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[LibOS] Allow inaccessible files during getdents()

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Previously, if user performed getdents() on a directory containing
inaccessible files (because user doesn't have permission), whole
getdents failed with -EACCES. This is incorrect behavior: files must
still be listed. This commit fixes the root cause of this bug by
marking inaccessible files as DENTRY_NEGATIVE.
This commit is contained in:
Dmitrii Kuvaiskii
2019-12-18 02:59:02 -08:00
parent 860e1083a2
commit 05cc50945f
2 changed files with 11 additions and 6 deletions
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LibOS/shim/include/shim_fs.h
+1 -1
View File
@@ -104,7 +104,7 @@ struct shim_fs_ops {
};
#define DENTRY_VALID 0x0001 /* this dentry is verified to be valid */
#define DENTRY_NEGATIVE 0x0002 /* negative, recently deleted */
#define DENTRY_NEGATIVE 0x0002 /* recently deleted or inaccessible */
#define DENTRY_RECENTLY 0x0004 /* recently used */
#define DENTRY_PERSIST 0x0008 /* added as a persistent dentry */
#define DENTRY_HASHED 0x0010 /* added in the dcache */
LibOS/shim/src/fs/shim_namei.c
+10 -5
View File
@@ -198,9 +198,9 @@ int lookup_dentry (struct shim_dentry * parent, const char * name, int namelen,
* Not done in original code, so leaving for now.
*/
if (err) {
if (err == -ENOENT) {
// Let ENOENT fall through so we can get negative dentries in
// the cache
if (err == -ENOENT || err == -EACCES) {
/* Non-existing files and inaccessible files are marked as
* negative dentries, so they can still be cached */
dent->state |= DENTRY_NEGATIVE;
} else {
@@ -759,8 +759,12 @@ int list_directory_dentry (struct shim_dentry *dent) {
for ( ; d ; d = d->next) {
struct shim_dentry * child;
if ((ret = lookup_dentry(dent, d->name, strlen(d->name),
&child, fs)) < 0)
goto done_read;
&child, fs)) < 0) {
if (ret != -ENOENT) {
/* if the file is recently deleted or inaccessible, ignore it */
goto done_read;
}
}
if (child->state & DENTRY_NEGATIVE)
continue;
@@ -774,6 +778,7 @@ int list_directory_dentry (struct shim_dentry *dent) {
}
dent->state |= DENTRY_LISTED;
ret = 0;
done_read:
unlock(&dcache_lock);