crypto/openssh/buffer.c

1 /* $OpenBSD: buffer.c,v 1.33 2013/05/17 00:13:13 djm Exp $ */
25 #include "buffer.h"
32 /* Initializes the buffer structure. */
35 buffer_init(Buffer *buffer)
39 	buffer->alloc = 0;
40 	buffer->buf = xmalloc(len);
41 	buffer->alloc = len;
42 	buffer->offset = 0;
43 	buffer->end = 0;
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);
53 		buffer->alloc = 0;
54 		free(buffer->buf);
59  * Clears any data from the buffer, making it empty.  This does not actually
64 buffer_clear(Buffer *buffer)
66 	buffer->offset = 0;
67 	buffer->end = 0;
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
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;
91 		buffer->offset = 0;
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
104 buffer_append_space(Buffer *buffer, u_int len)
112 	/* If the buffer is empty, start using it from the beginning. */
113 	if (buffer->offset == buffer->end) {
114 		buffer->offset = 0;
115 		buffer->end = 0;
119 	if (buffer->end + len < buffer->alloc) {
120 		p = buffer->buf + buffer->end;
121 		buffer->end += len;
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);
134 	buffer->buf = xrealloc(buffer->buf, 1, newlen);
135 	buffer->alloc = newlen;
141  * Check whether an allocation of 'len' will fit in the buffer
145 buffer_check_alloc(Buffer *buffer, u_int len)
147 	if (buffer->offset == buffer->end) {
148 		buffer->offset = 0;
149 		buffer->end = 0;
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. */
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++) {
254 		if ((i-buffer->offset)%16==15)
256 		else if ((i-buffer->offset)%2==1)