syscalls: chroot, fchmodat, fchownat, faccessat

[lunaix-os.git] / lunaix-os / kernel / fs / path_walk.c

diff --git a/lunaix-os/kernel/fs/path_walk.c b/lunaix-os/kernel/fs/path_walk.c
index c80d7134d22596d89a7f53addcfb59929c3da8a5..7b49219edbad435fd1c9892676be55d110e2bf68 100644 (file)
--- a/lunaix-os/kernel/fs/path_walk.c
+++ b/lunaix-os/kernel/fs/path_walk.c
@@ -1,10 +1,14 @@
 #include <lunaix/fs.h>
 #include <lunaix/mm/valloc.h>
+#include <lunaix/process.h>
 #include <lunaix/spike.h>
 
+#include <usr/lunaix/fcntl_defs.h>
+
 #include <klibc/string.h>
 
 #define VFS_SYMLINK_DEPTH 16
+#define VFS_SYMLINK_MAXLEN 512
 
 extern struct lru_zone *dnode_lru, *inode_lru;
 
@@ -27,11 +31,16 @@ __vfs_walk(struct v_dnode* start,
     if (path[0] == VFS_PATH_DELIM || !start) {
         if ((walk_options & VFS_WALK_FSRELATIVE) && start) {
             start = start->super_block->root;
-        } else {
+        } 
+        else if (unlikely(!__current)) {
             start = vfs_sysroot;
-            if (!vfs_sysroot->mnt) {
-                panick("vfs: no root");
-            }
+        }
+        else {
+            start = __current->root ?: vfs_sysroot;
+        }
+
+        if (unlikely(!start || !start->mnt)) {
+            fail("vfs: no root");
         }
 
         if (path[0] == VFS_PATH_DELIM) {
@@ -42,15 +51,18 @@ __vfs_walk(struct v_dnode* start,
     assert(start);
 
     struct v_dnode* dnode;
-    struct v_inode* current_inode;
     struct v_dnode* current_level = start;
+    struct v_inode* current_inode = current_level->inode;
 
     struct hstr name = HSTR(fname_buffer, 0);
 
     char current = path[i++], lookahead;
-    while (current) {
+    while (current) 
+    {
         lookahead = path[i++];
-        if (current != VFS_PATH_DELIM) {
+
+        if (current != VFS_PATH_DELIM) 
+        {
             if (j >= VFS_NAME_MAXLEN - 1) {
                 return ENAMETOOLONG;
             }
@@ -79,43 +91,17 @@ __vfs_walk(struct v_dnode* start,
             break;
         }
 
-        current_inode = current_level->inode;
-
-        if ((current_inode->itype & VFS_IFSYMLINK) &&
-            !(walk_options & VFS_WALK_NOFOLLOW)) {
-            const char* link;
-
-            lock_inode(current_inode);
-            if ((errno =
-                   current_inode->ops->read_symlink(current_inode, &link))) {
-                unlock_inode(current_inode);
-                goto error;
-            }
-            unlock_inode(current_inode);
-
-            errno = __vfs_walk(current_level->parent,
-                               link,
-                               &dnode,
-                               NULL,
-                               0,
-                               depth + 1,
-                               fname_buffer + name.len + 1);
-
-            if (errno) {
-                goto error;
-            }
+        lock_dnode(current_level);
 
-            // reposition the resolved subtree pointed by symlink
-            vfs_dcache_rehash(current_level->parent, dnode);
-            current_level = dnode;
-            current_inode = dnode->inode;
+        if (!check_allow_execute(current_inode)) {
+            errno = EACCESS;
+            goto error;
         }
 
-        lock_dnode(current_level);
-
         dnode = vfs_dcache_lookup(current_level, &name);
 
-        if (!dnode) {
+        if (!dnode) 
+        {
             dnode = vfs_d_alloc(current_level, &name);
 
             if (!dnode) {
@@ -148,6 +134,49 @@ __vfs_walk(struct v_dnode* start,
 
         j = 0;
         current_level = dnode;
+        current_inode = current_level->inode;
+
+        assert(current_inode);
+        
+        if (check_symlink_node(current_inode) &&
+            !(walk_options & VFS_WALK_NOFOLLOW)) 
+        {
+            const char* link;
+            struct v_inode_ops* iops;
+
+            iops = current_inode->ops;
+
+            if (!iops->read_symlink) {
+                errno = ENOTSUP;
+                goto error;
+            }
+
+            lock_inode(current_inode);
+
+            errno = iops->read_symlink(current_inode, &link);
+            if ((errno < 0)) {
+                unlock_inode(current_inode);
+                goto error;
+            }
+
+            unlock_inode(current_inode);
+
+            errno = __vfs_walk(current_level->parent,
+                               link,
+                               &dnode,
+                               NULL,
+                               0,
+                               depth + 1,
+                               fname_buffer + name.len + 1);
+
+            if (errno) {
+                goto error;
+            }
+
+            current_level = dnode;
+            current_inode = dnode->inode;
+        }
+
     cont:
         current = lookahead;
     };
@@ -157,6 +186,7 @@ __vfs_walk(struct v_dnode* start,
 
 cleanup:
     vfs_d_free(dnode);
+
 error:
     *dentry = NULL;
     return errno;
@@ -169,6 +199,11 @@ vfs_walk(struct v_dnode* start,
          struct hstr* component,
          int options)
 {
+    if (!path) {
+        *dentry = NULL;
+        return 0;
+    }
+
     // allocate a file name stack for path walking and recursion to resolve
     // symlink
     char* name_buffer = valloc(2048);
@@ -187,4 +222,36 @@ vfs_walk_proc(const char* path,
               int options)
 {
     return vfs_walk(__current->cwd, path, dentry, component, options);
+}
+
+int
+vfs_walkat(int fd, const char* path, int at_opts, struct v_dnode** dnode_out)
+{
+    int errno, options = 0;
+    struct v_dnode *root_dnode;
+    struct v_fd* _fd;
+
+    if ((at_opts & AT_FDCWD)) {
+        root_dnode = __current->cwd;
+    }
+    else 
+    {
+        errno = vfs_getfd(fd, &_fd);
+        if (errno) {
+            return errno;
+        }
+
+        root_dnode = _fd->file->dnode;
+    }
+
+    if ((at_opts & AT_SYMLINK_NOFOLLOW)) {
+        options |= VFS_WALK_NOFOLLOW;
+    }
+
+    errno = vfs_walk(root_dnode, path, dnode_out, NULL, options);
+    if (errno) {
+        return errno;
+    }
+
+    return 0;
 }
\ No newline at end of file