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