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1 | /* | |
2 | * | |
3 | * buffer.c | |
4 | * | |
5 | * Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | * | |
7 | * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | * All rights reserved | |
9 | * | |
10 | * Created: Sat Mar 18 04:15:33 1995 ylo | |
11 | * | |
12 | * Functions for manipulating fifo buffers (that can grow if needed). | |
13 | * | |
14 | */ | |
15 | ||
16 | #include "includes.h" | |
17 | RCSID("$Id$"); | |
18 | ||
19 | #include "xmalloc.h" | |
20 | #include "buffer.h" | |
21 | #include "ssh.h" | |
22 | ||
23 | /* Initializes the buffer structure. */ | |
24 | ||
25 | void | |
26 | buffer_init(Buffer *buffer) | |
27 | { | |
28 | buffer->alloc = 4096; | |
29 | buffer->buf = xmalloc(buffer->alloc); | |
30 | buffer->offset = 0; | |
31 | buffer->end = 0; | |
32 | } | |
33 | ||
34 | /* Frees any memory used for the buffer. */ | |
35 | ||
36 | void | |
37 | buffer_free(Buffer *buffer) | |
38 | { | |
39 | memset(buffer->buf, 0, buffer->alloc); | |
40 | xfree(buffer->buf); | |
41 | } | |
42 | ||
43 | /* | |
44 | * Clears any data from the buffer, making it empty. This does not actually | |
45 | * zero the memory. | |
46 | */ | |
47 | ||
48 | void | |
49 | buffer_clear(Buffer *buffer) | |
50 | { | |
51 | buffer->offset = 0; | |
52 | buffer->end = 0; | |
53 | } | |
54 | ||
55 | /* Appends data to the buffer, expanding it if necessary. */ | |
56 | ||
57 | void | |
58 | buffer_append(Buffer *buffer, const char *data, unsigned int len) | |
59 | { | |
60 | char *cp; | |
61 | buffer_append_space(buffer, &cp, len); | |
62 | memcpy(cp, data, len); | |
63 | } | |
64 | ||
65 | /* | |
66 | * Appends space to the buffer, expanding the buffer if necessary. This does | |
67 | * not actually copy the data into the buffer, but instead returns a pointer | |
68 | * to the allocated region. | |
69 | */ | |
70 | ||
71 | void | |
72 | buffer_append_space(Buffer *buffer, char **datap, unsigned int len) | |
73 | { | |
74 | /* If the buffer is empty, start using it from the beginning. */ | |
75 | if (buffer->offset == buffer->end) { | |
76 | buffer->offset = 0; | |
77 | buffer->end = 0; | |
78 | } | |
79 | restart: | |
80 | /* If there is enough space to store all data, store it now. */ | |
81 | if (buffer->end + len < buffer->alloc) { | |
82 | *datap = buffer->buf + buffer->end; | |
83 | buffer->end += len; | |
84 | return; | |
85 | } | |
86 | /* | |
87 | * If the buffer is quite empty, but all data is at the end, move the | |
88 | * data to the beginning and retry. | |
89 | */ | |
90 | if (buffer->offset > buffer->alloc / 2) { | |
91 | memmove(buffer->buf, buffer->buf + buffer->offset, | |
92 | buffer->end - buffer->offset); | |
93 | buffer->end -= buffer->offset; | |
94 | buffer->offset = 0; | |
95 | goto restart; | |
96 | } | |
97 | /* Increase the size of the buffer and retry. */ | |
98 | buffer->alloc += len + 32768; | |
99 | buffer->buf = xrealloc(buffer->buf, buffer->alloc); | |
100 | goto restart; | |
101 | } | |
102 | ||
103 | /* Returns the number of bytes of data in the buffer. */ | |
104 | ||
105 | unsigned int | |
106 | buffer_len(Buffer *buffer) | |
107 | { | |
108 | return buffer->end - buffer->offset; | |
109 | } | |
110 | ||
111 | /* Gets data from the beginning of the buffer. */ | |
112 | ||
113 | void | |
114 | buffer_get(Buffer *buffer, char *buf, unsigned int len) | |
115 | { | |
116 | if (len > buffer->end - buffer->offset) | |
117 | fatal("buffer_get trying to get more bytes than in buffer"); | |
118 | memcpy(buf, buffer->buf + buffer->offset, len); | |
119 | buffer->offset += len; | |
120 | } | |
121 | ||
122 | /* Consumes the given number of bytes from the beginning of the buffer. */ | |
123 | ||
124 | void | |
125 | buffer_consume(Buffer *buffer, unsigned int bytes) | |
126 | { | |
127 | if (bytes > buffer->end - buffer->offset) | |
128 | fatal("buffer_get trying to get more bytes than in buffer"); | |
129 | buffer->offset += bytes; | |
130 | } | |
131 | ||
132 | /* Consumes the given number of bytes from the end of the buffer. */ | |
133 | ||
134 | void | |
135 | buffer_consume_end(Buffer *buffer, unsigned int bytes) | |
136 | { | |
137 | if (bytes > buffer->end - buffer->offset) | |
138 | fatal("buffer_get trying to get more bytes than in buffer"); | |
139 | buffer->end -= bytes; | |
140 | } | |
141 | ||
142 | /* Returns a pointer to the first used byte in the buffer. */ | |
143 | ||
144 | char * | |
145 | buffer_ptr(Buffer *buffer) | |
146 | { | |
147 | return buffer->buf + buffer->offset; | |
148 | } | |
149 | ||
150 | /* Dumps the contents of the buffer to stderr. */ | |
151 | ||
152 | void | |
153 | buffer_dump(Buffer *buffer) | |
154 | { | |
155 | int i; | |
156 | unsigned char *ucp = (unsigned char *) buffer->buf; | |
157 | ||
158 | for (i = buffer->offset; i < buffer->end; i++) | |
159 | fprintf(stderr, " %02x", ucp[i]); | |
160 | fprintf(stderr, "\n"); | |
161 | } |