apps: Add a syscall fuzzer

apps/CMakeLists.txt

@@ -30,3 +30,4 @@ luna_app(ps.cpp ps)
 luna_app(time.cpp time)
 luna_app(ln.cpp ln)
 luna_app(mktemp.cpp mktemp)
+luna_app(sysfuzz.cpp sysfuzz)

apps/sysfuzz.cpp

@@ -0,0 +1,73 @@
+#include <luna/Syscall.h>
+#include <os/ArgumentParser.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+static const char* syscall_list[] = {
+#undef __enumerate
+#define __enumerate(name) #name,
+    enumerate_syscalls(__enumerate)
+#undef __enumerate
+};
+
+int random_syscall()
+{
+    int sys;
+
+    while (true)
+    {
+        sys = rand() % Syscalls::__count;
+        if (sys == SYS_exit || sys == SYS_usleep || sys == SYS_fork) continue;
+        break;
+    }
+
+    return sys;
+}
+
+void random_args(int args[5])
+{
+    for (int i = 0; i < 5; i++) { args[i] = rand(); }
+}
+
+int main(int argc, char** argv)
+{
+    StringView times_sv = "20"_sv;
+    StringView interval_sv = "1000"_sv;
+
+    os::ArgumentParser parser;
+    parser.add_description("System call fuzzer (invokes system calls with random arguments to test system stability)");
+    parser.add_system_program_info("sysfuzz"_sv);
+    parser.add_value_argument(times_sv, 't', "times"_sv, true, "the number of syscalls to invoke"_sv);
+    parser.add_value_argument(interval_sv, 'i', "interval"_sv, true,
+                              "the interval between system calls (in milliseconds)"_sv);
+    parser.parse(argc, argv);
+
+    srand((unsigned)time(nullptr));
+
+    int times = atoi(times_sv.chars());
+    int interval = atoi(interval_sv.chars());
+
+    while (times--)
+    {
+        int args[5];
+        int sys = random_syscall();
+        random_args(args);
+
+        printf("%s(%d, %d, %d, %d, %d) -> ", syscall_list[sys], args[0], args[1], args[2], args[3], args[4]);
+
+        long rc = syscall(sys, args[0], args[1], args[2], args[3], args[4]);
+
+        if (rc < 0)
+        {
+            int error = (int)-rc;
+            printf("%ld (%s)\n", rc, strerror(error));
+        }
+        else
+            printf("%ld\n", rc);
+
+        usleep(interval * 1000);
+    }
+}

kernel/src/sys/usleep.cpp

@@ -6,6 +6,9 @@ Result<u64> sys_usleep(Registers*, SyscallArgs args)
 {
     useconds_t us = (useconds_t)args[0];
 
+    // FIXME: Allow usleep() to use a more precise resolution.
+    if (us < 1000) return 0;
+
     kernel_sleep(us / 1000);
 
     return 0;

kernel/src/thread/Scheduler.cpp

@@ -271,7 +271,7 @@ namespace Scheduler
         {
             if (thread->state == ThreadState::Sleeping)
             {
-                if (--thread->sleep_ticks_left == 0) thread->wake_up();
+                if (thread->sleep_ticks_left == 0 || --thread->sleep_ticks_left == 0) thread->wake_up();
             }
         }