buffer.c revision 65668
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 1.8 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 23void 24buffer_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 34void 35buffer_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 46void 47buffer_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 55void 56buffer_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 69void 70buffer_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 } 77restart: 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 103unsigned int 104buffer_len(Buffer *buffer) 105{ 106 return buffer->end - buffer->offset; 107} 108 109/* Gets data from the beginning of the buffer. */ 110 111void 112buffer_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 122void 123buffer_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 132void 133buffer_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 142char * 143buffer_ptr(Buffer *buffer) 144{ 145 return buffer->buf + buffer->offset; 146} 147 148/* Dumps the contents of the buffer to stderr. */ 149 150void 151buffer_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} 160