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AVFS: Return actual last dir when path is named by a symlink

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Last_dir didn't consider paths that end in a symlink and hence didn't
actually return the last_dir when provided with one. For example,
/var/log is a symlink to /usr/log. Issuing `>/var/log' would trigger
an assert in AVFS, because /var/ is not the actual last directory; /usr/
is.

Last_dir now verifies the final component is not a symlink. If it is, it
follows the symlink and restarts finding of the last the directory.
This commit is contained in:
Thomas Veerman 2012-01-12 11:32:31 +00:00
parent c89aaf7a87
commit e6c98c3c55
3 changed files with 168 additions and 51 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
servers/avfs/link.c
View file

@ -97,7 +97,7 @@ PUBLIC int do_unlink()
char fullpath[PATH_MAX];
struct lookup resolve;
lookup_init(&resolve, fullpath, PATH_NOFLAGS, &vmp, &dirp);
lookup_init(&resolve, fullpath, PATH_RET_SYMLINK, &vmp, &dirp);
resolve.l_vmnt_lock = VMNT_WRITE;
resolve.l_vnode_lock = VNODE_READ;
@ -106,6 +106,7 @@ PUBLIC int do_unlink()
return(err_code);
if ((dirp = last_dir(&resolve, fp)) == NULL) return(err_code);
assert(vmp != NULL);
/* Make sure that the object is a directory */
if ((dirp->v_mode & I_TYPE) != I_DIRECTORY) {
@ -149,9 +150,10 @@ PUBLIC int do_unlink()
}
}
assert(vmp != NULL);
tll_upgrade(&vmp->m_lock);
if(call_nr == UNLINK)
if (call_nr == UNLINK)
r = req_unlink(dirp->v_fs_e, dirp->v_inode_nr, fullpath);
else
r = req_rmdir(dirp->v_fs_e, dirp->v_inode_nr, fullpath);

4
servers/avfs/open.c
View file

@ -322,7 +322,9 @@ PRIVATE struct vnode *new_node(struct lookup *resolve, int oflags, mode_t bits)
findnode.l_vnode_lock = (oflags & O_TRUNC) ? VNODE_WRITE : VNODE_OPCL;
vp = advance(dirp, &findnode, fp);
assert(vp_vmp == NULL); /* Lookup to last dir should have yielded lock
* on vmp or final component does not exist. */
* on vmp or final component does not exist.
* Either way, vp_vmp ought to be not set.
*/
/* The combination of a symlink with absolute path followed by a danglink
* symlink results in a new path that needs to be re-resolved entirely. */

209
servers/avfs/path.c
View file

@ -133,7 +133,6 @@ struct fproc *rfp;
return(vp);
}
/*===========================================================================*
* eat_path *
*===========================================================================*/
@ -148,7 +147,6 @@ struct fproc *rfp;
return advance(start_dir, resolve, rfp);
}
/*===========================================================================*
* last_dir *
*===========================================================================*/
@ -168,72 +166,187 @@ struct fproc *rfp;
size_t len;
char *cp;
char dir_entry[NAME_MAX+1];
struct vnode *start_dir, *res;
int r;
struct vnode *start_dir, *res_vp, *sym_vp, *new_res_vp, *loop_start;
struct vmnt *sym_vmp = NULL;
int r, symloop = 0, ret_on_symlink = 0;
struct lookup symlink;
*resolve->l_vnode = NULL;
*resolve->l_vmp = NULL;
loop_start = NULL;
sym_vp = NULL;
/* Is the path absolute or relative? Initialize 'start_dir' accordingly. */
start_dir = (resolve->l_path[0] == '/' ? rfp->fp_rd : rfp->fp_wd);
ret_on_symlink = !!(resolve->l_flags & PATH_RET_SYMLINK);
len = strlen(resolve->l_path);
do {
/* Is the path absolute or relative? Initialize 'start_dir'
* accordingly. Use loop_start in case we're looping.
*/
if (loop_start != NULL)
start_dir = loop_start;
else
start_dir = (resolve->l_path[0] == '/' ? rfp->fp_rd:rfp->fp_wd);
/* If path is empty, return ENOENT. */
if (len == 0) {
err_code = ENOENT;
return(NULL);
}
len = strlen(resolve->l_path);
/* If path is empty, return ENOENT. */
if (len == 0) {
err_code = ENOENT;
res_vp = NULL;
break;
}
#if !DO_POSIX_PATHNAME_RES
/* Remove trailing slashes */
while (len > 1 && resolve->l_path[len-1] == '/') {
len--;
resolve->l_path[len]= '\0';
}
/* Remove trailing slashes */
while (len > 1 && resolve->l_path[len-1] == '/') {
len--;
resolve->l_path[len]= '\0';
}
#endif
cp = strrchr(resolve->l_path, '/');
if (cp == NULL) {
/* Just one entry in the current working directory */
struct vmnt *vmp;
cp = strrchr(resolve->l_path, '/');
if (cp == NULL) {
/* Just an entry in the current working directory */
struct vmnt *vmp;
vmp = find_vmnt(start_dir->v_fs_e);
r = lock_vmnt(vmp, resolve->l_vmnt_lock);
if (r == EDEADLK)
return(NULL);
else if (r == OK)
*resolve->l_vmp = vmp;
vmp = find_vmnt(start_dir->v_fs_e);
r = lock_vmnt(vmp, resolve->l_vmnt_lock);
if (r == EDEADLK) {
res_vp = NULL;
break;
} else if (r == OK)
*resolve->l_vmp = vmp;
lock_vnode(start_dir, resolve->l_vnode_lock);
*resolve->l_vnode = start_dir;
dup_vnode(start_dir);
return(start_dir);
lock_vnode(start_dir, resolve->l_vnode_lock);
*resolve->l_vnode = start_dir;
dup_vnode(start_dir);
if (loop_start != NULL) {
unlock_vnode(loop_start);
put_vnode(loop_start);
}
return(start_dir);
} else if (cp[1] == '\0') {
/* Path ends in a slash. The directory entry is '.' */
strcpy(dir_entry, ".");
} else {
/* A path name for the directory and a directory entry */
strncpy(dir_entry, cp+1, NAME_MAX);
cp[1] = '\0';
dir_entry[NAME_MAX] = '\0';
}
} else if (cp[1] == '\0') {
/* Path ends in a slash. The directory entry is '.' */
strcpy(dir_entry, ".");
} else {
/* A path name for the directory and a directory entry */
strncpy(dir_entry, cp+1, NAME_MAX);
cp[1] = '\0';
dir_entry[NAME_MAX] = '\0';
/* Remove trailing slashes */
while (cp > resolve->l_path && cp[0] == '/') {
cp[0]= '\0';
cp--;
}
/* Resolve up to and including the last directory of the path. Turn off
* PATH_RET_SYMLINK, because we do want to follow the symlink in this
* case. That is, the flag is meant for the actual filename of the path,
* not the last directory.
*/
resolve->l_flags &= ~PATH_RET_SYMLINK;
if ((res_vp = advance(start_dir, resolve, rfp)) == NULL) {
break;
}
/* If the directory entry is not a symlink we're done now. If it is a
* symlink, then we're not at the last directory, yet. */
/* Copy the directory entry back to user_fullpath */
strncpy(resolve->l_path, dir_entry, NAME_MAX + 1);
/* Look up the directory entry, but do not follow the symlink when it
* is one.
*/
lookup_init(&symlink, resolve->l_path,
resolve->l_flags|PATH_RET_SYMLINK, &sym_vmp, &sym_vp);
symlink.l_vnode_lock = VNODE_READ;
symlink.l_vmnt_lock = VMNT_READ;
sym_vp = advance(res_vp, &symlink, rfp);
/* Advance caused us to either switch to a different vmnt or we're
* still at the same vmnt. The former might've yielded a new vmnt lock,
* the latter should not have. Verify. */
if (sym_vmp != NULL) {
/* We got a vmnt lock, so the endpoints of the vnodes must
* differ.
*/
assert(sym_vp->v_fs_e != res_vp->v_fs_e);
}
if (sym_vp != NULL && S_ISLNK(sym_vp->v_mode)) {
/* Last component is a symlink, but if we've been asked to not
* resolve it, return now.
*/
if (ret_on_symlink) {
break;
}
r = req_rdlink(sym_vp->v_fs_e, sym_vp->v_inode_nr, NONE,
resolve->l_path, PATH_MAX - 1, 1);
if (r < 0) {
/* Failed to read link */
err_code = r;
unlock_vnode(res_vp);
unlock_vmnt(*resolve->l_vmp);
put_vnode(res_vp);
*resolve->l_vmp = NULL;
*resolve->l_vnode = NULL;
res_vp = NULL;
break;
}
resolve->l_path[r] = '\0';
if (strrchr(resolve->l_path, '/') != NULL) {
unlock_vnode(sym_vp);
unlock_vmnt(*resolve->l_vmp);
if (sym_vmp != NULL)
unlock_vmnt(sym_vmp);
*resolve->l_vmp = NULL;
put_vnode(sym_vp);
sym_vp = NULL;
symloop++;
/* Relative symlinks are relative to res_vp, not cwd */
if (resolve->l_path[0] != '/') {
loop_start = res_vp;
} else {
/* Absolute symlink, forget about res_vp */
unlock_vnode(res_vp);
put_vnode(res_vp);
}
continue;
}
}
break;
} while (symloop < SYMLOOP_MAX);
if (symloop >= SYMLOOP_MAX) {
err_code = ELOOP;
res_vp = NULL;
}
/* Remove trailing slashes */
while(cp > resolve->l_path && cp[0] == '/') {
cp[0]= '\0';
cp--;
if (sym_vp != NULL) {
unlock_vnode(sym_vp);
if (sym_vmp != NULL) {
unlock_vmnt(sym_vmp);
}
put_vnode(sym_vp);
}
resolve->l_flags = PATH_NOFLAGS;
res = advance(start_dir, resolve, rfp);
if (res == NULL) return(NULL);
if (loop_start != NULL) {
unlock_vnode(loop_start);
put_vnode(loop_start);
}
/* Copy the directory entry back to user_fullpath */
strncpy(resolve->l_path, dir_entry, NAME_MAX + 1);
return(res);
return(res_vp);
}
/*===========================================================================*