From 85e7bbfaa416fb3beeda56146f372c6ad828e044 Mon Sep 17 00:00:00 2001
From: Mike Yuan <me@yhndnzj.com>
Date: Tue, 19 Nov 2024 20:57:41 +0100
Subject: [PATCH] pidfd-util: introduce pidfd_get_{ppid,uid,cgroupid} which
 goes via PIDFD_GET_INFO too

---
 src/basic/pidfd-util.c | 54 ++++++++++++++++++++++++++++++++++++++++++
 src/basic/pidfd-util.h |  4 ++++
 2 files changed, 58 insertions(+)

diff --git a/src/basic/pidfd-util.c b/src/basic/pidfd-util.c
index b4e6eb8dce3..b2a2188e4ba 100644
--- a/src/basic/pidfd-util.c
+++ b/src/basic/pidfd-util.c
@@ -176,6 +176,60 @@ int pidfd_verify_pid(int pidfd, pid_t pid) {
         return current_pid != pid ? -ESRCH : 0;
 }
 
+int pidfd_get_ppid(int fd, pid_t *ret) {
+        struct pidfd_info info = { .mask = PIDFD_INFO_PID };
+        int r;
+
+        assert(fd >= 0);
+
+        r = pidfd_get_info(fd, &info);
+        if (r < 0)
+                return r;
+
+        assert(FLAGS_SET(info.mask, PIDFD_INFO_PID));
+
+        if (info.ppid == 0)
+                return -EADDRNOTAVAIL;
+
+        if (ret)
+                *ret = info.ppid;
+        return 0;
+}
+
+int pidfd_get_uid(int fd, uid_t *ret) {
+        struct pidfd_info info = { .mask = PIDFD_INFO_CREDS };
+        int r;
+
+        assert(fd >= 0);
+
+        r = pidfd_get_info(fd, &info);
+        if (r < 0)
+                return r;
+
+        assert(FLAGS_SET(info.mask, PIDFD_INFO_CREDS));
+
+        if (ret)
+                *ret = info.ruid;
+        return 0;
+}
+
+int pidfd_get_cgroupid(int fd, uint64_t *ret) {
+        struct pidfd_info info = { .mask = PIDFD_INFO_CGROUPID };
+        int r;
+
+        assert(fd >= 0);
+
+        r = pidfd_get_info(fd, &info);
+        if (r < 0)
+                return r;
+
+        assert(FLAGS_SET(info.mask, PIDFD_INFO_CGROUPID));
+
+        if (ret)
+                *ret = info.cgroupid;
+        return 0;
+}
+
 int pidfd_get_inode_id(int fd, uint64_t *ret) {
         int r;
 
diff --git a/src/basic/pidfd-util.h b/src/basic/pidfd-util.h
index 2ffece0c4fe..374e96261b0 100644
--- a/src/basic/pidfd-util.h
+++ b/src/basic/pidfd-util.h
@@ -12,4 +12,8 @@ int pidfd_get_namespace(int fd, unsigned long ns_type_cmd);
 int pidfd_get_pid(int fd, pid_t *ret);
 int pidfd_verify_pid(int pidfd, pid_t pid);
 
+int pidfd_get_ppid(int fd, pid_t *ret);
+int pidfd_get_uid(int fd, uid_t *ret);
+int pidfd_get_cgroupid(int fd, uint64_t *ret);
+
 int pidfd_get_inode_id(int fd, uint64_t *ret);
-- 
2.47.3