2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * Functions for manipulating fifo buffers (that can grow if needed).
7 * As far as I am concerned, the code I have written for this software
8 * can be used freely for any purpose. Any derived versions of this
9 * software must be clearly marked as such, and if the derived work is
10 * incompatible with the protocol description in the RFC file, it must be
11 * called by a name other than "ssh" or "Secure Shell".
15 RCSID("$OpenBSD: buffer.c,v 1.8 2000/09/07 20:27:50 deraadt Exp $");
21 /* Initializes the buffer structure. */
24 buffer_init(Buffer *buffer)
27 buffer->buf = xmalloc(buffer->alloc);
32 /* Frees any memory used for the buffer. */
35 buffer_free(Buffer *buffer)
37 memset(buffer->buf, 0, buffer->alloc);
42 * Clears any data from the buffer, making it empty. This does not actually
47 buffer_clear(Buffer *buffer)
53 /* Appends data to the buffer, expanding it if necessary. */
56 buffer_append(Buffer *buffer, const char *data, unsigned int len)
59 buffer_append_space(buffer, &cp, len);
60 memcpy(cp, data, len);
64 * Appends space to the buffer, expanding the buffer if necessary. This does
65 * not actually copy the data into the buffer, but instead returns a pointer
66 * to the allocated region.
70 buffer_append_space(Buffer *buffer, char **datap, unsigned int len)
72 /* If the buffer is empty, start using it from the beginning. */
73 if (buffer->offset == buffer->end) {
78 /* If there is enough space to store all data, store it now. */
79 if (buffer->end + len < buffer->alloc) {
80 *datap = buffer->buf + buffer->end;
85 * If the buffer is quite empty, but all data is at the end, move the
86 * data to the beginning and retry.
88 if (buffer->offset > buffer->alloc / 2) {
89 memmove(buffer->buf, buffer->buf + buffer->offset,
90 buffer->end - buffer->offset);
91 buffer->end -= buffer->offset;
95 /* Increase the size of the buffer and retry. */
96 buffer->alloc += len + 32768;
97 buffer->buf = xrealloc(buffer->buf, buffer->alloc);
101 /* Returns the number of bytes of data in the buffer. */
104 buffer_len(Buffer *buffer)
106 return buffer->end - buffer->offset;
109 /* Gets data from the beginning of the buffer. */
112 buffer_get(Buffer *buffer, char *buf, unsigned int len)
114 if (len > buffer->end - buffer->offset)
115 fatal("buffer_get: trying to get more bytes than in buffer");
116 memcpy(buf, buffer->buf + buffer->offset, len);
117 buffer->offset += len;
120 /* Consumes the given number of bytes from the beginning of the buffer. */
123 buffer_consume(Buffer *buffer, unsigned int bytes)
125 if (bytes > buffer->end - buffer->offset)
126 fatal("buffer_consume: trying to get more bytes than in buffer");
127 buffer->offset += bytes;
130 /* Consumes the given number of bytes from the end of the buffer. */
133 buffer_consume_end(Buffer *buffer, unsigned int bytes)
135 if (bytes > buffer->end - buffer->offset)
136 fatal("buffer_consume_end: trying to get more bytes than in buffer");
137 buffer->end -= bytes;
140 /* Returns a pointer to the first used byte in the buffer. */
143 buffer_ptr(Buffer *buffer)
145 return buffer->buf + buffer->offset;
148 /* Dumps the contents of the buffer to stderr. */
151 buffer_dump(Buffer *buffer)
154 unsigned char *ucp = (unsigned char *) buffer->buf;
156 for (i = buffer->offset; i < buffer->end; i++)
157 fprintf(stderr, " %02x", ucp[i]);
158 fprintf(stderr, "\n");