gfapi: fix handling of dot and double dot in path

This patch is to handle "." and ".." in file path. Which means
this special dentry names will be resolved before sending fops
on the path.

Backport of>
>Change-Id: I5e92f6d1ad1412bf432eb2488e53fb7731edb013
>BUG: 1447266
>Signed-off-by: Mohammed Rafi KC <rkavunga@redhat.com>
>Reviewed-on: https://review.gluster.org/17177
>Smoke: Gluster Build System <jenkins@build.gluster.org>
>Reviewed-by: Niels de Vos <ndevos@redhat.com>
>CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
>NetBSD-regression: NetBSD Build System <jenkins@build.gluster.org>
>Reviewed-by: Jeff Darcy <jeff@pl.atyp.us>

Change-Id: I5e92f6d1ad1412bf432eb2488e53fb7731edb013
BUG: 1463528
Signed-off-by: Mohammed Rafi KC <rkavunga@redhat.com>
Reviewed-on: https://review.gluster.org/17237
Smoke: Gluster Build System <jenkins@build.gluster.org>
Tested-by: Shyamsundar Ranganathan <srangana@redhat.com>
CentOS-regression: Gluster Build System <jenkins@build.gluster.org>
Reviewed-by: Shyamsundar Ranganathan <srangana@redhat.com>

2 files changed, 127 insertions, 0 deletions

diff --git a/libglusterfs/src/inode.c b/libglusterfs/src/inode.c
index 3a6464ac5e1..6f3bc535a14 100644
--- a/libglusterfs/src/inode.c
+++ b/libglusterfs/src/inode.c
@@ -2569,3 +2569,113 @@ inode_ctx_size (inode_t *inode)
 out:
         return size;
 }
+
+static void
+inode_parent_null_check(inode_t **parent, inode_t *inode, char **component)
+{
+        GF_VALIDATE_OR_GOTO ("inode", inode, out);
+        GF_VALIDATE_OR_GOTO ("inode", (*component), out);
+
+        if (!(*parent) && __is_root_gfid (inode->gfid)) {
+                *parent = inode_ref (inode);
+                *component = "/";
+        }
+out:
+        return;
+}
+
+/*
+ * This function changes component name and parent inode
+ * if the component name is either "." or ".."
+ *
+ * @Paramas:
+ * Parent : Parent inode of current dentry
+ * component : component name that we need to test
+ * dentry_name : Address for memory if need to change component.
+ *               The caller has to preallocate this memory with
+ *               PATH_MAX as the size.
+ *
+ * We return the updated parent inode and component in the
+ * respective structures.
+ *
+ * Basic Idea of the function:
+ *
+ * Example 1 :
+ * Path /out_dir/dir/in_dir/.
+ *     In put values :
+ *         parent = in_dir
+ *         component : "."
+ *
+ *     Out put values:
+ *         parent : dir
+ *         component : "in_dir"
+ *
+ * Example 2 :
+ * Path /out_dir/dir/in_dir/..
+ *     In put values :
+ *         parent = in_dir
+ *         component : ".."
+ *
+ *     Out put values:
+ *         parent : output_dir
+ *         component : "dir"
+ */
+void
+glusterfs_normalize_dentry (inode_t **parent, char **component,
+                          char *dentry_name)
+{
+        inode_t         *temp_inode             = NULL;
+        dentry_t        *dentry                 = NULL;
+
+        GF_VALIDATE_OR_GOTO ("inode", (*parent), out);
+        GF_VALIDATE_OR_GOTO ("inode", (*component), out);
+        GF_VALIDATE_OR_GOTO ("inode", (dentry_name), out);
+
+        /* After this point, there should not be "." or ".."
+         * in the path. Dot and double dots are replaced with
+         * appropriate base name and parent inode.
+         */
+
+        /* During the resolving, if it goes beyond the mount point
+         * we do lookup on the mount itself like "/.. " will be
+         * converted as "/"
+         */
+        if (strcmp (*component, ".") == 0) {
+                temp_inode = *parent;
+                *parent = inode_parent (*parent, 0, 0);
+                inode_parent_null_check (parent, temp_inode, component);
+                pthread_mutex_lock (&temp_inode->table->lock);
+                {
+                        dentry = __dentry_search_arbit (temp_inode);
+                        if (dentry) {
+                                snprintf (dentry_name, PATH_MAX, "%s",
+                                          dentry->name);
+                                *component = dentry_name;
+                        }
+                }
+                pthread_mutex_unlock (&temp_inode->table->lock);
+                inode_unref (temp_inode);
+        } else if (strcmp (*component, "..") == 0) {
+                temp_inode = *parent;
+                *parent = inode_parent (*parent, 0, 0);
+                inode_parent_null_check (parent, temp_inode, component);
+                inode_unref (temp_inode);
+
+                temp_inode = *parent;
+                *parent = inode_parent (*parent, 0, 0);
+                inode_parent_null_check (parent, temp_inode, component);
+                pthread_mutex_lock (&temp_inode->table->lock);
+                {
+                        dentry = __dentry_search_arbit (temp_inode);
+                        if (dentry) {
+                                snprintf (dentry_name, PATH_MAX, "%s",
+                                          dentry->name);
+                                *component = dentry_name;
+                        }
+                }
+                pthread_mutex_unlock (&temp_inode->table->lock);
+                inode_unref (temp_inode);
+        }
+out:
+        return;
+}
diff --git a/libglusterfs/src/inode.h b/libglusterfs/src/inode.h
index cdc2095a0e8..253196378a8 100644
--- a/libglusterfs/src/inode.h
+++ b/libglusterfs/src/inode.h
@@ -286,4 +286,21 @@ inode_has_dentry (inode_t *inode);
 size_t
 inode_ctx_size (inode_t *inode);
 
+/*
+ * This function is used to change the dentry from a path
+ * if it contains any "." or ".." .
+ *
+ * It replaces "." and ".." to proper bname after resolving
+ * and will change the component accordingly.
+ *
+ * This fucntion also replaces the parent inode based on the
+ * bname.
+ *
+ * We should give a allocated memory as a third argument to store
+ * the component in case if we are modifying it.
+ */
+
+void
+glusterfs_normalize_dentry (inode_t **parent, char **component,
+                            char *dentry_name);
 #endif /* _INODE_H */