1 /* $NetBSD: rawfs.c,v 1.10 2008/01/12 09:54:30 tsutsui Exp $ */ 2 3 /* 4 * Copyright (c) 1995 Gordon W. Ross 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. The name of the author may not be used to endorse or promote products 16 * derived from this software without specific prior written permission. 17 * 4. All advertising materials mentioning features or use of this software 18 * must display the following acknowledgement: 19 * This product includes software developed by Gordon W. Ross 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Raw file system - for stream devices like tapes. 35 * No random access, only sequential read allowed. 36 * This exists only to allow upper level code to be 37 * shielded from the fact that the device must be 38 * read only with whole block position and size. 39 */ 40 41 #include <sys/param.h> 42 #include <lib/libsa/stand.h> 43 #include <rawfs.h> 44 45 extern int debug; 46 47 #define RAWFS_BSIZE 8192 48 49 /* 50 * In-core open file. 51 */ 52 struct file { 53 daddr_t fs_nextblk; /* block number to read next */ 54 daddr_t fs_curblk; /* block number currently in buffer */ 55 int fs_len; /* amount left in f_buf */ 56 char *fs_ptr; /* read pointer into f_buf */ 57 char fs_buf[RAWFS_BSIZE]; 58 }; 59 60 static int rawfs_get_block(struct open_file *); 61 62 int rawfs_open(const char *path, struct open_file *f) 63 { 64 struct file *fs; 65 66 /* 67 * The actual PROM driver has already been opened. 68 * Just allocate the I/O buffer, etc. 69 */ 70 fs = alloc(sizeof(struct file)); 71 fs->fs_nextblk = 0; 72 fs->fs_curblk = -1; 73 fs->fs_len = 0; 74 fs->fs_ptr = fs->fs_buf; 75 76 f->f_fsdata = fs; 77 return 0; 78 } 79 80 int rawfs_close(struct open_file *f) 81 { 82 struct file *fs; 83 84 fs = (struct file *)f->f_fsdata; 85 f->f_fsdata = NULL; 86 87 if (fs != NULL) 88 dealloc(fs, sizeof(*fs)); 89 90 return 0; 91 } 92 93 int rawfs_read(struct open_file *f, void *start, u_int size, u_int *resid) 94 { 95 struct file *fs = (struct file *)f->f_fsdata; 96 char *addr = start; 97 int error = 0; 98 size_t csize; 99 100 while (size != 0) { 101 102 if (fs->fs_len == 0) 103 if ((error = rawfs_get_block(f)) != 0) 104 break; 105 106 if (fs->fs_len <= 0) 107 break; /* EOF */ 108 109 csize = size; 110 if (csize > fs->fs_len) 111 csize = fs->fs_len; 112 113 memcpy(addr, fs->fs_ptr, csize); 114 fs->fs_ptr += csize; 115 fs->fs_len -= csize; 116 addr += csize; 117 size -= csize; 118 } 119 if (resid) 120 *resid = size; 121 122 if (error) { 123 errno = error; 124 error = -1; 125 } 126 127 return error; 128 } 129 130 int rawfs_write(struct open_file *f, void *start, size_t size, size_t *resid) 131 { 132 133 errno = EROFS; 134 return -1; 135 } 136 137 off_t rawfs_seek(struct open_file *f, off_t offset, int where) 138 { 139 struct file *fs = (struct file *)f->f_fsdata; 140 daddr_t curblk, targblk; 141 off_t newoff; 142 int err, idx; 143 144 /* 145 * We support a very minimal feature set for lseek(2); just 146 * enough to allow loadfile() to work with the parameters 147 * we pass to it on boot. 148 * 149 * In all cases, we can't seek back past the start of the 150 * current block. 151 */ 152 curblk = (fs->fs_curblk < 0) ? 0 : fs->fs_curblk; 153 154 /* 155 * Only support SEEK_SET and SEEK_CUR which result in offsets 156 * which don't require seeking backwards. 157 */ 158 switch (where) { 159 case SEEK_SET: 160 newoff = offset; 161 break; 162 163 case SEEK_CUR: 164 if (fs->fs_curblk < 0) 165 newoff = 0; 166 else { 167 newoff = fs->fs_curblk * RAWFS_BSIZE; 168 newoff += RAWFS_BSIZE - fs->fs_len; 169 } 170 newoff += offset; 171 break; 172 173 default: 174 errno = EINVAL; 175 return -1; 176 } 177 178 if (newoff < (curblk * RAWFS_BSIZE)) { 179 errno = EINVAL; 180 return -1; 181 } 182 183 targblk = newoff / RAWFS_BSIZE; 184 185 /* 186 * If necessary, skip blocks until we hit the required target 187 */ 188 err = 0; 189 while (fs->fs_curblk != targblk && (err = rawfs_get_block(f)) == 0) 190 ; 191 192 if (err) { 193 errno = err; 194 return -1; 195 } 196 197 /* 198 * Update the index within the loaded block 199 */ 200 idx = newoff % RAWFS_BSIZE; 201 fs->fs_len = RAWFS_BSIZE - idx; 202 fs->fs_ptr = &fs->fs_buf[idx]; 203 204 return newoff; 205 } 206 207 int rawfs_stat(struct open_file *f, struct stat *sb) 208 { 209 210 errno = EFTYPE; 211 return -1; 212 } 213 214 215 /* 216 * Read a block from the underlying stream device 217 * (In our case, a tape drive.) 218 */ 219 static int 220 rawfs_get_block(struct open_file *f) 221 { 222 struct file *fs; 223 int error; 224 size_t len; 225 226 fs = (struct file *)f->f_fsdata; 227 fs->fs_ptr = fs->fs_buf; 228 229 twiddle(); 230 error = f->f_dev->dv_strategy(f->f_devdata, F_READ, 231 fs->fs_nextblk * (RAWFS_BSIZE / DEV_BSIZE), 232 RAWFS_BSIZE, fs->fs_buf, &len); 233 234 if (error == 0) { 235 fs->fs_len = len; 236 fs->fs_curblk = fs->fs_nextblk; 237 fs->fs_nextblk += 1; 238 } else { 239 errno = error; 240 error = -1; 241 } 242 243 return error; 244 } 245