Don't crash if $HOME is empty

If both $XDG_CONFIG_HOME and $HOME are unset, we'd try to copy a NULL
string, causing a crash. This is the environment systemd provides to
its daemons, and that was causing upowerd to crash.

http://libiphone.lighthouseapp.com/projects/27916-libiphone/tickets/273-patch-fix-segfault-when-running-with-home-unset#ticket-273-2
http://libiphone.lighthouseapp.com/projects/27916/tickets/265-userpref_get_config_dir-segfaults-when-home-is-undefined
https://bugzilla.redhat.com/show_bug.cgi?id=834359

1 files changed, 22 insertions, 1 deletions

diff --git a/src/userpref.c b/src/userpref.c
index a0c3545..0e774b7 100644
--- a/src/userpref.c
+++ b/src/userpref.c
@@ -102,6 +102,20 @@ static char *userpref_utf16_to_utf8(wchar_t *unistr, long len, long *items_read,
 }
 #endif
 
+static const char *userpref_get_tmp_dir()
+{
+        const char *cdir = getenv("TMPDIR");
+        if (cdir && cdir[0])
+                return cdir;
+        cdir = getenv("TMP");
+        if (cdir && cdir[0])
+                return cdir;
+        cdir = getenv("TEMP");
+        if (cdir && cdir[0])
+                return cdir;
+        return "/tmp";
+}
+
 static const char *userpref_get_config_dir()
 {
         if (__config_dir[0]) return __config_dir;
@@ -125,7 +139,14 @@ static const char *userpref_get_config_dir()
         const char *cdir = getenv("XDG_CONFIG_HOME");
         if (!cdir) {
                 cdir = getenv("HOME");
-                strcpy(__config_dir, cdir);
+                if (!cdir || !cdir[0]) {
+                        const char *tdir = userpref_get_tmp_dir();
+                        strcpy(__config_dir, tdir);
+                        strcat(__config_dir, DIR_SEP_S);
+                        strcat(__config_dir, "root");
+                } else {
+                        strcpy(__config_dir, cdir);
+                }
                 strcat(__config_dir, DIR_SEP_S);
                 strcat(__config_dir, ".config");
         } else {