1 /* $OpenBSD: buffer.c,v 1.35 2014/02/02 03:44:31 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".
19 #include <sys/param.h>
30 #define BUFFER_MAX_CHUNK 0x100000
31 #define BUFFER_MAX_LEN 0x4000000 /* 64MB */
32 #define BUFFER_ALLOCSZ 0x008000
34 /* Initializes the buffer structure. */
37 buffer_init(Buffer *buffer)
39 const u_int len = 4096;
42 buffer->buf = xmalloc(len);
48 /* Frees any memory used for the buffer. */
51 buffer_free(Buffer *buffer)
53 if (buffer->alloc > 0) {
54 explicit_bzero(buffer->buf, buffer->alloc);
61 * Clears any data from the buffer, making it empty. This does not actually
66 buffer_clear(Buffer *buffer)
72 /* Appends data to the buffer, expanding it if necessary. */
75 buffer_append(Buffer *buffer, const void *data, u_int len)
78 p = buffer_append_space(buffer, len);
83 buffer_compact(Buffer *buffer)
86 * If the buffer is quite empty, but all data is at the end, move the
87 * data to the beginning.
89 if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) {
90 memmove(buffer->buf, buffer->buf + buffer->offset,
91 buffer->end - buffer->offset);
92 buffer->end -= buffer->offset;
100 * Appends space to the buffer, expanding the buffer if necessary. This does
101 * not actually copy the data into the buffer, but instead returns a pointer
102 * to the allocated region.
106 buffer_append_space(Buffer *buffer, u_int len)
111 if (len > BUFFER_MAX_CHUNK)
112 fatal("buffer_append_space: len %u not supported", len);
114 /* If the buffer is empty, start using it from the beginning. */
115 if (buffer->offset == buffer->end) {
120 /* If there is enough space to store all data, store it now. */
121 if (buffer->end + len < buffer->alloc) {
122 p = buffer->buf + buffer->end;
127 /* Compact data back to the start of the buffer if necessary */
128 if (buffer_compact(buffer))
131 /* Increase the size of the buffer and retry. */
132 newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ);
133 if (newlen > BUFFER_MAX_LEN)
134 fatal("buffer_append_space: alloc %u not supported",
136 buffer->buf = xrealloc(buffer->buf, 1, newlen);
137 buffer->alloc = newlen;
143 * Check whether an allocation of 'len' will fit in the buffer
144 * This must follow the same math as buffer_append_space
147 buffer_check_alloc(Buffer *buffer, u_int len)
149 if (buffer->offset == buffer->end) {
154 if (buffer->end + len < buffer->alloc)
156 if (buffer_compact(buffer))
158 if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN)
163 /* Returns the number of bytes of data in the buffer. */
166 buffer_len(const Buffer *buffer)
168 return buffer->end - buffer->offset;
171 /* Returns the maximum number of bytes of data that may be in the buffer. */
173 buffer_get_max_len(void)
175 return (BUFFER_MAX_LEN);
178 /* Gets data from the beginning of the buffer. */
181 buffer_get_ret(Buffer *buffer, void *buf, u_int len)
183 if (len > buffer->end - buffer->offset) {
184 error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
185 len, buffer->end - buffer->offset);
188 memcpy(buf, buffer->buf + buffer->offset, len);
189 buffer->offset += len;
194 buffer_get(Buffer *buffer, void *buf, u_int len)
196 if (buffer_get_ret(buffer, buf, len) == -1)
197 fatal("buffer_get: buffer error");
200 /* Consumes the given number of bytes from the beginning of the buffer. */
203 buffer_consume_ret(Buffer *buffer, u_int bytes)
205 if (bytes > buffer->end - buffer->offset) {
206 error("buffer_consume_ret: trying to get more bytes than in buffer");
209 buffer->offset += bytes;
214 buffer_consume(Buffer *buffer, u_int bytes)
216 if (buffer_consume_ret(buffer, bytes) == -1)
217 fatal("buffer_consume: buffer error");
220 /* Consumes the given number of bytes from the end of the buffer. */
223 buffer_consume_end_ret(Buffer *buffer, u_int bytes)
225 if (bytes > buffer->end - buffer->offset)
227 buffer->end -= bytes;
232 buffer_consume_end(Buffer *buffer, u_int bytes)
234 if (buffer_consume_end_ret(buffer, bytes) == -1)
235 fatal("buffer_consume_end: trying to get more bytes than in buffer");
238 /* Returns a pointer to the first used byte in the buffer. */
241 buffer_ptr(const Buffer *buffer)
243 return buffer->buf + buffer->offset;
246 /* Dumps the contents of the buffer to stderr. */
249 buffer_dump(const Buffer *buffer)
252 u_char *ucp = buffer->buf;
254 for (i = buffer->offset; i < buffer->end; i++) {
255 fprintf(stderr, "%02x", ucp[i]);
256 if ((i-buffer->offset)%16==15)
257 fprintf(stderr, "\r\n");
258 else if ((i-buffer->offset)%2==1)
259 fprintf(stderr, " ");
261 fprintf(stderr, "\r\n");