buffer.c revision 120489
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" 15RCSID("$OpenBSD: buffer.c,v 1.17 2003/09/16 03:03:47 deraadt Exp $"); 16 17#include "xmalloc.h" 18#include "buffer.h" 19#include "log.h" 20 21/* Initializes the buffer structure. */ 22 23void 24buffer_init(Buffer *buffer) 25{ 26 const u_int len = 4096; 27 28 buffer->alloc = 0; 29 buffer->buf = xmalloc(len); 30 buffer->alloc = len; 31 buffer->offset = 0; 32 buffer->end = 0; 33} 34 35/* Frees any memory used for the buffer. */ 36 37void 38buffer_free(Buffer *buffer) 39{ 40 if (buffer->alloc > 0) { 41 memset(buffer->buf, 0, buffer->alloc); 42 xfree(buffer->buf); 43 } 44} 45 46/* 47 * Clears any data from the buffer, making it empty. This does not actually 48 * zero the memory. 49 */ 50 51void 52buffer_clear(Buffer *buffer) 53{ 54 buffer->offset = 0; 55 buffer->end = 0; 56} 57 58/* Appends data to the buffer, expanding it if necessary. */ 59 60void 61buffer_append(Buffer *buffer, const void *data, u_int len) 62{ 63 void *p; 64 p = buffer_append_space(buffer, len); 65 memcpy(p, data, len); 66} 67 68/* 69 * Appends space to the buffer, expanding the buffer if necessary. This does 70 * not actually copy the data into the buffer, but instead returns a pointer 71 * to the allocated region. 72 */ 73 74void * 75buffer_append_space(Buffer *buffer, u_int len) 76{ 77 u_int newlen; 78 void *p; 79 80 if (len > 0x100000) 81 fatal("buffer_append_space: len %u not supported", len); 82 83 /* If the buffer is empty, start using it from the beginning. */ 84 if (buffer->offset == buffer->end) { 85 buffer->offset = 0; 86 buffer->end = 0; 87 } 88restart: 89 /* If there is enough space to store all data, store it now. */ 90 if (buffer->end + len < buffer->alloc) { 91 p = buffer->buf + buffer->end; 92 buffer->end += len; 93 return p; 94 } 95 /* 96 * If the buffer is quite empty, but all data is at the end, move the 97 * data to the beginning and retry. 98 */ 99 if (buffer->offset > buffer->alloc / 2) { 100 memmove(buffer->buf, buffer->buf + buffer->offset, 101 buffer->end - buffer->offset); 102 buffer->end -= buffer->offset; 103 buffer->offset = 0; 104 goto restart; 105 } 106 /* Increase the size of the buffer and retry. */ 107 108 newlen = buffer->alloc + len + 32768; 109 if (newlen > 0xa00000) 110 fatal("buffer_append_space: alloc %u not supported", 111 newlen); 112 buffer->buf = xrealloc(buffer->buf, newlen); 113 buffer->alloc = newlen; 114 goto restart; 115 /* NOTREACHED */ 116} 117 118/* Returns the number of bytes of data in the buffer. */ 119 120u_int 121buffer_len(Buffer *buffer) 122{ 123 return buffer->end - buffer->offset; 124} 125 126/* Gets data from the beginning of the buffer. */ 127 128void 129buffer_get(Buffer *buffer, void *buf, u_int len) 130{ 131 if (len > buffer->end - buffer->offset) 132 fatal("buffer_get: trying to get more bytes %d than in buffer %d", 133 len, buffer->end - buffer->offset); 134 memcpy(buf, buffer->buf + buffer->offset, len); 135 buffer->offset += len; 136} 137 138/* Consumes the given number of bytes from the beginning of the buffer. */ 139 140void 141buffer_consume(Buffer *buffer, u_int bytes) 142{ 143 if (bytes > buffer->end - buffer->offset) 144 fatal("buffer_consume: trying to get more bytes than in buffer"); 145 buffer->offset += bytes; 146} 147 148/* Consumes the given number of bytes from the end of the buffer. */ 149 150void 151buffer_consume_end(Buffer *buffer, u_int bytes) 152{ 153 if (bytes > buffer->end - buffer->offset) 154 fatal("buffer_consume_end: trying to get more bytes than in buffer"); 155 buffer->end -= bytes; 156} 157 158/* Returns a pointer to the first used byte in the buffer. */ 159 160void * 161buffer_ptr(Buffer *buffer) 162{ 163 return buffer->buf + buffer->offset; 164} 165 166/* Dumps the contents of the buffer to stderr. */ 167 168void 169buffer_dump(Buffer *buffer) 170{ 171 int i; 172 u_char *ucp = buffer->buf; 173 174 for (i = buffer->offset; i < buffer->end; i++) { 175 fprintf(stderr, "%02x", ucp[i]); 176 if ((i-buffer->offset)%16==15) 177 fprintf(stderr, "\r\n"); 178 else if ((i-buffer->offset)%2==1) 179 fprintf(stderr, " "); 180 } 181 fprintf(stderr, "\r\n"); 182} 183