shared: include root when canonicalizing conf paths

The conf_files_list family accepts an alternate root path to prefix all
directories in the list but path_strv_canonicalize_uniq doesn't use it.
This results in the suspicious behavior of resolving directory symlinks
based on the contents of / instead of the alternate root.

This adds a prefix argument to path_strv_canonicalize which will now
prepend the prefix, if given, to every path in the list. To avoid
answering what a relative path means when called with a root prefix
path_strv_canonicalize is now path_strv_canonicalize_absolute and only
considers absolute paths. Fortunately all users of already call
path_strv_canonicalize with a list of absolute paths.

1 files changed, 19 insertions, 10 deletions

diff --git a/src/shared/path-util.c b/src/shared/path-util.c
index fc42a704b7..bdc54a9aa5 100644
--- a/src/shared/path-util.c
+++ b/src/shared/path-util.c
@@ -153,7 +153,7 @@ char **path_strv_make_absolute_cwd(char **l) {
         return l;
 }
 
-char **path_strv_canonicalize(char **l) {
+char **path_strv_canonicalize_absolute(char **l, const char *prefix) {
         char **s;
         unsigned k = 0;
         bool enomem = false;
@@ -168,13 +168,21 @@ char **path_strv_canonicalize(char **l) {
         STRV_FOREACH(s, l) {
                 char *t, *u;
 
-                t = path_make_absolute_cwd(*s);
-                free(*s);
-                *s = NULL;
-
-                if (!t) {
-                        enomem = true;
+                if (!path_is_absolute(*s))
                         continue;
+
+                if (prefix) {
+                        t = strappend(prefix, *s);
+                        free(*s);
+                        *s = NULL;
+
+                        if (!t) {
+                                enomem = true;
+                                continue;
+                        }
+                } else {
+                        t = *s;
+                        *s = NULL;
                 }
 
                 errno = 0;
@@ -184,7 +192,7 @@ char **path_strv_canonicalize(char **l) {
                                 u = t;
                         else {
                                 free(t);
-                                if (errno == ENOMEM || !errno)
+                                if (errno == ENOMEM || errno == 0)
                                         enomem = true;
 
                                 continue;
@@ -203,11 +211,12 @@ char **path_strv_canonicalize(char **l) {
         return l;
 }
 
-char **path_strv_canonicalize_uniq(char **l) {
+char **path_strv_canonicalize_absolute_uniq(char **l, const char *prefix) {
+
         if (strv_isempty(l))
                 return l;
 
-        if (!path_strv_canonicalize(l))
+        if (!path_strv_canonicalize_absolute(l, prefix))
                 return NULL;
 
         return strv_uniq(l);