Linux sandbox: add space for 8 parameters to the Syscall() class

sandbox/linux/seccomp-bpf/syscall.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__
 #define SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "sandbox/sandbox_export.h"
 
 namespace sandbox {
 
 // This purely static class can be used to perform system calls with some
 // low-level control.
 class SANDBOX_EXPORT Syscall {
  public:
-  // This performs system call |nr| with the arguments p0 to p5 from a constant
-  // userland address, which is for instance observable by seccomp-bpf filters.
-  // The constant userland address from which these system calls are made will
-  // be returned if |nr| is passed as -1.
-  // On error, this function will return a value between -1 and -4095 which
-  // should be interpreted as -errno.
-  static intptr_t Call(int nr,
-                       intptr_t p0,
-                       intptr_t p1,
-                       intptr_t p2,
-                       intptr_t p3,
-                       intptr_t p4,
-                       intptr_t p5);
-
-  // System calls can take up to six parameters. Traditionally, glibc
+  // System calls can take up to six parameters (up to eight on some
+  // architectures). Traditionally, glibc
   // implements this property by using variadic argument lists. This works, but
   // confuses modern tools such as valgrind, because we are nominally passing
   // uninitialized data whenever we call through this function and pass less
   // than the full six arguments.
   // So, instead, we use C++'s template system to achieve a very similar
   // effect. C++ automatically sets the unused parameters to zero for us, and
   // it also does the correct type expansion (e.g. from 32bit to 64bit) where
   // necessary.
   // We have to use C-style cast operators as we want to be able to accept both
   // integer and pointer types.
+  template <class T0,
+            class T1,
+            class T2,
+            class T3,
+            class T4,
+            class T5,
+            class T6,
+            class T7>
+  static inline intptr_t
+  Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6, T7 p7) {
+    return Call(nr,
+                (intptr_t)p0,
+                (intptr_t)p1,
+                (intptr_t)p2,
+                (intptr_t)p3,
+                (intptr_t)p4,
+                (intptr_t)p5,
+                (intptr_t)p6,
+                (intptr_t)p7);
+  }
+
+  template <class T0,
+            class T1,
+            class T2,
+            class T3,
+            class T4,
+            class T5,
+            class T6>
+  static inline intptr_t
+  Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5, T6 p6) {
+    return Call(nr,
+                (intptr_t)p0,
+                (intptr_t)p1,
+                (intptr_t)p2,
+                (intptr_t)p3,
+                (intptr_t)p4,
+                (intptr_t)p5,
+                (intptr_t)p6,
+                0);
+  }
+
   template <class T0, class T1, class T2, class T3, class T4, class T5>
   static inline intptr_t
   Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4, T5 p5) {
     return Call(nr,
                 (intptr_t)p0,
                 (intptr_t)p1,
                 (intptr_t)p2,
                 (intptr_t)p3,
                 (intptr_t)p4,
-                (intptr_t)p5);
+                (intptr_t)p5,
+                0,
+                0);
   }
 
   template <class T0, class T1, class T2, class T3, class T4>
   static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3, T4 p4) {
-    return Call(nr, p0, p1, p2, p3, p4, 0);
+    return Call(nr, p0, p1, p2, p3, p4, 0, 0, 0);
   }
 
   template <class T0, class T1, class T2, class T3>
   static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2, T3 p3) {
-    return Call(nr, p0, p1, p2, p3, 0, 0);
+    return Call(nr, p0, p1, p2, p3, 0, 0, 0, 0);
   }
 
   template <class T0, class T1, class T2>
   static inline intptr_t Call(int nr, T0 p0, T1 p1, T2 p2) {
-    return Call(nr, p0, p1, p2, 0, 0, 0);
+    return Call(nr, p0, p1, p2, 0, 0, 0, 0, 0);
   }
 
   template <class T0, class T1>
   static inline intptr_t Call(int nr, T0 p0, T1 p1) {
-    return Call(nr, p0, p1, 0, 0, 0, 0);
+    return Call(nr, p0, p1, 0, 0, 0, 0, 0, 0);
   }
 
   template <class T0>
   static inline intptr_t Call(int nr, T0 p0) {
-    return Call(nr, p0, 0, 0, 0, 0, 0);
+    return Call(nr, p0, 0, 0, 0, 0, 0, 0, 0);
   }
 
-  static inline intptr_t Call(int nr) { return Call(nr, 0, 0, 0, 0, 0, 0); }
+  static inline intptr_t Call(int nr) {
+    return Call(nr, 0, 0, 0, 0, 0, 0, 0, 0);
+  }
 
  private:
+  // This performs system call |nr| with the arguments p0 to p7 from a constant
+  // userland address, which is for instance observable by seccomp-bpf filters.
+  // The constant userland address from which these system calls are made will
+  // be returned if |nr| is passed as -1.
+  // On error, this function will return a value between -1 and -4095 which
+  // should be interpreted as -errno.
+  static intptr_t Call(int nr,
+                       intptr_t p0,
+                       intptr_t p1,
+                       intptr_t p2,
+                       intptr_t p3,
+                       intptr_t p4,
+                       intptr_t p5,
+                       intptr_t p6,
+                       intptr_t p7);
+
   DISALLOW_IMPLICIT_CONSTRUCTORS(Syscall);
 };
 
 }  // namespace sandbox
 
 #endif  // SANDBOX_LINUX_SECCOMP_BPF_SYSCALL_H__