1 /* 2 * QNX4 file system, Linux implementation. 3 * 4 * Version : 0.2.1 5 * 6 * Using parts of the xiafs filesystem. 7 * 8 * History : 9 * 10 * 01-06-1998 by Richard Frowijn : first release. 11 * 21-06-1998 by Frank Denis : dcache support, fixed error codes. 12 * 04-07-1998 by Frank Denis : first step for rmdir/unlink. 13 */ 14 15 #include <linux/smp_lock.h> 16 #include <linux/buffer_head.h> 17 #include "qnx4.h" 18 19 20 /* 21 * check if the filename is correct. For some obscure reason, qnx writes a 22 * new file twice in the directory entry, first with all possible options at 0 23 * and for a second time the way it is, they want us not to access the qnx 24 * filesystem when whe are using linux. 25 */ 26 static int qnx4_match(int len, const char *name, 27 struct buffer_head *bh, unsigned long *offset) 28 { 29 struct qnx4_inode_entry *de; 30 int namelen, thislen; 31 32 if (bh == NULL) { 33 printk(KERN_WARNING "qnx4: matching unassigned buffer !\n"); 34 return 0; 35 } 36 de = (struct qnx4_inode_entry *) (bh->b_data + *offset); 37 *offset += QNX4_DIR_ENTRY_SIZE; 38 if ((de->di_status & QNX4_FILE_LINK) != 0) { 39 namelen = QNX4_NAME_MAX; 40 } else { 41 namelen = QNX4_SHORT_NAME_MAX; 42 } 43 /* "" means "." ---> so paths like "/usr/lib//libc.a" work */ 44 if (!len && (de->di_fname[0] == '.') && (de->di_fname[1] == '\0')) { 45 return 1; 46 } 47 thislen = strlen( de->di_fname ); 48 if ( thislen > namelen ) 49 thislen = namelen; 50 if (len != thislen) { 51 return 0; 52 } 53 if (strncmp(name, de->di_fname, len) == 0) { 54 if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) { 55 return 1; 56 } 57 } 58 return 0; 59 } 60 61 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir, 62 const char *name, struct qnx4_inode_entry **res_dir, int *ino) 63 { 64 unsigned long block, offset, blkofs; 65 struct buffer_head *bh; 66 67 *res_dir = NULL; 68 if (!dir->i_sb) { 69 printk(KERN_WARNING "qnx4: no superblock on dir.\n"); 70 return NULL; 71 } 72 bh = NULL; 73 block = offset = blkofs = 0; 74 while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) { 75 if (!bh) { 76 bh = qnx4_bread(dir, blkofs, 0); 77 if (!bh) { 78 blkofs++; 79 continue; 80 } 81 } 82 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset); 83 if (qnx4_match(len, name, bh, &offset)) { 84 block = qnx4_block_map( dir, blkofs ); 85 *ino = block * QNX4_INODES_PER_BLOCK + 86 (offset / QNX4_DIR_ENTRY_SIZE) - 1; 87 return bh; 88 } 89 if (offset < bh->b_size) { 90 continue; 91 } 92 brelse(bh); 93 bh = NULL; 94 offset = 0; 95 blkofs++; 96 } 97 brelse(bh); 98 *res_dir = NULL; 99 return NULL; 100 } 101 102 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd) 103 { 104 int ino; 105 struct qnx4_inode_entry *de; 106 struct qnx4_link_info *lnk; 107 struct buffer_head *bh; 108 const char *name = dentry->d_name.name; 109 int len = dentry->d_name.len; 110 struct inode *foundinode = NULL; 111 112 lock_kernel(); 113 if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino))) 114 goto out; 115 /* The entry is linked, let's get the real info */ 116 if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) { 117 lnk = (struct qnx4_link_info *) de; 118 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) * 119 QNX4_INODES_PER_BLOCK + 120 lnk->dl_inode_ndx; 121 } 122 brelse(bh); 123 124 foundinode = qnx4_iget(dir->i_sb, ino); 125 if (IS_ERR(foundinode)) { 126 unlock_kernel(); 127 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n", 128 PTR_ERR(foundinode))); 129 return ERR_CAST(foundinode); 130 } 131 out: 132 unlock_kernel(); 133 d_add(dentry, foundinode); 134 135 return NULL; 136 } 137