util: add generic calls for prefixing a root directory to a path

So far a number of utilities implemented their own calls for this, unify
them in prefix_root() and prefix_roota(). The former uses heap memory,
the latter allocates from the stack via alloca().

Port over most users of a --root= logic.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/shared/conf-files.c b/src/shared/conf-files.c
index 9ab08355e3..da8745b284 100644
--- a/src/shared/conf-files.c
+++ b/src/shared/conf-files.c
@@ -36,12 +36,13 @@
 
 static int files_add(Hashmap *h, const char *root, const char *path, const char *suffix) {
         _cleanup_closedir_ DIR *dir = NULL;
-        char *dirpath;
+        const char *dirpath;
+        int r;
 
         assert(path);
         assert(suffix);
 
-        dirpath = strjoina(root ? root : "", path);
+        dirpath = prefix_roota(root, path);
 
         dir = opendir(dirpath);
         if (!dir) {
@@ -53,7 +54,6 @@ static int files_add(Hashmap *h, const char *root, const char *path, const char
         for (;;) {
                 struct dirent *de;
                 char *p;
-                int r;
 
                 errno = 0;
                 de = readdir(dir);