include/linux/fdtable.h

Source file repositories/reference/linux-study-clean/include/linux/fdtable.h

File Facts

System
Linux kernel
Corpus path
include/linux/fdtable.h
Extension
.h
Size
3155 bytes
Lines
119
Domain
Core OS
Bucket
Core Kernel Interface
Inferred role
Core OS: operation-table or driver-model contract
Status
pattern implementation candidate

Why This File Exists

Core operating-system implementation surface: boot, tasks, memory, VFS, syscall-facing interfaces, synchronization, credentials, and isolation.

Dependency Surface

Detected Declarations

Annotated Snippet

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);
	unsigned long mask = array_index_mask_nospec(fd, fdt->max_fds);
	struct file *needs_masking;

	/*
	 * 'mask' is zero for an out-of-bounds fd, all ones for ok.
	 * 'fd&mask' is 'fd' for ok, or 0 for out of bounds.
	 *
	 * Accessing fdt->fd[0] is ok, but needs masking of the result.
	 */
	needs_masking = rcu_dereference_raw(fdt->fd[fd&mask]);
	return (struct file *)(mask & (unsigned long)needs_masking);
}

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 bool close_on_exec(unsigned int fd, const struct files_struct *files)
{
	return test_bit(fd, files_fdtable(files)->close_on_exec);
}

struct task_struct;

void put_files_struct(struct files_struct *fs);
int unshare_files(void);
struct fd_range {
	unsigned int from, to;
};
struct files_struct *dup_fd(struct files_struct *, struct fd_range *) __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 struct file *file_close_fd(unsigned int fd);

extern struct kmem_cache *files_cachep;

#endif /* __LINUX_FDTABLE_H */

Annotation

Implementation Notes