utils: fix print_r() debugging helper

Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

diff --git a/src/lxc/utils.c b/src/lxc/utils.c
index d64fbf6b1c08211bf83c50db844a3128f452ac34..55995405c74f1960cf73f783c679de706aae3151 100644 (file)
--- a/src/lxc/utils.c
+++ b/src/lxc/utils.c
@@ -1858,19 +1858,34 @@ bool multiply_overflow(int64_t base, uint64_t mult, int64_t *res)
 
 int print_r(int fd, const char *path)
 {
-       __do_close int dfd = -EBADF;
+       __do_close int dfd = -EBADF, dfd_dup = -EBADF;
        __do_closedir DIR *dir = NULL;
        int ret = 0;
        struct dirent *direntp;
        struct stat st;
 
-       if (is_empty_string(path))
-               dfd = dup(fd);
-       else
-               dfd = openat(fd, path, O_CLOEXEC | O_DIRECTORY);
+       if (is_empty_string(path)) {
+               char buf[LXC_PROC_SELF_FD_LEN];
+
+               ret = strnprintf(buf, sizeof(buf), "/proc/self/fd/%d", fd);
+               if (ret < 0)
+                       return ret_errno(EIO);
+
+               /*
+                * O_PATH file descriptors can't be used so we need to re-open
+                * just in case.
+                */
+               dfd = openat(-EBADF, buf, O_CLOEXEC | O_DIRECTORY, 0);
+       } else {
+               dfd = openat(fd, path, O_CLOEXEC | O_DIRECTORY, 0);
+       }
        if (dfd < 0)
                return -1;
 
+       dfd_dup = dup_cloexec(dfd);
+       if (dfd_dup < 0)
+               return -1;
+
        dir = fdopendir(dfd);
        if (!dir)
                return -1;
@@ -1882,26 +1897,29 @@ int print_r(int fd, const char *path)
                    !strcmp(direntp->d_name, ".."))
                        continue;
 
-               ret = fstatat(dfd, direntp->d_name, &st, AT_SYMLINK_NOFOLLOW);
+               ret = fstatat(dfd_dup, direntp->d_name, &st, AT_SYMLINK_NOFOLLOW);
                if (ret < 0 && errno != ENOENT)
                        break;
 
                ret = 0;
                if (S_ISDIR(st.st_mode))
-                       ret = print_r(dfd, direntp->d_name);
+                       ret = print_r(dfd_dup, direntp->d_name);
                else
-                       INFO("mode(%o):uid(%d):gid(%d) -> %s/%s\n",
-                            (st.st_mode & ~S_IFMT), st.st_uid, st.st_gid, path,
+                       INFO("mode(%o):uid(%d):gid(%d) -> %d/%s\n",
+                            (st.st_mode & ~S_IFMT), st.st_uid, st.st_gid, dfd_dup,
                             direntp->d_name);
                if (ret < 0 && errno != ENOENT)
                        break;
        }
 
-       ret = fstatat(fd, path, &st, AT_SYMLINK_NOFOLLOW);
+       if (is_empty_string(path))
+               ret = fstatat(fd, "", &st, AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW | AT_EMPTY_PATH);
+       else
+               ret = fstatat(fd, path, &st, AT_NO_AUTOMOUNT | AT_SYMLINK_NOFOLLOW);
        if (ret)
                return -1;
        else
                INFO("mode(%o):uid(%d):gid(%d) -> %s",
-                    (st.st_mode & ~S_IFMT), st.st_uid, st.st_gid, path);
+                    (st.st_mode & ~S_IFMT), st.st_uid, st.st_gid, maybe_empty(path));
        return ret;
 }