From 9a7fdb2dae8f0ae0f9c5b0596bb2710f782925aa Mon Sep 17 00:00:00 2001
From: Elliott Hughes <enh@google.com>
Date: Wed, 16 Jul 2014 15:18:54 -0700
Subject: [PATCH] ptrace(3) should be varargs.

Bug: 16352070

(cherry picked from commit 98b088dce70a2625d5cfa1872e427af5f06bfd99)

Change-Id: I6193ef44df9a5668020916eaca90b47fc4c8ab77
---
 libc/bionic/ptrace.cpp    | 40 ++++++++++++++++++++-------------------
 libc/include/sys/ptrace.h |  8 ++++----
 2 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/libc/bionic/ptrace.cpp b/libc/bionic/ptrace.cpp
index 5715b0934..5156ec24c 100644
--- a/libc/bionic/ptrace.cpp
+++ b/libc/bionic/ptrace.cpp
@@ -26,28 +26,30 @@
  * SUCH DAMAGE.
  */
 
-#include <sys/types.h>
+#include <stdarg.h>
 #include <sys/ptrace.h>
 
-extern "C" long __ptrace(int request, pid_t pid, void* addr, void* data);
+extern "C" long __ptrace(int req, pid_t pid, void* addr, void* data);
 
-long ptrace(int request, pid_t pid, void* addr, void* data) {
-  switch (request) {
-    case PTRACE_PEEKUSR:
-    case PTRACE_PEEKTEXT:
-    case PTRACE_PEEKDATA:
-      {
-      long word;
-      long ret = __ptrace(request, pid, addr, &word);
-      if (ret == 0) {
-        return word;
-      } else {
-        // __ptrace already set errno for us.
-        return -1;
-      }
-    }
+long ptrace(int req, ...) {
+  bool is_peek = (req == PTRACE_PEEKUSR || req == PTRACE_PEEKTEXT || req == PTRACE_PEEKDATA);
+  long peek_result;
 
-    default:
-      return __ptrace(request, pid, addr, data);
+  va_list args;
+  va_start(args, req);
+  pid_t pid = va_arg(args, pid_t);
+  void* addr = va_arg(args, void*);
+  void* data;
+  if (is_peek) {
+    data = &peek_result;
+  } else {
+    data = va_arg(args, void*);
   }
+  va_end(args);
+
+  long result = __ptrace(req, pid, addr, data);
+  if (is_peek && result == 0) {
+    return peek_result;
+  }
+  return result;
 }
diff --git a/libc/include/sys/ptrace.h b/libc/include/sys/ptrace.h
index 848416b64..8bba9fe43 100644
--- a/libc/include/sys/ptrace.h
+++ b/libc/include/sys/ptrace.h
@@ -30,15 +30,15 @@
 
 #include <sys/cdefs.h>
 #include <sys/types.h>
-/* For all of the defines */
 #include <linux/ptrace.h>
 
 __BEGIN_DECLS
 
-#define PTRACE_POKEUSER     PTRACE_POKEUSR
-#define PTRACE_PEEKUSER     PTRACE_PEEKUSR
+/* glibc uses different names from the kernel for these two... */
+#define PTRACE_POKEUSER PTRACE_POKEUSR
+#define PTRACE_PEEKUSER PTRACE_PEEKUSR
 
-extern long ptrace(int request, pid_t pid, void *addr, void *data);
+extern long ptrace(int, ...);
 
 __END_DECLS