import of mdb (minix debugger), some ptrace and signals unbreaking

seem to have made it work (runtime debugging and core reading).

commands/mdb/trace.c

@@ -0,0 +1,51 @@
+/* 
+ * trace.c for mdb 
+ */
+
+#include "mdb.h"
+#include <stdio.h>
+#include <sys/ptrace.h>
+#include "proto.h"
+
+/* mdbtrace()
+ * Call ptrace and check for error if debugging running process
+ * Otherwise read 'core' file
+ */ 
+PUBLIC long mdbtrace(req, pid, addr, data)
+int req, pid;
+long addr, data;
+{
+  long val;
+  int i;
+  int segment;
+
+#ifdef  DEBUG
+  if (debug) Printf("ptrace: req=%d pid=%d addr=%lx data=%lx\n",
+		req, pid, addr, data);
+#endif
+
+  if (corepid < 0) 
+  {
+	errno = 0;
+	/* Call normal ptrace and check for error */
+	val = ptrace(req, pid, addr, data);
+	if (errno != 0) {
+		do_error("mdb ptrace error ");
+		mdb_error("\n");
+	}
+#ifdef  DEBUG
+	if (debug) Printf("ptrace: val=>%lx\n", val);
+#endif
+	return val;
+  } 
+  else
+	return read_core(req, addr, data);
+}
+
+/* Used by disassembler */
+PUBLIC u32_t peek_dword(addr)
+off_t addr;
+{
+    return mdbtrace(T_GETINS, curpid, addr, 0L);
+}
+