sysupdate: Evaluate all patterns before descending into a subdir

When we have two match patterns, e.g., because the repository layout
changed and we look for old and new style files, we can have the case
that one pattern suggests a descend into a subdir but the other pattern
would be a direct match. This was missed and only the descent was done.
Yet the other way round also has to be covered: We can't just use the
direct match because it might be that it's rejected if the type doesn't
fit (directory vs. regular file). In this case we should still descent.

Remember that we want to descend but continue checking the other
pattern first to maybe get a direct match. Introduce a new combined
return code YES_AND_RETRY to give the full information to the caller
which now can decide to fallback to a descent. While at it, use the
stat info for the directory check. Also add tests to ensure that the
order of patterns doesn't matter and we handle the above corner cases.

src/sysupdate/sysupdate-cleanup.c

@@ -184,7 +184,7 @@ static int context_is_path_currently_owned(
                         return log_error_errno(r, "Failed to match patterns '%s' against '%s': %m", cl, relpath);
                 }
 
-                if (IN_SET(r, PATTERN_MATCH_YES, PATTERN_MATCH_RETRY)) /* Yay, this path is pinned by this transfer file */
+                if (IN_SET(r, PATTERN_MATCH_YES, PATTERN_MATCH_RETRY, PATTERN_MATCH_YES_AND_RETRY)) /* Yay, this path is pinned by this transfer file */
                         return true;
 
                 assert(r == PATTERN_MATCH_NO);

src/sysupdate/sysupdate-pattern.c

@@ -454,12 +454,20 @@ retry:
 }
 
 int pattern_match_many(char **patterns, const char *s, InstanceMetadata *ret) {
-        _cleanup_(instance_metadata_destroy) InstanceMetadata found = INSTANCE_METADATA_NULL;
+        _cleanup_(instance_metadata_destroy) InstanceMetadata matched = INSTANCE_METADATA_NULL;
+        bool have_match = false, retry_descent = false;
         int r;
 
+        /* Evaluate all patterns and report the combined result: a direct match wins and provides the
+         * extracted fields, but when another pattern would descend into a subdirectory this is reported
+         * too, so the caller can descend as fallback when the direct match is no valid candidate. */
         STRV_FOREACH(p, patterns) {
+                _cleanup_(instance_metadata_destroy) InstanceMetadata found = INSTANCE_METADATA_NULL;
                 const char *pat = *p, *input_path;
 
+                if (have_match && retry_descent)
+                        break; /* nothing more to learn */
+
                 /* A glob directory prefix on a pattern means to match the rest of the pattern against the
                  * last path component only (the basename, "find this file anywhere under the source tree") */
                 if (pattern_skip_glob_directory_prefix(&pat))
@@ -470,20 +478,20 @@ int pattern_match_many(char **patterns, const char *s, InstanceMetadata *ret) {
                 r = pattern_match(pat, input_path, &found);
                 if (r < 0)
                         return r;
-                if (r != PATTERN_MATCH_NO) {
-                        if (ret) {
-                                *ret = found;
-                                found = (InstanceMetadata) INSTANCE_METADATA_NULL;
-                        }
-
-                        return r;
+                if (r == PATTERN_MATCH_YES && !have_match) {
+                        matched = TAKE_GENERIC(found, InstanceMetadata, INSTANCE_METADATA_NULL);
+                        have_match = true;
                 }
+                if (r == PATTERN_MATCH_RETRY)
+                        retry_descent = true;
         }
 
         if (ret)
-                *ret = (InstanceMetadata) INSTANCE_METADATA_NULL;
+                *ret = TAKE_GENERIC(matched, InstanceMetadata, INSTANCE_METADATA_NULL);
 
-        return PATTERN_MATCH_NO;
+        if (have_match)
+                return retry_descent ? PATTERN_MATCH_YES_AND_RETRY : PATTERN_MATCH_YES;
+        return retry_descent ? PATTERN_MATCH_RETRY : PATTERN_MATCH_NO;
 }
 
 bool pattern_skip_glob_directory_prefix(const char **pattern) {

src/sysupdate/sysupdate-pattern.h

@@ -7,6 +7,7 @@ enum {
         PATTERN_MATCH_NO,
         PATTERN_MATCH_YES,
         PATTERN_MATCH_RETRY,
+        PATTERN_MATCH_YES_AND_RETRY,
 };
 
 int pattern_match(const char *pattern, const char *s, InstanceMetadata *ret);

src/sysupdate/sysupdate-resource.c

@@ -185,7 +185,10 @@ static int resource_load_from_directory_recursive(
                                 if (!S_ISDIR(st.st_mode)) /* The pattern continues with '/' but this is no directory */
                                         continue;
                                 descend = true;
-                        }
+                        } else if (r == PATTERN_MATCH_YES_AND_RETRY && S_ISDIR(st.st_mode) && m != S_IFDIR)
+                                /* The direct match is unusable since a directory can't be an instance here,
+                                 * but another pattern wants to descend, so do that instead */
+                                descend = true;
                 }
 
                 if (descend) {
@@ -205,7 +208,7 @@ static int resource_load_from_directory_recursive(
                         continue;
                 }
 
-                if (de->d_type == DT_DIR && m != S_IFDIR)
+                if (S_ISDIR(st.st_mode) && m != S_IFDIR)
                         continue;
 
                 joined = path_join(rr->path, rel_joined);
@@ -610,7 +613,7 @@ static int resource_load_from_web(
                         r = pattern_match_many(rr->patterns, fn, &extracted_fields);
                         if (r < 0)
                                 return log_error_errno(r, "Failed to match pattern: %m");
-                        if (r == PATTERN_MATCH_YES) {
+                        if (IN_SET(r, PATTERN_MATCH_YES, PATTERN_MATCH_YES_AND_RETRY)) {
                                 _cleanup_free_ char *path = NULL;
 
                                 r = import_url_append_component(rr->path, fn, &path);