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Soft links: Fix logic and remove kludge of last commit. Rename inode_dereference() as inode_linktarget() and make global.

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This commit is contained in:
Gregory Nutt 2017-02-03 13:22:33 -06:00
parent 7c59e05305
commit 60ba5a5261
4 changed files with 178 additions and 114 deletions
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99
fs/inode/fs_inodesearch.c
View File

@ -134,52 +134,6 @@ static int _inode_compare(FAR const char *fname,
} }
} }
/****************************************************************************
* Name: _inode_dereference
*
* 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
static inline FAR struct inode *
_inode_dereference(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(&copy, peer, parent, relpath);
if (node == NULL && ++count > SYMLOOP_MAX)
{
return NULL;
}
}
return node;
}
#endif
/**************************************************************************** /****************************************************************************
* Public Functions * Public Functions
****************************************************************************/ ****************************************************************************/
@ -266,7 +220,7 @@ FAR struct inode *inode_search(FAR const char **path,
FAR const char *nextname = inode_nextname(name); FAR const char *nextname = inode_nextname(name);
if (*nextname != '\0') if (*nextname != '\0')
{ {
newnode = _inode_dereference(node, NULL, &above, relpath); newnode = inode_linktarget(node, NULL, &above, relpath);
if (newnode == NULL) if (newnode == NULL)
{ {
/* Probably means that the node is a symbolic link, but /* Probably means that the node is a symbolic link, but
@ -340,7 +294,7 @@ FAR struct inode *inode_search(FAR const char **path,
* continue searching with that inode instead. * continue searching with that inode instead.
*/ */
newnode = _inode_dereference(node, NULL, NULL, relpath); newnode = inode_linktarget(node, NULL, NULL, relpath);
if (newnode == NULL) if (newnode == NULL)
{ {
/* Probably means that the node is a symbolic link, but /* Probably means that the node is a symbolic link, but
@ -438,7 +392,54 @@ FAR struct inode *inode_search(FAR const char **path,
* return that inode instead. * return that inode instead.
*/ */
return _inode_dereference(node, peer, parent, relpath); 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(&copy, peer, parent, relpath);
if (node == NULL && ++count > SYMLOOP_MAX)
{
return NULL;
}
} }
return node; return node;

20
fs/inode/inode.h
View File

@ -141,6 +141,26 @@ FAR struct inode *inode_search_nofollow(FAR const char **path,
# define inode_search_nofollow(p,l,a,r) inode_search(p,l,a,r) # define inode_search_nofollow(p,l,a,r) inode_search(p,l,a,r)
#endif #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);
#endif
/**************************************************************************** /****************************************************************************
* Name: inode_free * Name: inode_free
* *

90
fs/vfs/fs_stat.c
View File

@ -79,48 +79,84 @@ static inline int statpseudo(FAR struct inode *inode, FAR struct stat *buf)
#if defined(CONFIG_FS_SHM) #if defined(CONFIG_FS_SHM)
if (INODE_IS_SHM(inode)) */ if (INODE_IS_SHM(inode)) */
{ {
buf->st_mode | S_IFSHM; buf->st_mode = S_IFSHM;
} }
else else
#endif #endif
{ {
} }
} }
else if (inode->u.i_ops) else if (inode->u.i_ops != NULL)
{ {
if (inode->u.i_ops->read) #ifdef CONFIG_PSEUDOFS_SOFTLINKS
{ /* Handle softlinks differently. Just call stat() recursively on the
buf->st_mode = S_IROTH | S_IRGRP | S_IRUSR; * target of the softlink.
} *
* REVISIT: This has the possibility of an infinite loop!
*/
if (inode->u.i_ops->write) if (INODE_IS_SOFTLINK(inode))
{ {
buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR; int ret;
}
if (INODE_IS_MOUNTPT(inode)) /* stat() the target of the soft link.
{ *
buf->st_mode |= S_IFDIR; * Note: We don't really handle links to links nicely. I suppose
} * that we should repetitively deference the symbolic link inodes
else if (INODE_IS_BLOCK(inode)) * until we discover the true target link?
{ */
/* What is if also has child inodes? */
buf->st_mode |= S_IFBLK; ret = stat((FAR const char *)inode->u.i_link, buf);
}
#if 0 /* ifdef CONFIG_PSEUDOFS_SOFTLINKS See REVISIT in stat() */ /* If stat() fails, then there is a probleml with target of the
else if (INODE_IS_SOFTLINK(inode)) * symbolic link, but not with the symbolic link itself. We should
{ * still report success, just with less information.
/* Should not have child inodes. */ */
if (ret < 0)
{
memset(buf, 0, sizeof(struct stat));
}
/* And make sure that the caller knows that this really a symbolic link. */
buf->st_mode |= S_IFLNK; buf->st_mode |= S_IFLNK;
} }
else
#endif #endif
else /* if (INODE_IS_DRIVER(inode)) */
{ {
/* What is it if it also has child inodes? */ /* Determine read/write privileges based on the existence of read
* and write methods.
*/
buf->st_mode |= S_IFCHR; if (inode->u.i_ops->read)
{
buf->st_mode = S_IROTH | S_IRGRP | S_IRUSR;
}
if (inode->u.i_ops->write)
{
buf->st_mode |= S_IWOTH | S_IWGRP | S_IWUSR;
}
/* Determine the type of the inode */
if (INODE_IS_MOUNTPT(inode))
{
buf->st_mode |= S_IFDIR;
}
else if (INODE_IS_BLOCK(inode))
{
/* What is if also has child inodes? */
buf->st_mode |= S_IFBLK;
}
else /* if (INODE_IS_DRIVER(inode)) */
{
/* What is it if it also has child inodes? */
buf->st_mode |= S_IFCHR;
}
} }
} }
else else
@ -199,11 +235,7 @@ int stat(FAR const char *path, FAR struct stat *buf)
/* Get an inode for this file */ /* Get an inode for this file */
#if 0 /* REVISIT: inode_find_nofollow needed for symlinks but conflicts with other usage */
inode = inode_find_nofollow(path, &relpath); inode = inode_find_nofollow(path, &relpath);
#else
inode = inode_find(path, &relpath);
#endif
if (!inode) if (!inode)
{ {
/* This name does not refer to a psudeo-inode and there is no /* This name does not refer to a psudeo-inode and there is no

83
include/sys/stat.h
View File

@ -50,51 +50,62 @@
/* mode_t bit settings (most of these do not apply to Nuttx). This assumes /* mode_t bit settings (most of these do not apply to Nuttx). This assumes
* that the full size of a mode_t is 16-bits. (However, mode_t must be size * that the full size of a mode_t is 16-bits. (However, mode_t must be size
* 'int' because it is promoted to size int when passed in varargs). * 'int' because it is promoted to size int when passed in varargs).
*
* LTTT ...U UUGG GOOO
*
* Bits 0-2: Permissions for others
* Bits 3-5: Group permissions
* Bits 6-8: Owner permissions
* Bits 9-11: Not used
* Bits 12-14: File type bits
* Bit 15: Symbolic link
*/ */
#define S_IXOTH 0000001 /* Permissions for others: RWX */ #define S_IXOTH (1 << 0) /* Bits 0-2: Permissions for others: RWX */
#define S_IWOTH 0000002 #define S_IWOTH (1 << 1)
#define S_IROTH 0000004 #define S_IROTH (1 << 2)
#define S_IRWXO 0000007 #define S_IRWXO (7 << 0)
#define S_IXGRP 0000010 /* Group permissions: RWX */ #define S_IXGRP (1 << 3) /* Bits 3-5: Group permissions: RWX */
#define S_IWGRP 0000020 #define S_IWGRP (1 << 4)
#define S_IRGRP 0000040 #define S_IRGRP (1 << 5)
#define S_IRWXG 0000070 #define S_IRWXG (7 << 3)
#define S_IXUSR 0000100 /* Owner permissions: RWX */ #define S_IXUSR (1 << 6) /* Bits 6-8: Owner permissions: RWX */
#define S_IWUSR 0000200 #define S_IWUSR (1 << 7)
#define S_IRUSR 0000400 #define S_IRUSR (1 << 8)
#define S_IRWXU 0000700 #define S_IRWXU (7 << 6)
#define S_ISVTX 0001000 /* "sticky" bit */ #define S_ISVTX 0 /* "Sticky" bit (not used) */
#define S_ISGID 0002000 /* Set group ID bit */ #define S_ISGID 0 /* Set group ID bit (not used)*/
#define S_ISUID 0004000 /* Set UID bit */ #define S_ISUID 0 /* Set UID bit (not used) */
#define S_IFIFO 0010000 /* File type bytes */ #define S_IFIFO 0 /* Bits 12-14: File type bits (not all used) */
#define S_IFCHR 0020000 #define S_IFCHR (1 << 12)
#define S_IFDIR 0040000 #define S_IFDIR (2 << 12)
#define S_IFBLK 0060000 #define S_IFBLK (3 << 12)
#define S_IFREG 0100000 #define S_IFREG (4 << 12)
#define S_IFLNK 0120000 #define S_IFSOCK 0
#define S_IFSOCK 0140000 #define S_IFMQ (5 << 12)
#define S_IFMQ 0150000 #define S_IFSEM (6 << 12)
#define S_IFSEM 0160000 #define S_IFSHM (7 << 12)
#define S_IFSHM 0170000 #define s_IFTGT (7 << 12) /* May be the target of a symbolic link */
#define S_IFMT 0170000
#define S_IFLNK (1 << 15) /* Bit 15: Symbolic link */
#define S_IFMT (15 << 15) /* Bits 12-15: Full file type */
/* File type macros that operate on an instance of mode_t */ /* File type macros that operate on an instance of mode_t */
#define S_ISLNK(m) (((m) & S_IFMT) == S_IFLNK) #define S_ISLNK(m) (((m) & S_IFLNK) != 0)
#define S_ISREG(m) (((m) & S_IFMT) == S_IFREG) #define S_ISFIFO(m) (0)
#define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR) #define S_ISCHR(m) (((m) & s_IFTGT) == S_IFCHR)
#define S_ISCHR(m) (((m) & S_IFMT) == S_IFCHR) #define S_ISDIR(m) (((m) & s_IFTGT) == S_IFDIR)
#define S_ISBLK(m) (((m) & S_IFMT) == S_IFBLK) #define S_ISBLK(m) (((m) & s_IFTGT) == S_IFBLK)
#define S_ISFIFO(m) (((m) & S_IFMT) == S_IFIFO) #define S_ISREG(m) (((m) & s_IFTGT) == S_IFREG)
#define S_ISSOCK(m) (((m) & S_IFMT) == S_IFSOCK) #define S_ISSOCK(m) (0)
#define S_ISMQ(m) (((m) & S_IFMT) == S_IFMQ) #define S_ISMQ(m) (((m) & s_IFTGT) == S_IFMQ)
#define S_ISSSEM(m) (((m) & S_IFMT) == S_IFSEM) #define S_ISSEM(m) (((m) & s_IFTGT) == S_IFSEM)
#define S_ISSHM(m) (((m) & S_IFMT) == S_IFSHM) #define S_ISSHM(m) (((m) & s_IFTGT) == S_IFSHM)
/**************************************************************************** /****************************************************************************
* Type Definitions * Type Definitions