From 5bff40e719ba2eca0c8cb894930b8d4928c2c1f9 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 14 Mar 2023 10:38:58 +0100
Subject: [PATCH] uid-range: add uid_range_overlaps() helper

---
 src/basic/uid-range.c | 20 ++++++++++++++++++++
 src/basic/uid-range.h |  2 ++
 2 files changed, 22 insertions(+)

diff --git a/src/basic/uid-range.c b/src/basic/uid-range.c
index 90eb0cd911..65504b899a 100644
--- a/src/basic/uid-range.c
+++ b/src/basic/uid-range.c
@@ -253,3 +253,23 @@ int uid_range_load_userns(UIDRange **ret, const char *path) {
         *ret = TAKE_PTR(range);
         return 0;
 }
+
+bool uid_range_overlaps(const UIDRange *range, uid_t start, uid_t nr) {
+
+        if (!range)
+                return false;
+
+        /* Avoid overflow */
+        if (start > UINT32_MAX - nr)
+                nr = UINT32_MAX - start;
+
+        if (nr == 0)
+                return false;
+
+        FOREACH_ARRAY(entry, range->entries, range->n_entries)
+                if (start < entry->start + entry->nr &&
+                    start + nr >= entry->start)
+                        return true;
+
+        return false;
+}
diff --git a/src/basic/uid-range.h b/src/basic/uid-range.h
index 5c4aac3726..acfb7191e9 100644
--- a/src/basic/uid-range.h
+++ b/src/basic/uid-range.h
@@ -34,3 +34,5 @@ static inline bool uid_range_contains(const UIDRange *range, uid_t uid) {
 int uid_map_read_one(FILE *f, uid_t *ret_base, uid_t *ret_shift, uid_t *ret_range);
 
 int uid_range_load_userns(UIDRange **ret, const char *path);
+
+bool uid_range_overlaps(const UIDRange *range, uid_t start, uid_t nr);