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".
18 #include <sys/param.h>
29 #define BUFFER_MAX_CHUNK 0x100000
30 #define BUFFER_MAX_LEN 0x4000000 /* 64MB */
31 #define BUFFER_ALLOCSZ 0x008000
33 /* Initializes the buffer structure. */
36 buffer_init(Buffer *buffer)
38 const u_int len = 4096;
41 buffer->buf = xmalloc(len);
47 /* Frees any memory used for the buffer. */
50 buffer_free(Buffer *buffer)
52 if (buffer->alloc > 0) {
53 explicit_bzero(buffer->buf, buffer->alloc);
60 * Clears any data from the buffer, making it empty. This does not actually
65 buffer_clear(Buffer *buffer)
71 /* Appends data to the buffer, expanding it if necessary. */
74 buffer_append(Buffer *buffer, const void *data, u_int len)
77 p = buffer_append_space(buffer, len);
82 buffer_compact(Buffer *buffer)
85 * If the buffer is quite empty, but all data is at the end, move the
86 * data to the beginning.
88 if (buffer->offset > MIN(buffer->alloc, BUFFER_MAX_CHUNK)) {
89 memmove(buffer->buf, buffer->buf + buffer->offset,
90 buffer->end - buffer->offset);
91 buffer->end -= buffer->offset;
99 * Appends space to the buffer, expanding the buffer if necessary. This does
100 * not actually copy the data into the buffer, but instead returns a pointer
101 * to the allocated region.
105 buffer_append_space(Buffer *buffer, u_int len)
110 if (len > BUFFER_MAX_CHUNK)
111 fatal("buffer_append_space: len %u not supported", len);
113 /* If the buffer is empty, start using it from the beginning. */
114 if (buffer->offset == buffer->end) {
119 /* If there is enough space to store all data, store it now. */
120 if (buffer->end + len < buffer->alloc) {
121 p = buffer->buf + buffer->end;
126 /* Compact data back to the start of the buffer if necessary */
127 if (buffer_compact(buffer))
130 /* Increase the size of the buffer and retry. */
131 newlen = roundup(buffer->alloc + len, BUFFER_ALLOCSZ);
132 if (newlen > BUFFER_MAX_LEN)
133 fatal("buffer_append_space: alloc %u not supported",
135 buffer->buf = xrealloc(buffer->buf, 1, newlen);
136 buffer->alloc = newlen;
142 * Check whether an allocation of 'len' will fit in the buffer
143 * This must follow the same math as buffer_append_space
146 buffer_check_alloc(Buffer *buffer, u_int len)
148 if (buffer->offset == buffer->end) {
153 if (buffer->end + len < buffer->alloc)
155 if (buffer_compact(buffer))
157 if (roundup(buffer->alloc + len, BUFFER_ALLOCSZ) <= BUFFER_MAX_LEN)
162 /* Returns the number of bytes of data in the buffer. */
165 buffer_len(const Buffer *buffer)
167 return buffer->end - buffer->offset;
170 /* Returns the maximum number of bytes of data that may be in the buffer. */
172 buffer_get_max_len(void)
174 return (BUFFER_MAX_LEN);
177 /* Gets data from the beginning of the buffer. */
180 buffer_get_ret(Buffer *buffer, void *buf, u_int len)
182 if (len > buffer->end - buffer->offset) {
183 error("buffer_get_ret: trying to get more bytes %d than in buffer %d",
184 len, buffer->end - buffer->offset);
187 memcpy(buf, buffer->buf + buffer->offset, len);
188 buffer->offset += len;
193 buffer_get(Buffer *buffer, void *buf, u_int len)
195 if (buffer_get_ret(buffer, buf, len) == -1)
196 fatal("buffer_get: buffer error");
199 /* Consumes the given number of bytes from the beginning of the buffer. */
202 buffer_consume_ret(Buffer *buffer, u_int bytes)
204 if (bytes > buffer->end - buffer->offset) {
205 error("buffer_consume_ret: trying to get more bytes than in buffer");
208 buffer->offset += bytes;
213 buffer_consume(Buffer *buffer, u_int bytes)
215 if (buffer_consume_ret(buffer, bytes) == -1)
216 fatal("buffer_consume: buffer error");
219 /* Consumes the given number of bytes from the end of the buffer. */
222 buffer_consume_end_ret(Buffer *buffer, u_int bytes)
224 if (bytes > buffer->end - buffer->offset)
226 buffer->end -= bytes;
231 buffer_consume_end(Buffer *buffer, u_int bytes)
233 if (buffer_consume_end_ret(buffer, bytes) == -1)
234 fatal("buffer_consume_end: trying to get more bytes than in buffer");
237 /* Returns a pointer to the first used byte in the buffer. */
240 buffer_ptr(const Buffer *buffer)
242 return buffer->buf + buffer->offset;
245 /* Dumps the contents of the buffer to stderr. */
248 buffer_dump(const Buffer *buffer)
251 u_char *ucp = buffer->buf;
253 for (i = buffer->offset; i < buffer->end; i++) {
254 fprintf(stderr, "%02x", ucp[i]);
255 if ((i-buffer->offset)%16==15)
256 fprintf(stderr, "\r\n");
257 else if ((i-buffer->offset)%2==1)
258 fprintf(stderr, " ");
260 fprintf(stderr, "\r\n");