unix_apply.c: fix overwriting existing readonly files

[wimlib] / src / unix_apply.c

diff --git a/src/unix_apply.c b/src/unix_apply.c
index f1962d9884b63752892217f3eed71b29393a777c..3746f504a3695954e9de7c0126872d151075681e 100644 (file)
--- a/src/unix_apply.c
+++ b/src/unix_apply.c
@@ -3,7 +3,7 @@
  */
 
 /*
- * Copyright (C) 2012, 2013, 2014 Eric Biggers
+ * Copyright (C) 2012-2016 Eric Biggers
  *
  * This file is free software; you can redistribute it and/or modify it under
  * the terms of the GNU Lesser General Public License as published by the Free
@@ -156,7 +156,9 @@ unix_build_extraction_path(const struct wim_dentry *dentry,
        d = dentry;
        do {
                p -= d->d_extraction_name_nchars;
-               memcpy(p, d->d_extraction_name, d->d_extraction_name_nchars);
+               if (d->d_extraction_name_nchars)
+                       memcpy(p, d->d_extraction_name,
+                              d->d_extraction_name_nchars);
                *--p = '/';
                d = d->d_parent;
        } while (!dentry_is_root(d) && will_extract_dentry(d));
@@ -434,7 +436,7 @@ unix_extract_if_empty_file(const struct wim_dentry *dentry,
 
                path = unix_build_extraction_path(dentry, ctx);
        retry_create:
-               fd = open(path, O_TRUNC | O_CREAT | O_WRONLY | O_NOFOLLOW, 0644);
+               fd = open(path, O_EXCL | O_CREAT | O_WRONLY | O_NOFOLLOW, 0644);
                if (fd < 0) {
                        if (errno == EEXIST && !unlink(path))
                                goto retry_create;
@@ -575,7 +577,7 @@ unix_begin_extract_blob_instance(const struct blob_descriptor *blob,
        first_dentry = inode_first_extraction_dentry(inode);
        first_path = unix_build_extraction_path(first_dentry, ctx);
 retry_create:
-       fd = open(first_path, O_TRUNC | O_CREAT | O_WRONLY | O_NOFOLLOW, 0644);
+       fd = open(first_path, O_EXCL | O_CREAT | O_WRONLY | O_NOFOLLOW, 0644);
        if (fd < 0) {
                if (errno == EEXIST && !unlink(first_path))
                        goto retry_create;