1 /* $NetBSD: filedesc.h,v 1.73 2025/07/16 19:14:14 kre Exp $ */ 2 3 /*- 4 * Copyright (c) 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 17 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 18 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 19 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 20 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 26 * POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 /* 30 * Copyright (c) 1990, 1993 31 * The Regents of the University of California. All rights reserved. 32 * 33 * Redistribution and use in source and binary forms, with or without 34 * modification, are permitted provided that the following conditions 35 * are met: 36 * 1. Redistributions of source code must retain the above copyright 37 * notice, this list of conditions and the following disclaimer. 38 * 2. Redistributions in binary form must reproduce the above copyright 39 * notice, this list of conditions and the following disclaimer in the 40 * documentation and/or other materials provided with the distribution. 41 * 3. Neither the name of the University nor the names of its contributors 42 * may be used to endorse or promote products derived from this software 43 * without specific prior written permission. 44 * 45 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 48 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 55 * SUCH DAMAGE. 56 * 57 * @(#)filedesc.h 8.1 (Berkeley) 6/2/93 58 */ 59 60 #ifndef _SYS_FILEDESC_H_ 61 #define _SYS_FILEDESC_H_ 62 63 #include <sys/param.h> 64 #include <sys/queue.h> 65 #include <sys/mutex.h> 66 #include <sys/rwlock.h> 67 #include <sys/condvar.h> 68 69 /* 70 * This structure is used for the management of descriptors. It may be 71 * shared by multiple processes. 72 * 73 * A process is initially started out with NDFILE descriptors stored within 74 * this structure, selected to be enough for typical applications based on 75 * the historical limit of 20 open files (and the usage of descriptors by 76 * shells). If these descriptors are exhausted, a larger descriptor table 77 * may be allocated, up to a process' resource limit; the internal arrays 78 * are then unused. The initial expansion is set to NDEXTENT; each time 79 * it runs out, it is doubled until the resource limit is reached. NDEXTENT 80 * should be selected to be the biggest multiple of OFILESIZE (see below) 81 * that will fit in a power-of-two sized piece of memory. 82 */ 83 #define NDFILE 20 84 #define NDEXTENT 50 /* 250 bytes in 256-byte alloc */ 85 #define NDENTRIES 32 /* 32 fds per entry */ 86 #define NDENTRYMASK (NDENTRIES - 1) 87 #define NDENTRYSHIFT 5 /* bits per entry */ 88 #define NDLOSLOTS(x) (((x) + NDENTRIES - 1) >> NDENTRYSHIFT) 89 #define NDHISLOTS(x) ((NDLOSLOTS(x) + NDENTRIES - 1) >> NDENTRYSHIFT) 90 #define NDFDFILE 6 /* first 6 descriptors are free */ 91 92 /* 93 * Process-private descriptor reference, one for each descriptor slot 94 * in use. Locks: 95 * 96 * : unlocked 97 * a atomic operations + filedesc_t::fd_lock in some cases 98 * d filedesc_t::fd_lock 99 * 100 * Note that ff_exclose and ff_allocated are likely to be byte sized 101 * (bool). In general adjacent sub-word sized fields must be locked 102 * the same way, but in this case it's ok: ff_exclose can only be 103 * modified while the descriptor slot is live, and ff_allocated when 104 * it's invalid. 105 * 106 * NOTE: ff_exclose should generally be set with fd_set_exclose(), not 107 * written to directly, when implementing flags like O_CLOEXEC or 108 * SOCK_CLOEXEC, so that struct filedesc::fd_exclose is updated as 109 * needed. See PR kern/58822: close-on-exec is broken for dup3 and 110 * opening cloning devices (fixed). 111 * Same with fd_set_foclose() for O_CLOFORK, SOCK_CLOFORK, etc. 112 */ 113 typedef struct fdfile { 114 bool ff_exclose; /* :: close on exec (fd_set_exclose) */ 115 bool ff_foclose; /* :: close on fork (fd_set_foclose) */ 116 bool ff_allocated; /* d: descriptor slot is allocated */ 117 u_int ff_refcnt; /* a: reference count on structure */ 118 struct file *ff_file; /* d: pointer to file if open */ 119 SLIST_HEAD(,knote) ff_knlist; /* d: knotes attached to this fd */ 120 kcondvar_t ff_closing; /* d: notifier for close */ 121 } fdfile_t; 122 123 #define FDFILE_SIZE ((sizeof(fdfile_t)+CACHE_LINE_SIZE-1)/CACHE_LINE_SIZE*CACHE_LINE_SIZE) 124 125 /* Reference count */ 126 #define FR_CLOSING (0x80000000) /* closing: must interlock */ 127 #define FR_MASK (~FR_CLOSING) /* reference count */ 128 129 /* 130 * Open file table, potentially many 'active' tables per filedesc_t 131 * in a multi-threaded process, or with a shared filedesc_t (clone()). 132 * nfiles is first to avoid pointer arithmetic. 133 */ 134 typedef struct fdtab { 135 u_int dt_nfiles; /* number of open files allocated */ 136 struct fdtab *dt_link; /* for lists of dtab */ 137 fdfile_t *dt_ff[NDFILE]; /* file structures for open fds */ 138 } fdtab_t; 139 140 typedef struct filedesc { 141 /* 142 * Built-in fdfile_t records first, since they have strict 143 * alignment requirements. 144 */ 145 uint8_t fd_dfdfile[NDFDFILE][FDFILE_SIZE]; 146 /* 147 * All of the remaining fields are locked by fd_lock. 148 */ 149 kmutex_t fd_lock; /* lock on structure */ 150 fdtab_t * volatile fd_dt; /* active descriptor table */ 151 uint32_t *fd_himap; /* each bit points to 32 fds */ 152 uint32_t *fd_lomap; /* bitmap of free fds */ 153 struct klist *fd_knhash; /* hash of attached non-fd knotes */ 154 int fd_lastkqfile; /* max descriptor for kqueue */ 155 int fd_lastfile; /* high-water mark of fd_ofiles */ 156 int fd_refcnt; /* reference count */ 157 u_long fd_knhashmask; /* size of fd_knhash */ 158 int fd_freefile; /* approx. next free file */ 159 int fd_unused; /* unused */ 160 bool fd_exclose; /* non-zero if >0 fd with EXCLOSE */ 161 bool fd_foclose; /* non-zero if >0 fd with FOCLOSE */ 162 /* 163 * This structure is used when the number of open files is 164 * <= NDFILE, and are then pointed to by the pointers above. 165 */ 166 fdtab_t fd_dtbuiltin; 167 /* 168 * These arrays are used when the number of open files is 169 * <= 1024, and are then pointed to by the pointers above. 170 */ 171 #define fd_startzero fd_dhimap /* area to zero on return to cache */ 172 uint32_t fd_dhimap[NDENTRIES >> NDENTRYSHIFT]; 173 uint32_t fd_dlomap[NDENTRIES]; 174 } filedesc_t; 175 176 /* 177 * Working directory, root and umask information. Serialization: 178 * 179 * a atomic operations 180 * l cwdi_lock 181 */ 182 typedef struct cwdinfo { 183 struct vnode *cwdi_cdir; /* l: current directory */ 184 struct vnode *cwdi_rdir; /* l: root directory */ 185 struct vnode *cwdi_edir; /* l: emulation root (if known) */ 186 u_int cwdi_cmask; /* a: mask for file creation */ 187 u_int cwdi_refcnt; /* a: reference count */ 188 189 krwlock_t cwdi_lock /* :: lock on struct */ 190 __aligned(COHERENCY_UNIT); /* -> gets own cache line */ 191 } cwdinfo_t; 192 193 #ifdef _KERNEL 194 195 struct fileops; 196 struct socket; 197 struct proc; 198 199 extern struct cwdinfo cwdi0; 200 201 /* 202 * Kernel global variables and routines. 203 */ 204 void fd_sys_init(void); 205 int fd_open(const char*, int, int, int*); 206 int fd_dupopen(int, bool, int, int *); 207 int fd_alloc(struct proc *, int, int *); 208 void fd_tryexpand(struct proc *); 209 int fd_allocfile(file_t **, int *); 210 void fd_affix(struct proc *, file_t *, unsigned); 211 void fd_abort(struct proc *, file_t *, unsigned); 212 filedesc_t *fd_copy(void); 213 filedesc_t *fd_init(filedesc_t *); 214 void fd_share(proc_t *); 215 void fd_hold(lwp_t *); 216 void fd_free(void); 217 void fd_closeexec(void); 218 void fd_ktrexecfd(void); 219 int fd_checkstd(void); 220 file_t *fd_getfile(unsigned); 221 file_t *fd_getfile2(proc_t *, unsigned); 222 void fd_putfile(unsigned); 223 int fd_getvnode(unsigned, file_t **); 224 int fd_getsock(unsigned, struct socket **); 225 int fd_getsock1(unsigned, struct socket **, file_t **); 226 void fd_putvnode(unsigned); 227 void fd_putsock(unsigned); 228 int fd_close(unsigned); 229 int fd_dup(file_t *, int, int *, bool, bool); 230 int fd_dup2(file_t *, unsigned, int); 231 int fd_clone(file_t *, unsigned, int, const struct fileops *, void *); 232 void fd_set_exclose(struct lwp *, int, bool); 233 void fd_set_foclose(struct lwp *, int, bool); 234 int pipe1(struct lwp *, int *, int); 235 int dodup(struct lwp *, int, int, int, register_t *); 236 237 void cwd_sys_init(void); 238 struct cwdinfo *cwdinit(void); 239 void cwdshare(proc_t *); 240 void cwdunshare(proc_t *); 241 void cwdfree(struct cwdinfo *); 242 void cwdexec(struct proc *); 243 244 #define GETCWD_CHECK_ACCESS 0x0001 245 int getcwd_common(struct vnode *, struct vnode *, char **, char *, int, 246 int, struct lwp *); 247 int vnode_to_path(char *, size_t, struct vnode *, struct lwp *, 248 struct proc *); 249 250 int closef(file_t *); 251 file_t *fgetdummy(void); 252 void fputdummy(file_t *); 253 254 struct stat; 255 int do_sys_fstat(int, struct stat *); 256 struct flock; 257 int do_fcntl_lock(int, int, struct flock *); 258 int do_posix_fadvise(int, off_t, off_t, int); 259 260 extern kmutex_t filelist_lock; 261 extern filedesc_t filedesc0; 262 263 #endif /* _KERNEL */ 264 265 #endif /* !_SYS_FILEDESC_H_ */ 266
Indexes created Sat Sep 20 22:09:52 GMT 2025