| 1 | /* |
| 2 | * descriptor table internals; you almost certainly want file.h instead. |
| 3 | */ |
| 4 | |
| 5 | #ifndef __LINUX_FDTABLE_H |
| 6 | #define __LINUX_FDTABLE_H |
| 7 | |
| 8 | #include <linux/posix_types.h> |
| 9 | #include <linux/compiler.h> |
| 10 | #include <linux/spinlock.h> |
| 11 | #include <linux/rcupdate.h> |
| 12 | #include <linux/types.h> |
| 13 | #include <linux/init.h> |
| 14 | #include <linux/fs.h> |
| 15 | |
| 16 | #include <linux/atomic.h> |
| 17 | |
| 18 | /* |
| 19 | * The default fd array needs to be at least BITS_PER_LONG, |
| 20 | * as this is the granularity returned by copy_fdset(). |
| 21 | */ |
| 22 | #define NR_OPEN_DEFAULT BITS_PER_LONG |
| 23 | |
| 24 | struct fdtable { |
| 25 | unsigned int max_fds; |
| 26 | struct file __rcu **fd; /* current fd array */ |
| 27 | unsigned long *close_on_exec; |
| 28 | unsigned long *open_fds; |
| 29 | unsigned long *full_fds_bits; |
| 30 | struct rcu_head rcu; |
| 31 | }; |
| 32 | |
| 33 | static inline bool close_on_exec(int fd, const struct fdtable *fdt) |
| 34 | { |
| 35 | return test_bit(fd, fdt->close_on_exec); |
| 36 | } |
| 37 | |
| 38 | static inline bool fd_is_open(int fd, const struct fdtable *fdt) |
| 39 | { |
| 40 | return test_bit(fd, fdt->open_fds); |
| 41 | } |
| 42 | |
| 43 | /* |
| 44 | * Open file table structure |
| 45 | */ |
| 46 | struct files_struct { |
| 47 | /* |
| 48 | * read mostly part |
| 49 | */ |
| 50 | atomic_t count; |
| 51 | bool resize_in_progress; |
| 52 | wait_queue_head_t resize_wait; |
| 53 | |
| 54 | struct fdtable __rcu *fdt; |
| 55 | struct fdtable fdtab; |
| 56 | /* |
| 57 | * written part on a separate cache line in SMP |
| 58 | */ |
| 59 | spinlock_t file_lock ____cacheline_aligned_in_smp; |
| 60 | int next_fd; |
| 61 | unsigned long close_on_exec_init[1]; |
| 62 | unsigned long open_fds_init[1]; |
| 63 | unsigned long full_fds_bits_init[1]; |
| 64 | struct file __rcu * fd_array[NR_OPEN_DEFAULT]; |
| 65 | }; |
| 66 | |
| 67 | struct file_operations; |
| 68 | struct vfsmount; |
| 69 | struct dentry; |
| 70 | |
| 71 | #define rcu_dereference_check_fdtable(files, fdtfd) \ |
| 72 | rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock)) |
| 73 | |
| 74 | #define files_fdtable(files) \ |
| 75 | rcu_dereference_check_fdtable((files), (files)->fdt) |
| 76 | |
| 77 | /* |
| 78 | * The caller must ensure that fd table isn't shared or hold rcu or file lock |
| 79 | */ |
| 80 | static inline struct file *__fcheck_files(struct files_struct *files, unsigned int fd) |
| 81 | { |
| 82 | struct fdtable *fdt = rcu_dereference_raw(files->fdt); |
| 83 | |
| 84 | if (fd < fdt->max_fds) |
| 85 | return rcu_dereference_raw(fdt->fd[fd]); |
| 86 | return NULL; |
| 87 | } |
| 88 | |
| 89 | static inline struct file *fcheck_files(struct files_struct *files, unsigned int fd) |
| 90 | { |
| 91 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && |
| 92 | !lockdep_is_held(&files->file_lock), |
| 93 | "suspicious rcu_dereference_check() usage"); |
| 94 | return __fcheck_files(files, fd); |
| 95 | } |
| 96 | |
| 97 | /* |
| 98 | * Check whether the specified fd has an open file. |
| 99 | */ |
| 100 | #define fcheck(fd) fcheck_files(current->files, fd) |
| 101 | |
| 102 | struct task_struct; |
| 103 | |
| 104 | struct files_struct *get_files_struct(struct task_struct *); |
| 105 | void put_files_struct(struct files_struct *fs); |
| 106 | void reset_files_struct(struct files_struct *); |
| 107 | int unshare_files(struct files_struct **); |
| 108 | struct files_struct *dup_fd(struct files_struct *, int *); |
| 109 | void do_close_on_exec(struct files_struct *); |
| 110 | int iterate_fd(struct files_struct *, unsigned, |
| 111 | int (*)(const void *, struct file *, unsigned), |
| 112 | const void *); |
| 113 | |
| 114 | extern int __alloc_fd(struct files_struct *files, |
| 115 | unsigned start, unsigned end, unsigned flags); |
| 116 | extern void __fd_install(struct files_struct *files, |
| 117 | unsigned int fd, struct file *file); |
| 118 | extern int __close_fd(struct files_struct *files, |
| 119 | unsigned int fd); |
| 120 | |
| 121 | extern struct kmem_cache *files_cachep; |
| 122 | |
| 123 | #endif /* __LINUX_FDTABLE_H */ |