1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * QNX4 file system, Linux implementation. 4 * 5 * Version : 0.2.1 6 * 7 * Using parts of the xiafs filesystem. 8 * 9 * History : 10 * 11 * 01-06-1998 by Richard Frowijn : first release. 12 * 21-06-1998 by Frank Denis : dcache support, fixed error codes. 13 * 04-07-1998 by Frank Denis : first step for rmdir/unlink. 14 */ 15 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 thislen = strlen( de->di_fname ); 44 if ( thislen > namelen ) 45 thislen = namelen; 46 if (len != thislen) { 47 return 0; 48 } 49 if (strncmp(name, de->di_fname, len) == 0) { 50 if ((de->di_status & (QNX4_FILE_USED|QNX4_FILE_LINK)) != 0) { 51 return 1; 52 } 53 } 54 return 0; 55 } 56 57 static struct buffer_head *qnx4_find_entry(int len, struct inode *dir, 58 const char *name, struct qnx4_inode_entry **res_dir, int *ino) 59 { 60 unsigned long block, offset, blkofs; 61 struct buffer_head *bh; 62 63 *res_dir = NULL; 64 bh = NULL; 65 block = offset = blkofs = 0; 66 while (blkofs * QNX4_BLOCK_SIZE + offset < dir->i_size) { 67 if (!bh) { 68 block = qnx4_block_map(dir, blkofs); 69 if (block) 70 bh = sb_bread(dir->i_sb, block); 71 if (!bh) { 72 blkofs++; 73 continue; 74 } 75 } 76 *res_dir = (struct qnx4_inode_entry *) (bh->b_data + offset); 77 if (qnx4_match(len, name, bh, &offset)) { 78 *ino = block * QNX4_INODES_PER_BLOCK + 79 (offset / QNX4_DIR_ENTRY_SIZE) - 1; 80 return bh; 81 } 82 if (offset < bh->b_size) { 83 continue; 84 } 85 brelse(bh); 86 bh = NULL; 87 offset = 0; 88 blkofs++; 89 } 90 brelse(bh); 91 *res_dir = NULL; 92 return NULL; 93 } 94 95 struct dentry * qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags) 96 { 97 int ino; 98 struct qnx4_inode_entry *de; 99 struct qnx4_link_info *lnk; 100 struct buffer_head *bh; 101 const char *name = dentry->d_name.name; 102 int len = dentry->d_name.len; 103 struct inode *foundinode = NULL; 104 105 if (!(bh = qnx4_find_entry(len, dir, name, &de, &ino))) 106 goto out; 107 /* The entry is linked, let's get the real info */ 108 if ((de->di_status & QNX4_FILE_LINK) == QNX4_FILE_LINK) { 109 lnk = (struct qnx4_link_info *) de; 110 ino = (le32_to_cpu(lnk->dl_inode_blk) - 1) * 111 QNX4_INODES_PER_BLOCK + 112 lnk->dl_inode_ndx; 113 } 114 brelse(bh); 115 116 foundinode = qnx4_iget(dir->i_sb, ino); 117 if (IS_ERR(foundinode)) 118 QNX4DEBUG((KERN_ERR "qnx4: lookup->iget -> error %ld\n", 119 PTR_ERR(foundinode))); 120 out: 121 return d_splice_alias(foundinode, dentry); 122 } 123