From c96e341a0d317d6345dbf1f43a8ca0e0c31aaf7d Mon Sep 17 00:00:00 2001

From: Djalal Harouni <tixxdz@opendz.org>

Date: Thu, 17 Apr 2014 01:47:11 +0100

Subject: [PATCH 387/389] install: create_symlink() check unlink() return value

create_symlink() do not check the return value of unlink(), this may

confuse the user.

Before the unlink() call we check the 'force' argument. If it is not set

we fail with -EEXIST, otherwise we unlink() the file, therefore the next

symlink() should not fail with -EEXIST (do not count races...).

However since callers may not have appropriate privileges to unlink()

the file we lose the -EPERM or any other errno code of unlink(), and

return the -EEXIST of the next symlink(). Fix this by checking unlink()

results.

Before:

$ systemctl --force --root=~/container-03 set-default multi-user.target

Failed to set default target: File exists

After:

$ systemctl --force --root=~/container-03 set-default multi-user.target

Failed to set default target: Permission denied

(cherry picked from commit af7fce1cdb6c0d6ce56bcddccbc31dd3d64a8cd8)

(cherry picked from commit ac19aafa62b4dd47e26b368b54c17e6e1c71d8fb)

---

 src/shared/install.c | 4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/shared/install.c b/src/shared/install.c

index b9c85b7..e6a61fa 100644

--- a/src/shared/install.c

+++ b/src/shared/install.c

@@ -1172,7 +1172,9 @@ static int create_symlink(

         if (!force)

                 return -EEXIST;

-        unlink(new_path);

+        r = unlink(new_path);

+        if (r < 0 && errno != ENOENT)

+                return -errno;

         if (symlink(old_path, new_path) >= 0) {

                 add_file_change(changes, n_changes, UNIT_FILE_UNLINK, new_path, NULL);

-- 

1.8.3.1