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 1411536ea8e4963f2fe951058daac69b2715f5dd..4ca60c0c0d972018486bc725c17752725a07ebeb 100644 (file)
--- a/src/libadacl.c
+++ b/src/libadacl.c
@@ -607,8 +607,14 @@ int acl_copy_xattr(int src_fd,
     return ACL_ERROR;
   }
   char* src_acl_p = alloca(src_size_guess);
-  /* The actual size may be smaller than our guess? I don't know. */
-  ssize_t src_size = fgetxattr(src_fd, src_name, src_acl_p, src_size_guess);
+  /* The actual size may be smaller than our guess? I don't know. The
+     return value from fgetxattr() will either be nonnegative, or
+     XATTR_ERROR (which we've already ruled out), so it's safe to cast
+     it to an unsigned size_t here to avoid a compiler warning. */
+  ssize_t src_size = fgetxattr(src_fd,
+                               src_name,
+                               src_acl_p,
+                               (size_t)src_size_guess);
   if (src_size == XATTR_ERROR) {
     if (errno == ENODATA) {
       /* A missing ACL isn't an error. */
@@ -618,7 +624,14 @@ int acl_copy_xattr(int src_fd,
     return ACL_ERROR;
   }
 
-  if (fsetxattr(dst_fd, dst_name, src_acl_p, src_size, 0) == XATTR_ERROR) {
+  /* See above: src_size must be nonnegative at this point,so we cast
+     it to size_t to avoid a compiler warning. */
+  if (fsetxattr(dst_fd,
+                dst_name,
+                src_acl_p,
+                (size_t)src_size,
+                0)
+      == XATTR_ERROR) {
     perror("acl_copy_xattr (fsetxattr)");
     return ACL_ERROR;
   }
@@ -680,9 +693,7 @@ int has_default_acl_fd(int fd) {
  *   - @c ACL_FAILURE - If symlinks or hard links are encountered.
  *   - @c ACL_ERROR - Unexpected library error.
  */
-int apply_default_acl_fds(int parent_fd,
-                          int fd,
-                          bool recursive) {
+int apply_default_acl_fds(int parent_fd, int fd, bool recursive) {
   int result = ACL_SUCCESS;
 
   /* The new ACL for this path */
@@ -992,7 +1003,30 @@ int apply_default_acl(const char* path, bool recursive) {
     return ACL_ERROR;
   }
   char* parent = dirname(dirname_path_copy);
+
+  basename_path_copy = strdup(path);
+  if (basename_path_copy == NULL) {
+    perror("apply_default_acl (strdup)");
+    result = ACL_ERROR;
+    goto cleanup;
+  }
+  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)
@@ -1008,15 +1042,20 @@ 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)");
-    return ACL_ERROR;
+   * 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, child, O_NOFOLLOW);
   }
-  fd = openat(parent_fd, basename(basename_path_copy), O_NOFOLLOW);
   if (fd == OPEN_ERROR) {
     if (errno == ELOOP || errno == ENOTDIR) {
       /* We hit a symlink, either in the last path component (ELOOP)