1 /* vfs_vnops.c 4.11 81/05/15 */ 2 3 #include "../h/param.h" 4 #include "../h/systm.h" 5 #include "../h/dir.h" 6 #include "../h/user.h" 7 #include "../h/filsys.h" 8 #include "../h/file.h" 9 #include "../h/conf.h" 10 #include "../h/inode.h" 11 #include "../h/reg.h" 12 #include "../h/acct.h" 13 #include "../h/mount.h" 14 15 /* 16 * Convert a user supplied 17 * file descriptor into a pointer 18 * to a file structure. 19 * Only task is to check range 20 * of the descriptor. 21 */ 22 struct file * 23 getf(f) 24 register int f; 25 { 26 register struct file *fp; 27 28 if ((unsigned)f >= NOFILE || (fp = u.u_ofile[f]) == NULL) { 29 u.u_error = EBADF; 30 return (NULL); 31 } 32 return (fp); 33 } 34 35 /* 36 * Internal form of close. 37 * Decrement reference count on 38 * file structure. 39 * Also make sure the pipe protocol 40 * does not constipate. 41 * 42 * Decrement reference count on the inode following 43 * removal to the referencing file structure. 44 * Call device handler on last close. 45 */ 46 closef(fp) 47 register struct file *fp; 48 { 49 register struct inode *ip; 50 register struct mount *mp; 51 int flag, mode; 52 dev_t dev; 53 register int (*cfunc)(); 54 55 if(fp == NULL) 56 return; 57 if (fp->f_count > 1) { 58 fp->f_count--; 59 return; 60 } 61 flag = fp->f_flag; 62 #ifdef BBNNET 63 if (flag&FNET) { 64 netclose(fp); 65 return; 66 } 67 #endif 68 if (flag & FPORT) { 69 ptclose(fp); 70 fp->f_count = 0; 71 return; 72 } 73 ip = fp->f_inode; 74 dev = (dev_t)ip->i_un.i_rdev; 75 mode = ip->i_mode & IFMT; 76 plock(ip); 77 iput(ip); 78 fp->f_count = 0; 79 80 switch (mode) { 81 82 case IFCHR: 83 case IFMPC: 84 cfunc = cdevsw[major(dev)].d_close; 85 break; 86 87 case IFBLK: 88 /* 89 * We don't want to really close the device if it is mounted 90 */ 91 for (mp = mount; mp < &mount[NMOUNT]; mp++) 92 if (mp->m_bufp != NULL && mp->m_dev == dev) 93 return; 94 case IFMPB: 95 cfunc = bdevsw[major(dev)].d_close; 96 break; 97 default: 98 return; 99 } 100 101 if ((flag & FMP) == 0) { 102 for(fp=file; fp < fileNFILE; fp++) 103 if (fp->f_count && (ip = fp->f_inode) && 104 ip->i_un.i_rdev == dev && 105 (ip->i_mode&IFMT) == mode) 106 return; 107 if (mode == IFBLK) { 108 /* 109 * on last close of a block device (that isn't mounted) 110 * we must invalidate any in core blocks 111 */ 112 bflush(dev); 113 binval(dev); 114 } 115 } 116 (*cfunc)(dev, flag, fp); 117 } 118 119 /* 120 * openi called to allow handler 121 * of special files to initialize and 122 * validate before actual IO. 123 */ 124 openi(ip, rw) 125 register struct inode *ip; 126 { 127 dev_t dev; 128 register unsigned int maj; 129 130 dev = (dev_t)ip->i_un.i_rdev; 131 maj = major(dev); 132 switch(ip->i_mode&IFMT) { 133 134 case IFCHR: 135 case IFMPC: 136 if(maj >= nchrdev) 137 goto bad; 138 (*cdevsw[maj].d_open)(dev, rw); 139 break; 140 141 case IFBLK: 142 case IFMPB: 143 if(maj >= nblkdev) 144 goto bad; 145 (*bdevsw[maj].d_open)(dev, rw); 146 } 147 return; 148 149 bad: 150 u.u_error = ENXIO; 151 } 152 153 /* 154 * Check mode permission on inode pointer. 155 * Mode is READ, WRITE or EXEC. 156 * In the case of WRITE, the 157 * read-only status of the file 158 * system is checked. 159 * Also in WRITE, prototype text 160 * segments cannot be written. 161 * The mode is shifted to select 162 * the owner/group/other fields. 163 * The super user is granted all 164 * permissions. 165 */ 166 access(ip, mode) 167 register struct inode *ip; 168 { 169 register m; 170 171 m = mode; 172 if(m == IWRITE) { 173 if(getfs(ip->i_dev)->s_ronly != 0) { 174 u.u_error = EROFS; 175 return(1); 176 } 177 if (ip->i_flag&ITEXT) /* try to free text */ 178 xrele(ip); 179 if(ip->i_flag & ITEXT) { 180 u.u_error = ETXTBSY; 181 return(1); 182 } 183 } 184 if(u.u_uid == 0) 185 return(0); 186 if(u.u_uid != ip->i_uid) { 187 m >>= 3; 188 if(u.u_gid != ip->i_gid) 189 m >>= 3; 190 } 191 if((ip->i_mode&m) != 0) 192 return(0); 193 194 u.u_error = EACCES; 195 return(1); 196 } 197 198 /* 199 * Look up a pathname and test if 200 * the resultant inode is owned by the 201 * current user. 202 * If not, try for super-user. 203 * If permission is granted, 204 * return inode pointer. 205 */ 206 struct inode * 207 owner() 208 { 209 register struct inode *ip; 210 211 ip = namei(uchar, 0); 212 if(ip == NULL) 213 return(NULL); 214 if(u.u_uid == ip->i_uid) 215 return(ip); 216 if(suser()) 217 return(ip); 218 iput(ip); 219 return(NULL); 220 } 221 222 /* 223 * Test if the current user is the 224 * super user. 225 */ 226 suser() 227 { 228 229 if(u.u_uid == 0) { 230 u.u_acflag |= ASU; 231 return(1); 232 } 233 u.u_error = EPERM; 234 return(0); 235 } 236 237 /* 238 * Allocate a user file descriptor. 239 */ 240 ufalloc() 241 { 242 register i; 243 244 for(i=0; i<NOFILE; i++) 245 if(u.u_ofile[i] == NULL) { 246 u.u_r.r_val1 = i; 247 u.u_pofile[i] = 0; 248 return(i); 249 } 250 u.u_error = EMFILE; 251 return(-1); 252 } 253 254 struct file *lastf; 255 /* 256 * Allocate a user file descriptor 257 * and a file structure. 258 * Initialize the descriptor 259 * to point at the file structure. 260 */ 261 struct file * 262 falloc() 263 { 264 register struct file *fp; 265 register i; 266 267 i = ufalloc(); 268 if (i < 0) 269 return(NULL); 270 if (lastf == 0) 271 lastf = file; 272 for (fp = lastf; fp < fileNFILE; fp++) 273 if (fp->f_count == 0) 274 goto slot; 275 for (fp = file; fp < lastf; fp++) 276 if (fp->f_count == 0) 277 goto slot; 278 tablefull("file"); 279 u.u_error = ENFILE; 280 return (NULL); 281 slot: 282 u.u_ofile[i] = fp; 283 fp->f_count++; 284 fp->f_un.f_offset = 0; 285 fp->f_inode = 0; 286 lastf = fp + 1; 287 return (fp); 288 } 289