1 files changed, 778 insertions, 0 deletions

diff --git a/src/fs/namei.c b/src/fs/namei.c
new file mode 100644
index 0000000..97d0de4
--- /dev/null
+++ b/src/fs/namei.c
@@ -0,0 +1,778 @@
+/*
+ *  linux/fs/namei.c
+ *
+ *  (C) 1991  Linus Torvalds
+ */
+
+/*
+ * Some corrections by tytso.
+ */
+
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <asm/segment.h>
+
+#include <string.h> 
+#include <fcntl.h>
+#include <errno.h>
+#include <const.h>
+#include <sys/stat.h>
+
+#define ACC_MODE(x) ("\004\002\006\377"[(x)&O_ACCMODE])
+
+/*
+ * comment out this line if you want names > NAME_LEN chars to be
+ * truncated. Else they will be disallowed.
+ */
+/* #define NO_TRUNCATE */
+
+#define MAY_EXEC 1
+#define MAY_WRITE 2
+#define MAY_READ 4
+
+/*
+ *      permission()
+ *
+ * is used to check for read/write/execute permissions on a file.
+ * I don't know if we should look at just the euid or both euid and
+ * uid, but that should be easily changed.
+ */
+static int permission(struct m_inode * inode,int mask)
+{
+        int mode = inode->i_mode;
+
+/* special case: not even root can read/write a deleted file */
+        if (inode->i_dev && !inode->i_nlinks)
+                return 0;
+        else if (current->euid==inode->i_uid)
+                mode >>= 6;
+        else if (current->egid==inode->i_gid)
+                mode >>= 3;
+        if (((mode & mask & 0007) == mask) || suser())
+                return 1;
+        return 0;
+}
+
+/*
+ * ok, we cannot use strncmp, as the name is not in our data space.
+ * Thus we'll have to use match. No big problem. Match also makes
+ * some sanity tests.
+ *
+ * NOTE! unlike strncmp, match returns 1 for success, 0 for failure.
+ */
+static int match(int len,const char * name,struct dir_entry * de)
+{
+        register int same ;
+
+        if (!de || !de->inode || len > NAME_LEN)
+                return 0;
+        if (len < 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)
+                );
+        return same;
+}
+
+/*
+ *      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.
+ *
+ * This also takes care of the few special cases due to '..'-traversal
+ * over a pseudo-root and a mount point.
+ */
+static struct buffer_head * find_entry(struct m_inode ** dir,
+        const char * name, int namelen, struct dir_entry ** res_dir)
+{
+        int entries;
+        int block,i;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+        struct super_block * sb;
+
+#ifdef NO_TRUNCATE
+        if (namelen > NAME_LEN)
+                return NULL;
+#else
+        if (namelen > NAME_LEN)
+                namelen = NAME_LEN;
+#endif
+        entries = (*dir)->i_size / (sizeof (struct dir_entry));
+        *res_dir = NULL;
+        if (!namelen)
+                return NULL;
+/* check for '..', as we might have to do some "magic" for it */
+        if (namelen==2 && get_fs_byte(name)=='.' && get_fs_byte(name+1)=='.') {
+/* '..' in a pseudo-root results in a faked '.' (just change namelen) */
+                if ((*dir) == current->root)
+                        namelen=1;
+                else if ((*dir)->i_num == ROOT_INO) {
+/* '..' over a mount-point results in 'dir' being exchanged for the mounted
+   directory-inode. NOTE! We set mounted, so that we can iput the new dir */
+                        sb=get_super((*dir)->i_dev);
+                        if (sb->s_imount) {
+                                iput(*dir);
+                                (*dir)=sb->s_imount;
+                                (*dir)->i_count++;
+                        }
+                }
+        }
+        if (!(block = (*dir)->i_zone[0]))
+                return NULL;
+        if (!(bh = bread((*dir)->i_dev,block)))
+                return NULL;
+        i = 0;
+        de = (struct dir_entry *) bh->b_data;
+        while (i < entries) {
+                if ((char *)de >= BLOCK_SIZE+bh->b_data) {
+                        brelse(bh);
+                        bh = NULL;
+                        if (!(block = bmap(*dir,i/DIR_ENTRIES_PER_BLOCK)) ||
+                            !(bh = bread((*dir)->i_dev,block))) {
+                                i += DIR_ENTRIES_PER_BLOCK;
+                                continue;
+                        }
+                        de = (struct dir_entry *) bh->b_data;
+                }
+                if (match(namelen,name,de)) {
+                        *res_dir = de;
+                        return bh;
+                }
+                de++;
+                i++;
+        }
+        brelse(bh);
+        return NULL;
+}
+
+/*
+ *      add_entry()
+ *
+ * adds a file entry to the specified directory, using the same
+ * semantics as 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 * add_entry(struct m_inode * dir,
+        const char * name, int namelen, struct dir_entry ** res_dir)
+{
+        int block,i;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+
+        *res_dir = NULL;
+#ifdef NO_TRUNCATE
+        if (namelen > NAME_LEN)
+                return NULL;
+#else
+        if (namelen > NAME_LEN)
+                namelen = NAME_LEN;
+#endif
+        if (!namelen)
+                return NULL;
+        if (!(block = dir->i_zone[0]))
+                return NULL;
+        if (!(bh = bread(dir->i_dev,block)))
+                return NULL;
+        i = 0;
+        de = (struct dir_entry *) bh->b_data;
+        while (1) {
+                if ((char *)de >= BLOCK_SIZE+bh->b_data) {
+                        brelse(bh);
+                        bh = NULL;
+                        block = create_block(dir,i/DIR_ENTRIES_PER_BLOCK);
+                        if (!block)
+                                return NULL;
+                        if (!(bh = bread(dir->i_dev,block))) {
+                                i += DIR_ENTRIES_PER_BLOCK;
+                                continue;
+                        }
+                        de = (struct dir_entry *) bh->b_data;
+                }
+                if (i*sizeof(struct dir_entry) >= dir->i_size) {
+                        de->inode=0;
+                        dir->i_size = (i+1)*sizeof(struct dir_entry);
+                        dir->i_dirt = 1;
+                        dir->i_ctime = CURRENT_TIME;
+                }
+                if (!de->inode) {
+                        dir->i_mtime = CURRENT_TIME;
+                        for (i=0; i < 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;
+}
+
+/*
+ *      get_dir()
+ *
+ * Getdir traverses the pathname until it hits the topmost directory.
+ * It returns NULL on failure.
+ */
+static struct m_inode * get_dir(const char * pathname)
+{
+        char c;
+        const char * thisname;
+        struct m_inode * inode;
+        struct buffer_head * bh;
+        int namelen,inr,idev;
+        struct dir_entry * de;
+
+        if (!current->root || !current->root->i_count)
+                panic("No root inode");
+        if (!current->pwd || !current->pwd->i_count)
+                panic("No cwd inode");
+        if ((c=get_fs_byte(pathname))=='/') {
+                inode = current->root;
+                pathname++;
+        } else if (c)
+                inode = current->pwd;
+        else
+                return NULL;    /* empty name is bad */
+        inode->i_count++;
+        while (1) {
+                thisname = pathname;
+                if (!S_ISDIR(inode->i_mode) || !permission(inode,MAY_EXEC)) {
+                        iput(inode);
+                        return NULL;
+                }
+                for(namelen=0;(c=get_fs_byte(pathname++))&&(c!='/');namelen++)
+                        /* nothing */ ;
+                if (!c)
+                        return inode;
+                if (!(bh = find_entry(&inode,thisname,namelen,&de))) {
+                        iput(inode);
+                        return NULL;
+                }
+                inr = de->inode;
+                idev = inode->i_dev;
+                brelse(bh);
+                iput(inode);
+                if (!(inode = iget(idev,inr)))
+                        return NULL;
+        }
+}
+
+/*
+ *      dir_namei()
+ *
+ * dir_namei() returns the inode of the directory of the
+ * specified name, and the name within that directory.
+ */
+static struct m_inode * dir_namei(const char * pathname,
+        int * namelen, const char ** name)
+{
+        char c;
+        const char * basename;
+        struct m_inode * dir;
+
+        if (!(dir = get_dir(pathname)))
+                return NULL;
+        basename = pathname;
+        while ((c=get_fs_byte(pathname++)))
+                if (c=='/')
+                        basename=pathname;
+        *namelen = pathname-basename-1;
+        *name = basename;
+        return dir;
+}
+
+/*
+ *      namei()
+ *
+ * is used by most simple commands to get the inode of a specified name.
+ * Open, link etc use their own routines, but this is enough for things
+ * like 'chmod' etc.
+ */
+struct m_inode * namei(const char * pathname)
+{
+        const char * basename;
+        int inr,dev,namelen;
+        struct m_inode * dir;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+
+        if (!(dir = dir_namei(pathname,&namelen,&basename)))
+                return NULL;
+        if (!namelen)                   /* special case: '/usr/' etc */
+                return dir;
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (!bh) {
+                iput(dir);
+                return NULL;
+        }
+        inr = de->inode;
+        dev = dir->i_dev;
+        brelse(bh);
+        iput(dir);
+        dir=iget(dev,inr);
+        if (dir) {
+                dir->i_atime=CURRENT_TIME;
+                dir->i_dirt=1;
+        }
+        return dir;
+}
+
+/*
+ *      open_namei()
+ *
+ * namei for open - this is in fact almost the whole open-routine.
+ */
+int open_namei(const char * pathname, int flag, int mode,
+        struct m_inode ** res_inode)
+{
+        const char * basename;
+        int inr,dev,namelen;
+        struct m_inode * dir, *inode;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+
+        if ((flag & O_TRUNC) && !(flag & O_ACCMODE))
+                flag |= O_WRONLY;
+        mode &= 0777 & ~current->umask;
+        mode |= I_REGULAR;
+        if (!(dir = dir_namei(pathname,&namelen,&basename)))
+                return -ENOENT;
+        if (!namelen) {                 /* special case: '/usr/' etc */
+                if (!(flag & (O_ACCMODE|O_CREAT|O_TRUNC))) {
+                        *res_inode=dir;
+                        return 0;
+                }
+                iput(dir);
+                return -EISDIR;
+        }
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (!bh) {
+                if (!(flag & O_CREAT)) {
+                        iput(dir);
+                        return -ENOENT;
+                }
+                if (!permission(dir,MAY_WRITE)) {
+                        iput(dir);
+                        return -EACCES;
+                }
+                inode = new_inode(dir->i_dev);
+                if (!inode) {
+                        iput(dir);
+                        return -ENOSPC;
+                }
+                inode->i_uid = current->euid;
+                inode->i_mode = mode;
+                inode->i_dirt = 1;
+                bh = add_entry(dir,basename,namelen,&de);
+                if (!bh) {
+                        inode->i_nlinks--;
+                        iput(inode);
+                        iput(dir);
+                        return -ENOSPC;
+                }
+                de->inode = inode->i_num;
+                bh->b_dirt = 1;
+                brelse(bh);
+                iput(dir);
+                *res_inode = inode;
+                return 0;
+        }
+        inr = de->inode;
+        dev = dir->i_dev;
+        brelse(bh);
+        iput(dir);
+        if (flag & O_EXCL)
+                return -EEXIST;
+        if (!(inode=iget(dev,inr)))
+                return -EACCES;
+        if ((S_ISDIR(inode->i_mode) && (flag & O_ACCMODE)) ||
+            !permission(inode,ACC_MODE(flag))) {
+                iput(inode);
+                return -EPERM;
+        }
+        inode->i_atime = CURRENT_TIME;
+        if (flag & O_TRUNC)
+                truncate(inode);
+        *res_inode = inode;
+        return 0;
+}
+
+int sys_mknod(const char * filename, int mode, int dev)
+{
+        const char * basename;
+        int namelen;
+        struct m_inode * dir, * inode;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+        
+        if (!suser())
+                return -EPERM;
+        if (!(dir = dir_namei(filename,&namelen,&basename)))
+                return -ENOENT;
+        if (!namelen) {
+                iput(dir);
+                return -ENOENT;
+        }
+        if (!permission(dir,MAY_WRITE)) {
+                iput(dir);
+                return -EPERM;
+        }
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (bh) {
+                brelse(bh);
+                iput(dir);
+                return -EEXIST;
+        }
+        inode = new_inode(dir->i_dev);
+        if (!inode) {
+                iput(dir);
+                return -ENOSPC;
+        }
+        inode->i_mode = mode;
+        if (S_ISBLK(mode) || S_ISCHR(mode))
+                inode->i_zone[0] = dev;
+        inode->i_mtime = inode->i_atime = CURRENT_TIME;
+        inode->i_dirt = 1;
+        bh = add_entry(dir,basename,namelen,&de);
+        if (!bh) {
+                iput(dir);
+                inode->i_nlinks=0;
+                iput(inode);
+                return -ENOSPC;
+        }
+        de->inode = inode->i_num;
+        bh->b_dirt = 1;
+        iput(dir);
+        iput(inode);
+        brelse(bh);
+        return 0;
+}
+
+int sys_mkdir(const char * pathname, int mode)
+{
+        const char * basename;
+        int namelen;
+        struct m_inode * dir, * inode;
+        struct buffer_head * bh, *dir_block;
+        struct dir_entry * de;
+
+        if (!suser())
+                return -EPERM;
+        if (!(dir = dir_namei(pathname,&namelen,&basename)))
+                return -ENOENT;
+        if (!namelen) {
+                iput(dir);
+                return -ENOENT;
+        }
+        if (!permission(dir,MAY_WRITE)) {
+                iput(dir);
+                return -EPERM;
+        }
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (bh) {
+                brelse(bh);
+                iput(dir);
+                return -EEXIST;
+        }
+        inode = new_inode(dir->i_dev);
+        if (!inode) {
+                iput(dir);
+                return -ENOSPC;
+        }
+        inode->i_size = 32;
+        inode->i_dirt = 1;
+        inode->i_mtime = inode->i_atime = CURRENT_TIME;
+        if (!(inode->i_zone[0]=new_block(inode->i_dev))) {
+                iput(dir);
+                inode->i_nlinks--;
+                iput(inode);
+                return -ENOSPC;
+        }
+        inode->i_dirt = 1;
+        if (!(dir_block=bread(inode->i_dev,inode->i_zone[0]))) {
+                iput(dir);
+                free_block(inode->i_dev,inode->i_zone[0]);
+                inode->i_nlinks--;
+                iput(inode);
+                return -ERROR;
+        }
+        de = (struct dir_entry *) dir_block->b_data;
+        de->inode=inode->i_num;
+        strcpy(de->name,".");
+        de++;
+        de->inode = dir->i_num;
+        strcpy(de->name,"..");
+        inode->i_nlinks = 2;
+        dir_block->b_dirt = 1;
+        brelse(dir_block);
+        inode->i_mode = I_DIRECTORY | (mode & 0777 & ~current->umask);
+        inode->i_dirt = 1;
+        bh = add_entry(dir,basename,namelen,&de);
+        if (!bh) {
+                iput(dir);
+                free_block(inode->i_dev,inode->i_zone[0]);
+                inode->i_nlinks=0;
+                iput(inode);
+                return -ENOSPC;
+        }
+        de->inode = inode->i_num;
+        bh->b_dirt = 1;
+        dir->i_nlinks++;
+        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 m_inode * inode)
+{
+        int nr,block;
+        int len;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+
+        len = inode->i_size / sizeof (struct dir_entry);
+        if (len<2 || !inode->i_zone[0] ||
+            !(bh=bread(inode->i_dev,inode->i_zone[0]))) {
+                printk("warning - bad directory on dev %04x\n",inode->i_dev);
+                return 0;
+        }
+        de = (struct dir_entry *) bh->b_data;
+        if (de[0].inode != inode->i_num || !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=bmap(inode,nr/DIR_ENTRIES_PER_BLOCK);
+                        if (!block) {
+                                nr += DIR_ENTRIES_PER_BLOCK;
+                                continue;
+                        }
+                        if (!(bh=bread(inode->i_dev,block)))
+                                return 0;
+                        de = (struct dir_entry *) bh->b_data;
+                }
+                if (de->inode) {
+                        brelse(bh);
+                        return 0;
+                }
+                de++;
+                nr++;
+        }
+        brelse(bh);
+        return 1;
+}
+
+int sys_rmdir(const char * name)
+{
+        const char * basename;
+        int namelen;
+        struct m_inode * dir, * inode;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+
+        if (!suser())
+                return -EPERM;
+        if (!(dir = dir_namei(name,&namelen,&basename)))
+                return -ENOENT;
+        if (!namelen) {
+                iput(dir);
+                return -ENOENT;
+        }
+        if (!permission(dir,MAY_WRITE)) {
+                iput(dir);
+                return -EPERM;
+        }
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (!bh) {
+                iput(dir);
+                return -ENOENT;
+        }
+        if (!(inode = iget(dir->i_dev, de->inode))) {
+                iput(dir);
+                brelse(bh);
+                return -EPERM;
+        }
+        if ((dir->i_mode & S_ISVTX) && current->euid &&
+            inode->i_uid != current->euid) {
+                iput(dir);
+                iput(inode);
+                brelse(bh);
+                return -EPERM;
+        }
+        if (inode->i_dev != dir->i_dev || inode->i_count>1) {
+                iput(dir);
+                iput(inode);
+                brelse(bh);
+                return -EPERM;
+        }
+        if (inode == dir) {     /* we may not delete ".", but "../dir" is ok */
+                iput(inode);
+                iput(dir);
+                brelse(bh);
+                return -EPERM;
+        }
+        if (!S_ISDIR(inode->i_mode)) {
+                iput(inode);
+                iput(dir);
+                brelse(bh);
+                return -ENOTDIR;
+        }
+        if (!empty_dir(inode)) {
+                iput(inode);
+                iput(dir);
+                brelse(bh);
+                return -ENOTEMPTY;
+        }
+        if (inode->i_nlinks != 2)
+                printk("empty directory has nlink!=2 (%d)",inode->i_nlinks);
+        de->inode = 0;
+        bh->b_dirt = 1;
+        brelse(bh);
+        inode->i_nlinks=0;
+        inode->i_dirt=1;
+        dir->i_nlinks--;
+        dir->i_ctime = dir->i_mtime = CURRENT_TIME;
+        dir->i_dirt=1;
+        iput(dir);
+        iput(inode);
+        return 0;
+}
+
+int sys_unlink(const char * name)
+{
+        const char * basename;
+        int namelen;
+        struct m_inode * dir, * inode;
+        struct buffer_head * bh;
+        struct dir_entry * de;
+
+        if (!(dir = dir_namei(name,&namelen,&basename)))
+                return -ENOENT;
+        if (!namelen) {
+                iput(dir);
+                return -ENOENT;
+        }
+        if (!permission(dir,MAY_WRITE)) {
+                iput(dir);
+                return -EPERM;
+        }
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (!bh) {
+                iput(dir);
+                return -ENOENT;
+        }
+        if (!(inode = iget(dir->i_dev, de->inode))) {
+                iput(dir);
+                brelse(bh);
+                return -ENOENT;
+        }
+        if ((dir->i_mode & S_ISVTX) && !suser() &&
+            current->euid != inode->i_uid &&
+            current->euid != dir->i_uid) {
+                iput(dir);
+                iput(inode);
+                brelse(bh);
+                return -EPERM;
+        }
+        if (S_ISDIR(inode->i_mode)) {
+                iput(inode);
+                iput(dir);
+                brelse(bh);
+                return -EPERM;
+        }
+        if (!inode->i_nlinks) {
+                printk("Deleting nonexistent file (%04x:%d), %d\n",
+                        inode->i_dev,inode->i_num,inode->i_nlinks);
+                inode->i_nlinks=1;
+        }
+        de->inode = 0;
+        bh->b_dirt = 1;
+        brelse(bh);
+        inode->i_nlinks--;
+        inode->i_dirt = 1;
+        inode->i_ctime = CURRENT_TIME;
+        iput(inode);
+        iput(dir);
+        return 0;
+}
+
+int sys_link(const char * oldname, const char * newname)
+{
+        struct dir_entry * de;
+        struct m_inode * oldinode, * dir;
+        struct buffer_head * bh;
+        const char * basename;
+        int namelen;
+
+        oldinode=namei(oldname);
+        if (!oldinode)
+                return -ENOENT;
+        if (S_ISDIR(oldinode->i_mode)) {
+                iput(oldinode);
+                return -EPERM;
+        }
+        dir = dir_namei(newname,&namelen,&basename);
+        if (!dir) {
+                iput(oldinode);
+                return -EACCES;
+        }
+        if (!namelen) {
+                iput(oldinode);
+                iput(dir);
+                return -EPERM;
+        }
+        if (dir->i_dev != oldinode->i_dev) {
+                iput(dir);
+                iput(oldinode);
+                return -EXDEV;
+        }
+        if (!permission(dir,MAY_WRITE)) {
+                iput(dir);
+                iput(oldinode);
+                return -EACCES;
+        }
+        bh = find_entry(&dir,basename,namelen,&de);
+        if (bh) {
+                brelse(bh);
+                iput(dir);
+                iput(oldinode);
+                return -EEXIST;
+        }
+        bh = add_entry(dir,basename,namelen,&de);
+        if (!bh) {
+                iput(dir);
+                iput(oldinode);
+                return -ENOSPC;
+        }
+        de->inode = oldinode->i_num;
+        bh->b_dirt = 1;
+        brelse(bh);
+        iput(dir);
+        oldinode->i_nlinks++;
+        oldinode->i_ctime = CURRENT_TIME;
+        oldinode->i_dirt = 1;
+        iput(oldinode);
+        return 0;
+}