1 /* vfs_vnops.c 4.26 82/08/03 */ 2 3 #include "../h/param.h" 4 #include "../h/systm.h" 5 #include "../h/dir.h" 6 #include "../h/user.h" 7 #include "../h/fs.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 #include "../h/socket.h" 15 #include "../h/socketvar.h" 16 #include "../h/proc.h" 17 18 /* 19 * Openi called to allow handler 20 * of special files to initialize and 21 * validate before actual IO. 22 */ 23 openi(ip, mode) 24 register struct inode *ip; 25 { 26 dev_t dev; 27 register unsigned int maj; 28 29 dev = (dev_t)ip->i_rdev; 30 maj = major(dev); 31 switch (ip->i_mode&IFMT) { 32 33 case IFCHR: 34 if (maj >= nchrdev) 35 goto bad; 36 (*cdevsw[maj].d_open)(dev, mode); 37 break; 38 39 case IFBLK: 40 if (maj >= nblkdev) 41 goto bad; 42 (*bdevsw[maj].d_open)(dev, mode); 43 } 44 return; 45 46 bad: 47 u.u_error = ENXIO; 48 } 49 50 /* 51 * Check mode permission on inode pointer. 52 * Mode is READ, WRITE or EXEC. 53 * In the case of WRITE, the 54 * read-only status of the file 55 * system is checked. 56 * Also in WRITE, prototype text 57 * segments cannot be written. 58 * The mode is shifted to select 59 * the owner/group/other fields. 60 * The super user is granted all 61 * permissions. 62 */ 63 access(ip, mode) 64 register struct inode *ip; 65 int mode; 66 { 67 register m; 68 69 m = mode; 70 if (m == IWRITE) { 71 if (ip->i_fs->fs_ronly != 0) { 72 u.u_error = EROFS; 73 return (1); 74 } 75 if (ip->i_flag&ITEXT) /* try to free text */ 76 xrele(ip); 77 if (ip->i_flag & ITEXT) { 78 u.u_error = ETXTBSY; 79 return (1); 80 } 81 } 82 if (u.u_uid == 0) 83 return (0); 84 if (u.u_uid != ip->i_uid) { 85 m >>= 3; 86 if (ip->i_gid >= NGRPS || 87 (u.u_grps[ip->i_gid/(sizeof(int)*8)] & 88 (1 << ip->i_gid%(sizeof(int)*8)) == 0)) 89 m >>= 3; 90 } 91 if ((ip->i_mode&m) != 0) 92 return (0); 93 u.u_error = EACCES; 94 return (1); 95 } 96 97 /* 98 * Look up a pathname and test if 99 * the resultant inode is owned by the 100 * current user. 101 * If not, try for super-user. 102 * If permission is granted, 103 * return inode pointer. 104 */ 105 struct inode * 106 owner(follow) 107 int follow; 108 { 109 register struct inode *ip; 110 111 ip = namei(uchar, 0, follow); 112 if (ip == NULL) 113 return (NULL); 114 if (u.u_uid == ip->i_uid) 115 return (ip); 116 if (suser()) 117 return (ip); 118 iput(ip); 119 return (NULL); 120 } 121 122 /* 123 * Test if the current user is the 124 * super user. 125 */ 126 suser() 127 { 128 129 if (u.u_uid == 0) { 130 u.u_acflag |= ASU; 131 return (1); 132 } 133 u.u_error = EPERM; 134 return (0); 135 } 136