/*===========================================================================*
* do_chdir *
*===========================================================================*/
PUBLIC int do_chdir()
{
/* Change directory. This function is also called by MM to simulate a chdir
* in order to do EXEC, etc. It also changes the root directory, the uids and
* gids, and the umask.
*/
int r;
register struct fproc *rfp;
if (who == MM_PROC_NR) {
rfp = &fproc[slot1];
put_inode(fp->fp_rootdir);
dup_inode(fp->fp_rootdir = rfp->fp_rootdir);
put_inode(fp->fp_workdir);
dup_inode(fp->fp_workdir = rfp->fp_workdir);
/* MM uses access() to check permissions. To make this work, pretend
* that the user's real ids are the same as the user's effective ids.
* FS calls other than access() do not use the real ids, so are not
* affected.
*/
fp->fp_realuid =
fp->fp_effuid = rfp->fp_effuid;
fp->fp_realgid =
fp->fp_effgid = rfp->fp_effgid;
fp->fp_umask = rfp->fp_umask;
return(OK);
}
/* Perform the chdir(name) system call. */
r = change(&fp->fp_workdir, name, name_length);
return(r);
}
/*===========================================================================*
* do_fchdir *
*===========================================================================*/
PUBLIC int do_fchdir()
{
/* Change directory on already-opened fd. */
struct filp *rfilp;
/* Is the file descriptor valid? */
if ( (rfilp = get_filp(m_in.fd)) == NIL_FILP) return(err_code);
dup_inode(rfilp->filp_ino);
return change_into(&fp->fp_workdir, rfilp->filp_ino);
}
/*===========================================================================*
* do_pipe *
*===========================================================================*/
PUBLIC int do_pipe()
{
/* Perform the pipe(fil_des) system call. */
register struct fproc *rfp;
register struct inode *rip;
int r;
struct filp *fil_ptr0, *fil_ptr1;
int fil_des[2]; /* reply goes here */
/* Acquire two file descriptors. */
rfp = fp;
if ( (r = get_fd(0, R_BIT, &fil_des[0], &fil_ptr0)) != OK) return(r);
rfp->fp_filp[fil_des[0]] = fil_ptr0;
fil_ptr0->filp_count = 1;
if ( (r = get_fd(0, W_BIT, &fil_des[1], &fil_ptr1)) != OK) {
rfp->fp_filp[fil_des[0]] = NIL_FILP;
fil_ptr0->filp_count = 0;
return(r);
}
rfp->fp_filp[fil_des[1]] = fil_ptr1;
fil_ptr1->filp_count = 1;
/* Make the inode on the pipe device. */
if ( (rip = alloc_inode(root_dev, I_REGULAR) ) == NIL_INODE) {
rfp->fp_filp[fil_des[0]] = NIL_FILP;
fil_ptr0->filp_count = 0;
rfp->fp_filp[fil_des[1]] = NIL_FILP;
fil_ptr1->filp_count = 0;
return(err_code);
}
if (read_only(rip) != OK)
panic(__FILE__,"pipe device is read only", NO_NUM);
rip->i_pipe = I_PIPE;
rip->i_mode &= ~I_REGULAR;
rip->i_mode |= I_NAMED_PIPE; /* pipes and FIFOs have this bit set */
fil_ptr0->filp_ino = rip;
fil_ptr0->filp_flags = O_RDONLY;
dup_inode(rip); /* for double usage */
fil_ptr1->filp_ino = rip;
fil_ptr1->filp_flags = O_WRONLY;
rw_inode(rip, WRITING); /* mark inode as allocated */
m_out.reply_i1 = fil_des[0];
m_out.reply_i2 = fil_des[1];
rip->i_update = ATIME | CTIME | MTIME;
return(OK);
}
struct inode* get_inode(ino_t i)
{
struct inode *i_node;
struct dir_extent *extent;
if (i == 0)
return NULL;
/* Try to get inode from cache. */
i_node = find_inode(i);
if (i_node != NULL) {
dup_inode(i_node);
return i_node;
}
/*
* Inode wasn't in cache, try to load it.
* FIXME: a fake extent of one logical block is created for
* read_inode(). Reading a inode this way could be problematic if
* additional extents are stored behind the block boundary.
*/
i_node = alloc_inode();
extent = alloc_extent();
extent->location = i / v_pri.logical_block_size_l;
extent->length = 1;
if (read_inode(i_node, extent, i % v_pri.logical_block_size_l,
NULL) != OK) {
free_extent(extent);
put_inode(i_node);
return NULL;
}
free_extent(extent);
return i_node;
}
/*===========================================================================*
* do_rename *
*===========================================================================*/
PUBLIC int do_rename()
{
/* Perform the rename(name1, name2) system call. */
struct inode *old_dirp, *old_ip; /* ptrs to old dir, file inodes */
struct inode *new_dirp, *new_ip; /* ptrs to new dir, file inodes */
struct inode *new_superdirp, *next_new_superdirp;
int r = OK; /* error flag; initially no error */
int odir, ndir; /* TRUE iff {old|new} file is dir */
int same_pdir; /* TRUE iff parent dirs are the same */
char old_name[NAME_MAX], new_name[NAME_MAX];
ino_t numb;
int r1;
/* See if 'name1' (existing file) exists. Get dir and file inodes. */
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
if ( (old_dirp = last_dir(user_path, old_name))==NIL_INODE) return(err_code);
if ( (old_ip = advance(old_dirp, old_name)) == NIL_INODE) r = err_code;
/* See if 'name2' (new name) exists. Get dir and file inodes. */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) r = err_code;
if ( (new_dirp = last_dir(user_path, new_name)) == NIL_INODE) r = err_code;
new_ip = advance(new_dirp, new_name); /* not required to exist */
if (old_ip != NIL_INODE)
odir = ((old_ip->i_mode & I_TYPE) == I_DIRECTORY); /* TRUE iff dir */
/* If it is ok, check for a variety of possible errors. */
if (r == OK) {
same_pdir = (old_dirp == new_dirp);
/* The old inode must not be a superdirectory of the new last dir. */
if (odir && !same_pdir) {
dup_inode(new_superdirp = new_dirp);
while (TRUE) { /* may hang in a file system loop */
if (new_superdirp == old_ip) {
r = EINVAL;
break;
}
next_new_superdirp = advance(new_superdirp, dot2);
put_inode(new_superdirp);
if (next_new_superdirp == new_superdirp)
break; /* back at system root directory */
new_superdirp = next_new_superdirp;
if (new_superdirp == NIL_INODE) {
/* Missing ".." entry. Assume the worst. */
r = EINVAL;
break;
}
}
put_inode(new_superdirp);
}
/* The old or new name must not be . or .. */
if (strcmp(old_name, ".")==0 || strcmp(old_name, "..")==0 ||
strcmp(new_name, ".")==0 || strcmp(new_name, "..")==0) r = EINVAL;
/* Both parent directories must be on the same device. */
if (old_dirp->i_dev != new_dirp->i_dev) r = EXDEV;
/* Parent dirs must be writable, searchable and on a writable device */
if ((r1 = forbidden(old_dirp, W_BIT | X_BIT)) != OK ||
(r1 = forbidden(new_dirp, W_BIT | X_BIT)) != OK) r = r1;
/* Some tests apply only if the new path exists. */
if (new_ip == NIL_INODE) {
/* don't rename a file with a file system mounted on it. */
if (old_ip->i_dev != old_dirp->i_dev) r = EXDEV;
if (odir && new_dirp->i_nlinks >=
(new_dirp->i_sp->s_version == V1 ? CHAR_MAX : SHRT_MAX) &&
!same_pdir && r == OK) r = EMLINK;
} else {
if (old_ip == new_ip) r = SAME; /* old=new */
/* has the old file or new file a file system mounted on it? */
if (old_ip->i_dev != new_ip->i_dev) r = EXDEV;
ndir = ((new_ip->i_mode & I_TYPE) == I_DIRECTORY); /* dir ? */
if (odir == TRUE && ndir == FALSE) r = ENOTDIR;
if (odir == FALSE && ndir == TRUE) r = EISDIR;
}
}
/* If a process has another root directory than the system root, we might
* "accidently" be moving it's working directory to a place where it's
* root directory isn't a super directory of it anymore. This can make
* the function chroot useless. If chroot will be used often we should
* probably check for it here.
*/
/* The rename will probably work. Only two things can go wrong now:
* 1. being unable to remove the new file. (when new file already exists)
* 2. being unable to make the new directory entry. (new file doesn't exists)
* [directory has to grow by one block and cannot because the disk
* is completely full].
*/
if (r == OK) {
if (new_ip != NIL_INODE) {
/* There is already an entry for 'new'. Try to remove it. */
if (odir)
r = remove_dir(new_dirp, new_ip, new_name);
else
r = unlink_file(new_dirp, new_ip, new_name);
}
/* if r is OK, the rename will succeed, while there is now an
* unused entry in the new parent directory.
*/
}
if (r == OK) {
/* If the new name will be in the same parent directory as the old one,
* first remove the old name to free an entry for the new name,
* otherwise first try to create the new name entry to make sure
* the rename will succeed.
*/
numb = old_ip->i_num; /* inode number of old file */
if (same_pdir) {
r = search_dir(old_dirp, old_name, (ino_t *) 0, DELETE);
/* shouldn't go wrong. */
if (r==OK) (void) search_dir(old_dirp, new_name, &numb, ENTER);
} else {
r = search_dir(new_dirp, new_name, &numb, ENTER);
if (r == OK)
(void) search_dir(old_dirp, old_name, (ino_t *) 0, DELETE);
}
}
/* If r is OK, the ctime and mtime of old_dirp and new_dirp have been marked
* for update in search_dir.
*/
if (r == OK && odir && !same_pdir) {
/* Update the .. entry in the directory (still points to old_dirp). */
numb = new_dirp->i_num;
(void) unlink_file(old_ip, NIL_INODE, dot2);
if (search_dir(old_ip, dot2, &numb, ENTER) == OK) {
/* New link created. */
new_dirp->i_nlinks++;
new_dirp->i_dirt = DIRTY;
}
}
/* Release the inodes. */
put_inode(old_dirp);
put_inode(old_ip);
put_inode(new_dirp);
put_inode(new_ip);
return(r == SAME ? OK : r);
}
/*===========================================================================*
* do_mount *
*===========================================================================*/
PUBLIC int do_mount()
{
/* Perform the mount(name, mfile, rd_only) system call. */
register struct inode *rip, *root_ip;
struct super_block *xp, *sp;
dev_t dev;
mode_t bits;
int rdir, mdir; /* TRUE iff {root|mount} file is dir */
int i, r, found;
struct fproc *tfp;
/* Only the super-user may do MOUNT. */
if (!super_user) return(EPERM);
/* If 'name' is not for a block special file, return error. */
if (fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
if ( (dev = name_to_dev(user_path)) == NO_DEV) return(err_code);
/* Scan super block table to see if dev already mounted & find a free slot.*/
sp = NIL_SUPER;
found = FALSE;
for (xp = &super_block[0]; xp < &super_block[NR_SUPERS]; xp++) {
if (xp->s_dev == dev)
{
/* is it mounted already? */
found = TRUE;
sp= xp;
break;
}
if (xp->s_dev == NO_DEV) sp = xp; /* record free slot */
}
if (found)
{
printf(
"do_mount: s_imount = 0x%x (%x, %d), s_isup = 0x%x (%x, %d), fp_rootdir = 0x%x\n",
xp->s_imount, xp->s_imount->i_dev, xp->s_imount->i_num,
xp->s_isup, xp->s_isup->i_dev, xp->s_isup->i_num,
fproc[FS_PROC_NR].fp_rootdir);
/* It is possible that we have an old root lying around that
* needs to be remounted.
*/
if (xp->s_imount != xp->s_isup ||
xp->s_isup == fproc[FS_PROC_NR].fp_rootdir)
{
/* Normally, s_imount refers to the mount point. For a root
* filesystem, s_imount is equal to the root inode. We assume
* that the root of FS is always the real root. If the two
* inodes are different or if the root of FS is equal two the
* root of the filesystem we found, we found a filesystem that
* is in use.
*/
return(EBUSY); /* already mounted */
}
if (root_dev == xp->s_dev)
{
panic("fs", "inconsistency remounting old root",
NO_NUM);
}
/* Now get the inode of the file to be mounted on. */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
return(err_code);
}
if ( (rip = eat_path(user_path)) == NIL_INODE) {
return(err_code);
}
r = OK;
/* It may not be special. */
bits = rip->i_mode & I_TYPE;
if (bits == I_BLOCK_SPECIAL || bits == I_CHAR_SPECIAL)
r = ENOTDIR;
/* Get the root inode of the mounted file system. */
root_ip= sp->s_isup;
/* File types of 'rip' and 'root_ip' may not conflict. */
if (r == OK) {
mdir = ((rip->i_mode & I_TYPE) == I_DIRECTORY);
/* TRUE iff dir */
rdir = ((root_ip->i_mode & I_TYPE) == I_DIRECTORY);
if (!mdir && rdir) r = EISDIR;
}
/* If error, return the mount point. */
if (r != OK) {
put_inode(rip);
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
rip->i_mount = I_MOUNT; /* this bit says the inode is
* mounted on
*/
put_inode(sp->s_imount);
sp->s_imount = rip;
sp->s_rd_only = m_in.rd_only;
allow_newroot= 0; /* The root is now fixed */
return(OK);
}
if (sp == NIL_SUPER) return(ENFILE); /* no super block available */
/* Open the device the file system lives on. */
if (dev_open(dev, who_e, m_in.rd_only ? R_BIT : (R_BIT|W_BIT)) != OK)
return(EINVAL);
/* Make the cache forget about blocks it has open on the filesystem */
(void) do_sync();
invalidate(dev);
/* Fill in the super block. */
sp->s_dev = dev; /* read_super() needs to know which dev */
r = read_super(sp);
/* Is it recognized as a Minix filesystem? */
if (r != OK) {
dev_close(dev);
sp->s_dev = NO_DEV;
return(r);
}
/* Now get the inode of the file to be mounted on. */
if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK) {
dev_close(dev);
sp->s_dev = NO_DEV;
return(err_code);
}
if (strcmp(user_path, "/") == 0 && allow_newroot)
{
printf("Replacing root\n");
/* Get the root inode of the mounted file system. */
if ( (root_ip = get_inode(dev, ROOT_INODE)) == NIL_INODE) r = err_code;
if (root_ip != NIL_INODE && root_ip->i_mode == 0) {
r = EINVAL;
}
/* If error, return the super block and both inodes; release the
* maps.
*/
if (r != OK) {
put_inode(root_ip);
(void) do_sync();
invalidate(dev);
dev_close(dev);
sp->s_dev = NO_DEV;
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
sp->s_imount = root_ip;
dup_inode(root_ip);
sp->s_isup = root_ip;
sp->s_rd_only = m_in.rd_only;
root_dev= dev;
/* Replace all root and working directories */
for (i= 0, tfp= fproc; i<NR_PROCS; i++, tfp++)
{
if (tfp->fp_pid == PID_FREE)
continue;
if (tfp->fp_rootdir == NULL)
panic("fs", "do_mount: null rootdir", i);
put_inode(tfp->fp_rootdir);
dup_inode(root_ip);
tfp->fp_rootdir= root_ip;
if (tfp->fp_workdir == NULL)
panic("fs", "do_mount: null workdir", i);
put_inode(tfp->fp_workdir);
dup_inode(root_ip);
tfp->fp_workdir= root_ip;
}
/* Leave the old filesystem lying around. */
return(OK);
}
if ( (rip = eat_path(user_path)) == NIL_INODE) {
dev_close(dev);
sp->s_dev = NO_DEV;
return(err_code);
}
/* It may not be busy. */
r = OK;
if (rip->i_count > 1) r = EBUSY;
/* It may not be special. */
bits = rip->i_mode & I_TYPE;
if (bits == I_BLOCK_SPECIAL || bits == I_CHAR_SPECIAL) r = ENOTDIR;
/* Get the root inode of the mounted file system. */
root_ip = NIL_INODE; /* if 'r' not OK, make sure this is defined */
if (r == OK) {
if ( (root_ip = get_inode(dev, ROOT_INODE)) == NIL_INODE) r = err_code;
}
if (root_ip != NIL_INODE && root_ip->i_mode == 0) {
r = EINVAL;
}
/* File types of 'rip' and 'root_ip' may not conflict. */
if (r == OK) {
mdir = ((rip->i_mode & I_TYPE) == I_DIRECTORY); /* TRUE iff dir */
rdir = ((root_ip->i_mode & I_TYPE) == I_DIRECTORY);
if (!mdir && rdir) r = EISDIR;
}
/* If error, return the super block and both inodes; release the maps. */
if (r != OK) {
put_inode(rip);
put_inode(root_ip);
(void) do_sync();
invalidate(dev);
dev_close(dev);
sp->s_dev = NO_DEV;
return(r);
}
/* Nothing else can go wrong. Perform the mount. */
rip->i_mount = I_MOUNT; /* this bit says the inode is mounted on */
sp->s_imount = rip;
sp->s_isup = root_ip;
sp->s_rd_only = m_in.rd_only;
allow_newroot= 0; /* The root is now fixed */
return(OK);
}
