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1 | /* | |
2 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
3 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
4 | * All rights reserved | |
5 | * Functions for manipulating fifo buffers (that can grow if needed). | |
6 | * | |
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". | |
12 | */ | |
13 | ||
14 | #include "includes.h" | |
15 | RCSID("$OpenBSD: buffer.c,v 1.8 2000/09/07 20:27:50 deraadt Exp $"); | |
16 | ||
17 | #include "xmalloc.h" | |
18 | #include "buffer.h" | |
19 | #include "ssh.h" | |
20 | ||
21 | /* Initializes the buffer structure. */ | |
22 | ||
23 | void | |
24 | buffer_init(Buffer *buffer) | |
25 | { | |
26 | buffer->alloc = 4096; | |
27 | buffer->buf = xmalloc(buffer->alloc); | |
28 | buffer->offset = 0; | |
29 | buffer->end = 0; | |
30 | } | |
31 | ||
32 | /* Frees any memory used for the buffer. */ | |
33 | ||
34 | void | |
35 | buffer_free(Buffer *buffer) | |
36 | { | |
37 | memset(buffer->buf, 0, buffer->alloc); | |
38 | xfree(buffer->buf); | |
39 | } | |
40 | ||
41 | /* | |
42 | * Clears any data from the buffer, making it empty. This does not actually | |
43 | * zero the memory. | |
44 | */ | |
45 | ||
46 | void | |
47 | buffer_clear(Buffer *buffer) | |
48 | { | |
49 | buffer->offset = 0; | |
50 | buffer->end = 0; | |
51 | } | |
52 | ||
53 | /* Appends data to the buffer, expanding it if necessary. */ | |
54 | ||
55 | void | |
56 | buffer_append(Buffer *buffer, const char *data, unsigned int len) | |
57 | { | |
58 | char *cp; | |
59 | buffer_append_space(buffer, &cp, len); | |
60 | memcpy(cp, data, len); | |
61 | } | |
62 | ||
63 | /* | |
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. | |
67 | */ | |
68 | ||
69 | void | |
70 | buffer_append_space(Buffer *buffer, char **datap, unsigned int len) | |
71 | { | |
72 | /* If the buffer is empty, start using it from the beginning. */ | |
73 | if (buffer->offset == buffer->end) { | |
74 | buffer->offset = 0; | |
75 | buffer->end = 0; | |
76 | } | |
77 | restart: | |
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; | |
81 | buffer->end += len; | |
82 | return; | |
83 | } | |
84 | /* | |
85 | * If the buffer is quite empty, but all data is at the end, move the | |
86 | * data to the beginning and retry. | |
87 | */ | |
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; | |
92 | buffer->offset = 0; | |
93 | goto restart; | |
94 | } | |
95 | /* Increase the size of the buffer and retry. */ | |
96 | buffer->alloc += len + 32768; | |
97 | buffer->buf = xrealloc(buffer->buf, buffer->alloc); | |
98 | goto restart; | |
99 | } | |
100 | ||
101 | /* Returns the number of bytes of data in the buffer. */ | |
102 | ||
103 | unsigned int | |
104 | buffer_len(Buffer *buffer) | |
105 | { | |
106 | return buffer->end - buffer->offset; | |
107 | } | |
108 | ||
109 | /* Gets data from the beginning of the buffer. */ | |
110 | ||
111 | void | |
112 | buffer_get(Buffer *buffer, char *buf, unsigned int len) | |
113 | { | |
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; | |
118 | } | |
119 | ||
120 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
121 | ||
122 | void | |
123 | buffer_consume(Buffer *buffer, unsigned int bytes) | |
124 | { | |
125 | if (bytes > buffer->end - buffer->offset) | |
126 | fatal("buffer_consume: trying to get more bytes than in buffer"); | |
127 | buffer->offset += bytes; | |
128 | } | |
129 | ||
130 | /* Consumes the given number of bytes from the end of the buffer. */ | |
131 | ||
132 | void | |
133 | buffer_consume_end(Buffer *buffer, unsigned int bytes) | |
134 | { | |
135 | if (bytes > buffer->end - buffer->offset) | |
136 | fatal("buffer_consume_end: trying to get more bytes than in buffer"); | |
137 | buffer->end -= bytes; | |
138 | } | |
139 | ||
140 | /* Returns a pointer to the first used byte in the buffer. */ | |
141 | ||
142 | char * | |
143 | buffer_ptr(Buffer *buffer) | |
144 | { | |
145 | return buffer->buf + buffer->offset; | |
146 | } | |
147 | ||
148 | /* Dumps the contents of the buffer to stderr. */ | |
149 | ||
150 | void | |
151 | buffer_dump(Buffer *buffer) | |
152 | { | |
153 | int i; | |
154 | unsigned char *ucp = (unsigned char *) buffer->buf; | |
155 | ||
156 | for (i = buffer->offset; i < buffer->end; i++) | |
157 | fprintf(stderr, " %02x", ucp[i]); | |
158 | fprintf(stderr, "\n"); | |
159 | } |