Annotation of src/usr.bin/ssh/buffer.c, Revision 1.8
1.1 deraadt 1: /*
1.3 deraadt 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).
1.6 markus 6: *
1.8 ! deraadt 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".
1.3 deraadt 12: */
1.1 deraadt 13:
14: #include "includes.h"
1.8 ! deraadt 15: RCSID("$OpenBSD: buffer.c,v 1.7 2000/06/20 01:39:39 markus Exp $");
1.1 deraadt 16:
17: #include "xmalloc.h"
18: #include "buffer.h"
19: #include "ssh.h"
20:
21: /* Initializes the buffer structure. */
22:
1.6 markus 23: void
1.2 markus 24: buffer_init(Buffer *buffer)
1.1 deraadt 25: {
1.2 markus 26: buffer->alloc = 4096;
27: buffer->buf = xmalloc(buffer->alloc);
28: buffer->offset = 0;
29: buffer->end = 0;
1.1 deraadt 30: }
31:
32: /* Frees any memory used for the buffer. */
33:
1.6 markus 34: void
1.2 markus 35: buffer_free(Buffer *buffer)
1.1 deraadt 36: {
1.2 markus 37: memset(buffer->buf, 0, buffer->alloc);
38: xfree(buffer->buf);
1.1 deraadt 39: }
40:
1.4 markus 41: /*
42: * Clears any data from the buffer, making it empty. This does not actually
43: * zero the memory.
44: */
1.1 deraadt 45:
1.6 markus 46: void
1.2 markus 47: buffer_clear(Buffer *buffer)
1.1 deraadt 48: {
1.2 markus 49: buffer->offset = 0;
50: buffer->end = 0;
1.1 deraadt 51: }
52:
53: /* Appends data to the buffer, expanding it if necessary. */
54:
1.6 markus 55: void
1.2 markus 56: buffer_append(Buffer *buffer, const char *data, unsigned int len)
1.1 deraadt 57: {
1.2 markus 58: char *cp;
59: buffer_append_space(buffer, &cp, len);
60: memcpy(cp, data, len);
1.1 deraadt 61: }
62:
1.4 markus 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: */
1.1 deraadt 68:
1.6 markus 69: void
1.2 markus 70: buffer_append_space(Buffer *buffer, char **datap, unsigned int len)
1.1 deraadt 71: {
1.2 markus 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: }
1.4 markus 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: */
1.2 markus 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;
1.1 deraadt 99: }
100:
101: /* Returns the number of bytes of data in the buffer. */
102:
1.6 markus 103: unsigned int
1.2 markus 104: buffer_len(Buffer *buffer)
1.1 deraadt 105: {
1.2 markus 106: return buffer->end - buffer->offset;
1.1 deraadt 107: }
108:
109: /* Gets data from the beginning of the buffer. */
110:
1.6 markus 111: void
1.2 markus 112: buffer_get(Buffer *buffer, char *buf, unsigned int len)
1.1 deraadt 113: {
1.2 markus 114: if (len > buffer->end - buffer->offset)
1.5 markus 115: fatal("buffer_get: trying to get more bytes than in buffer");
1.2 markus 116: memcpy(buf, buffer->buf + buffer->offset, len);
117: buffer->offset += len;
1.1 deraadt 118: }
119:
120: /* Consumes the given number of bytes from the beginning of the buffer. */
121:
1.6 markus 122: void
1.2 markus 123: buffer_consume(Buffer *buffer, unsigned int bytes)
1.1 deraadt 124: {
1.2 markus 125: if (bytes > buffer->end - buffer->offset)
1.5 markus 126: fatal("buffer_consume: trying to get more bytes than in buffer");
1.2 markus 127: buffer->offset += bytes;
128: }
1.1 deraadt 129:
130: /* Consumes the given number of bytes from the end of the buffer. */
131:
1.6 markus 132: void
1.2 markus 133: buffer_consume_end(Buffer *buffer, unsigned int bytes)
1.1 deraadt 134: {
1.2 markus 135: if (bytes > buffer->end - buffer->offset)
1.5 markus 136: fatal("buffer_consume_end: trying to get more bytes than in buffer");
1.2 markus 137: buffer->end -= bytes;
138: }
1.1 deraadt 139:
140: /* Returns a pointer to the first used byte in the buffer. */
141:
1.2 markus 142: char *
143: buffer_ptr(Buffer *buffer)
1.1 deraadt 144: {
1.2 markus 145: return buffer->buf + buffer->offset;
1.1 deraadt 146: }
147:
148: /* Dumps the contents of the buffer to stderr. */
149:
1.6 markus 150: void
1.2 markus 151: buffer_dump(Buffer *buffer)
1.1 deraadt 152: {
1.2 markus 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");
1.1 deraadt 159: }
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