rawfs.c revision 1.5
1 /* $NetBSD: rawfs.c,v 1.5 2005/12/11 12:19:29 christos 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 <stand.h> 43 44 #include "rawfs.h" 45 46 extern int debug; 47 48 /* Our devices are generally willing to do 8K transfers. */ 49 #define RAWFS_BSIZE 0x2000 50 51 /* 52 * In-core open file. 53 */ 54 struct file { 55 daddr_t fs_nextblk; /* block number to read next */ 56 off_t fs_off; /* seek offset in file */ 57 int fs_len; /* amount left in f_buf */ 58 char * fs_ptr; /* read pointer into f_buf */ 59 char fs_buf[RAWFS_BSIZE]; 60 }; 61 62 static int rawfs_get_block(struct open_file *); 63 64 int 65 rawfs_open(const char *path, struct open_file *f) 66 { 67 struct file *fs; 68 69 /* 70 * The actual PROM driver has already been opened. 71 * Just allocate the I/O buffer, etc. 72 */ 73 fs = alloc(sizeof(struct file)); 74 fs->fs_nextblk = 0; 75 fs->fs_off = 0; 76 fs->fs_len = 0; 77 fs->fs_ptr = fs->fs_buf; 78 79 #ifdef DEBUG_RAWFS 80 printf("rawfs_open: fs=0x%x\n", fs); 81 #endif 82 83 f->f_fsdata = fs; 84 return (0); 85 } 86 87 int 88 rawfs_close(struct open_file *f) 89 { 90 struct file *fs; 91 92 fs = (struct file *) f->f_fsdata; 93 f->f_fsdata = NULL; 94 95 #ifdef DEBUG_RAWFS 96 if (debug) { 97 printf("rawfs_close: breakpoint...", fs->fs_buf); 98 __asm (" trap #0"); 99 } 100 #endif 101 102 if (fs != NULL) 103 free(fs, sizeof(*fs)); 104 105 return (0); 106 } 107 108 int 109 rawfs_read(struct open_file *f, void *start, u_int size, u_int *resid) 110 { 111 struct file *fs = (struct file *)f->f_fsdata; 112 char *addr = start; 113 int error = 0; 114 size_t csize; 115 116 while (size != 0) { 117 if (fs->fs_len == 0) 118 if ((error = rawfs_get_block(f)) != 0) 119 break; 120 121 if (fs->fs_len <= 0) 122 break; /* EOF */ 123 124 csize = size; 125 if (csize > fs->fs_len) 126 csize = fs->fs_len; 127 128 memcpy(addr, fs->fs_ptr, csize); 129 fs->fs_off += csize; 130 fs->fs_ptr += csize; 131 fs->fs_len -= csize; 132 addr += csize; 133 size -= csize; 134 } 135 if (resid) 136 *resid = size; 137 return (error); 138 } 139 140 int 141 rawfs_write(struct open_file *f, void *start, size_t size, size_t *resid) 142 { 143 #ifdef DEBUG_RAWFS 144 panic("rawfs_write"); 145 #endif 146 return (EROFS); 147 } 148 149 off_t 150 rawfs_seek(struct open_file *f, off_t offset, int where) 151 { 152 struct file *fs = (struct file *)f->f_fsdata; 153 off_t csize; 154 155 switch (where) { 156 case SEEK_SET: 157 offset -= fs->fs_off; 158 /* FALLTHROUGH */ 159 case SEEK_CUR: 160 if (offset >= 0) 161 break; 162 /* FALLTHROUGH */ 163 case SEEK_END: 164 default: 165 return (-1); 166 } 167 168 while (offset != 0) { 169 170 if (fs->fs_len == 0) 171 if (rawfs_get_block(f) != 0) 172 return (-1); 173 174 if (fs->fs_len <= 0) 175 break; /* EOF */ 176 177 csize = offset; 178 if (csize > fs->fs_len) 179 csize = fs->fs_len; 180 181 fs->fs_off += csize; 182 fs->fs_ptr += csize; 183 fs->fs_len -= csize; 184 offset -= csize; 185 } 186 return (fs->fs_off); 187 } 188 189 int 190 rawfs_stat(struct open_file *f, struct stat *sb) 191 { 192 #ifdef DEBUG_RAWFS 193 panic("rawfs_stat"); 194 #endif 195 return (EFTYPE); 196 } 197 198 199 /* 200 * Read a block from the underlying stream device 201 * (In our case, a tape drive.) 202 */ 203 static int 204 rawfs_get_block(struct open_file *f) 205 { 206 struct file *fs; 207 int error, len; 208 209 fs = (struct file *)f->f_fsdata; 210 fs->fs_ptr = fs->fs_buf; 211 212 twiddle(); 213 error = f->f_dev->dv_strategy(f->f_devdata, F_READ, 214 fs->fs_nextblk, RAWFS_BSIZE, fs->fs_buf, &len); 215 216 if (!error) { 217 fs->fs_len = len; 218 fs->fs_nextblk += (RAWFS_BSIZE / DEV_BSIZE); 219 } 220 221 return (error); 222 } 223
Indexes created Wed Oct 01 15:09:59 GMT 2025