fix (hopefully) PTRACE_TRACEME (command 0) argument handling

diff --git a/src/misc/ptrace.c b/src/misc/ptrace.c
index f854069..83b8022 100644 (file)
--- a/src/misc/ptrace.c
+++ b/src/misc/ptrace.c
@@ -17,9 +17,9 @@ long ptrace(int req, ...)
        addr2 = va_arg(ap, void *);
        va_end(ap);
 
-       if (req<4U) data = &result;
+       if (req-1U < 3) data = &result;
        ret = syscall(SYS_ptrace, req, pid, addr, data, addr2);
 
-       if (ret<0 || req>=4U) return ret;
+       if (ret < 0 || req-1U >= 3) return ret;
        return result;
 }