tree-wide: warn when a directory path already exists but has bad mode/owner/type

When we are attempting to create directory somewhere in the bowels of /var/lib
and get an error that it already exists, it can be quite hard to diagnose what
is wrong (especially for a user who is not aware that the directory must have
the specified owner, and permissions not looser than what was requested). Let's
print a warning in most cases. A warning is appropriate, because such state is
usually a sign of borked installation and needs to be resolved by the adminstrator.

$ build/test-fs-util

Path "/tmp/test-readlink_and_make_absolute" already exists and is not a directory, refusing.
   (or)
Directory "/tmp/test-readlink_and_make_absolute" already exists, but has mode 0775 that is too permissive (0755 was requested), refusing.
   (or)
Directory "/tmp/test-readlink_and_make_absolute" already exists, but is owned by 1001:1000 (1000:1000 was requested), refusing.

Assertion 'mkdir_safe(tempdir, 0755, getuid(), getgid(), MKDIR_WARN_MODE) >= 0' failed at ../src/test/test-fs-util.c:320, function test_readlink_and_make_absolute(). Aborting.

No functional change except for the new log lines.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/basic/mkdir.h b/src/basic/mkdir.h
index 2ce8bfc3e9..59d0fb6d81 100644
--- a/src/basic/mkdir.h
+++ b/src/basic/mkdir.h
@@ -25,6 +25,7 @@
 
 typedef enum MkdirFlags {
         MKDIR_FOLLOW_SYMLINK = 1 << 0,
+        MKDIR_WARN_MODE      = 1 << 1,
 } MkdirFlags;
 
 int mkdir_errno_wrapper(const char *pathname, mode_t mode);