1 /*
2 * linux/ipc/shm.c
3 * Copyright (C) 1992, 1993 Krishna Balasubramanian
4 * Many improvements/fixes by Bruno Haible.
5 * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
6 * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
7 *
8 * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
9 * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
10 * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
11 * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
12 * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
13 * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
14 * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
15 *
16 */
17
18 #include <linux/config.h>
19 #include <linux/slab.h>
20 #include <linux/shm.h>
21 #include <linux/init.h>
22 #include <linux/file.h>
23 #include <linux/mman.h>
24 #include <linux/proc_fs.h>
25 #include <asm/uaccess.h>
26
27 #include "util.h"
28
29 struct shmid_kernel /* private to the kernel */
30 {
31 struct kern_ipc_perm shm_perm;
32 struct file * shm_file;
33 int id;
34 unsigned long shm_nattch;
35 unsigned long shm_segsz;
36 time_t shm_atim;
37 time_t shm_dtim;
38 time_t shm_ctim;
39 pid_t shm_cprid;
40 pid_t shm_lprid;
41 };
42
43 #define shm_flags shm_perm.mode
44
45 static struct file_operations shm_file_operations;
46 static struct vm_operations_struct shm_vm_ops;
47
48 static struct ipc_ids shm_ids;
49
50 #define shm_lock(id) ((struct shmid_kernel*)ipc_lock(&shm_ids,id))
51 #define shm_unlock(id) ipc_unlock(&shm_ids,id)
52 #define shm_lockall() ipc_lockall(&shm_ids)
53 #define shm_unlockall() ipc_unlockall(&shm_ids)
54 #define shm_get(id) ((struct shmid_kernel*)ipc_get(&shm_ids,id))
55 #define shm_buildid(id, seq) \
56 ipc_buildid(&shm_ids, id, seq)
57
58 static int newseg (key_t key, int shmflg, size_t size);
59 static void shm_open (struct vm_area_struct *shmd);
60 static void shm_close (struct vm_area_struct *shmd);
61 #ifdef CONFIG_PROC_FS
62 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data);
63 #endif
64
65 size_t shm_ctlmax = SHMMAX;
66 size_t shm_ctlall = SHMALL;
67 int shm_ctlmni = SHMMNI;
68
69 static int shm_tot; /* total number of shared memory pages */
70
shm_init(void)71 void __init shm_init (void)
72 {
73 ipc_init_ids(&shm_ids, 1);
74 #ifdef CONFIG_PROC_FS
75 create_proc_read_entry("sysvipc/shm", 0, 0, sysvipc_shm_read_proc, NULL);
76 #endif
77 }
78
shm_checkid(struct shmid_kernel * s,int id)79 static inline int shm_checkid(struct shmid_kernel *s, int id)
80 {
81 if (ipc_checkid(&shm_ids,&s->shm_perm,id))
82 return -EIDRM;
83 return 0;
84 }
85
shm_rmid(int id)86 static inline struct shmid_kernel *shm_rmid(int id)
87 {
88 return (struct shmid_kernel *)ipc_rmid(&shm_ids,id);
89 }
90
shm_addid(struct shmid_kernel * shp)91 static inline int shm_addid(struct shmid_kernel *shp)
92 {
93 return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni+1);
94 }
95
96
97
shm_inc(int id)98 static inline void shm_inc (int id) {
99 struct shmid_kernel *shp;
100
101 if(!(shp = shm_lock(id)))
102 BUG();
103 shp->shm_atim = CURRENT_TIME;
104 shp->shm_lprid = current->pid;
105 shp->shm_nattch++;
106 shm_unlock(id);
107 }
108
109 /* This is called by fork, once for every shm attach. */
shm_open(struct vm_area_struct * shmd)110 static void shm_open (struct vm_area_struct *shmd)
111 {
112 shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino);
113 }
114
115 /*
116 * shm_destroy - free the struct shmid_kernel
117 *
118 * @shp: struct to free
119 *
120 * It has to be called with shp and shm_ids.sem locked,
121 * but returns with shp unlocked and freed.
122 */
shm_destroy(struct shmid_kernel * shp)123 static void shm_destroy (struct shmid_kernel *shp)
124 {
125 shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
126 shm_rmid (shp->id);
127 shm_unlock(shp->id);
128 shmem_lock(shp->shm_file, 0);
129 fput (shp->shm_file);
130 kfree (shp);
131 }
132
133 /*
134 * remove the attach descriptor shmd.
135 * free memory for segment if it is marked destroyed.
136 * The descriptor has already been removed from the current->mm->mmap list
137 * and will later be kfree()d.
138 */
shm_close(struct vm_area_struct * shmd)139 static void shm_close (struct vm_area_struct *shmd)
140 {
141 struct file * file = shmd->vm_file;
142 int id = file->f_dentry->d_inode->i_ino;
143 struct shmid_kernel *shp;
144
145 down (&shm_ids.sem);
146 /* remove from the list of attaches of the shm segment */
147 if(!(shp = shm_lock(id)))
148 BUG();
149 shp->shm_lprid = current->pid;
150 shp->shm_dtim = CURRENT_TIME;
151 shp->shm_nattch--;
152 if(shp->shm_nattch == 0 &&
153 shp->shm_flags & SHM_DEST)
154 shm_destroy (shp);
155 else
156 shm_unlock(id);
157 up (&shm_ids.sem);
158 }
159
shm_mmap(struct file * file,struct vm_area_struct * vma)160 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
161 {
162 UPDATE_ATIME(file->f_dentry->d_inode);
163 vma->vm_ops = &shm_vm_ops;
164 if (!(vma->vm_flags & VM_WRITE))
165 vma->vm_flags &= ~VM_MAYWRITE;
166 shm_inc(file->f_dentry->d_inode->i_ino);
167 return 0;
168 }
169
170 static struct file_operations shm_file_operations = {
171 mmap: shm_mmap
172 };
173
174 static struct vm_operations_struct shm_vm_ops = {
175 open: shm_open, /* callback for a new vm-area open */
176 close: shm_close, /* callback for when the vm-area is released */
177 nopage: shmem_nopage,
178 };
179
newseg(key_t key,int shmflg,size_t size)180 static int newseg (key_t key, int shmflg, size_t size)
181 {
182 int error;
183 struct shmid_kernel *shp;
184 int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
185 struct file * file;
186 char name[13];
187 int id;
188
189 if (size < SHMMIN || size > shm_ctlmax)
190 return -EINVAL;
191
192 if (shm_tot + numpages >= shm_ctlall)
193 return -ENOSPC;
194
195 shp = (struct shmid_kernel *) kmalloc (sizeof (*shp), GFP_USER);
196 if (!shp)
197 return -ENOMEM;
198 sprintf (name, "SYSV%08x", key);
199 file = shmem_file_setup(name, size);
200 error = PTR_ERR(file);
201 if (IS_ERR(file))
202 goto no_file;
203
204 error = -ENOSPC;
205 id = shm_addid(shp);
206 if(id == -1)
207 goto no_id;
208 shp->shm_perm.key = key;
209 shp->shm_flags = (shmflg & S_IRWXUGO);
210 shp->shm_cprid = current->pid;
211 shp->shm_lprid = 0;
212 shp->shm_atim = shp->shm_dtim = 0;
213 shp->shm_ctim = CURRENT_TIME;
214 shp->shm_segsz = size;
215 shp->shm_nattch = 0;
216 shp->id = shm_buildid(id,shp->shm_perm.seq);
217 shp->shm_file = file;
218 file->f_dentry->d_inode->i_ino = shp->id;
219 file->f_op = &shm_file_operations;
220 shm_tot += numpages;
221 shm_unlock (id);
222 return shp->id;
223
224 no_id:
225 fput(file);
226 no_file:
227 kfree(shp);
228 return error;
229 }
230
sys_shmget(key_t key,size_t size,int shmflg)231 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
232 {
233 struct shmid_kernel *shp;
234 int err, id = 0;
235
236 down(&shm_ids.sem);
237 if (key == IPC_PRIVATE) {
238 err = newseg(key, shmflg, size);
239 } else if ((id = ipc_findkey(&shm_ids, key)) == -1) {
240 if (!(shmflg & IPC_CREAT))
241 err = -ENOENT;
242 else
243 err = newseg(key, shmflg, size);
244 } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
245 err = -EEXIST;
246 } else {
247 shp = shm_lock(id);
248 if(shp==NULL)
249 BUG();
250 if (shp->shm_segsz < size)
251 err = -EINVAL;
252 else if (ipcperms(&shp->shm_perm, shmflg))
253 err = -EACCES;
254 else
255 err = shm_buildid(id, shp->shm_perm.seq);
256 shm_unlock(id);
257 }
258 up(&shm_ids.sem);
259 return err;
260 }
261
copy_shmid_to_user(void * buf,struct shmid64_ds * in,int version)262 static inline unsigned long copy_shmid_to_user(void *buf, struct shmid64_ds *in, int version)
263 {
264 switch(version) {
265 case IPC_64:
266 return copy_to_user(buf, in, sizeof(*in));
267 case IPC_OLD:
268 {
269 struct shmid_ds out;
270
271 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
272 out.shm_segsz = in->shm_segsz;
273 out.shm_atime = in->shm_atime;
274 out.shm_dtime = in->shm_dtime;
275 out.shm_ctime = in->shm_ctime;
276 out.shm_cpid = in->shm_cpid;
277 out.shm_lpid = in->shm_lpid;
278 out.shm_nattch = in->shm_nattch;
279
280 return copy_to_user(buf, &out, sizeof(out));
281 }
282 default:
283 return -EINVAL;
284 }
285 }
286
287 struct shm_setbuf {
288 uid_t uid;
289 gid_t gid;
290 mode_t mode;
291 };
292
copy_shmid_from_user(struct shm_setbuf * out,void * buf,int version)293 static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void *buf, int version)
294 {
295 switch(version) {
296 case IPC_64:
297 {
298 struct shmid64_ds tbuf;
299
300 if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
301 return -EFAULT;
302
303 out->uid = tbuf.shm_perm.uid;
304 out->gid = tbuf.shm_perm.gid;
305 out->mode = tbuf.shm_flags;
306
307 return 0;
308 }
309 case IPC_OLD:
310 {
311 struct shmid_ds tbuf_old;
312
313 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
314 return -EFAULT;
315
316 out->uid = tbuf_old.shm_perm.uid;
317 out->gid = tbuf_old.shm_perm.gid;
318 out->mode = tbuf_old.shm_flags;
319
320 return 0;
321 }
322 default:
323 return -EINVAL;
324 }
325 }
326
copy_shminfo_to_user(void * buf,struct shminfo64 * in,int version)327 static inline unsigned long copy_shminfo_to_user(void *buf, struct shminfo64 *in, int version)
328 {
329 switch(version) {
330 case IPC_64:
331 return copy_to_user(buf, in, sizeof(*in));
332 case IPC_OLD:
333 {
334 struct shminfo out;
335
336 if(in->shmmax > INT_MAX)
337 out.shmmax = INT_MAX;
338 else
339 out.shmmax = (int)in->shmmax;
340
341 out.shmmin = in->shmmin;
342 out.shmmni = in->shmmni;
343 out.shmseg = in->shmseg;
344 out.shmall = in->shmall;
345
346 return copy_to_user(buf, &out, sizeof(out));
347 }
348 default:
349 return -EINVAL;
350 }
351 }
352
shm_get_stat(unsigned long * rss,unsigned long * swp)353 static void shm_get_stat (unsigned long *rss, unsigned long *swp)
354 {
355 struct shmem_inode_info *info;
356 int i;
357
358 *rss = 0;
359 *swp = 0;
360
361 for(i = 0; i <= shm_ids.max_id; i++) {
362 struct shmid_kernel* shp;
363 struct inode * inode;
364
365 shp = shm_get(i);
366 if(shp == NULL)
367 continue;
368 inode = shp->shm_file->f_dentry->d_inode;
369 info = SHMEM_I(inode);
370 spin_lock (&info->lock);
371 *rss += inode->i_mapping->nrpages;
372 *swp += info->swapped;
373 spin_unlock (&info->lock);
374 }
375 }
376
sys_shmctl(int shmid,int cmd,struct shmid_ds * buf)377 asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds *buf)
378 {
379 struct shm_setbuf setbuf;
380 struct shmid_kernel *shp;
381 int err, version;
382
383 if (cmd < 0 || shmid < 0)
384 return -EINVAL;
385
386 version = ipc_parse_version(&cmd);
387
388 switch (cmd) { /* replace with proc interface ? */
389 case IPC_INFO:
390 {
391 struct shminfo64 shminfo;
392
393 memset(&shminfo,0,sizeof(shminfo));
394 shminfo.shmmni = shminfo.shmseg = shm_ctlmni;
395 shminfo.shmmax = shm_ctlmax;
396 shminfo.shmall = shm_ctlall;
397
398 shminfo.shmmin = SHMMIN;
399 if(copy_shminfo_to_user (buf, &shminfo, version))
400 return -EFAULT;
401 /* reading a integer is always atomic */
402 err= shm_ids.max_id;
403 if(err<0)
404 err = 0;
405 return err;
406 }
407 case SHM_INFO:
408 {
409 struct shm_info shm_info;
410
411 memset(&shm_info,0,sizeof(shm_info));
412 down(&shm_ids.sem);
413 shm_lockall();
414 shm_info.used_ids = shm_ids.in_use;
415 shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp);
416 shm_info.shm_tot = shm_tot;
417 shm_info.swap_attempts = 0;
418 shm_info.swap_successes = 0;
419 err = shm_ids.max_id;
420 shm_unlockall();
421 up(&shm_ids.sem);
422 if(copy_to_user (buf, &shm_info, sizeof(shm_info)))
423 return -EFAULT;
424
425 return err < 0 ? 0 : err;
426 }
427 case SHM_STAT:
428 case IPC_STAT:
429 {
430 struct shmid64_ds tbuf;
431 int result;
432 memset(&tbuf, 0, sizeof(tbuf));
433 shp = shm_lock(shmid);
434 if(shp==NULL)
435 return -EINVAL;
436 if(cmd==SHM_STAT) {
437 err = -EINVAL;
438 if (shmid > shm_ids.max_id)
439 goto out_unlock;
440 result = shm_buildid(shmid, shp->shm_perm.seq);
441 } else {
442 err = shm_checkid(shp,shmid);
443 if(err)
444 goto out_unlock;
445 result = 0;
446 }
447 err=-EACCES;
448 if (ipcperms (&shp->shm_perm, S_IRUGO))
449 goto out_unlock;
450 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
451 tbuf.shm_segsz = shp->shm_segsz;
452 tbuf.shm_atime = shp->shm_atim;
453 tbuf.shm_dtime = shp->shm_dtim;
454 tbuf.shm_ctime = shp->shm_ctim;
455 tbuf.shm_cpid = shp->shm_cprid;
456 tbuf.shm_lpid = shp->shm_lprid;
457 tbuf.shm_nattch = shp->shm_nattch;
458 shm_unlock(shmid);
459 if(copy_shmid_to_user (buf, &tbuf, version))
460 return -EFAULT;
461 return result;
462 }
463 case SHM_LOCK:
464 case SHM_UNLOCK:
465 {
466 /* Allow superuser to lock segment in memory */
467 /* Should the pages be faulted in here or leave it to user? */
468 /* need to determine interaction with current->swappable */
469 if (!capable(CAP_IPC_LOCK))
470 return -EPERM;
471
472 shp = shm_lock(shmid);
473 if(shp==NULL)
474 return -EINVAL;
475 err = shm_checkid(shp,shmid);
476 if(err)
477 goto out_unlock;
478 if(cmd==SHM_LOCK) {
479 shmem_lock(shp->shm_file, 1);
480 shp->shm_flags |= SHM_LOCKED;
481 } else {
482 shmem_lock(shp->shm_file, 0);
483 shp->shm_flags &= ~SHM_LOCKED;
484 }
485 shm_unlock(shmid);
486 return err;
487 }
488 case IPC_RMID:
489 {
490 /*
491 * We cannot simply remove the file. The SVID states
492 * that the block remains until the last person
493 * detaches from it, then is deleted. A shmat() on
494 * an RMID segment is legal in older Linux and if
495 * we change it apps break...
496 *
497 * Instead we set a destroyed flag, and then blow
498 * the name away when the usage hits zero.
499 */
500 down(&shm_ids.sem);
501 shp = shm_lock(shmid);
502 err = -EINVAL;
503 if (shp == NULL)
504 goto out_up;
505 err = shm_checkid(shp, shmid);
506 if(err)
507 goto out_unlock_up;
508 if (current->euid != shp->shm_perm.uid &&
509 current->euid != shp->shm_perm.cuid &&
510 !capable(CAP_SYS_ADMIN)) {
511 err=-EPERM;
512 goto out_unlock_up;
513 }
514 if (shp->shm_nattch){
515 shp->shm_flags |= SHM_DEST;
516 /* Do not find it any more */
517 shp->shm_perm.key = IPC_PRIVATE;
518 shm_unlock(shmid);
519 } else
520 shm_destroy (shp);
521 up(&shm_ids.sem);
522 return err;
523 }
524
525 case IPC_SET:
526 {
527 if(copy_shmid_from_user (&setbuf, buf, version))
528 return -EFAULT;
529 down(&shm_ids.sem);
530 shp = shm_lock(shmid);
531 err=-EINVAL;
532 if(shp==NULL)
533 goto out_up;
534 err = shm_checkid(shp,shmid);
535 if(err)
536 goto out_unlock_up;
537 err=-EPERM;
538 if (current->euid != shp->shm_perm.uid &&
539 current->euid != shp->shm_perm.cuid &&
540 !capable(CAP_SYS_ADMIN)) {
541 goto out_unlock_up;
542 }
543
544 shp->shm_perm.uid = setbuf.uid;
545 shp->shm_perm.gid = setbuf.gid;
546 shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO)
547 | (setbuf.mode & S_IRWXUGO);
548 shp->shm_ctim = CURRENT_TIME;
549 break;
550 }
551
552 default:
553 return -EINVAL;
554 }
555
556 err = 0;
557 out_unlock_up:
558 shm_unlock(shmid);
559 out_up:
560 up(&shm_ids.sem);
561 return err;
562 out_unlock:
563 shm_unlock(shmid);
564 return err;
565 }
566
567 /*
568 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
569 */
sys_shmat(int shmid,char * shmaddr,int shmflg,ulong * raddr)570 asmlinkage long sys_shmat (int shmid, char *shmaddr, int shmflg, ulong *raddr)
571 {
572 struct shmid_kernel *shp;
573 unsigned long addr;
574 unsigned long size;
575 struct file * file;
576 int err;
577 unsigned long flags;
578 unsigned long prot;
579 unsigned long o_flags;
580 int acc_mode;
581 void *user_addr;
582
583 if (shmid < 0)
584 return -EINVAL;
585
586 if ((addr = (ulong)shmaddr)) {
587 if (addr & (SHMLBA-1)) {
588 if (shmflg & SHM_RND)
589 addr &= ~(SHMLBA-1); /* round down */
590 else
591 return -EINVAL;
592 }
593 flags = MAP_SHARED | MAP_FIXED;
594 } else {
595 if ((shmflg & SHM_REMAP))
596 return -EINVAL;
597
598 flags = MAP_SHARED;
599 }
600
601 if (shmflg & SHM_RDONLY) {
602 prot = PROT_READ;
603 o_flags = O_RDONLY;
604 acc_mode = S_IRUGO;
605 } else {
606 prot = PROT_READ | PROT_WRITE;
607 o_flags = O_RDWR;
608 acc_mode = S_IRUGO | S_IWUGO;
609 }
610
611 /*
612 * We cannot rely on the fs check since SYSV IPC does have an
613 * additional creator id...
614 */
615 shp = shm_lock(shmid);
616 if(shp == NULL)
617 return -EINVAL;
618 err = shm_checkid(shp,shmid);
619 if (err) {
620 shm_unlock(shmid);
621 return err;
622 }
623 if (ipcperms(&shp->shm_perm, acc_mode)) {
624 shm_unlock(shmid);
625 return -EACCES;
626 }
627 file = shp->shm_file;
628 size = file->f_dentry->d_inode->i_size;
629 shp->shm_nattch++;
630 shm_unlock(shmid);
631
632 down_write(¤t->mm->mmap_sem);
633 if (addr && !(shmflg & SHM_REMAP)) {
634 user_addr = ERR_PTR(-EINVAL);
635 if (find_vma_intersection(current->mm, addr, addr + size))
636 goto invalid;
637 /*
638 * If shm segment goes below stack, make sure there is some
639 * space left for the stack to grow (at least 4 pages).
640 */
641 if (addr < current->mm->start_stack &&
642 addr > current->mm->start_stack - size - PAGE_SIZE * 5)
643 goto invalid;
644 }
645
646 user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0);
647
648 invalid:
649 up_write(¤t->mm->mmap_sem);
650
651 down (&shm_ids.sem);
652 if(!(shp = shm_lock(shmid)))
653 BUG();
654 shp->shm_nattch--;
655 if(shp->shm_nattch == 0 &&
656 shp->shm_flags & SHM_DEST)
657 shm_destroy (shp);
658 else
659 shm_unlock(shmid);
660 up (&shm_ids.sem);
661
662 *raddr = (unsigned long) user_addr;
663 err = 0;
664 if (IS_ERR(user_addr))
665 err = PTR_ERR(user_addr);
666 return err;
667
668 }
669
670 /*
671 * detach and kill segment if marked destroyed.
672 * The work is done in shm_close.
673 */
sys_shmdt(char * shmaddr)674 asmlinkage long sys_shmdt (char *shmaddr)
675 {
676 struct mm_struct *mm = current->mm;
677 struct vm_area_struct *shmd, *shmdnext;
678 int retval = -EINVAL;
679
680 down_write(&mm->mmap_sem);
681 for (shmd = mm->mmap; shmd; shmd = shmdnext) {
682 shmdnext = shmd->vm_next;
683 if (shmd->vm_ops == &shm_vm_ops
684 && shmd->vm_start - (shmd->vm_pgoff << PAGE_SHIFT) == (ulong) shmaddr) {
685 do_munmap(mm, shmd->vm_start, shmd->vm_end - shmd->vm_start);
686 retval = 0;
687 }
688 }
689 up_write(&mm->mmap_sem);
690 return retval;
691 }
692
693 #ifdef CONFIG_PROC_FS
sysvipc_shm_read_proc(char * buffer,char ** start,off_t offset,int length,int * eof,void * data)694 static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data)
695 {
696 off_t pos = 0;
697 off_t begin = 0;
698 int i, len = 0;
699
700 down(&shm_ids.sem);
701 len += sprintf(buffer, " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n");
702
703 for(i = 0; i <= shm_ids.max_id; i++) {
704 struct shmid_kernel* shp;
705
706 shp = shm_lock(i);
707 if(shp!=NULL) {
708 #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
709 #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
710 char *format;
711
712 if (sizeof(size_t) <= sizeof(int))
713 format = SMALL_STRING;
714 else
715 format = BIG_STRING;
716 len += sprintf(buffer + len, format,
717 shp->shm_perm.key,
718 shm_buildid(i, shp->shm_perm.seq),
719 shp->shm_flags,
720 shp->shm_segsz,
721 shp->shm_cprid,
722 shp->shm_lprid,
723 shp->shm_nattch,
724 shp->shm_perm.uid,
725 shp->shm_perm.gid,
726 shp->shm_perm.cuid,
727 shp->shm_perm.cgid,
728 shp->shm_atim,
729 shp->shm_dtim,
730 shp->shm_ctim);
731 shm_unlock(i);
732
733 pos += len;
734 if(pos < offset) {
735 len = 0;
736 begin = pos;
737 }
738 if(pos > offset + length)
739 goto done;
740 }
741 }
742 *eof = 1;
743 done:
744 up(&shm_ids.sem);
745 *start = buffer + (offset - begin);
746 len -= (offset - begin);
747 if(len > length)
748 len = length;
749 if(len < 0)
750 len = 0;
751 return len;
752 }
753 #endif
754