/* * linux/fs/minix/namei.c * * (C) 1991 Linus Torvalds */ #include <linux/sched.h> #include <linux/minix_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 > MINIX_NAME_LEN chars to be * truncated. Else they will be disallowed. */ /* #define NO_TRUNCATE */ /* * ok, we cannot use strncmp, as the name is not in our data space. * Thus we'll have to use minix_match. No big problem. Match also makes * some sanity tests. * * NOTE! unlike strncmp, minix_match returns 1 for success, 0 for failure. */ static int minix_match(int len,const char * name,struct minix_dir_entry * de) { register int same __asm__("ax"); if (!de || !de->inode || len > MINIX_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 < MINIX_NAME_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; } /* * minix_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. */ static struct buffer_head * minix_find_entry(struct inode * dir, const char * name, int namelen, struct minix_dir_entry ** res_dir) { int entries; int block,i; struct buffer_head * bh; struct minix_dir_entry * de; *res_dir = NULL; if (!dir) return NULL; #ifdef NO_TRUNCATE if (namelen > MINIX_NAME_LEN) return NULL; #else if (namelen > MINIX_NAME_LEN) namelen = MINIX_NAME_LEN; #endif entries = dir->i_size / (sizeof (struct minix_dir_entry)); if (!(block = dir->i_data[0])) return NULL; if (!(bh = bread(dir->i_dev,block))) return NULL; i = 0; de = (struct minix_dir_entry *) bh->b_data; while (i < entries) { if ((char *)de >= BLOCK_SIZE+bh->b_data) { brelse(bh); bh = NULL; if (!(block = minix_bmap(dir,i/MINIX_DIR_ENTRIES_PER_BLOCK)) || !(bh = bread(dir->i_dev,block))) { i += MINIX_DIR_ENTRIES_PER_BLOCK; continue; } de = (struct minix_dir_entry *) bh->b_data; } if (minix_match(namelen,name,de)) { *res_dir = de; return bh; } de++; i++; } brelse(bh); return NULL; } int minix_lookup(struct inode * dir,const char * name, int len, struct inode ** result) { int ino; struct minix_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 = minix_find_entry(dir,name,len,&de))) { iput(dir); return -ENOENT; } ino = de->inode; brelse(bh); if (!(*result = iget(dir->i_dev,ino))) { iput(dir); return -EACCES; } iput(dir); return 0; } /* * minix_add_entry() * * adds a file entry to the specified directory, using the same * semantics as minix_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 * minix_add_entry(struct inode * dir, const char * name, int namelen, struct minix_dir_entry ** res_dir) { int block,i; struct buffer_head * bh; struct minix_dir_entry * de; *res_dir = NULL; if (!dir) return NULL; #ifdef NO_TRUNCATE if (namelen > MINIX_NAME_LEN) return NULL; #else if (namelen > MINIX_NAME_LEN) namelen = MINIX_NAME_LEN; #endif if (!namelen) return NULL; if (!(block = dir->i_data[0])) return NULL; if (!(bh = bread(dir->i_dev,block))) return NULL; i = 0; de = (struct minix_dir_entry *) bh->b_data; while (1) { if ((char *)de >= BLOCK_SIZE+bh->b_data) { brelse(bh); bh = NULL; block = minix_create_block(dir,i/MINIX_DIR_ENTRIES_PER_BLOCK); if (!block) return NULL; if (!(bh = bread(dir->i_dev,block))) { i += MINIX_DIR_ENTRIES_PER_BLOCK; continue; } de = (struct minix_dir_entry *) bh->b_data; } if (i*sizeof(struct minix_dir_entry) >= dir->i_size) { de->inode=0; dir->i_size = (i+1)*sizeof(struct minix_dir_entry); dir->i_dirt = 1; dir->i_ctime = CURRENT_TIME; } if (!de->inode) { dir->i_mtime = CURRENT_TIME; for (i=0; i < MINIX_NAME_LEN ; i++) de->name[i]=(i<namelen)?get_fs_byte(name+i):0; bh->b_dirt = 1; *res_dir = de; return bh; } de++; i++; } brelse(bh); return NULL; } int minix_create(struct inode * dir,const char * name, int len, int mode, struct inode ** result) { struct inode * inode; struct buffer_head * bh; struct minix_dir_entry * de; *result = NULL; if (!dir) return -ENOENT; inode = minix_new_inode(dir->i_dev); if (!inode) { iput(dir); return -ENOSPC; } inode->i_op = &minix_file_inode_operations; inode->i_mode = mode; inode->i_dirt = 1; bh = minix_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 minix_mknod(struct inode * dir, const char * name, int len, int mode, int rdev) { struct inode * inode; struct buffer_head * bh; struct minix_dir_entry * de; if (!dir) return -ENOENT; bh = minix_find_entry(dir,name,len,&de); if (bh) { brelse(bh); iput(dir); return -EEXIST; } inode = minix_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 = &minix_file_inode_operations; else if (S_ISDIR(inode->i_mode)) inode->i_op = &minix_dir_inode_operations; else if (S_ISLNK(inode->i_mode)) inode->i_op = &minix_symlink_inode_operations; else if (S_ISCHR(inode->i_mode)) inode->i_op = &minix_chrdev_inode_operations; else if (S_ISBLK(inode->i_mode)) inode->i_op = &minix_blkdev_inode_operations; else if (S_ISFIFO(inode->i_mode)) { inode->i_op = &minix_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 = minix_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 minix_mkdir(struct inode * dir, const char * name, int len, int mode) { struct inode * inode; struct buffer_head * bh, *dir_block; struct minix_dir_entry * de; bh = minix_find_entry(dir,name,len,&de); if (bh) { brelse(bh); iput(dir); return -EEXIST; } inode = minix_new_inode(dir->i_dev); if (!inode) { iput(dir); return -ENOSPC; } inode->i_op = &minix_dir_inode_operations; inode->i_size = 2 * sizeof (struct minix_dir_entry); inode->i_mtime = inode->i_atime = CURRENT_TIME; if (!(inode->i_data[0] = minix_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 minix_dir_entry *) dir_block->b_data; de->inode=inode->i_ino; strcpy(de->name,"."); de++; de->inode = dir->i_ino; 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 = minix_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; struct buffer_head * bh; struct minix_dir_entry * de; len = inode->i_size / sizeof (struct minix_dir_entry); if (len<2 || !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 minix_dir_entry *) bh->b_data; if (de[0].inode != inode->i_ino || !de[1].inode || strcmp(".",de[0].name) || strcmp("..",de[1].name)) { printk("warning - bad directory on dev %04x\n",inode->i_dev); return 0; } nr = 2; de += 2; while (nr<len) { if ((void *) de >= (void *) (bh->b_data+BLOCK_SIZE)) { brelse(bh); block = minix_bmap(inode,nr/MINIX_DIR_ENTRIES_PER_BLOCK); if (!block) { nr += MINIX_DIR_ENTRIES_PER_BLOCK; continue; } if (!(bh=bread(inode->i_dev,block))) return 0; de = (struct minix_dir_entry *) bh->b_data; } if (de->inode) { brelse(bh); return 0; } de++; nr++; } brelse(bh); return 1; } int minix_rmdir(struct inode * dir, const char * name, int len) { int retval; struct inode * inode; struct buffer_head * bh; struct minix_dir_entry * de; inode = NULL; bh = minix_find_entry(dir,name,len,&de); 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; 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 minix_unlink(struct inode * dir, const char * name, int len) { int retval; struct inode * inode; struct buffer_head * bh; struct minix_dir_entry * de; retval = -ENOENT; inode = NULL; bh = minix_find_entry(dir,name,len,&de); 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; 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 minix_symlink(struct inode * dir, const char * name, int len, const char * symname) { struct minix_dir_entry * de; struct inode * inode = NULL; struct buffer_head * bh = NULL, * name_block = NULL; int i; char c; if (!(inode = minix_new_inode(dir->i_dev))) { iput(dir); return -ENOSPC; } inode->i_mode = S_IFLNK | 0777; inode->i_op = &minix_symlink_inode_operations; if (!(inode->i_data[0] = minix_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 = minix_find_entry(dir,name,len,&de); if (bh) { inode->i_nlink--; inode->i_dirt = 1; iput(inode); brelse(bh); iput(dir); return -EEXIST; } bh = minix_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 minix_link(struct inode * oldinode, struct inode * dir, const char * name, int len) { struct minix_dir_entry * de; struct buffer_head * bh; if (S_ISDIR(oldinode->i_mode)) { iput(oldinode); iput(dir); return -EPERM; } bh = minix_find_entry(dir,name,len,&de); if (bh) { brelse(bh); iput(dir); iput(oldinode); return -EEXIST; } bh = minix_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 (minix_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 minix_dir_entry *) (buffer))[1].inode) #define PARENT_NAME(buffer) \ (((struct minix_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_minix_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 minix_dir_entry * old_de, * new_de; 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 = minix_find_entry(old_dir,old_name,old_len,&old_de); 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 = minix_find_entry(new_dir,new_name,new_len,&new_de); 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 = minix_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; 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 minix_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_minix_rename(old_dir, old_name, old_len, new_dir, new_name, new_len); lock = 0; wake_up(&wait); return result; }