1 files changed, 65 insertions, 0 deletions
diff --git a/src/basic/pidref.h b/src/basic/pidref.h
new file mode 100644
index 0000000..dada069
--- /dev/null
+++ b/src/basic/pidref.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+#pragma once
+
+#include "macro.h"
+
+/* An embeddable structure carrying a reference to a process. Supposed to be used when tracking processes continuously. */
+typedef struct PidRef {
+        pid_t pid; /* always valid */
+        int fd;    /* only valid if pidfd are available in the kernel, and we manage to get an fd */
+} PidRef;
+
+#define PIDREF_NULL (const PidRef) { .fd = -EBADF }
+
+/* Turns a pid_t into a PidRef structure on-the-fly *without* acquiring a pidfd for it. (As opposed to
+ * pidref_set_pid() which does so *with* acquiring one, see below) */
+#define PIDREF_MAKE_FROM_PID(x) (PidRef) { .pid = (x), .fd = -EBADF }
+
+static inline bool pidref_is_set(const PidRef *pidref) {
+        return pidref && pidref->pid > 0;
+}
+
+static inline bool pidref_equal(const PidRef *a, const PidRef *b) {
+
+        if (pidref_is_set(a)) {
+                if (!pidref_is_set(b))
+                        return false;
+
+                return a->pid == b->pid;
+        }
+
+        return !pidref_is_set(b);
+}
+
+/* This turns a pid_t into a PidRef structure, and acquires a pidfd for it, if possible. (As opposed to
+ * PIDREF_MAKE_FROM_PID() above, which does not acquire a pidfd.) */
+int pidref_set_pid(PidRef *pidref, pid_t pid);
+int pidref_set_pidstr(PidRef *pidref, const char *pid);
+int pidref_set_pidfd(PidRef *pidref, int fd);
+int pidref_set_pidfd_take(PidRef *pidref, int fd); /* takes ownership of the passed pidfd on success*/
+int pidref_set_pidfd_consume(PidRef *pidref, int fd); /* takes ownership of the passed pidfd in both success and failure */
+
+static inline int pidref_set_self(PidRef *pidref) {
+        return pidref_set_pid(pidref, 0);
+}
+
+bool pidref_is_self(const PidRef *pidref);
+
+void pidref_done(PidRef *pidref);
+PidRef *pidref_free(PidRef *pidref);
+DEFINE_TRIVIAL_CLEANUP_FUNC(PidRef*, pidref_free);
+
+int pidref_dup(const PidRef *pidref, PidRef **ret);
+
+int pidref_new_from_pid(pid_t pid, PidRef **ret);
+
+int pidref_kill(const PidRef *pidref, int sig);
+int pidref_kill_and_sigcont(const PidRef *pidref, int sig);
+int pidref_sigqueue(const PidRef *pidfref, int sig, int value);
+
+int pidref_verify(const PidRef *pidref);
+
+#define TAKE_PIDREF(p) TAKE_GENERIC((p), PidRef, PIDREF_NULL)
+
+extern const struct hash_ops pidref_hash_ops;
+extern const struct hash_ops pidref_hash_ops_free; /* Has destructor call for pidref_free(), i.e. expects heap allocated PidRef as keys */