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Union FS. Add logic to omit duplicates in file system 2 when doing directory listing

This commit is contained in:
Gregory Nutt 2015-06-06 09:49:13 -06:00
parent 05e6d9409d
commit 597493221e
2 changed files with 154 additions and 23 deletions
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176
fs/unionfs/fs_unionfs.c
View File

@ -45,6 +45,7 @@
#include <stdint.h>
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <semaphore.h>
@ -133,6 +134,8 @@ static int unionfs_trystatdir(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix);
static int unionfs_trystatfile(FAR struct inode *inode,
FAR const char *relpath, FAR const char *prefix);
static FAR char *unionfs_relpath(FAR const char *path,
FAR const char *name);
static void unionfs_unhooked(FAR struct unionfs_inode_s *ui);
static void unionfs_destroy(FAR struct unionfs_inode_s *ui);
@ -560,6 +563,52 @@ static int unionfs_tryrmdir(FAR struct inode *inode, FAR const char *relpath,
return ops->rmdir(inode, trypath);
}
/****************************************************************************
* Name: unionfs_relpath
****************************************************************************/
static FAR char *unionfs_relpath(FAR const char *path, FAR const char *name)
{
FAR char *relpath;
int pathlen;
int ret;
/* Check if there is a valid, non-zero-legnth path */
if (path && (pathlen = strlen(path)) > 0)
{
/* Yes.. extend the file name by prepending the path */
if (path[pathlen-1] == '/')
{
ret = asprintf(&relpath, "%s%s", path, name);
}
else
{
ret = asprintf(&relpath, "%s/%s", path, name);
}
/* Handle errors */
if (ret < 0)
{
return NULL;
}
else
{
return relpath;
}
}
else
{
/* There is no path... just duplicate the name (so that kmm_free()
* will work later).
*/
return strdup(name);
}
}
/****************************************************************************
* Name: unionfs_unhooked
****************************************************************************/
@ -1123,13 +1172,26 @@ static int unionfs_opendir(FAR struct inode *mountpt, FAR const char *relpath,
DEBUGASSERT(dir);
fu = &dir->u.unionfs;
/* Clone the path. We will need this when we traverse file system 2 to
* omit duplicates on file system 1.
*/
if (relpath && strlen(relpath) > 0)
{
fu->fu_relpath = strdup(relpath);
if (!fu->fu_relpath)
{
goto errout_with_semaphore;
}
}
/* Allocate another dirent structure for the lower file system */
lowerdir = (FAR struct fs_dirent_s *)kmm_zalloc(sizeof(struct fs_dirent_s));
if (lowerdir == NULL)
{
ret = -ENOMEM;
goto errout_with_semaphore;
goto errout_with_relpath;
}
/* Check file system 2 first. */
@ -1186,7 +1248,7 @@ static int unionfs_opendir(FAR struct inode *mountpt, FAR const char *relpath,
{
/* Neither file system was opened! */
goto errout_with_semaphore;
goto errout_with_relpath;
}
}
@ -1208,6 +1270,12 @@ errout_with_fs2open:
kmm_free(fu->fu_lower[1]);
errout_with_relpath:
if (fu->fu_relpath != NULL)
{
kmm_free(fu->fu_relpath);
}
errout_with_semaphore:
unionfs_semgive(ui);
return ret;
@ -1267,7 +1335,15 @@ static int unionfs_closedir(FAR struct inode *mountpt,
}
}
/* Free any allocated path */
if (fu->fu_relpath != NULL)
{
kmm_free(fu->fu_relpath);
}
fu->fu_ndx = 0;
fu->fu_relpath = NULL;
fu->fu_lower[0] = NULL;
fu->fu_lower[1] = NULL;
@ -1296,8 +1372,12 @@ static int unionfs_readdir(struct inode *mountpt, struct fs_dirent_s *dir)
{
FAR struct unionfs_inode_s *ui;
FAR struct unionfs_mountpt_s *um;
FAR struct unionfs_mountpt_s *um0;
FAR const struct mountpt_operations *ops;
FAR struct fs_unionfsdir_s *fu;
FAR char *relpath;
struct stat buf;
bool duplicate;
int ret = -ENOSYS;
/* Recover the union file system data from the struct inode instance */
@ -1320,39 +1400,89 @@ static int unionfs_readdir(struct inode *mountpt, struct fs_dirent_s *dir)
if (ops->readdir)
{
ret = ops->readdir(um->um_node, fu->fu_lower[fu->fu_ndx]);
/* Loop if we discard duplicate directory entries in filey system 2 */
/* Did the read operation fail because we reached the end of the
* directory? In that case, the error would be -ENOENT. If we hit
* the end-of-directory on file system, we need to seamlessly move
* to the second file system (if there is one).
*/
if (ret == -ENOENT && fu->fu_ndx == 0 && fu->fu_lower[1] != NULL)
do
{
/* Switch to the second file system */
/* Read the directory entry */
fu->fu_ndx = 1;
um = &ui->ui_fs[1];
ret = ops->readdir(um->um_node, fu->fu_lower[fu->fu_ndx]);
DEBUGASSERT(um != NULL && um->um_node != NULL && um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Make sure that the second file system directory enumeration
* is rewound to the beginning of the directory.
/* Did the read operation fail because we reached the end of the
* directory? In that case, the error would be -ENOENT. If we
* hit the end-of-directory on file system, we need to seamlessly
* move to the second file system (if there is one).
*/
if (ops->rewinddir != NULL)
if (ret == -ENOENT && fu->fu_ndx == 0 && fu->fu_lower[1] != NULL)
{
ret = ops->rewinddir(um->um_node, fu->fu_lower[1]);
/* Switch to the second file system */
fu->fu_ndx = 1;
um = &ui->ui_fs[1];
DEBUGASSERT(um != NULL && um->um_node != NULL &&
um->um_node->u.i_mops != NULL);
ops = um->um_node->u.i_mops;
/* Make sure that the second file system directory enumeration
* is rewound to the beginning of the directory.
*/
if (ops->rewinddir != NULL)
{
ret = ops->rewinddir(um->um_node, fu->fu_lower[1]);
}
/* Then try the read operation again */
ret = ops->readdir(um->um_node, fu->fu_lower[1]);
}
/* Then try the read operation again */
/* Did we successfully read a directory from file system 2? If
* so, we need to omit an duplicates that should be occluded by
* the matching file on file system 1 (if we are enumerating
* file system 1).
*/
ret = ops->readdir(um->um_node, fu->fu_lower[1]);
duplicate = false;
if (ret >= 0 && fu->fu_ndx == 1 && fu->fu_lower[0] != NULL)
{
/* Get the relative path to the same file on file system 1.
* NOTE: the on any failures we just assume that the filep
* is not a duplicate.
*/
relpath = unionfs_relpath(fu->fu_relpath,
fu->fu_lower[1]->fd_dir.d_name);
if (relpath)
{
int tmp;
/* Check if anything exists at this path on file system 1 */
um0 = &ui->ui_fs[0];
tmp = unionfs_trystat(um0->um_node, relpath,
um0->um_prefix, &buf);
if (tmp >= 0)
{
/* There is something there!
* REVISIT: We could allow files and directories to
* have duplicat names.
*/
duplicate = true;
}
/* Free the allocated relpath */
kmm_free(relpath);
}
}
}
while (duplicate);
/* Copy the return information into the diret structure that the
/* Copy the return information into the dirent structure that the
* application will see.
*/

1
include/nuttx/fs/dirent.h
View File

@ -157,6 +157,7 @@ struct fs_dirent_s; /* Forward reference */
struct fs_unionfsdir_s
{
uint8_t fu_ndx; /* Index of file system being enumerated */
FAR char *fu_relpath; /* Path being enumerated */
FAR struct fs_dirent_s *fu_lower[2]; /* dirent struct used by contained file system */
};
#endif