 buffer->alloc = newlen;
141 * Check whether an allocation of 'len' will fit in the buffer
142 * This must follow the same math as buffer_append_space
145 buffer_check_alloc(Buffer *buffer, u_int len)
147 if (buffer->offset == buffer->end) {
152 if (buffer->end + len < buffer->alloc)
154 if (buffer_compact(buffer))
156 if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN)
161 /* Returns the number of bytes of data in the buffer. */
164 buffer_len(const Buffer *buffer)
166 return buffer->end - buffer->offset;
169 /* Returns the maximum number of bytes of data that may be in the buffer. */
171 buffer_get_max_len(void)
173 return (BUFFER_MAX_LEN);
176 /* Gets data from the beginning of the buffer. */
179 buffer_get_ret(Buffer *buffer, void *buf, u_int len)
181 if (len > buffer->end - buffer->offset) {
182 error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
183 len, buffer->end - buffer->offset);
186 memcpy(buf, buffer->buf + buffer->offset, len);
187 buffer->offset += len;
192 buffer_get(Buffer *buffer, void *buf, u_int len)
194 if (buffer_get_ret(buffer, buf, len) == -1)
195 fatal("buffer_get: buffer error");
198 /* Consumes the given number of bytes from the beginning of the buffer. */
201 buffer_consume_ret(Buffer *buffer, u_int bytes)
203 if (bytes > buffer->end - buffer->offset) {
204 error("buffer_consume_ret: trying to get more bytes than in buffer");
207 buffer->offset += bytes;
212 buffer_consume(Buffer *buffer, u_int bytes)
214 if (buffer_consume_ret(buffer, bytes) == -1)
215 fatal("buffer_consume: buffer error");
218 /* Consumes the given number of bytes from the end of the buffer. */
221 buffer_consume_end_ret(Buffer *buffer, u_int bytes)
223 if (bytes > buffer->end - buffer->offset)
225 buffer->end -= bytes;
230 buffer_consume_end(Buffer *buffer, u_int bytes)
232 if (buffer_consume_end_ret(buffer, bytes) == -1)
233 fatal("buffer_consume_end: trying to get more bytes than in buffer");
236 /* Returns a pointer to the first used byte in the buffer. */
239 buffer_ptr(const Buffer *buffer)
241 return buffer->buf + buffer->offset;
244 /* Dumps the contents of the buffer to stderr. */
247 buffer_dump(const Buffer *buffer)
250 u_char *ucp = buffer->buf;
252 for (i = buffer->offset; i < buffer->end; i++) {
253 fprintf(stderr, "%02x", ucp[i]);
254 if ((i-buffer->offset)%16==15)
255 fprintf(stderr, "\r\n");
256 else if ((i-buffer->offset)%2==1)
257 fprintf(stderr, " ");
259 fprintf(stderr, "\r\n");