diff options
Diffstat (limited to 'include/linux/fdtable.h')
-rw-r--r-- | include/linux/fdtable.h | 134 |
1 files changed, 134 insertions, 0 deletions
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h new file mode 100644 index 000000000..e066816f3 --- /dev/null +++ b/include/linux/fdtable.h @@ -0,0 +1,134 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * descriptor table internals; you almost certainly want file.h instead. + */ + +#ifndef __LINUX_FDTABLE_H +#define __LINUX_FDTABLE_H + +#include <linux/posix_types.h> +#include <linux/compiler.h> +#include <linux/spinlock.h> +#include <linux/rcupdate.h> +#include <linux/nospec.h> +#include <linux/types.h> +#include <linux/init.h> +#include <linux/fs.h> + +#include <linux/atomic.h> + +/* + * The default fd array needs to be at least BITS_PER_LONG, + * as this is the granularity returned by copy_fdset(). + */ +#define NR_OPEN_DEFAULT BITS_PER_LONG +#define NR_OPEN_MAX ~0U + +struct fdtable { + unsigned int max_fds; + struct file __rcu **fd; /* current fd array */ + unsigned long *close_on_exec; + unsigned long *open_fds; + unsigned long *full_fds_bits; + struct rcu_head rcu; +}; + +static inline bool close_on_exec(unsigned int fd, const struct fdtable *fdt) +{ + return test_bit(fd, fdt->close_on_exec); +} + +static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt) +{ + return test_bit(fd, fdt->open_fds); +} + +/* + * Open file table structure + */ +struct files_struct { + /* + * read mostly part + */ + atomic_t count; + bool resize_in_progress; + wait_queue_head_t resize_wait; + + struct fdtable __rcu *fdt; + struct fdtable fdtab; + /* + * written part on a separate cache line in SMP + */ + spinlock_t file_lock ____cacheline_aligned_in_smp; + unsigned int next_fd; + unsigned long close_on_exec_init[1]; + unsigned long open_fds_init[1]; + unsigned long full_fds_bits_init[1]; + struct file __rcu * fd_array[NR_OPEN_DEFAULT]; +}; + +struct file_operations; +struct vfsmount; +struct dentry; + +#define rcu_dereference_check_fdtable(files, fdtfd) \ + rcu_dereference_check((fdtfd), lockdep_is_held(&(files)->file_lock)) + +#define files_fdtable(files) \ + rcu_dereference_check_fdtable((files), (files)->fdt) + +/* + * The caller must ensure that fd table isn't shared or hold rcu or file lock + */ +static inline struct file *files_lookup_fd_raw(struct files_struct *files, unsigned int fd) +{ + struct fdtable *fdt = rcu_dereference_raw(files->fdt); + + if (fd < fdt->max_fds) { + fd = array_index_nospec(fd, fdt->max_fds); + return rcu_dereference_raw(fdt->fd[fd]); + } + return NULL; +} + +static inline struct file *files_lookup_fd_locked(struct files_struct *files, unsigned int fd) +{ + RCU_LOCKDEP_WARN(!lockdep_is_held(&files->file_lock), + "suspicious rcu_dereference_check() usage"); + return files_lookup_fd_raw(files, fd); +} + +static inline struct file *files_lookup_fd_rcu(struct files_struct *files, unsigned int fd) +{ + RCU_LOCKDEP_WARN(!rcu_read_lock_held(), + "suspicious rcu_dereference_check() usage"); + return files_lookup_fd_raw(files, fd); +} + +static inline struct file *lookup_fd_rcu(unsigned int fd) +{ + return files_lookup_fd_rcu(current->files, fd); +} + +struct file *task_lookup_fd_rcu(struct task_struct *task, unsigned int fd); +struct file *task_lookup_next_fd_rcu(struct task_struct *task, unsigned int *fd); + +struct task_struct; + +void put_files_struct(struct files_struct *fs); +int unshare_files(void); +struct files_struct *dup_fd(struct files_struct *, unsigned, int *) __latent_entropy; +void do_close_on_exec(struct files_struct *); +int iterate_fd(struct files_struct *, unsigned, + int (*)(const void *, struct file *, unsigned), + const void *); + +extern int close_fd(unsigned int fd); +extern int __close_range(unsigned int fd, unsigned int max_fd, unsigned int flags); +extern struct file *close_fd_get_file(unsigned int fd); +extern int unshare_fd(unsigned long unshare_flags, unsigned int max_fds, + struct files_struct **new_fdp); + +extern struct kmem_cache *files_cachep; + +#endif /* __LINUX_FDTABLE_H */ |