| /* |
| * linux/ipc/shm.c |
| * Copyright (C) 1992, 1993 Krishna Balasubramanian |
| * Many improvements/fixes by Bruno Haible. |
| * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994. |
| * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli. |
| * |
| * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com> |
| * BIGMEM support, Andrea Arcangeli <andrea@suse.de> |
| * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr> |
| * HIGHMEM support, Ingo Molnar <mingo@redhat.com> |
| * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com> |
| * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com> |
| * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com> |
| * |
| */ |
| |
| #include <linux/config.h> |
| #include <linux/slab.h> |
| #include <linux/shm.h> |
| #include <linux/init.h> |
| #include <linux/file.h> |
| #include <linux/mman.h> |
| #include <linux/proc_fs.h> |
| #include <asm/uaccess.h> |
| |
| #include "util.h" |
| |
| struct shmid_kernel /* private to the kernel */ |
| { |
| struct kern_ipc_perm shm_perm; |
| struct file * shm_file; |
| int id; |
| unsigned long shm_nattch; |
| unsigned long shm_segsz; |
| time_t shm_atim; |
| time_t shm_dtim; |
| time_t shm_ctim; |
| pid_t shm_cprid; |
| pid_t shm_lprid; |
| }; |
| |
| #define shm_flags shm_perm.mode |
| |
| static struct file_operations shm_file_operations; |
| static struct vm_operations_struct shm_vm_ops; |
| |
| static struct ipc_ids shm_ids; |
| |
| #define shm_lock(id) ((struct shmid_kernel*)ipc_lock(&shm_ids,id)) |
| #define shm_unlock(id) ipc_unlock(&shm_ids,id) |
| #define shm_lockall() ipc_lockall(&shm_ids) |
| #define shm_unlockall() ipc_unlockall(&shm_ids) |
| #define shm_get(id) ((struct shmid_kernel*)ipc_get(&shm_ids,id)) |
| #define shm_buildid(id, seq) \ |
| ipc_buildid(&shm_ids, id, seq) |
| |
| static int newseg (key_t key, int shmflg, size_t size); |
| static void shm_open (struct vm_area_struct *shmd); |
| static void shm_close (struct vm_area_struct *shmd); |
| #ifdef CONFIG_PROC_FS |
| static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data); |
| #endif |
| |
| size_t shm_ctlmax = SHMMAX; |
| size_t shm_ctlall = SHMALL; |
| int shm_ctlmni = SHMMNI; |
| |
| static int shm_tot; /* total number of shared memory pages */ |
| |
| void __init shm_init (void) |
| { |
| ipc_init_ids(&shm_ids, 1); |
| #ifdef CONFIG_PROC_FS |
| create_proc_read_entry("sysvipc/shm", 0, 0, sysvipc_shm_read_proc, NULL); |
| #endif |
| } |
| |
| static inline int shm_checkid(struct shmid_kernel *s, int id) |
| { |
| if (ipc_checkid(&shm_ids,&s->shm_perm,id)) |
| return -EIDRM; |
| return 0; |
| } |
| |
| static inline struct shmid_kernel *shm_rmid(int id) |
| { |
| return (struct shmid_kernel *)ipc_rmid(&shm_ids,id); |
| } |
| |
| static inline int shm_addid(struct shmid_kernel *shp) |
| { |
| return ipc_addid(&shm_ids, &shp->shm_perm, shm_ctlmni+1); |
| } |
| |
| |
| |
| static inline void shm_inc (int id) { |
| struct shmid_kernel *shp; |
| |
| if(!(shp = shm_lock(id))) |
| BUG(); |
| shp->shm_atim = CURRENT_TIME; |
| shp->shm_lprid = current->pid; |
| shp->shm_nattch++; |
| shm_unlock(id); |
| } |
| |
| /* This is called by fork, once for every shm attach. */ |
| static void shm_open (struct vm_area_struct *shmd) |
| { |
| shm_inc (shmd->vm_file->f_dentry->d_inode->i_ino); |
| } |
| |
| /* |
| * shm_destroy - free the struct shmid_kernel |
| * |
| * @shp: struct to free |
| * |
| * It has to be called with shp and shm_ids.sem locked, |
| * but returns with shp unlocked and freed. |
| */ |
| static void shm_destroy (struct shmid_kernel *shp) |
| { |
| shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| shm_rmid (shp->id); |
| shm_unlock(shp->id); |
| shmem_lock(shp->shm_file, 0); |
| fput (shp->shm_file); |
| kfree (shp); |
| } |
| |
| /* |
| * remove the attach descriptor shmd. |
| * free memory for segment if it is marked destroyed. |
| * The descriptor has already been removed from the current->mm->mmap list |
| * and will later be kfree()d. |
| */ |
| static void shm_close (struct vm_area_struct *shmd) |
| { |
| struct file * file = shmd->vm_file; |
| int id = file->f_dentry->d_inode->i_ino; |
| struct shmid_kernel *shp; |
| |
| down (&shm_ids.sem); |
| /* remove from the list of attaches of the shm segment */ |
| if(!(shp = shm_lock(id))) |
| BUG(); |
| shp->shm_lprid = current->pid; |
| shp->shm_dtim = CURRENT_TIME; |
| shp->shm_nattch--; |
| if(shp->shm_nattch == 0 && |
| shp->shm_flags & SHM_DEST) |
| shm_destroy (shp); |
| else |
| shm_unlock(id); |
| up (&shm_ids.sem); |
| } |
| |
| static int shm_mmap(struct file * file, struct vm_area_struct * vma) |
| { |
| UPDATE_ATIME(file->f_dentry->d_inode); |
| vma->vm_ops = &shm_vm_ops; |
| if (!(vma->vm_flags & VM_WRITE)) |
| vma->vm_flags &= ~VM_MAYWRITE; |
| shm_inc(file->f_dentry->d_inode->i_ino); |
| return 0; |
| } |
| |
| static struct file_operations shm_file_operations = { |
| mmap: shm_mmap |
| }; |
| |
| static struct vm_operations_struct shm_vm_ops = { |
| open: shm_open, /* callback for a new vm-area open */ |
| close: shm_close, /* callback for when the vm-area is released */ |
| nopage: shmem_nopage, |
| }; |
| |
| static int newseg (key_t key, int shmflg, size_t size) |
| { |
| int error; |
| struct shmid_kernel *shp; |
| int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT; |
| struct file * file; |
| char name[13]; |
| int id; |
| |
| if (size < SHMMIN || size > shm_ctlmax) |
| return -EINVAL; |
| |
| if (shm_tot + numpages >= shm_ctlall) |
| return -ENOSPC; |
| |
| shp = (struct shmid_kernel *) kmalloc (sizeof (*shp), GFP_USER); |
| if (!shp) |
| return -ENOMEM; |
| sprintf (name, "SYSV%08x", key); |
| file = shmem_file_setup(name, size); |
| error = PTR_ERR(file); |
| if (IS_ERR(file)) |
| goto no_file; |
| |
| error = -ENOSPC; |
| id = shm_addid(shp); |
| if(id == -1) |
| goto no_id; |
| shp->shm_perm.key = key; |
| shp->shm_flags = (shmflg & S_IRWXUGO); |
| shp->shm_cprid = current->pid; |
| shp->shm_lprid = 0; |
| shp->shm_atim = shp->shm_dtim = 0; |
| shp->shm_ctim = CURRENT_TIME; |
| shp->shm_segsz = size; |
| shp->shm_nattch = 0; |
| shp->id = shm_buildid(id,shp->shm_perm.seq); |
| shp->shm_file = file; |
| file->f_dentry->d_inode->i_ino = shp->id; |
| file->f_op = &shm_file_operations; |
| shm_tot += numpages; |
| shm_unlock (id); |
| return shp->id; |
| |
| no_id: |
| fput(file); |
| no_file: |
| kfree(shp); |
| return error; |
| } |
| |
| asmlinkage long sys_shmget (key_t key, size_t size, int shmflg) |
| { |
| struct shmid_kernel *shp; |
| int err, id = 0; |
| |
| down(&shm_ids.sem); |
| if (key == IPC_PRIVATE) { |
| err = newseg(key, shmflg, size); |
| } else if ((id = ipc_findkey(&shm_ids, key)) == -1) { |
| if (!(shmflg & IPC_CREAT)) |
| err = -ENOENT; |
| else |
| err = newseg(key, shmflg, size); |
| } else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) { |
| err = -EEXIST; |
| } else { |
| shp = shm_lock(id); |
| if(shp==NULL) |
| BUG(); |
| if (shp->shm_segsz < size) |
| err = -EINVAL; |
| else if (ipcperms(&shp->shm_perm, shmflg)) |
| err = -EACCES; |
| else |
| err = shm_buildid(id, shp->shm_perm.seq); |
| shm_unlock(id); |
| } |
| up(&shm_ids.sem); |
| return err; |
| } |
| |
| static inline unsigned long copy_shmid_to_user(void *buf, struct shmid64_ds *in, int version) |
| { |
| switch(version) { |
| case IPC_64: |
| return copy_to_user(buf, in, sizeof(*in)); |
| case IPC_OLD: |
| { |
| struct shmid_ds out; |
| |
| memset(&out, 0, sizeof(out)); |
| ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm); |
| out.shm_segsz = in->shm_segsz; |
| out.shm_atime = in->shm_atime; |
| out.shm_dtime = in->shm_dtime; |
| out.shm_ctime = in->shm_ctime; |
| out.shm_cpid = in->shm_cpid; |
| out.shm_lpid = in->shm_lpid; |
| out.shm_nattch = in->shm_nattch; |
| |
| return copy_to_user(buf, &out, sizeof(out)); |
| } |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| struct shm_setbuf { |
| uid_t uid; |
| gid_t gid; |
| mode_t mode; |
| }; |
| |
| static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void *buf, int version) |
| { |
| switch(version) { |
| case IPC_64: |
| { |
| struct shmid64_ds tbuf; |
| |
| if (copy_from_user(&tbuf, buf, sizeof(tbuf))) |
| return -EFAULT; |
| |
| out->uid = tbuf.shm_perm.uid; |
| out->gid = tbuf.shm_perm.gid; |
| out->mode = tbuf.shm_flags; |
| |
| return 0; |
| } |
| case IPC_OLD: |
| { |
| struct shmid_ds tbuf_old; |
| |
| if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) |
| return -EFAULT; |
| |
| out->uid = tbuf_old.shm_perm.uid; |
| out->gid = tbuf_old.shm_perm.gid; |
| out->mode = tbuf_old.shm_flags; |
| |
| return 0; |
| } |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| static inline unsigned long copy_shminfo_to_user(void *buf, struct shminfo64 *in, int version) |
| { |
| switch(version) { |
| case IPC_64: |
| return copy_to_user(buf, in, sizeof(*in)); |
| case IPC_OLD: |
| { |
| struct shminfo out; |
| |
| if(in->shmmax > INT_MAX) |
| out.shmmax = INT_MAX; |
| else |
| out.shmmax = (int)in->shmmax; |
| |
| out.shmmin = in->shmmin; |
| out.shmmni = in->shmmni; |
| out.shmseg = in->shmseg; |
| out.shmall = in->shmall; |
| |
| return copy_to_user(buf, &out, sizeof(out)); |
| } |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| static void shm_get_stat (unsigned long *rss, unsigned long *swp) |
| { |
| struct shmem_inode_info *info; |
| int i; |
| |
| *rss = 0; |
| *swp = 0; |
| |
| for(i = 0; i <= shm_ids.max_id; i++) { |
| struct shmid_kernel* shp; |
| struct inode * inode; |
| |
| shp = shm_get(i); |
| if(shp == NULL) |
| continue; |
| inode = shp->shm_file->f_dentry->d_inode; |
| info = SHMEM_I(inode); |
| spin_lock (&info->lock); |
| *rss += inode->i_mapping->nrpages; |
| *swp += info->swapped; |
| spin_unlock (&info->lock); |
| } |
| } |
| |
| asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds *buf) |
| { |
| struct shm_setbuf setbuf; |
| struct shmid_kernel *shp; |
| int err, version; |
| |
| if (cmd < 0 || shmid < 0) |
| return -EINVAL; |
| |
| version = ipc_parse_version(&cmd); |
| |
| switch (cmd) { /* replace with proc interface ? */ |
| case IPC_INFO: |
| { |
| struct shminfo64 shminfo; |
| |
| memset(&shminfo,0,sizeof(shminfo)); |
| shminfo.shmmni = shminfo.shmseg = shm_ctlmni; |
| shminfo.shmmax = shm_ctlmax; |
| shminfo.shmall = shm_ctlall; |
| |
| shminfo.shmmin = SHMMIN; |
| if(copy_shminfo_to_user (buf, &shminfo, version)) |
| return -EFAULT; |
| /* reading a integer is always atomic */ |
| err= shm_ids.max_id; |
| if(err<0) |
| err = 0; |
| return err; |
| } |
| case SHM_INFO: |
| { |
| struct shm_info shm_info; |
| |
| memset(&shm_info,0,sizeof(shm_info)); |
| down(&shm_ids.sem); |
| shm_lockall(); |
| shm_info.used_ids = shm_ids.in_use; |
| shm_get_stat (&shm_info.shm_rss, &shm_info.shm_swp); |
| shm_info.shm_tot = shm_tot; |
| shm_info.swap_attempts = 0; |
| shm_info.swap_successes = 0; |
| err = shm_ids.max_id; |
| shm_unlockall(); |
| up(&shm_ids.sem); |
| if(copy_to_user (buf, &shm_info, sizeof(shm_info))) |
| return -EFAULT; |
| |
| return err < 0 ? 0 : err; |
| } |
| case SHM_STAT: |
| case IPC_STAT: |
| { |
| struct shmid64_ds tbuf; |
| int result; |
| memset(&tbuf, 0, sizeof(tbuf)); |
| shp = shm_lock(shmid); |
| if(shp==NULL) |
| return -EINVAL; |
| if(cmd==SHM_STAT) { |
| err = -EINVAL; |
| if (shmid > shm_ids.max_id) |
| goto out_unlock; |
| result = shm_buildid(shmid, shp->shm_perm.seq); |
| } else { |
| err = shm_checkid(shp,shmid); |
| if(err) |
| goto out_unlock; |
| result = 0; |
| } |
| err=-EACCES; |
| if (ipcperms (&shp->shm_perm, S_IRUGO)) |
| goto out_unlock; |
| kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm); |
| tbuf.shm_segsz = shp->shm_segsz; |
| tbuf.shm_atime = shp->shm_atim; |
| tbuf.shm_dtime = shp->shm_dtim; |
| tbuf.shm_ctime = shp->shm_ctim; |
| tbuf.shm_cpid = shp->shm_cprid; |
| tbuf.shm_lpid = shp->shm_lprid; |
| tbuf.shm_nattch = shp->shm_nattch; |
| shm_unlock(shmid); |
| if(copy_shmid_to_user (buf, &tbuf, version)) |
| return -EFAULT; |
| return result; |
| } |
| case SHM_LOCK: |
| case SHM_UNLOCK: |
| { |
| /* Allow superuser to lock segment in memory */ |
| /* Should the pages be faulted in here or leave it to user? */ |
| /* need to determine interaction with current->swappable */ |
| if (!capable(CAP_IPC_LOCK)) |
| return -EPERM; |
| |
| shp = shm_lock(shmid); |
| if(shp==NULL) |
| return -EINVAL; |
| err = shm_checkid(shp,shmid); |
| if(err) |
| goto out_unlock; |
| if(cmd==SHM_LOCK) { |
| shmem_lock(shp->shm_file, 1); |
| shp->shm_flags |= SHM_LOCKED; |
| } else { |
| shmem_lock(shp->shm_file, 0); |
| shp->shm_flags &= ~SHM_LOCKED; |
| } |
| shm_unlock(shmid); |
| return err; |
| } |
| case IPC_RMID: |
| { |
| /* |
| * We cannot simply remove the file. The SVID states |
| * that the block remains until the last person |
| * detaches from it, then is deleted. A shmat() on |
| * an RMID segment is legal in older Linux and if |
| * we change it apps break... |
| * |
| * Instead we set a destroyed flag, and then blow |
| * the name away when the usage hits zero. |
| */ |
| down(&shm_ids.sem); |
| shp = shm_lock(shmid); |
| err = -EINVAL; |
| if (shp == NULL) |
| goto out_up; |
| err = shm_checkid(shp, shmid); |
| if(err) |
| goto out_unlock_up; |
| if (current->euid != shp->shm_perm.uid && |
| current->euid != shp->shm_perm.cuid && |
| !capable(CAP_SYS_ADMIN)) { |
| err=-EPERM; |
| goto out_unlock_up; |
| } |
| if (shp->shm_nattch){ |
| shp->shm_flags |= SHM_DEST; |
| /* Do not find it any more */ |
| shp->shm_perm.key = IPC_PRIVATE; |
| shm_unlock(shmid); |
| } else |
| shm_destroy (shp); |
| up(&shm_ids.sem); |
| return err; |
| } |
| |
| case IPC_SET: |
| { |
| if(copy_shmid_from_user (&setbuf, buf, version)) |
| return -EFAULT; |
| down(&shm_ids.sem); |
| shp = shm_lock(shmid); |
| err=-EINVAL; |
| if(shp==NULL) |
| goto out_up; |
| err = shm_checkid(shp,shmid); |
| if(err) |
| goto out_unlock_up; |
| err=-EPERM; |
| if (current->euid != shp->shm_perm.uid && |
| current->euid != shp->shm_perm.cuid && |
| !capable(CAP_SYS_ADMIN)) { |
| goto out_unlock_up; |
| } |
| |
| shp->shm_perm.uid = setbuf.uid; |
| shp->shm_perm.gid = setbuf.gid; |
| shp->shm_flags = (shp->shm_flags & ~S_IRWXUGO) |
| | (setbuf.mode & S_IRWXUGO); |
| shp->shm_ctim = CURRENT_TIME; |
| break; |
| } |
| |
| default: |
| return -EINVAL; |
| } |
| |
| err = 0; |
| out_unlock_up: |
| shm_unlock(shmid); |
| out_up: |
| up(&shm_ids.sem); |
| return err; |
| out_unlock: |
| shm_unlock(shmid); |
| return err; |
| } |
| |
| /* |
| * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists. |
| */ |
| asmlinkage long sys_shmat (int shmid, char *shmaddr, int shmflg, ulong *raddr) |
| { |
| struct shmid_kernel *shp; |
| unsigned long addr; |
| unsigned long size; |
| struct file * file; |
| int err; |
| unsigned long flags; |
| unsigned long prot; |
| unsigned long o_flags; |
| int acc_mode; |
| void *user_addr; |
| |
| if (shmid < 0) |
| return -EINVAL; |
| |
| if ((addr = (ulong)shmaddr)) { |
| if (addr & (SHMLBA-1)) { |
| if (shmflg & SHM_RND) |
| addr &= ~(SHMLBA-1); /* round down */ |
| else |
| return -EINVAL; |
| } |
| flags = MAP_SHARED | MAP_FIXED; |
| } else { |
| if ((shmflg & SHM_REMAP)) |
| return -EINVAL; |
| |
| flags = MAP_SHARED; |
| } |
| |
| if (shmflg & SHM_RDONLY) { |
| prot = PROT_READ; |
| o_flags = O_RDONLY; |
| acc_mode = S_IRUGO; |
| } else { |
| prot = PROT_READ | PROT_WRITE; |
| o_flags = O_RDWR; |
| acc_mode = S_IRUGO | S_IWUGO; |
| } |
| |
| /* |
| * We cannot rely on the fs check since SYSV IPC does have an |
| * additional creator id... |
| */ |
| shp = shm_lock(shmid); |
| if(shp == NULL) |
| return -EINVAL; |
| err = shm_checkid(shp,shmid); |
| if (err) { |
| shm_unlock(shmid); |
| return err; |
| } |
| if (ipcperms(&shp->shm_perm, acc_mode)) { |
| shm_unlock(shmid); |
| return -EACCES; |
| } |
| file = shp->shm_file; |
| size = file->f_dentry->d_inode->i_size; |
| shp->shm_nattch++; |
| shm_unlock(shmid); |
| |
| down_write(¤t->mm->mmap_sem); |
| if (addr && !(shmflg & SHM_REMAP)) { |
| user_addr = ERR_PTR(-EINVAL); |
| if (find_vma_intersection(current->mm, addr, addr + size)) |
| goto invalid; |
| /* |
| * If shm segment goes below stack, make sure there is some |
| * space left for the stack to grow (at least 4 pages). |
| */ |
| if (addr < current->mm->start_stack && |
| addr > current->mm->start_stack - size - PAGE_SIZE * 5) |
| goto invalid; |
| } |
| |
| user_addr = (void*) do_mmap (file, addr, size, prot, flags, 0); |
| |
| invalid: |
| up_write(¤t->mm->mmap_sem); |
| |
| down (&shm_ids.sem); |
| if(!(shp = shm_lock(shmid))) |
| BUG(); |
| shp->shm_nattch--; |
| if(shp->shm_nattch == 0 && |
| shp->shm_flags & SHM_DEST) |
| shm_destroy (shp); |
| else |
| shm_unlock(shmid); |
| up (&shm_ids.sem); |
| |
| *raddr = (unsigned long) user_addr; |
| err = 0; |
| if (IS_ERR(user_addr)) |
| err = PTR_ERR(user_addr); |
| return err; |
| |
| } |
| |
| /* |
| * detach and kill segment if marked destroyed. |
| * The work is done in shm_close. |
| */ |
| asmlinkage long sys_shmdt (char *shmaddr) |
| { |
| struct mm_struct *mm = current->mm; |
| struct vm_area_struct *shmd, *shmdnext; |
| int retval = -EINVAL; |
| |
| down_write(&mm->mmap_sem); |
| for (shmd = mm->mmap; shmd; shmd = shmdnext) { |
| shmdnext = shmd->vm_next; |
| if (shmd->vm_ops == &shm_vm_ops |
| && shmd->vm_start - (shmd->vm_pgoff << PAGE_SHIFT) == (ulong) shmaddr) { |
| do_munmap(mm, shmd->vm_start, shmd->vm_end - shmd->vm_start); |
| retval = 0; |
| } |
| } |
| up_write(&mm->mmap_sem); |
| return retval; |
| } |
| |
| #ifdef CONFIG_PROC_FS |
| static int sysvipc_shm_read_proc(char *buffer, char **start, off_t offset, int length, int *eof, void *data) |
| { |
| off_t pos = 0; |
| off_t begin = 0; |
| int i, len = 0; |
| |
| down(&shm_ids.sem); |
| len += sprintf(buffer, " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime\n"); |
| |
| for(i = 0; i <= shm_ids.max_id; i++) { |
| struct shmid_kernel* shp; |
| |
| shp = shm_lock(i); |
| if(shp!=NULL) { |
| #define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n" |
| #define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n" |
| char *format; |
| |
| if (sizeof(size_t) <= sizeof(int)) |
| format = SMALL_STRING; |
| else |
| format = BIG_STRING; |
| len += sprintf(buffer + len, format, |
| shp->shm_perm.key, |
| shm_buildid(i, shp->shm_perm.seq), |
| shp->shm_flags, |
| shp->shm_segsz, |
| shp->shm_cprid, |
| shp->shm_lprid, |
| shp->shm_nattch, |
| shp->shm_perm.uid, |
| shp->shm_perm.gid, |
| shp->shm_perm.cuid, |
| shp->shm_perm.cgid, |
| shp->shm_atim, |
| shp->shm_dtim, |
| shp->shm_ctim); |
| shm_unlock(i); |
| |
| pos += len; |
| if(pos < offset) { |
| len = 0; |
| begin = pos; |
| } |
| if(pos > offset + length) |
| goto done; |
| } |
| } |
| *eof = 1; |
| done: |
| up(&shm_ids.sem); |
| *start = buffer + (offset - begin); |
| len -= (offset - begin); |
| if(len > length) |
| len = length; |
| if(len < 0) |
| len = 0; |
| return len; |
| } |
| #endif |