util: replace close_nointr_nofail() by a more useful safe_close()

safe_close() automatically becomes a NOP when a negative fd is passed,
and returns -1 unconditionally. This makes it easy to write lines like
this:

        fd = safe_close(fd);

Which will close an fd if it is open, and reset the fd variable
correctly.

By making use of this new scheme we can drop a > 200 lines of code that
was required to test for non-negative fds or to reset the closed fd
variable afterwards.

1 files changed, 10 insertions, 25 deletions

diff --git a/src/core/switch-root.c b/src/core/switch-root.c
index ce0e41d510..518ec1f0a7 100644
--- a/src/core/switch-root.c
+++ b/src/core/switch-root.c
@@ -41,11 +41,10 @@ int switch_root(const char *new_root) {
                 "/sys\0"
                 "/run\0";
 
-        int r, old_root_fd = -1;
+        _cleanup_close_ int old_root_fd = -1;
         struct stat new_root_stat;
         bool old_root_remove;
-        const char *i;
-        _cleanup_free_ char *temporary_old_root = NULL;
+        const char *i, *temporary_old_root;
 
         if (path_equal(new_root, "/"))
                 return 0;
@@ -56,16 +55,13 @@ int switch_root(const char *new_root) {
          * directory we choose for this, but it should be more likely
          * than not that /mnt exists and is suitable as mount point
          * and is on the same fs as the old root dir */
-        temporary_old_root = strappend(new_root, "/mnt");
-        if (!temporary_old_root)
-                return -ENOMEM;
+        temporary_old_root = strappenda(new_root, "/mnt");
 
         old_root_remove = in_initrd();
 
         if (stat(new_root, &new_root_stat) < 0) {
-                r = -errno;
                 log_error("Failed to stat directory %s: %m", new_root);
-                goto fail;
+                return -errno;
         }
 
         /* Work-around for a kernel bug: for some reason the kernel
@@ -104,9 +100,8 @@ int switch_root(const char *new_root) {
         }
 
         if (chdir(new_root) < 0) {
-                r = -errno;
                 log_error("Failed to change directory to %s: %m", new_root);
-                goto fail;
+                return -errno;
         }
 
         if (old_root_remove) {
@@ -123,27 +118,23 @@ int switch_root(const char *new_root) {
                 /* Immediately get rid of the old root. Since we are
                  * running off it we need to do this lazily. */
                 if (umount2(temporary_old_root, MNT_DETACH) < 0) {
-                        r = -errno;
                         log_error("Failed to umount old root dir %s: %m", temporary_old_root);
-                        goto fail;
+                        return -errno;
                 }
 
         } else if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
-                r = -errno;
                 log_error("Failed to mount moving %s to /: %m", new_root);
-                goto fail;
+                return -errno;
         }
 
         if (chroot(".") < 0) {
-                r = -errno;
                 log_error("Failed to change root: %m");
-                goto fail;
+                return -errno;
         }
 
         if (chdir("/") < 0) {
-                r = -errno;
                 log_error("Failed to change directory: %m");
-                goto fail;
+                return -errno;
         }
 
         if (old_root_fd >= 0) {
@@ -157,11 +148,5 @@ int switch_root(const char *new_root) {
                 }
         }
 
-        r = 0;
-
-fail:
-        if (old_root_fd >= 0)
-                close_nointr_nofail(old_root_fd);
-
-        return r;
+        return 0;
 }