src/libadacl.c: use strncat instead of strcat to appease clang-tidy.

[apply-default-acl.git] / src / libadacl.c

diff --git a/src/libadacl.c b/src/libadacl.c
index 911e69ae3022736eab1f30e1e463b7bd18188e73..4ca60c0c0d972018486bc725c17752725a07ebeb 100644 (file)
--- a/src/libadacl.c
+++ b/src/libadacl.c
@@ -1004,24 +1004,29 @@ int apply_default_acl(const char* path, bool recursive) {
   }
   char* parent = dirname(dirname_path_copy);
 
-  /* Just kidding, if the path is ".", then dirname will do the wrong
-   * thing and give us "." as its parent, too. So, we handle that as a
-   * special case.
-   *
-   * WARNING: it is important that "parent" itself is not used after
-   * this point; otherwise we would need to store the correct parent
-   * path in there. But since everything uses file descriptors from
-   * now on, we only need to ensure that we get the correct parent_fd
-   * below. */
-  if (strcmp(path, ".") == 0 && strcmp(parent, ".") == 0) {
-    parent_fd = safe_open("..", O_DIRECTORY | O_NOFOLLOW);
-  }
-  else if (strcmp(path, "..") == 0 && strcmp(parent, ".") == 0) {
-    parent_fd = safe_open("../..", O_DIRECTORY | O_NOFOLLOW);
+  basename_path_copy = strdup(path);
+  if (basename_path_copy == NULL) {
+    perror("apply_default_acl (strdup)");
+    result = ACL_ERROR;
+    goto cleanup;
   }
-  else {
-    parent_fd = safe_open(parent, O_DIRECTORY | O_NOFOLLOW);
+  char* child = basename(basename_path_copy);
+
+  /* Just kidding, if the path is "." or "..", then dirname will do
+   * the wrong thing and give us "." as its parent, too. So, we handle
+   * those as special cases. We use "child" instead of "path" here to
+   * catch things like "./" and "../"
+   */
+  bool path_is_dots = strcmp(child, ".") == 0 || strcmp(child, "..") == 0;
+  char dots_parent[6] = "../";
+  if (path_is_dots) {
+    /* We know that "child" contains no more than two characters here, and
+       using strncat to enforce that belief keeps clang-tidy happy. */
+    parent = strncat(dots_parent, child, 2);
   }
+
+  parent_fd = safe_open(parent, O_DIRECTORY | O_NOFOLLOW);
+
   if (parent_fd == OPEN_ERROR) {
     if (errno == ELOOP || errno == ENOTDIR) {
       /* We hit a symlink, either in the last path component (ELOOP)
@@ -1037,27 +1042,19 @@ int apply_default_acl(const char* path, bool recursive) {
   }
 
   /* We already obtained the parent fd safely, so if we use the
-     basename of path here instead of the full thing, then we can get
-     away with using openat() and spare ourselves the slowness of
-     another safe_open(). */
-  basename_path_copy = strdup(path);
-  if (basename_path_copy == NULL) {
-    perror("apply_default_acl (strdup)");
-    result = ACL_ERROR;
-    goto cleanup;
-  }
-
-  /* If the basename is ".", then we don't want to open "." relative
-     to the parent_fd, so we need another special case for that
-     path. */
-  if (strcmp(path, ".") == 0 && strcmp(parent, ".") == 0) {
-    fd = open(".", O_NOFOLLOW);
-  }
-  else if (strcmp(path, "..") == 0 && strcmp(parent, ".") == 0) {
-    fd = open("..", O_NOFOLLOW);
+   * basename of path here instead of the full thing, then we can get
+   * away with using openat() and spare ourselves the slowness of
+   * another safe_open().
+   *
+   * Note that if the basename is "." or "..", then we don't want to
+   * open it relative to the parent_fd, so we need another special
+   * case for those paths here.
+   */
+  if (path_is_dots) {
+    fd = open(child, O_NOFOLLOW);
   }
   else {
-    fd = openat(parent_fd, basename(basename_path_copy), O_NOFOLLOW);
+    fd = openat(parent_fd, child, O_NOFOLLOW);
   }
   if (fd == OPEN_ERROR) {
     if (errno == ELOOP || errno == ENOTDIR) {