target/linux/generic/files/fs/yaffs2/yaffs_nameval.c

   1 /*
   2  * YAFFS: Yet Another Flash File System. A NAND-flash specific file system.
   3  *
   4  * Copyright (C) 2002-2010 Aleph One Ltd.
   5  *   for Toby Churchill Ltd and Brightstar Engineering
   6  *
   7  * Created by Charles Manning <charles@aleph1.co.uk>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 /*
  15  * This simple implementation of a name-value store assumes a small number of values and fits
  16  * into a small finite buffer.
  17  *
  18  * Each attribute is stored as a record:
  19  *  sizeof(int) bytes   record size.
  20  *  strnlen+1 bytes name null terminated.
  21  *  nbytes    value.
  22  *  ----------
  23  *  total size  stored in record size
  24  *
  25  * This code has not been tested with unicode yet.
  26  */
  27
  28
  29 #include "yaffs_nameval.h"
  30
  31 #include "yportenv.h"
  32
  33 static int nval_find(const char *xb, int xb_size, const YCHAR *name,
  34                 int *exist_size)
  35 {
  36         int pos=0;
  37         int size;
  38
  39         memcpy(&size,xb,sizeof(int));
  40         while(size > 0 && (size < xb_size) && (pos + size < xb_size)){
  41                 if(yaffs_strncmp((YCHAR *)(xb+pos+sizeof(int)),name,size) == 0){
  42                         if(exist_size)
  43                                 *exist_size = size;
  44                         return pos;
  45                 }
  46                 pos += size;
  47                 if(pos < xb_size -sizeof(int))
  48                         memcpy(&size,xb + pos,sizeof(int));
  49                 else
  50                         size = 0;
  51         }
  52         if(exist_size)
  53                 *exist_size = 0;
  54         return -1;
  55 }
  56
  57 static int nval_used(const char *xb, int xb_size)
  58 {
  59         int pos=0;
  60         int size;
  61
  62         memcpy(&size,xb + pos,sizeof(int));
  63         while(size > 0 && (size < xb_size) && (pos + size < xb_size)){
  64                 pos += size;
  65                 if(pos < xb_size -sizeof(int))
  66                         memcpy(&size,xb + pos,sizeof(int));
  67                 else
  68                         size = 0;
  69         }
  70         return pos;
  71 }
  72
  73 int nval_del(char *xb, int xb_size, const YCHAR *name)
  74 {
  75         int pos  = nval_find(xb, xb_size, name, NULL);
  76         int size;
  77
  78         if(pos >= 0 && pos < xb_size){
  79                 /* Find size, shift rest over this record, then zero out the rest of buffer */
  80                 memcpy(&size,xb+pos,sizeof(int));
  81                 memcpy(xb + pos, xb + pos + size, xb_size - (pos + size));
  82                 memset(xb + (xb_size - size),0,size);
  83                 return 0;
  84         } else
  85                 return -ENODATA;
  86 }
  87
  88 int nval_set(char *xb, int xb_size, const YCHAR *name, const char *buf, int bsize, int flags)
  89 {
  90         int pos;
  91         int namelen = yaffs_strnlen(name,xb_size);
  92         int reclen;
  93         int size_exist = 0;
  94         int space;
  95         int start;
  96
  97         pos = nval_find(xb,xb_size,name, &size_exist);
  98
  99         if(flags & XATTR_CREATE && pos >= 0)
 100                 return -EEXIST;
 101         if(flags & XATTR_REPLACE && pos < 0)
 102                 return -ENODATA;
 103
 104         start = nval_used(xb,xb_size);
 105         space = xb_size - start + size_exist;
 106
 107         reclen = (sizeof(int) + namelen + 1 + bsize);
 108
 109         if(reclen > space)
 110                 return -ENOSPC;
 111
 112         if(pos >= 0){
 113                 nval_del(xb,xb_size,name);
 114                 start = nval_used(xb, xb_size);
 115         }
 116
 117         pos = start;
 118
 119         memcpy(xb + pos,&reclen,sizeof(int));
 120         pos +=sizeof(int);
 121         yaffs_strncpy((YCHAR *)(xb + pos), name, reclen);
 122         pos+= (namelen+1);
 123         memcpy(xb + pos,buf,bsize);
 124         return 0;
 125 }
 126
 127 int nval_get(const char *xb, int xb_size, const YCHAR *name, char *buf, int bsize)
 128 {
 129         int pos = nval_find(xb,xb_size,name,NULL);
 130         int size;
 131
 132         if(pos >= 0 && pos< xb_size){
 133
 134                 memcpy(&size,xb +pos,sizeof(int));
 135                 pos+=sizeof(int); /* advance past record length */
 136                 size -= sizeof(int);
 137
 138                 /* Advance over name string */
 139                 while(xb[pos] && size > 0 && pos < xb_size){
 140                         pos++;
 141                         size--;
 142                 }
 143                 /*Advance over NUL */
 144                 pos++;
 145                 size--;
 146
 147                 if(size <= bsize){
 148                         memcpy(buf,xb + pos,size);
 149                         return size;
 150                 }
 151
 152         }
 153         if(pos >= 0)
 154                 return -ERANGE;
 155         else
 156                 return -ENODATA;
 157 }
 158
 159 int nval_list(const char *xb, int xb_size, char *buf, int bsize)
 160 {
 161         int pos = 0;
 162         int size;
 163         int name_len;
 164         int ncopied = 0;
 165         int filled = 0;
 166
 167         memcpy(&size,xb + pos,sizeof(int));
 168         while(size > sizeof(int) && size <= xb_size && (pos + size) < xb_size && !filled){
 169                 pos+= sizeof(int);
 170                 size-=sizeof(int);
 171                 name_len = yaffs_strnlen((YCHAR *)(xb + pos), size);
 172                 if(ncopied + name_len + 1 < bsize){
 173                         memcpy(buf,xb+pos,name_len * sizeof(YCHAR));
 174                         buf+= name_len;
 175                         *buf = '\0';
 176                         buf++;
 177                         if(sizeof(YCHAR) > 1){
 178                                 *buf = '\0';
 179                                 buf++;
 180                         }
 181                         ncopied += (name_len+1);
 182                 } else
 183                         filled = 1;
 184                 pos+=size;
 185                 if(pos < xb_size -sizeof(int))
 186                         memcpy(&size,xb + pos,sizeof(int));
 187                 else
 188                         size = 0;
 189         }
 190         return ncopied;
 191 }
 192
 193
 194 int nval_hasvalues(const char *xb, int xb_size)
 195 {
 196         return nval_used(xb, xb_size) > 0;
 197 }