/**************************************************************************** * fs/inode/fs_inodesearch.c * * Copyright (C) 2007-2009, 2011-2012, 2016-2017 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include "inode/inode.h" /**************************************************************************** * Public Data ****************************************************************************/ FAR struct inode *g_root_inode = NULL; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: _inode_compare * * Description: * Compare two inode names * ****************************************************************************/ static int _inode_compare(FAR const char *fname, FAR struct inode *node) { char *nname = node->i_name; if (!nname) { return 1; } if (!fname) { return -1; } for (; ; ) { /* At end of node name? */ if (!*nname) { /* Yes.. also end of find name? */ if (!*fname || *fname == '/') { /* Yes.. return match */ return 0; } else { /* No... return find name > node name */ return 1; } } /* At end of find name? */ else if (!*fname || *fname == '/') { /* Yes... return find name < node name */ return -1; } /* Check for non-matching characters */ else if (*fname > *nname) { return 1; } else if (*fname < *nname) { return -1; } /* Not at the end of either string and all of the * characters still match. keep looking. */ else { fname++; nname++; } } } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: inode_search and inode_search_nofollow * * Description: * Find the inode associated with 'path' returning the inode references * and references to its companion nodes. * * Both versions will follow soft links in path leading up to the terminal * node. inode_search() will deference that terminal node, * inode_search_nofollow will not. * * If a soft link is encountered that is not the terminal node in the path, * that that WILL be deferenced and the mountpoint inode will be returned. * * Assumptions: * The caller holds the g_inode_sem semaphore * ****************************************************************************/ #ifdef CONFIG_PSEUDOFS_SOFTLINKS FAR struct inode *inode_search_nofollow(FAR const char **path, FAR struct inode **peer, FAR struct inode **parent, FAR const char **relpath) #else FAR struct inode *inode_search(FAR const char **path, FAR struct inode **peer, FAR struct inode **parent, FAR const char **relpath) #endif { FAR const char *name = *path + 1; /* Skip over leading '/' */ FAR struct inode *node = g_root_inode; FAR struct inode *left = NULL; FAR struct inode *above = NULL; #ifdef CONFIG_PSEUDOFS_SOFTLINKS FAR struct inode *newnode; #endif /* Traverse the pseudo file system node tree until either (1) all nodes * have been examined without finding the matching node, or (2) the * matching node is found. */ while (node != NULL) { int result = _inode_compare(name, node); /* Case 1: The name is less than the name of the node. * Since the names are ordered, these means that there * is no peer node with this name and that there can be * no match in the fileystem. */ if (result < 0) { node = NULL; break; } /* Case 2: the name is greater than the name of the node. * In this case, the name may still be in the list to the * "right" */ else if (result > 0) { /* Continue looking to the "right" of this inode. */ left = node; node = node->i_peer; } /* The names match */ else { /* Now there are three remaining possibilities: * (1) This is the node that we are looking for. * (2) The node we are looking for is "below" this one. * (3) This node is a mountpoint and will absorb all request * below this one */ name = inode_nextname(name); if (*name == '\0' || INODE_IS_MOUNTPT(node)) { /* Either (1) we are at the end of the path, so this must be the * node we are looking for or else (2) this node is a mountpoint * and will handle the remaining part of the pathname */ if (relpath) { *relpath = name; } #ifdef CONFIG_PSEUDOFS_SOFTLINKS /* NOTE that if the terminal inode is a soft link, it is not * deferenced in this case. The raw inode is returned. * * In that case a wrapper function will perform that operation. */ #endif break; } else { /* More nodes to be examined in the path "below" this one. */ #ifdef CONFIG_PSEUDOFS_SOFTLINKS /* If this intermediate inode in the is a soft link, then (1) * get the name of the full path of the soft link, (2) recursively * look-up the inode referenced by the sof link, and (3) * continue searching with that inode instead. */ newnode = inode_linktarget(node, NULL, NULL, relpath); if (newnode == NULL) { /* Probably means that the node is a symbolic link, but * that the target of the symbolic link does not exist. */ break; } else if (newnode != node) { /* The node was a valid symbolic link and we have jumped to a * different, spot in the the pseudo file system tree. * * Continue from this new inode. */ node = newnode; /* Check if this took us to a mountpoint. */ if (INODE_IS_MOUNTPT(newnode)) { /* Yes.. return the mountpoint information. * REVISIT: The relpath is incorrect in this case. It is * relative to symbolic link, not to the root of the mount. */ if (relpath) { *relpath = name; } above = NULL; left = NULL; break; } } #endif /* Keep looking at the next level "down" */ above = node; left = NULL; node = node->i_child; } } } /* node is null. This can happen in one of four cases: * With node = NULL * (1) We went left past the final peer: The new node * name is larger than any existing node name at * that level. * (2) We broke out in the middle of the list of peers * because the name was not found in the ordered * list. * (3) We went down past the final parent: The new node * name is "deeper" than anything that we currently * have in the tree. * with node != NULL * (4) When the node matching the full path is found */ if (peer) { *peer = left; } if (parent) { *parent = above; } *path = name; return node; } #ifdef CONFIG_PSEUDOFS_SOFTLINKS FAR struct inode *inode_search(FAR const char **path, FAR struct inode **peer, FAR struct inode **parent, FAR const char **relpath) { /* Lookup the terminal inode */ FAR struct inode *node = inode_search_nofollow(path, peer, parent, relpath); /* Did we find it? inode_search_nofollow() will terminate in one of * three ways: * * 1. With an error (node == NULL) * 2. With node referring to the terminal inode which may be a symbolic * link, or * 3. with node referring to an intermediate MOUNTPOINT inode with the * residual path in relpath. * * REVISIT: The relpath is incorrect in the final case. It will be relative * to symbolic link, not to the root of the mount. */ if (node != NULL && INODE_IS_SOFTLINK(node)) { /* The terminating inode is a valid soft link: Return the inode, * corresponding to link target. */ return inode_linktarget(node, peer, parent, relpath); } return node; } #endif /**************************************************************************** * Name: inode_linktarget * * Description: * If the inode is a soft link, then (1) get the name of the full path of * the soft link, (2) recursively look-up the inode referenced by the soft * link, and (3) return the inode referenced by the soft link. * * Assumptions: * The caller holds the g_inode_sem semaphore * ****************************************************************************/ #ifdef CONFIG_PSEUDOFS_SOFTLINKS FAR struct inode *inode_linktarget(FAR struct inode *node, FAR struct inode **peer, FAR struct inode **parent, FAR const char **relpath) { FAR const char *copy; unsigned int count = 0; /* An infinite loop is avoided only by the loop count. * * REVISIT: The ELOOP error should be reported to the application in that * case but there is no simple mechanism to do that. */ while (node != NULL && INODE_IS_SOFTLINK(node)) { /* Careful: inode_search_nofollow overwrites the input string pointer */ copy = (FAR const char *)node->u.i_link; /* Now, look-up the inode associated with the target path */ node = inode_search_nofollow(©, peer, parent, relpath); if (node == NULL && ++count > SYMLOOP_MAX) { return NULL; } } return node; } #endif /**************************************************************************** * Name: inode_nextname * * Description: * Given a path with node names separated by '/', return the next path * segment name. * ****************************************************************************/ FAR const char *inode_nextname(FAR const char *name) { /* Search for the '/' delimiter or the NUL terminator at the end of the * path segment. */ while (*name && *name != '/') { name++; } /* If we found the '/' delimiter, then the path segment we want begins at * the next character (which might also be the NUL terminator). */ if (*name) { name++; } return name; }