/* $NetBSD: filedesc.h,v 1.73 2025/07/16 19:14:14 kre Exp $ */ /*- * Copyright (c) 2008 The NetBSD Foundation, Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1990, 1993 * The Regents of the University of California. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)filedesc.h 8.1 (Berkeley) 6/2/93 */ #ifndef _SYS_FILEDESC_H_ #define _SYS_FILEDESC_H_ #include <sys/param.h> #include <sys/queue.h> #include <sys/mutex.h> #include <sys/rwlock.h> #include <sys/condvar.h> /* * This structure is used for the management of descriptors. It may be * shared by multiple processes. * * A process is initially started out with NDFILE descriptors stored within * this structure, selected to be enough for typical applications based on * the historical limit of 20 open files (and the usage of descriptors by * shells). If these descriptors are exhausted, a larger descriptor table * may be allocated, up to a process' resource limit; the internal arrays * are then unused. The initial expansion is set to NDEXTENT; each time * it runs out, it is doubled until the resource limit is reached. NDEXTENT * should be selected to be the biggest multiple of OFILESIZE (see below) * that will fit in a power-of-two sized piece of memory. */ #define NDFILE 20 #define NDEXTENT 50 /* 250 bytes in 256-byte alloc */ #define NDENTRIES 32 /* 32 fds per entry */ #define NDENTRYMASK (NDENTRIES - 1) #define NDENTRYSHIFT 5 /* bits per entry */ #define NDLOSLOTS(x) (((x) + NDENTRIES - 1) >> NDENTRYSHIFT) #define NDHISLOTS(x) ((NDLOSLOTS(x) + NDENTRIES - 1) >> NDENTRYSHIFT) #define NDFDFILE 6 /* first 6 descriptors are free */ /* * Process-private descriptor reference, one for each descriptor slot * in use. Locks: * * : unlocked * a atomic operations + filedesc_t::fd_lock in some cases * d filedesc_t::fd_lock * * Note that ff_exclose and ff_allocated are likely to be byte sized * (bool). In general adjacent sub-word sized fields must be locked * the same way, but in this case it's ok: ff_exclose can only be * modified while the descriptor slot is live, and ff_allocated when * it's invalid. * * NOTE: ff_exclose should generally be set with fd_set_exclose(), not * written to directly, when implementing flags like O_CLOEXEC or * SOCK_CLOEXEC, so that struct filedesc::fd_exclose is updated as * needed. See PR kern/58822: close-on-exec is broken for dup3 and * opening cloning devices (fixed). * Same with fd_set_foclose() for O_CLOFORK, SOCK_CLOFORK, etc. */ typedef struct fdfile { bool ff_exclose; /* :: close on exec (fd_set_exclose) */ bool ff_foclose; /* :: close on fork (fd_set_foclose) */ bool ff_allocated; /* d: descriptor slot is allocated */ u_int ff_refcnt; /* a: reference count on structure */ struct file *ff_file; /* d: pointer to file if open */ SLIST_HEAD(,knote) ff_knlist; /* d: knotes attached to this fd */ kcondvar_t ff_closing; /* d: notifier for close */ } fdfile_t; #define FDFILE_SIZE ((sizeof(fdfile_t)+CACHE_LINE_SIZE-1)/CACHE_LINE_SIZE*CACHE_LINE_SIZE) /* Reference count */ #define FR_CLOSING (0x80000000) /* closing: must interlock */ #define FR_MASK (~FR_CLOSING) /* reference count */ /* * Open file table, potentially many 'active' tables per filedesc_t * in a multi-threaded process, or with a shared filedesc_t (clone()). * nfiles is first to avoid pointer arithmetic. */ typedef struct fdtab { u_int dt_nfiles; /* number of open files allocated */ struct fdtab *dt_link; /* for lists of dtab */ fdfile_t *dt_ff[NDFILE]; /* file structures for open fds */ } fdtab_t; typedef struct filedesc { /* * Built-in fdfile_t records first, since they have strict * alignment requirements. */ uint8_t fd_dfdfile[NDFDFILE][FDFILE_SIZE]; /* * All of the remaining fields are locked by fd_lock. */ kmutex_t fd_lock; /* lock on structure */ fdtab_t * volatile fd_dt; /* active descriptor table */ uint32_t *fd_himap; /* each bit points to 32 fds */ uint32_t *fd_lomap; /* bitmap of free fds */ struct klist *fd_knhash; /* hash of attached non-fd knotes */ int fd_lastkqfile; /* max descriptor for kqueue */ int fd_lastfile; /* high-water mark of fd_ofiles */ int fd_refcnt; /* reference count */ u_long fd_knhashmask; /* size of fd_knhash */ int fd_freefile; /* approx. next free file */ int fd_unused; /* unused */ bool fd_exclose; /* non-zero if >0 fd with EXCLOSE */ bool fd_foclose; /* non-zero if >0 fd with FOCLOSE */ /* * This structure is used when the number of open files is * <= NDFILE, and are then pointed to by the pointers above. */ fdtab_t fd_dtbuiltin; /* * These arrays are used when the number of open files is * <= 1024, and are then pointed to by the pointers above. */ #define fd_startzero fd_dhimap /* area to zero on return to cache */ uint32_t fd_dhimap[NDENTRIES >> NDENTRYSHIFT]; uint32_t fd_dlomap[NDENTRIES]; } filedesc_t; /* * Working directory, root and umask information. Serialization: * * a atomic operations * l cwdi_lock */ typedef struct cwdinfo { struct vnode *cwdi_cdir; /* l: current directory */ struct vnode *cwdi_rdir; /* l: root directory */ struct vnode *cwdi_edir; /* l: emulation root (if known) */ u_int cwdi_cmask; /* a: mask for file creation */ u_int cwdi_refcnt; /* a: reference count */ krwlock_t cwdi_lock /* :: lock on struct */ __aligned(COHERENCY_UNIT); /* -> gets own cache line */ } cwdinfo_t; #ifdef _KERNEL struct fileops; struct socket; struct proc; extern struct cwdinfo cwdi0; /* * Kernel global variables and routines. */ void fd_sys_init(void); int fd_open(const char*, int, int, int*); int fd_dupopen(int, bool, int, int *); int fd_alloc(struct proc *, int, int *); void fd_tryexpand(struct proc *); int fd_allocfile(file_t **, int *); void fd_affix(struct proc *, file_t *, unsigned); void fd_abort(struct proc *, file_t *, unsigned); filedesc_t *fd_copy(void); filedesc_t *fd_init(filedesc_t *); void fd_share(proc_t *); void fd_hold(lwp_t *); void fd_free(void); void fd_closeexec(void); void fd_ktrexecfd(void); int fd_checkstd(void); file_t *fd_getfile(unsigned); file_t *fd_getfile2(proc_t *, unsigned); void fd_putfile(unsigned); int fd_getvnode(unsigned, file_t **); int fd_getsock(unsigned, struct socket **); int fd_getsock1(unsigned, struct socket **, file_t **); void fd_putvnode(unsigned); void fd_putsock(unsigned); int fd_close(unsigned); int fd_dup(file_t *, int, int *, bool, bool); int fd_dup2(file_t *, unsigned, int); int fd_clone(file_t *, unsigned, int, const struct fileops *, void *); void fd_set_exclose(struct lwp *, int, bool); void fd_set_foclose(struct lwp *, int, bool); int pipe1(struct lwp *, int *, int); int dodup(struct lwp *, int, int, int, register_t *); void cwd_sys_init(void); struct cwdinfo *cwdinit(void); void cwdshare(proc_t *); void cwdunshare(proc_t *); void cwdfree(struct cwdinfo *); void cwdexec(struct proc *); #define GETCWD_CHECK_ACCESS 0x0001 int getcwd_common(struct vnode *, struct vnode *, char **, char *, int, int, struct lwp *); int vnode_to_path(char *, size_t, struct vnode *, struct lwp *, struct proc *); int closef(file_t *); file_t *fgetdummy(void); void fputdummy(file_t *); struct stat; int do_sys_fstat(int, struct stat *); struct flock; int do_fcntl_lock(int, int, struct flock *); int do_posix_fadvise(int, off_t, off_t, int); extern kmutex_t filelist_lock; extern filedesc_t filedesc0; #endif /* _KERNEL */ #endif /* !_SYS_FILEDESC_H_ */
