tests: add waitid test

sysdeps/linux/generic/sysdeps.cpp

@@ -1492,6 +1492,13 @@ int sys_semctl(int semid, int semnum, int cmd, void *semun, int *out) {
 	return 0;
 }
 
+int sys_waitid(idtype_t idtype, id_t id, siginfo_t *info, int options) {
+	auto ret = do_syscall(SYS_waitid, idtype, id, info, options, 0);
+	if(int e = sc_error(ret); e)
+		return e;
+	return sc_int_result<int>(ret);
+}
+
 #endif // __MLIBC_POSIX_OPTION
 
 #if __MLIBC_LINUX_OPTION

tests/meson.build

@@ -94,6 +94,7 @@ all_test_cases = [
 	'posix/posix-timer',
 	'posix/strdupa',
 	'posix/mkstemp',
+	'posix/waitid',
 	'glibc/getopt',
 	'glibc/ffsl-ffsll',
 	'glibc/error_message_count',

tests/posix/waitid.c

@@ -0,0 +1,20 @@
+#include <assert.h>
+#include <signal.h>
+#include <stdlib.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+siginfo_t si;
+
+int main() {
+	int pid = fork();
+
+	if(!pid)
+		exit(69);
+
+	int ret = waitid(P_ALL, 0, &si, WEXITED);
+	assert(ret == 0);
+	assert(si.si_pid == pid);
+	assert(si.si_signo == SIGCHLD);
+	assert(si.si_code == CLD_EXITED);
+}