fs/qnx4/qnx4.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #include <linux/fs.h>
   3 #include <linux/qnx4_fs.h>
   4
   5 #define QNX4_DEBUG 0
   6
   7 #if QNX4_DEBUG
   8 #define QNX4DEBUG(X) printk X
   9 #else
  10 #define QNX4DEBUG(X) (void) 0
  11 #endif
  12
  13 struct qnx4_sb_info {
  14         unsigned int            Version;        /* may be useful */
  15         struct qnx4_inode_entry *BitMap;        /* useful */
  16 };
  17
  18 struct qnx4_inode_info {
  19         struct qnx4_inode_entry raw;
  20         loff_t mmu_private;
  21         struct inode vfs_inode;
  22 };
  23
  24 extern struct inode *qnx4_iget(struct super_block *, unsigned long);
  25 extern struct dentry *qnx4_lookup(struct inode *dir, struct dentry *dentry, unsigned int flags);
  26 extern unsigned long qnx4_count_free_blocks(struct super_block *sb);
  27 extern unsigned long qnx4_block_map(struct inode *inode, long iblock);
  28
  29 extern const struct inode_operations qnx4_dir_inode_operations;
  30 extern const struct file_operations qnx4_dir_operations;
  31 extern int qnx4_is_free(struct super_block *sb, long block);
  32
  33 static inline struct qnx4_sb_info *qnx4_sb(struct super_block *sb)
  34 {
  35         return sb->s_fs_info;
  36 }
  37
  38 static inline struct qnx4_inode_info *qnx4_i(struct inode *inode)
  39 {
  40         return container_of(inode, struct qnx4_inode_info, vfs_inode);
  41 }
  42
  43 static inline struct qnx4_inode_entry *qnx4_raw_inode(struct inode *inode)
  44 {
  45         return &qnx4_i(inode)->raw;
  46 }
  47
  48 /*
  49  * A qnx4 directory entry is an inode entry or link info
  50  * depending on the status field in the last byte. The
  51  * first byte is where the name start either way, and a
  52  * zero means it's empty.
  53  *
  54  * Also, due to a bug in gcc, we don't want to use the
  55  * real (differently sized) name arrays in the inode and
  56  * link entries, but always the 'de_name[]' one in the
  57  * fake struct entry.
  58  *
  59  * See
  60  *
  61  *   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99578#c6
  62  *
  63  * for details, but basically gcc will take the size of the
  64  * 'name' array from one of the used union entries randomly.
  65  *
  66  * This use of 'de_name[]' (48 bytes) avoids the false positive
  67  * warnings that would happen if gcc decides to use 'inode.di_name'
  68  * (16 bytes) even when the pointer and size were to come from
  69  * 'link.dl_name' (48 bytes).
  70  *
  71  * In all cases the actual name pointer itself is the same, it's
  72  * only the gcc internal 'what is the size of this field' logic
  73  * that can get confused.
  74  */
  75 union qnx4_directory_entry {
  76         struct {
  77                 const char de_name[48];
  78                 u8 de_pad[15];
  79                 u8 de_status;
  80         };
  81         struct qnx4_inode_entry inode;
  82         struct qnx4_link_info link;
  83 };
  84
  85 static inline const char *get_entry_fname(union qnx4_directory_entry *de,
  86                                           int *size)
  87 {
  88         /* Make sure the status byte is in the same place for all structs. */
  89         BUILD_BUG_ON(offsetof(struct qnx4_inode_entry, di_status) !=
  90                         offsetof(struct qnx4_link_info, dl_status));
  91         BUILD_BUG_ON(offsetof(struct qnx4_inode_entry, di_status) !=
  92                         offsetof(union qnx4_directory_entry, de_status));
  93
  94         if (!de->de_name[0])
  95                 return NULL;
  96         if (!(de->de_status & (QNX4_FILE_USED|QNX4_FILE_LINK)))
  97                 return NULL;
  98         if (!(de->de_status & QNX4_FILE_LINK))
  99                 *size = sizeof(de->inode.di_fname);
 100         else
 101                 *size = sizeof(de->link.dl_fname);
 102
 103         *size = strnlen(de->de_name, *size);
 104
 105         return de->de_name;
 106 }