shared/pretty-print: silence gcc warning

gcc was very unhappy for some reason:

[988/1664] Compiling C object systemd-oomd.p/src_oom_oomd.c.o
In file included from ../src/basic/path-util.h:10,
                 from ../src/shared/pretty-print.c:14,
                 from ../src/oom/oomd.c:15:
../src/shared/pretty-print.c: In function ‘conf_files_cat’:
../src/basic/strv.h:123:32: warning: ‘prefixes’ may be used uninitialized [-Wmaybe-uninitialized]
  123 |         for ((s) = (l); (s) && *(s); (s)++)
      |                                ^
In file included from ../src/oom/oomd.c:15:
../src/shared/pretty-print.c:283:16: note: ‘prefixes’ was declared here
  283 |         char **prefixes, **prefix;
      |                ^~~~~~~~
../src/shared/pretty-print.c:305:12: warning: ‘is_collection’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  305 |         if (!is_collection) {
      |            ^
../src/shared/pretty-print.c:301:13: warning: ‘extension’ may be used uninitialized in this function [-Wmaybe-uninitialized]
  301 |         r = conf_files_list_strv(&files, extension, root, 0, (const char* const*) dirs);
      |             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Maybe this is caused by the statis char** variables?

1 files changed, 3 insertions, 1 deletions

diff --git a/src/shared/pretty-print.c b/src/shared/pretty-print.c
index 0f02f32760..137ba77b3a 100644
--- a/src/shared/pretty-print.c
+++ b/src/shared/pretty-print.c
@@ -280,7 +280,7 @@ static int guess_type(const char **name, char ***prefixes, bool *is_collection,
 int conf_files_cat(const char *root, const char *name) {
         _cleanup_strv_free_ char **dirs = NULL, **files = NULL;
         _cleanup_free_ char *path = NULL;
-        char **prefixes, **prefix;
+        char **prefix, **prefixes = NULL; /* explicit initialization to appease gcc */
         bool is_collection;
         const char *extension;
         char **t;
@@ -289,6 +289,8 @@ int conf_files_cat(const char *root, const char *name) {
         r = guess_type(&name, &prefixes, &is_collection, &extension);
         if (r < 0)
                 return r;
+        assert(prefixes);
+        assert(extension);
 
         STRV_FOREACH(prefix, prefixes) {
                 assert(endswith(*prefix, "/"));