core: rework unit name validation and manipulation logic

A variety of changes:

- Make sure all our calls distuingish OOM from other errors if OOM is
  not the only error possible.

- Be much stricter when parsing escaped paths, do not accept trailing or
  leading escaped slashes.

- Change unit validation to take a bit mask for allowing plain names,
  instance names or template names or an combination thereof.

- Refuse manipulating invalid unit name

1 files changed, 2 insertions, 14 deletions

diff --git a/src/shared/install-printf.c b/src/shared/install-printf.c
index 9996649424..7c25d36931 100644
--- a/src/shared/install-printf.c
+++ b/src/shared/install-printf.c
@@ -29,30 +29,18 @@
 
 static int specifier_prefix_and_instance(char specifier, void *data, void *userdata, char **ret) {
         InstallInfo *i = userdata;
-        char *n;
 
         assert(i);
 
-        n = unit_name_to_prefix_and_instance(i->name);
-        if (!n)
-                return -ENOMEM;
-
-        *ret = n;
-        return 0;
+        return unit_name_to_prefix_and_instance(i->name, ret);
 }
 
 static int specifier_prefix(char specifier, void *data, void *userdata, char **ret) {
         InstallInfo *i = userdata;
-        char *n;
 
         assert(i);
 
-        n = unit_name_to_prefix(i->name);
-        if (!n)
-                return -ENOMEM;
-
-        *ret = n;
-        return 0;
+        return unit_name_to_prefix(i->name, ret);
 }
 
 static int specifier_instance(char specifier, void *data, void *userdata, char **ret) {