306 lines
9.1 KiB
C
306 lines
9.1 KiB
C
/* This file handles the LINK and UNLINK system calls. It also deals with
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* deallocating the storage used by a file when the last UNLINK is done to a
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* file and the blocks must be returned to the free block pool.
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*
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* The entry points into this file are
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* do_link: perform the LINK system call
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* do_unlink: perform the UNLINK and RMDIR system calls
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* do_rename: perform the RENAME system call
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* do_truncate: perform the TRUNCATE system call
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* do_ftruncate: perform the FTRUNCATE system call
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* do_rdlink: perform the RDLNK system call
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*/
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#include "fs.h"
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#include <sys/stat.h>
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#include <string.h>
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#include <minix/com.h>
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#include <minix/callnr.h>
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#include <dirent.h>
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#include "file.h"
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#include "fproc.h"
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#include "param.h"
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#include <minix/vfsif.h>
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#include "vnode.h"
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/*===========================================================================*
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* do_link *
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*===========================================================================*/
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PUBLIC int do_link()
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{
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/* Perform the link(name1, name2) system call. */
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int r = OK;
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endpoint_t linked_fs_e, link_lastdir_fs_e;
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struct vnode *vp, *vp_d;
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/* See if 'name1' (file to be linked to) exists. */
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if(fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
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if ((vp = eat_path(PATH_NOFLAGS)) == NIL_VNODE) return(err_code);
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/* Does the final directory of 'name2' exist? */
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if (fetch_name(m_in.name2, m_in.name2_length, M1) != OK)
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r = err_code;
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else if ((vp_d = last_dir()) == NIL_VNODE)
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r = err_code;
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if (r != OK) {
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put_vnode(vp);
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return(r);
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}
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/* Check for links across devices. */
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if(vp->v_fs_e != vp_d->v_fs_e)
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r = EXDEV;
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else
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r = forbidden(vp_d, W_BIT | X_BIT);
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if (r == OK)
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r = req_link(vp->v_fs_e, vp_d->v_inode_nr, user_fullpath,
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vp->v_inode_nr);
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put_vnode(vp);
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put_vnode(vp_d);
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return(r);
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}
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/*===========================================================================*
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* do_unlink *
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*===========================================================================*/
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PUBLIC int do_unlink()
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{
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/* Perform the unlink(name) or rmdir(name) system call. The code for these two
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* is almost the same. They differ only in some condition testing. Unlink()
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* may be used by the superuser to do dangerous things; rmdir() may not.
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*/
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register struct fproc *rfp;
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struct vnode *vldirp, *vp;
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int r;
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/* Get the last directory in the path. */
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if(fetch_name(m_in.name, m_in.name_length, M3) != OK) return(err_code);
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if ((vldirp = last_dir()) == NIL_VNODE) return(err_code);
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/* Make sure that the object is a directory */
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if((vldirp->v_mode & I_TYPE) != I_DIRECTORY) {
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put_vnode(vldirp);
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return(ENOTDIR);
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}
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/* The caller must have both search and execute permission */
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if ((r = forbidden(vldirp, X_BIT | W_BIT)) != OK) {
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put_vnode(vldirp);
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return(r);
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}
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/* Also, if the sticky bit is set, only the owner of the file or a privileged
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user is allowed to unlink */
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if ((vldirp->v_mode & S_ISVTX) == S_ISVTX) {
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/* Look up inode of file to unlink to retrieve owner */
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vp = advance(vldirp, PATH_RET_SYMLINK);
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if (vp != NIL_VNODE) {
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if(vp->v_uid != fp->fp_effuid && fp->fp_effuid != SU_UID)
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r = EPERM;
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put_vnode(vp);
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} else
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r = err_code;
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if (r != OK) {
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put_vnode(vldirp);
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return(r);
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}
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}
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if(call_nr == UNLINK)
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r = req_unlink(vldirp->v_fs_e, vldirp->v_inode_nr, user_fullpath);
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else
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r = req_rmdir(vldirp->v_fs_e, vldirp->v_inode_nr, user_fullpath);
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put_vnode(vldirp);
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return(r);
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}
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/*===========================================================================*
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* do_rename *
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*===========================================================================*/
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PUBLIC int do_rename()
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{
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/* Perform the rename(name1, name2) system call. */
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int r = OK, r1;
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size_t len;
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struct vnode *old_dirp, *new_dirp, *vp;
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char old_name[PATH_MAX+1];
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/* See if 'name1' (existing file) exists. Get dir and file inodes. */
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if(fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
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if ((old_dirp = last_dir()) == NIL_VNODE) return(err_code);
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/* If the sticky bit is set, only the owner of the file or a privileged
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user is allowed to rename */
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if((old_dirp->v_mode & S_ISVTX) == S_ISVTX) {
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/* Look up inode of file to unlink to retrieve owner */
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vp = advance(old_dirp, PATH_RET_SYMLINK);
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if (vp != NIL_VNODE) {
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if(vp->v_uid != fp->fp_effuid && fp->fp_effuid != SU_UID)
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r = EPERM;
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put_vnode(vp);
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} else
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r = err_code;
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if (r != OK) {
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put_vnode(old_dirp);
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return(r);
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}
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}
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/* Save the last component of the old name */
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if(strlen(user_fullpath) >= sizeof(old_name)) {
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put_vnode(old_dirp);
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return(ENAMETOOLONG);
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}
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strcpy(old_name, user_fullpath);
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/* See if 'name2' (new name) exists. Get dir inode */
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if(fetch_name(m_in.name2, m_in.name2_length, M1) != OK)
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r = err_code;
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else if ((new_dirp = last_dir()) == NIL_VNODE)
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r = err_code;
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if (r != OK) {
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put_vnode(old_dirp);
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return r;
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}
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/* Both parent directories must be on the same device. */
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if(old_dirp->v_fs_e != new_dirp->v_fs_e) r = EXDEV;
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/* Parent dirs must be writable, searchable and on a writable device */
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if ((r1 = forbidden(old_dirp, W_BIT|X_BIT)) != OK ||
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(r1 = forbidden(new_dirp, W_BIT|X_BIT)) != OK) r = r1;
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if(r == OK)
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r = req_rename(old_dirp->v_fs_e, old_dirp->v_inode_nr, old_name,
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new_dirp->v_inode_nr, user_fullpath);
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put_vnode(old_dirp);
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put_vnode(new_dirp);
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return(r);
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}
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/*===========================================================================*
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* do_truncate *
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*===========================================================================*/
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PUBLIC int do_truncate()
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{
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/* truncate_vnode() does the actual work of do_truncate() and do_ftruncate().
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* do_truncate() and do_ftruncate() have to get hold of the inode, either
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* by name or fd, do checks on it, and call truncate_inode() to do the
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* work.
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*/
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struct vnode *vp;
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int r;
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if ((off_t) m_in.flength < 0) return(EINVAL);
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/* Temporarily open file */
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if (fetch_name(m_in.m2_p1, m_in.m2_i1, M1) != OK) return(err_code);
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if ((vp = eat_path(PATH_NOFLAGS)) == NIL_VNODE) return(err_code);
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/* Ask FS to truncate the file */
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if ((r = forbidden(vp, W_BIT)) == OK)
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r = truncate_vnode(vp, m_in.flength);
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put_vnode(vp);
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return(r);
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}
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/*===========================================================================*
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* do_ftruncate *
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*===========================================================================*/
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PUBLIC int do_ftruncate()
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{
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/* As with do_truncate(), truncate_vnode() does the actual work. */
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int r;
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struct filp *rfilp;
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if ((off_t) m_in.flength < 0) return(EINVAL);
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/* File is already opened; get a vnode pointer from filp */
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if ((rfilp = get_filp(m_in.m2_i1)) == NIL_FILP) return(err_code);
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if (!(rfilp->filp_mode & W_BIT)) return(EBADF);
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return truncate_vnode(rfilp->filp_vno, m_in.flength);
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}
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/*===========================================================================*
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* truncate_vnode *
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*===========================================================================*/
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PUBLIC int truncate_vnode(vp, newsize)
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struct vnode *vp;
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off_t newsize;
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{
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int r, file_type;
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file_type = vp->v_mode & I_TYPE;
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if (file_type != I_REGULAR && file_type != I_NAMED_PIPE) return(EINVAL);
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if ((r = req_ftrunc(vp->v_fs_e, vp->v_inode_nr, newsize, 0)) == OK)
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vp->v_size = newsize;
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return(r);
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}
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/*===========================================================================*
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* do_slink *
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*===========================================================================*/
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PUBLIC int do_slink()
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{
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/* Perform the symlink(name1, name2) system call. */
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int r, linklen;
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struct vnode *vp;
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char string[NAME_MAX]; /* last component of the new dir's path name */
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if(m_in.name1_length <= 1) return(ENOENT);
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if(m_in.name1_length >= SYMLINK_MAX) return(ENAMETOOLONG);
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/* Get dir inode of 'name2' */
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if(fetch_name(m_in.name2, m_in.name2_length, M1) != OK) return(err_code);
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if ((vp = last_dir()) == NIL_VNODE) return(err_code);
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if ((r = forbidden(vp, W_BIT|X_BIT)) == OK) {
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r = req_slink(vp->v_fs_e, vp->v_inode_nr, user_fullpath, who_e,
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m_in.name1, m_in.name1_length - 1, fp->fp_effuid,
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fp->fp_effgid);
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}
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put_vnode(vp);
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return(r);
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}
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/*===========================================================================*
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* do_rdlink *
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*===========================================================================*/
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PUBLIC int do_rdlink()
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{
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/* Perform the readlink(name, buf, bufsize) system call. */
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int r, copylen;
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struct vnode *vp;
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copylen = m_in.nbytes;
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if(copylen < 0) return(EINVAL);
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/* Temporarily open the file containing the symbolic link */
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if(fetch_name(m_in.name1, m_in.name1_length, M1) != OK) return(err_code);
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if ((vp = eat_path(PATH_RET_SYMLINK)) == NIL_VNODE) return(err_code);
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/* Make sure this is a symbolic link */
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if((vp->v_mode & I_TYPE) != I_SYMBOLIC_LINK)
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r = EINVAL;
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else
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r = req_rdlink(vp->v_fs_e, vp->v_inode_nr, who_e, m_in.name2, copylen);
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put_vnode(vp);
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return(r);
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}
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