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kern_fileassoc.c revision 1.10.2.2 
      1 /* $NetBSD: kern_fileassoc.c,v 1.10.2.2 2006/09/09 02:57:16 rpaulo Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2006 Elad Efrat <elad (at) NetBSD.org>
      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  * 3. All advertising materials mentioning features or use of this software
     16  *    must display the following acknowledgement:
     17  *      This product includes software developed by Elad Efrat.
     18  * 4. The name of the author may not be used to endorse or promote products
     19  *    derived from this software without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     23  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     24  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     26  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     27  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     28  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     29  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     30  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     31  */
     32 
     33 #include <sys/cdefs.h>
     34 __KERNEL_RCSID(0, "$NetBSD: kern_fileassoc.c,v 1.10.2.2 2006/09/09 02:57:16 rpaulo Exp $");
     35 
     36 #include <sys/param.h>
     37 #include <sys/mount.h>
     38 #include <sys/queue.h>
     39 #include <sys/malloc.h>
     40 #include <sys/vnode.h>
     41 #include <sys/namei.h>
     42 #include <sys/exec.h>
     43 #include <sys/proc.h>
     44 #include <sys/inttypes.h>
     45 #include <sys/errno.h>
     46 #include <sys/fileassoc.h>
     47 #include <sys/hash.h>
     48 #include <sys/fstypes.h>
     49 
     50 static struct fileassoc_hash_entry *
     51 fileassoc_file_lookup(struct vnode *, fhandle_t *);
     52 static struct fileassoc_hash_entry *
     53 fileassoc_file_add(struct vnode *, fhandle_t *);
     54 
     55 /*
     56  * Hook entry.
     57  * Includes the hook name for identification and private hook clear callback.
     58  */
     59 struct fileassoc_hook {
     60 	const char *hook_name;			/* Hook name. */
     61 	fileassoc_cleanup_cb_t hook_cleanup_cb;	/* Hook clear callback. */
     62 };
     63 
     64 /* An entry in the per-device hash table. */
     65 struct fileassoc_hash_entry {
     66 	fhandle_t *handle;				/* File handle */
     67 	void *hooks[FILEASSOC_NHOOKS];			/* Hooks. */
     68 	LIST_ENTRY(fileassoc_hash_entry) entries;	/* List pointer. */
     69 };
     70 
     71 LIST_HEAD(fileassoc_hashhead, fileassoc_hash_entry);
     72 
     73 struct fileassoc_table {
     74 	struct fileassoc_hashhead *hash_tbl;
     75 	size_t hash_size;				/* Number of slots. */
     76 	struct mount *tbl_mntpt;
     77 	u_long hash_mask;
     78 	void *tables[FILEASSOC_NHOOKS];
     79 	LIST_ENTRY(fileassoc_table) hash_list;		/* List pointer. */
     80 };
     81 
     82 struct fileassoc_hook fileassoc_hooks[FILEASSOC_NHOOKS];
     83 int fileassoc_nhooks;
     84 
     85 /* Global list of hash tables, one per device. */
     86 LIST_HEAD(, fileassoc_table) fileassoc_tables;
     87 
     88 /*
     89  * Hashing function: Takes a number modulus the mask to give back an
     90  * index into the hash table.
     91  */
     92 #define FILEASSOC_HASH(tbl, handle)	\
     93 	(hash32_buf((handle), FHANDLE_SIZE(handle), HASH32_BUF_INIT) \
     94 	 & ((tbl)->hash_mask))
     95 
     96 /*
     97  * Initialize the fileassoc subsystem.
     98  */
     99 void
    100 fileassoc_init(void)
    101 {
    102 	memset(fileassoc_hooks, 0, sizeof(fileassoc_hooks));
    103 	fileassoc_nhooks = 0;
    104 }
    105 
    106 /*
    107  * Register a new hook.
    108  */
    109 fileassoc_t
    110 fileassoc_register(const char *name, fileassoc_cleanup_cb_t cleanup_cb)
    111 {
    112 	int i;
    113 
    114 	if (fileassoc_nhooks >= FILEASSOC_NHOOKS)
    115 		return (-1);
    116 
    117 	for (i = 0; i < FILEASSOC_NHOOKS; i++)
    118 		if (fileassoc_hooks[i].hook_name == NULL)
    119 			break;
    120 
    121 	fileassoc_hooks[i].hook_name = name;
    122 	fileassoc_hooks[i].hook_cleanup_cb = cleanup_cb;
    123 
    124 	fileassoc_nhooks++;
    125 
    126 	return (i);
    127 }
    128 
    129 /*
    130  * Deregister a hook.
    131  */
    132 int
    133 fileassoc_deregister(fileassoc_t id)
    134 {
    135 	if (id < 0 || id >= FILEASSOC_NHOOKS)
    136 		return (EINVAL);
    137 
    138 	fileassoc_hooks[id].hook_name = NULL;
    139 	fileassoc_hooks[id].hook_cleanup_cb = NULL;
    140 
    141 	fileassoc_nhooks--;
    142 
    143 	return (0);
    144 }
    145 
    146 /*
    147  * Get the hash table for the specified device.
    148  */
    149 static struct fileassoc_table *
    150 fileassoc_table_lookup(struct mount *mp)
    151 {
    152 	struct fileassoc_table *tbl;
    153 
    154 	LIST_FOREACH(tbl, &fileassoc_tables, hash_list) {
    155 		if (tbl->tbl_mntpt == mp)
    156 			return (tbl);
    157 	}
    158 
    159 	return (NULL);
    160 }
    161 
    162 /*
    163  * Perform a lookup on a hash table.  If hint is non-zero then use the value
    164  * of the hint as the identifier instead of performing a lookup for the
    165  * fileid.
    166  */
    167 static struct fileassoc_hash_entry *
    168 fileassoc_file_lookup(struct vnode *vp, fhandle_t *hint)
    169 {
    170 	struct fileassoc_table *tbl;
    171 	struct fileassoc_hashhead *tble;
    172 	struct fileassoc_hash_entry *e;
    173 	size_t indx;
    174 	fhandle_t *th;
    175 	int error;
    176 
    177 	if (hint == NULL) {
    178 		error = vfs_composefh_alloc(vp, &th);
    179 		if (error)
    180 			return (NULL);
    181 	} else
    182 		th = hint;
    183 
    184 	tbl = fileassoc_table_lookup(vp->v_mount);
    185 	if (tbl == NULL) {
    186 		if (hint == NULL)
    187 			vfs_composefh_free(th);
    188 
    189 		return (NULL);
    190 	}
    191 
    192 	indx = FILEASSOC_HASH(tbl, th);
    193 	tble = &(tbl->hash_tbl[indx]);
    194 
    195 	LIST_FOREACH(e, tble, entries) {
    196 		if ((e != NULL) &&
    197 		    ((FHANDLE_FILEID(e->handle)->fid_len ==
    198 		     FHANDLE_FILEID(th)->fid_len)) &&
    199 		    (memcmp(FHANDLE_FILEID(e->handle), FHANDLE_FILEID(th),
    200 			   (FHANDLE_FILEID(th))->fid_len) == 0))
    201 			return (e);
    202 	}
    203 
    204 	if (hint == NULL)
    205 		vfs_composefh_free(th);
    206 
    207 	return (NULL);
    208 }
    209 
    210 /*
    211  * Return hook data associated with a vnode.
    212  */
    213 void *
    214 fileassoc_lookup(struct vnode *vp, fileassoc_t id)
    215 {
    216         struct fileassoc_hash_entry *mhe;
    217 
    218         mhe = fileassoc_file_lookup(vp, NULL);
    219         if (mhe == NULL)
    220                 return (NULL);
    221 
    222         return (mhe->hooks[id]);
    223 }
    224 
    225 /*
    226  * Create a new fileassoc table.
    227  */
    228 int
    229 fileassoc_table_add(struct mount *mp, size_t size)
    230 {
    231 	struct fileassoc_table *tbl;
    232 
    233 	/* Check for existing table for device. */
    234 	if (fileassoc_table_lookup(mp) != NULL)
    235 		return (EEXIST);
    236 
    237 	/* Allocate and initialize a Veriexec hash table. */
    238 	tbl = malloc(sizeof(*tbl), M_TEMP, M_WAITOK | M_ZERO);
    239 	tbl->hash_size = size;
    240 	tbl->tbl_mntpt = mp;
    241 	tbl->hash_tbl = hashinit(size, HASH_LIST, M_TEMP,
    242 				 M_WAITOK | M_ZERO, &tbl->hash_mask);
    243 
    244 	LIST_INSERT_HEAD(&fileassoc_tables, tbl, hash_list);
    245 
    246 	return (0);
    247 }
    248 
    249 /*
    250  * Delete a table.
    251  */
    252 int
    253 fileassoc_table_delete(struct mount *mp)
    254 {
    255 	struct fileassoc_table *tbl;
    256 	struct fileassoc_hashhead *hh;
    257 	u_long i;
    258 	int j;
    259 
    260 	tbl = fileassoc_table_lookup(mp);
    261 	if (tbl == NULL)
    262 		return (EEXIST);
    263 
    264 	/* Remove all entries from the table and lists */
    265 	hh = tbl->hash_tbl;
    266 	for (i = 0; i < tbl->hash_size; i++) {
    267 		struct fileassoc_hash_entry *mhe;
    268 
    269 		while (LIST_FIRST(&hh[i]) != NULL) {
    270 			mhe = LIST_FIRST(&hh[i]);
    271 			LIST_REMOVE(mhe, entries);
    272 
    273 			for (j = 0; j < fileassoc_nhooks; j++)
    274 				if (fileassoc_hooks[j].hook_cleanup_cb != NULL)
    275 					(fileassoc_hooks[j].hook_cleanup_cb)
    276 					    (mhe->hooks[j],
    277 					    FILEASSOC_CLEANUP_FILE);
    278 
    279 			vfs_composefh_free(mhe->handle);
    280 			free(mhe, M_TEMP);
    281 		}
    282 	}
    283 
    284 	for (j = 0; j < fileassoc_nhooks; j++)
    285 		if (fileassoc_hooks[j].hook_cleanup_cb != NULL)
    286 			(fileassoc_hooks[j].hook_cleanup_cb)(tbl->tables[j],
    287 			    FILEASSOC_CLEANUP_TABLE);
    288 
    289 	/* Remove hash table and sysctl node */
    290 	hashdone(tbl->hash_tbl, M_TEMP);
    291 	LIST_REMOVE(tbl, hash_list);
    292 
    293 	return (0);
    294 }
    295 
    296 /*
    297  * Run a callback for each hook entry in a table.
    298  */
    299 int
    300 fileassoc_table_run(struct mount *mp, fileassoc_t id, fileassoc_cb_t cb)
    301 {
    302 	struct fileassoc_table *tbl;
    303 	struct fileassoc_hashhead *hh;
    304 	u_long i;
    305 
    306 	tbl = fileassoc_table_lookup(mp);
    307 	if (tbl == NULL)
    308 		return (EEXIST);
    309 
    310 	hh = tbl->hash_tbl;
    311 	for (i = 0; i < tbl->hash_size; i++) {
    312 		struct fileassoc_hash_entry *mhe;
    313 
    314 		LIST_FOREACH(mhe, &hh[i], entries) {
    315 			if (mhe->hooks[id] != NULL)
    316 				cb(mhe->hooks[id]);
    317 		}
    318 	}
    319 
    320 	return (0);
    321 }
    322 
    323 /*
    324  * Clear a table for a given hook.
    325  */
    326 int
    327 fileassoc_table_clear(struct mount *mp, fileassoc_t id)
    328 {
    329 	struct fileassoc_table *tbl;
    330 	struct fileassoc_hashhead *hh;
    331 	fileassoc_cleanup_cb_t cleanup_cb;
    332 	u_long i;
    333 
    334 	tbl = fileassoc_table_lookup(mp);
    335 	if (tbl == NULL)
    336 		return (EEXIST);
    337 
    338 	cleanup_cb = fileassoc_hooks[id].hook_cleanup_cb;
    339 
    340 	hh = tbl->hash_tbl;
    341 	for (i = 0; i < tbl->hash_size; i++) {
    342 		struct fileassoc_hash_entry *mhe;
    343 
    344 		LIST_FOREACH(mhe, &hh[i], entries) {
    345 			if ((mhe->hooks[id] != NULL) && cleanup_cb != NULL)
    346 				cleanup_cb(mhe->hooks[id],
    347 				    FILEASSOC_CLEANUP_FILE);
    348 
    349 			mhe->hooks[id] = NULL;
    350 		}
    351 	}
    352 
    353 	if ((tbl->tables[id] != NULL) && cleanup_cb != NULL)
    354 		cleanup_cb(tbl->tables[id], FILEASSOC_CLEANUP_TABLE);
    355 
    356 	tbl->tables[id] = NULL;
    357 
    358 	return (0);
    359 }
    360 
    361 /*
    362  * Add hook-specific data on a fileassoc table.
    363  */
    364 int
    365 fileassoc_tabledata_add(struct mount *mp, fileassoc_t id, void *data)
    366 {
    367 	struct fileassoc_table *tbl;
    368 
    369 	tbl = fileassoc_table_lookup(mp);
    370 	if (tbl == NULL)
    371 		return (EFAULT);
    372 
    373 	tbl->tables[id] = data;
    374 
    375 	return (0);
    376 }
    377 
    378 /*
    379  * Clear hook-specific data on a fileassoc table.
    380  */
    381 int
    382 fileassoc_tabledata_clear(struct mount *mp, fileassoc_t id)
    383 {
    384 	struct fileassoc_table *tbl;
    385 
    386 	tbl = fileassoc_table_lookup(mp);
    387 	if (tbl == NULL)
    388 		return (EFAULT);
    389 
    390 	tbl->tables[id] = NULL;
    391 
    392 	return (0);
    393 }
    394 
    395 /*
    396  * Retrieve hook-specific data from a fileassoc table.
    397  */
    398 void *
    399 fileassoc_tabledata_lookup(struct mount *mp, fileassoc_t id)
    400 {
    401 	struct fileassoc_table *tbl;
    402 
    403 	tbl = fileassoc_table_lookup(mp);
    404 	if (tbl == NULL)
    405 		return (NULL);
    406 
    407 	return (tbl->tables[id]);
    408 }
    409 
    410 /*
    411  * Add a file entry to a table.
    412  */
    413 static struct fileassoc_hash_entry *
    414 fileassoc_file_add(struct vnode *vp, fhandle_t *hint)
    415 {
    416 	struct fileassoc_table *tbl;
    417 	struct fileassoc_hashhead *vhh;
    418 	struct fileassoc_hash_entry *e;
    419 	size_t indx;
    420 	fhandle_t *th;
    421 	int error;
    422 
    423 	if (hint == 0) {
    424 		error = vfs_composefh_alloc(vp, &th);
    425 		if (error)
    426 			return (NULL);
    427 	} else
    428 		th = hint;
    429 
    430 	e = fileassoc_file_lookup(vp, th);
    431 	if (e != NULL) {
    432 		if (hint == NULL)
    433 			vfs_composefh_free(th);
    434 
    435 		return (e);
    436 	}
    437 
    438 	tbl = fileassoc_table_lookup(vp->v_mount);
    439 	if (tbl == NULL) {
    440 		if (hint == NULL)
    441 			vfs_composefh_free(th);
    442 
    443 		return (NULL);
    444 	}
    445 
    446 	indx = FILEASSOC_HASH(tbl, th);
    447 	vhh = &(tbl->hash_tbl[indx]);
    448 
    449 	e = malloc(sizeof(*e), M_TEMP, M_WAITOK | M_ZERO);
    450 	e->handle = th;
    451 	LIST_INSERT_HEAD(vhh, e, entries);
    452 
    453 	return (e);
    454 }
    455 
    456 /*
    457  * Delete a file entry from a table.
    458  */
    459 int
    460 fileassoc_file_delete(struct vnode *vp)
    461 {
    462 	struct fileassoc_hash_entry *mhe;
    463 	int i;
    464 
    465 	mhe = fileassoc_file_lookup(vp, NULL);
    466 	if (mhe == NULL)
    467 		return (ENOENT);
    468 
    469 	LIST_REMOVE(mhe, entries);
    470 
    471 	for (i = 0; i < fileassoc_nhooks; i++)
    472 		if (fileassoc_hooks[i].hook_cleanup_cb != NULL)
    473 			(fileassoc_hooks[i].hook_cleanup_cb)(mhe->hooks[i],
    474 			    FILEASSOC_CLEANUP_FILE);
    475 
    476 	free(mhe, M_TEMP);
    477 
    478 	return (0);
    479 }
    480 
    481 /*
    482  * Add a hook to a vnode.
    483  */
    484 int
    485 fileassoc_add(struct vnode *vp, fileassoc_t id, void *data)
    486 {
    487 	struct fileassoc_hash_entry *e;
    488 
    489 	e = fileassoc_file_lookup(vp, NULL);
    490 	if (e == NULL) {
    491 		e = fileassoc_file_add(vp, NULL);
    492 		if (e == NULL)
    493 			return (ENOTDIR);
    494 	}
    495 
    496 	if (e->hooks[id] != NULL)
    497 		return (EEXIST);
    498 
    499 	e->hooks[id] = data;
    500 
    501 	return (0);
    502 }
    503 
    504 /*
    505  * Clear a hook from a vnode.
    506  */
    507 int
    508 fileassoc_clear(struct vnode *vp, fileassoc_t id)
    509 {
    510 	struct fileassoc_hash_entry *mhe;
    511 	fileassoc_cleanup_cb_t cleanup_cb;
    512 
    513 	mhe = fileassoc_file_lookup(vp, NULL);
    514 	if (mhe == NULL)
    515 		return (ENOENT);
    516 
    517 	cleanup_cb = fileassoc_hooks[id].hook_cleanup_cb;
    518 	if ((mhe->hooks[id] != NULL) && cleanup_cb != NULL)
    519 		cleanup_cb(mhe->hooks[id], FILEASSOC_CLEANUP_FILE);
    520 
    521 	mhe->hooks[id] = NULL;
    522 
    523 	return (0);
    524 }
    525