/* * linux/fs/ext/namei.c * * (C) 1992 Remy Card (card@masi.ibp.fr) * * from * * linux/fs/minix/namei.c * * (C) 1991 Linus Torvalds */ #include <linux/sched.h> #include <linux/ext_fs.h> #include <linux/kernel.h> #include <linux/string.h> #include <linux/stat.h> #include <linux/fcntl.h> #include <asm/segment.h> #include <errno.h> #include <const.h> /* * comment out this line if you want names > EXT_NAME_LEN chars to be * truncated. Else they will be disallowed. */ /* #define NO_TRUNCATE */ /* * EXT_DIR_PAD defines the directory entries boundaries * * NOTE: It must be a power of 2 and must be greater or equal than 8 * because a directory entry needs 8 bytes for its fixed part * (4 bytes for the inode, 2 bytes for the entry length and 2 bytes * for the name length) */ #define EXT_DIR_PAD 8 /* * * EXT_DIR_MIN_SIZE is the minimal size of a directory entry * * During allocations, a directory entry is split into 2 ones * *ONLY* if the size of the unused part is greater than or * equal to EXT_DIR_MIN_SIZE */ #define EXT_DIR_MIN_SIZE 12 /* * ok, we cannot use strncmp, as the name is not in our data space. * Thus we'll have to use ext_match. No big problem. Match also makes * some sanity tests. * * NOTE! unlike strncmp, ext_match returns 1 for success, 0 for failure. */ static int ext_match(int len,const char * name,struct ext_dir_entry * de) { register int same __asm__("ax"); if (!de || !de->inode || len > EXT_NAME_LEN) return 0; /* "" means "." ---> so paths like "/usr/lib//libc.a" work */ if (!len && (de->name[0]=='.') && (de->name[1]=='\0')) return 1; /* if (len < EXT_NAME_LEN && de->name[len]) return 0; */ if (len < EXT_NAME_LEN && len != de->name_len) return 0; __asm__("cld\n\t" "fs ; repe ; cmpsb\n\t" "setz %%al" :"=a" (same) :"0" (0),"S" ((long) name),"D" ((long) de->name),"c" (len) :"cx","di","si"); return same; } /* * ext_find_entry() * * finds an entry in the specified directory with the wanted name. It * returns the cache buffer in which the entry was found, and the entry * itself (as a parameter - res_dir). It does NOT read the inode of the * entry - you'll have to do that yourself if you want to. * * addition for the ext file system : this function returns the previous * and next directory entries in the parameters prev_dir and next_dir */ static struct buffer_head * ext_find_entry(struct inode * dir, const char * name, int namelen, struct ext_dir_entry ** res_dir, struct ext_dir_entry ** prev_dir, struct ext_dir_entry ** next_dir) { /* int entries; */ int block /* ,i */; long offset; struct buffer_head * bh; struct ext_dir_entry * de; *res_dir = NULL; if (!dir) return NULL; #ifdef NO_TRUNCATE if (namelen > EXT_NAME_LEN) return NULL; #else if (namelen > EXT_NAME_LEN) namelen = EXT_NAME_LEN; #endif /* entries = dir->i_size / (sizeof (struct ext_dir_entry)); */ if (!(block = dir->i_data[0])) return NULL; if (!(bh = bread(dir->i_dev,block))) return NULL; if (prev_dir) *prev_dir = NULL; if (next_dir) *next_dir = NULL; /* i = 0; */ offset = 0; de = (struct ext_dir_entry *) bh->b_data; while (offset < dir->i_size) { if ((char *)de >= BLOCK_SIZE+bh->b_data) { brelse(bh); bh = NULL; if (!(block = ext_bmap(dir,offset>>BLOCK_SIZE_BITS)) || !(bh = bread(dir->i_dev,block))) { /* i += EXT_DIR_ENTRIES_PER_BLOCK; */ /* offset += BLOCK_SIZE; */ continue; } de = (struct ext_dir_entry *) bh->b_data; if (prev_dir) *prev_dir = NULL; } if (ext_match(namelen,name,de)) { *res_dir = de; if (next_dir) if (offset + de->rec_len < dir->i_size) *next_dir = (struct ext_dir_entry *) ((char *) de + de->rec_len); else *next_dir = NULL; return bh; } offset += de->rec_len; if (prev_dir) *prev_dir = de; de = (struct ext_dir_entry *) ((char *) de + de->rec_len); /* i++; */ } brelse(bh); return NULL; } int ext_lookup(struct inode * dir,const char * name, int len, struct inode ** result) { int ino; struct ext_dir_entry * de; struct buffer_head * bh; *result = NULL; if (!dir) return -ENOENT; if (!S_ISDIR(dir->i_mode)) { iput(dir); return -ENOENT; } if (!(bh = ext_find_entry(dir,name,len,&de,NULL,NULL))) { iput(dir); return -ENOENT; } ino = de->inode; brelse(bh); if (!(*result = iget(dir->i_dev,ino))) { iput(dir); return -EACCES; } iput(dir); return 0; } /* * ext_add_entry() * * adds a file entry to the specified directory, using the same * semantics as ext_find_entry(). It returns NULL if it failed. * * NOTE!! The inode part of 'de' is left at 0 - which means you * may not sleep between calling this and putting something into * the entry, as someone else might have used it while you slept. */ static struct buffer_head * ext_add_entry(struct inode * dir, const char * name, int namelen, struct ext_dir_entry ** res_dir) { int block,i; long offset; unsigned short rec_len; struct buffer_head * bh; struct ext_dir_entry * de, * de1; *res_dir = NULL; if (!dir) return NULL; #ifdef NO_TRUNCATE if (namelen > EXT_NAME_LEN) return NULL; #else if (namelen > EXT_NAME_LEN) namelen = EXT_NAME_LEN; #endif if (!namelen) return NULL; if (!(block = dir->i_data[0])) return NULL; if (!(bh = bread(dir->i_dev,block))) return NULL; rec_len = ((8 + namelen + EXT_DIR_PAD - 1) / EXT_DIR_PAD) * EXT_DIR_PAD; /* i = 0; */ offset = 0; de = (struct ext_dir_entry *) bh->b_data; while (1) { if ((char *)de >= BLOCK_SIZE+bh->b_data && offset < dir->i_size) { #ifdef EXTFS_DEBUG printk ("ext_add_entry: skipping to next block\n"); #endif brelse(bh); bh = NULL; block = ext_create_block(dir,offset>>BLOCK_SIZE_BITS); if (!block) return NULL; if (!(bh = bread(dir->i_dev,block))) { /* i += EXT_DIR_ENTRIES_PER_BLOCK; */ offset += BLOCK_SIZE; continue; } de = (struct ext_dir_entry *) bh->b_data; } if (offset >= dir->i_size) { /* Check that the directory entry fits in the block */ if (offset % BLOCK_SIZE == 0 || (BLOCK_SIZE - (offset % BLOCK_SIZE)) < rec_len) { if ((offset % BLOCK_SIZE) != 0) { /* If the entry does not fit in the block, the remainder of the block becomes an unused entry */ de->inode = 0; de->rec_len = BLOCK_SIZE - (offset & (BLOCK_SIZE - 1)); de->name_len = 0; offset += de->rec_len; dir->i_size += de->rec_len; dir->i_dirt = 1; dir->i_ctime = CURRENT_TIME; bh->b_dirt = 1; } brelse (bh); bh = NULL; block = ext_create_block (dir,offset>>BLOCK_SIZE_BITS); #ifdef EXTFS_DEBUG printk ("ext_add_entry : creating next block\n"); #endif if (!block) return NULL; if (!(bh = bread(dir->i_dev,block))) return NULL; /* Other thing to do ??? */ de = (struct ext_dir_entry *) bh->b_data; } /* Allocate the entry */ de->inode=0; de->rec_len = rec_len; /* dir->i_size = (i+1)*sizeof(struct ext_dir_entry); */ dir->i_size += de->rec_len; dir->i_dirt = 1; dir->i_ctime = CURRENT_TIME; } if (!de->inode && de->rec_len >= rec_len) { if (de->rec_len > rec_len && de->rec_len - rec_len >= EXT_DIR_MIN_SIZE) { /* The found entry is too big : it is split into 2 ones : - the 1st one will be used to hold the name, - the 2nd one is unused */ de1 = (struct ext_dir_entry *) ((char *) de + rec_len); de1->inode = 0; de1->rec_len = de->rec_len - rec_len; de1->name_len = 0; de->rec_len = rec_len; } dir->i_mtime = CURRENT_TIME; de->name_len = namelen; for (i=0; i < namelen ; i++) de->name[i]=/*(i<namelen)?*/get_fs_byte(name+i)/*:0*/; bh->b_dirt = 1; *res_dir = de; return bh; } offset += de->rec_len; de = (struct ext_dir_entry *) ((char *) de + de->rec_len); } brelse(bh); return NULL; } int ext_create(struct inode * dir,const char * name, int len, int mode, struct inode ** result) { struct inode * inode; struct buffer_head * bh; struct ext_dir_entry * de; *result = NULL; if (!dir) return -ENOENT; inode = ext_new_inode(dir->i_dev); if (!inode) { iput(dir); return -ENOSPC; } inode->i_op = &ext_file_inode_operations; inode->i_mode = mode; inode->i_dirt = 1; bh = ext_add_entry(dir,name,len,&de); if (!bh) { inode->i_nlink--; inode->i_dirt = 1; iput(inode); iput(dir); return -ENOSPC; } de->inode = inode->i_ino; bh->b_dirt = 1; brelse(bh); iput(dir); *result = inode; return 0; } int ext_mknod(struct inode * dir, const char * name, int len, int mode, int rdev) { struct inode * inode; struct buffer_head * bh; struct ext_dir_entry * de; if (!dir) return -ENOENT; bh = ext_find_entry(dir,name,len,&de,NULL,NULL); if (bh) { brelse(bh); iput(dir); return -EEXIST; } inode = ext_new_inode(dir->i_dev); if (!inode) { iput(dir); return -ENOSPC; } inode->i_uid = current->euid; inode->i_mode = mode; inode->i_op = NULL; if (S_ISREG(inode->i_mode)) inode->i_op = &ext_file_inode_operations; else if (S_ISDIR(inode->i_mode)) inode->i_op = &ext_dir_inode_operations; else if (S_ISLNK(inode->i_mode)) inode->i_op = &ext_symlink_inode_operations; else if (S_ISCHR(inode->i_mode)) inode->i_op = &ext_chrdev_inode_operations; else if (S_ISBLK(inode->i_mode)) inode->i_op = &ext_blkdev_inode_operations; else if (S_ISFIFO(inode->i_mode)) { inode->i_op = &ext_fifo_inode_operations; inode->i_size = 0; inode->i_pipe = 1; PIPE_HEAD(*inode) = PIPE_TAIL(*inode) = 0; PIPE_READERS(*inode) = PIPE_WRITERS(*inode) = 0; } if (S_ISBLK(mode) || S_ISCHR(mode)) inode->i_rdev = rdev; inode->i_mtime = inode->i_atime = CURRENT_TIME; inode->i_dirt = 1; bh = ext_add_entry(dir,name,len,&de); if (!bh) { inode->i_nlink--; inode->i_dirt = 1; iput(inode); iput(dir); return -ENOSPC; } de->inode = inode->i_ino; bh->b_dirt = 1; brelse(bh); iput(dir); iput(inode); return 0; } int ext_mkdir(struct inode * dir, const char * name, int len, int mode) { struct inode * inode; struct buffer_head * bh, *dir_block; struct ext_dir_entry * de; bh = ext_find_entry(dir,name,len,&de,NULL,NULL); if (bh) { brelse(bh); iput(dir); return -EEXIST; } inode = ext_new_inode(dir->i_dev); if (!inode) { iput(dir); return -ENOSPC; } inode->i_op = &ext_dir_inode_operations; inode->i_size = 2 * 16; /* Each entry is coded on 16 bytes for "." and ".." - 4 bytes for the inode number, - 2 bytes for the record length - 2 bytes for the name length - 8 bytes for the name */ inode->i_mtime = inode->i_atime = CURRENT_TIME; if (!(inode->i_data[0] = ext_new_block(inode->i_dev))) { iput(dir); inode->i_nlink--; inode->i_dirt = 1; iput(inode); return -ENOSPC; } inode->i_dirt = 1; if (!(dir_block = bread(inode->i_dev,inode->i_data[0]))) { iput(dir); inode->i_nlink--; inode->i_dirt = 1; iput(inode); return -EIO; } de = (struct ext_dir_entry *) dir_block->b_data; de->inode=inode->i_ino; de->rec_len=16; de->name_len=1; strcpy(de->name,"."); /* de++; */ de = (struct ext_dir_entry *) ((char *) de + de->rec_len); de->inode = dir->i_ino; de->rec_len=16; de->name_len=2; strcpy(de->name,".."); inode->i_nlink = 2; dir_block->b_dirt = 1; brelse(dir_block); inode->i_mode = I_DIRECTORY | (mode & 0777 & ~current->umask); inode->i_dirt = 1; bh = ext_add_entry(dir,name,len,&de); if (!bh) { iput(dir); inode->i_nlink=0; iput(inode); return -ENOSPC; } de->inode = inode->i_ino; bh->b_dirt = 1; dir->i_nlink++; dir->i_dirt = 1; iput(dir); iput(inode); brelse(bh); return 0; } /* * routine to check that the specified directory is empty (for rmdir) */ static int empty_dir(struct inode * inode) { int /* nr, */ block; /* int len; */ unsigned long offset; struct buffer_head * bh; struct ext_dir_entry * de, * de1; /* len = inode->i_size / sizeof (struct ext_dir_entry); */ if (inode->i_size < 2 * 12 || !inode->i_data[0] || !(bh=bread(inode->i_dev,inode->i_data[0]))) { printk("warning - bad directory on dev %04x\n",inode->i_dev); return 0; } de = (struct ext_dir_entry *) bh->b_data; de1 = (struct ext_dir_entry *) ((char *) de + de->rec_len); if (de->inode != inode->i_ino || !de1->inode || strcmp(".",de->name) || strcmp("..",de1->name)) { printk("warning - bad directory on dev %04x\n",inode->i_dev); return 0; } /* nr = 2; */ offset = de->rec_len + de1->rec_len; de = (struct ext_dir_entry *) ((char *) de1 + de1->rec_len); while (offset < inode->i_size ) { if ((void *) de >= (void *) (bh->b_data+BLOCK_SIZE)) { brelse(bh); block = ext_bmap(inode, offset >> BLOCK_SIZE_BITS); if (!block) { offset += BLOCK_SIZE; continue; } if (!(bh=bread(inode->i_dev,block))) return 0; de = (struct ext_dir_entry *) bh->b_data; } if (de->inode) { brelse(bh); return 0; } offset += de->rec_len; de = (struct ext_dir_entry *) ((char *) de + de->rec_len); } brelse(bh); return 1; } static inline void ext_merge_entries (struct ext_dir_entry * de, struct ext_dir_entry * pde, struct ext_dir_entry * nde) { if (! nde->inode) de->rec_len += nde->rec_len; if (! pde->inode) pde->rec_len += de->rec_len; } int ext_rmdir(struct inode * dir, const char * name, int len) { int retval; struct inode * inode; struct buffer_head * bh; struct ext_dir_entry * de, * pde, * nde; inode = NULL; bh = ext_find_entry(dir,name,len,&de,&pde,&nde); retval = -ENOENT; if (!bh) goto end_rmdir; retval = -EPERM; if (!(inode = iget(dir->i_dev, de->inode))) goto end_rmdir; if ((dir->i_mode & S_ISVTX) && current->euid && inode->i_uid != current->euid) goto end_rmdir; if (inode->i_dev != dir->i_dev) goto end_rmdir; if (inode == dir) /* we may not delete ".", but "../dir" is ok */ goto end_rmdir; if (!S_ISDIR(inode->i_mode)) { retval = -ENOTDIR; goto end_rmdir; } if (!empty_dir(inode)) { retval = -ENOTEMPTY; goto end_rmdir; } if (inode->i_count > 1) { retval = -EBUSY; goto end_rmdir; } if (inode->i_nlink != 2) printk("empty directory has nlink!=2 (%d)\n",inode->i_nlink); de->inode = 0; de->name_len = 0; ext_merge_entries (de, pde, nde); bh->b_dirt = 1; inode->i_nlink=0; inode->i_dirt=1; dir->i_nlink--; dir->i_ctime = dir->i_mtime = CURRENT_TIME; dir->i_dirt=1; retval = 0; end_rmdir: iput(dir); iput(inode); brelse(bh); return retval; } int ext_unlink(struct inode * dir, const char * name, int len) { int retval; struct inode * inode; struct buffer_head * bh; struct ext_dir_entry * de, * pde, * nde; retval = -ENOENT; inode = NULL; bh = ext_find_entry(dir,name,len,&de,&pde,&nde); if (!bh) goto end_unlink; if (!(inode = iget(dir->i_dev, de->inode))) goto end_unlink; retval = -EPERM; if ((dir->i_mode & S_ISVTX) && !suser() && current->euid != inode->i_uid && current->euid != dir->i_uid) goto end_unlink; if (S_ISDIR(inode->i_mode)) goto end_unlink; if (!inode->i_nlink) { printk("Deleting nonexistent file (%04x:%d), %d\n", inode->i_dev,inode->i_ino,inode->i_nlink); inode->i_nlink=1; } de->inode = 0; de->name_len = 0; ext_merge_entries (de, pde, nde); bh->b_dirt = 1; inode->i_nlink--; inode->i_dirt = 1; inode->i_ctime = CURRENT_TIME; retval = 0; end_unlink: brelse(bh); iput(inode); iput(dir); return retval; } int ext_symlink(struct inode * dir, const char * name, int len, const char * symname) { struct ext_dir_entry * de; struct inode * inode = NULL; struct buffer_head * bh = NULL, * name_block = NULL; int i; char c; if (!(inode = ext_new_inode(dir->i_dev))) { iput(dir); return -ENOSPC; } inode->i_mode = S_IFLNK | 0777; inode->i_op = &ext_symlink_inode_operations; if (!(inode->i_data[0] = ext_new_block(inode->i_dev))) { iput(dir); inode->i_nlink--; inode->i_dirt = 1; iput(inode); return -ENOSPC; } inode->i_dirt = 1; if (!(name_block = bread(inode->i_dev,inode->i_data[0]))) { iput(dir); inode->i_nlink--; inode->i_dirt = 1; iput(inode); return -EIO; } i = 0; while (i < 1023 && (c=get_fs_byte(symname++))) name_block->b_data[i++] = c; name_block->b_data[i] = 0; name_block->b_dirt = 1; brelse(name_block); inode->i_size = i; inode->i_dirt = 1; bh = ext_find_entry(dir,name,len,&de,NULL,NULL); if (bh) { inode->i_nlink--; inode->i_dirt = 1; iput(inode); brelse(bh); iput(dir); return -EEXIST; } bh = ext_add_entry(dir,name,len,&de); if (!bh) { inode->i_nlink--; inode->i_dirt = 1; iput(inode); iput(dir); return -ENOSPC; } de->inode = inode->i_ino; bh->b_dirt = 1; brelse(bh); iput(dir); iput(inode); return 0; } int ext_link(struct inode * oldinode, struct inode * dir, const char * name, int len) { struct ext_dir_entry * de; struct buffer_head * bh; if (S_ISDIR(oldinode->i_mode)) { iput(oldinode); iput(dir); return -EPERM; } bh = ext_find_entry(dir,name,len,&de,NULL,NULL); if (bh) { brelse(bh); iput(dir); iput(oldinode); return -EEXIST; } bh = ext_add_entry(dir,name,len,&de); if (!bh) { iput(dir); iput(oldinode); return -ENOSPC; } de->inode = oldinode->i_ino; bh->b_dirt = 1; brelse(bh); iput(dir); oldinode->i_nlink++; oldinode->i_ctime = CURRENT_TIME; oldinode->i_dirt = 1; iput(oldinode); return 0; } static int subdir(struct inode * new, struct inode * old) { unsigned short fs; int ino; int result; __asm__("mov %%fs,%0":"=r" (fs)); __asm__("mov %0,%%fs"::"r" ((unsigned short) 0x10)); new->i_count++; result = 0; for (;;) { if (new == old) { result = 1; break; } if (new->i_dev != old->i_dev) break; ino = new->i_ino; if (ext_lookup(new,"..",2,&new)) break; if (new->i_ino == ino) break; } iput(new); __asm__("mov %0,%%fs"::"r" (fs)); return result; } #define PARENT_INO(buffer) \ ((struct ext_dir_entry *) ((char *) buffer + \ ((struct ext_dir_entry *) buffer)->rec_len))->inode /* (((struct ext_dir_entry *) (buffer))[1].inode) */ #define PARENT_NAME(buffer) \ ((struct ext_dir_entry *) ((char *) buffer + \ ((struct ext_dir_entry *) buffer)->rec_len))->name /* (((struct ext_dir_entry *) (buffer))[1].name) */ /* * rename uses retrying to avoid race-conditions: at least they should be minimal. * it tries to allocate all the blocks, then sanity-checks, and if the sanity- * checks fail, it tries to restart itself again. Very practical - no changes * are done until we know everything works ok.. and then all the changes can be * done in one fell swoop when we have claimed all the buffers needed. * * Anybody can rename anything with this: the permission checks are left to the * higher-level routines. */ static int do_ext_rename(struct inode * old_dir, const char * old_name, int old_len, struct inode * new_dir, const char * new_name, int new_len) { struct inode * old_inode, * new_inode; struct buffer_head * old_bh, * new_bh, * dir_bh; struct ext_dir_entry * old_de, * new_de, * pde, * nde; int retval; goto start_up; try_again: brelse(old_bh); brelse(new_bh); brelse(dir_bh); iput(old_inode); iput(new_inode); current->counter = 0; schedule(); start_up: old_inode = new_inode = NULL; old_bh = new_bh = dir_bh = NULL; old_bh = ext_find_entry(old_dir,old_name,old_len,&old_de,&pde,&nde); retval = -ENOENT; if (!old_bh) goto end_rename; old_inode = iget(old_dir->i_dev, old_de->inode); if (!old_inode) goto end_rename; if ((old_dir->i_mode & S_ISVTX) && current->euid != old_inode->i_uid && current->euid != old_dir->i_uid && !suser()) goto end_rename; new_bh = ext_find_entry(new_dir,new_name,new_len,&new_de,NULL,NULL); if (new_bh) { new_inode = iget(new_dir->i_dev, new_de->inode); if (!new_inode) { brelse(new_bh); new_bh = NULL; } } if (new_inode == old_inode) { retval = 0; goto end_rename; } if (S_ISDIR(old_inode->i_mode)) { retval = -EEXIST; if (new_bh) goto end_rename; retval = -EACCES; if (!permission(old_inode, MAY_WRITE)) goto end_rename; retval = -EINVAL; if (subdir(new_dir, old_inode)) goto end_rename; retval = -EIO; if (!old_inode->i_data[0]) goto end_rename; if (!(dir_bh = bread(old_inode->i_dev, old_inode->i_data[0]))) goto end_rename; if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino) goto end_rename; } if (!new_bh) new_bh = ext_add_entry(new_dir,new_name,new_len,&new_de); retval = -ENOSPC; if (!new_bh) goto end_rename; /* sanity checking before doing the rename - avoid races */ if (new_inode && (new_de->inode != new_inode->i_ino)) goto try_again; if (new_de->inode && !new_inode) goto try_again; if (old_de->inode != old_inode->i_ino) goto try_again; /* ok, that's it */ old_de->inode = 0; old_de->name_len = 0; ext_merge_entries (old_de, pde, nde); new_de->inode = old_inode->i_ino; if (new_inode) { new_inode->i_nlink--; new_inode->i_dirt = 1; } old_bh->b_dirt = 1; new_bh->b_dirt = 1; if (dir_bh) { PARENT_INO(dir_bh->b_data) = new_dir->i_ino; dir_bh->b_dirt = 1; old_dir->i_nlink--; new_dir->i_nlink++; old_dir->i_dirt = 1; new_dir->i_dirt = 1; } retval = 0; end_rename: brelse(dir_bh); brelse(old_bh); brelse(new_bh); iput(old_inode); iput(new_inode); iput(old_dir); iput(new_dir); return retval; } /* * Ok, rename also locks out other renames, as they can change the parent of * a directory, and we don't want any races. Other races are checked for by * "do_rename()", which restarts if there are inconsistencies. * * Note that there is no race between different filesystems: it's only within * the same device that races occur: many renames can happen at once, as long * as they are on different partitions. */ int ext_rename(struct inode * old_dir, const char * old_name, int old_len, struct inode * new_dir, const char * new_name, int new_len) { static struct task_struct * wait = NULL; static int lock = 0; int result; while (lock) sleep_on(&wait); lock = 1; result = do_ext_rename(old_dir, old_name, old_len, new_dir, new_name, new_len); lock = 0; wake_up(&wait); return result; }