github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/test/util/signal_util.h (about)

     1  // Copyright 2018 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  #ifndef GVISOR_TEST_UTIL_SIGNAL_UTIL_H_
    16  #define GVISOR_TEST_UTIL_SIGNAL_UTIL_H_
    17  
    18  #include <signal.h>
    19  #include <sys/syscall.h>
    20  #include <unistd.h>
    21  
    22  #include <ostream>
    23  
    24  #include "gmock/gmock.h"
    25  #include "test/util/cleanup.h"
    26  #include "test/util/posix_error.h"
    27  
    28  // Format a sigset_t as a comma separated list of numeric ranges.
    29  ::std::ostream& operator<<(::std::ostream& os, const sigset_t& sigset);
    30  
    31  namespace gvisor {
    32  namespace testing {
    33  
    34  // The maximum signal number.
    35  static constexpr int kMaxSignal = 64;
    36  
    37  // Wrapper for the tgkill(2) syscall, which glibc does not provide.
    38  inline int tgkill(pid_t tgid, pid_t tid, int sig) {
    39    return syscall(__NR_tgkill, tgid, tid, sig);
    40  }
    41  
    42  // Installs the passed sigaction and returns a cleanup function to restore the
    43  // previous handler when it goes out of scope.
    44  PosixErrorOr<Cleanup> ScopedSigaction(int sig, struct sigaction const& sa);
    45  
    46  // Updates the signal mask as per sigprocmask(2) and returns a cleanup function
    47  // to restore the previous signal mask when it goes out of scope.
    48  PosixErrorOr<Cleanup> ScopedSignalMask(int how, sigset_t const& set);
    49  
    50  // ScopedSignalMask variant that creates a mask of the single signal 'sig'.
    51  inline PosixErrorOr<Cleanup> ScopedSignalMask(int how, int sig) {
    52    sigset_t set;
    53    sigemptyset(&set);
    54    sigaddset(&set, sig);
    55    return ScopedSignalMask(how, set);
    56  }
    57  
    58  // Asserts equality of two sigset_t values.
    59  MATCHER_P(EqualsSigset, value, "equals " + ::testing::PrintToString(value)) {
    60    for (int sig = 1; sig <= kMaxSignal; ++sig) {
    61      if (sigismember(&arg, sig) != sigismember(&value, sig)) {
    62        return false;
    63      }
    64    }
    65    return true;
    66  }
    67  
    68  #ifdef __x86_64__
    69  // Fault can be used to generate a synchronous SIGSEGV.
    70  //
    71  // This fault can be fixed up in a handler via fixup, below.
    72  inline void Fault() {
    73    // Zero and dereference %ax.
    74    asm("movabs $0, %%rax\r\n"
    75        "mov 0(%%rax), %%rax\r\n"
    76        :
    77        :
    78        : "ax");
    79  }
    80  
    81  // FixupFault fixes up a fault generated by fault, above.
    82  inline void FixupFault(ucontext_t* ctx) {
    83    // Skip the bad instruction above.
    84    //
    85    // The encoding is 0x48 0xab 0x00.
    86    ctx->uc_mcontext.gregs[REG_RIP] += 3;
    87  }
    88  #elif __aarch64__
    89  inline void Fault() {
    90    // Zero and dereference x0.
    91    asm("mov x0, xzr\r\n"
    92        "str xzr, [x0]\r\n"
    93        :
    94        :
    95        : "x0");
    96  }
    97  
    98  inline void FixupFault(ucontext_t* ctx) {
    99    // Skip the bad instruction above.
   100    ctx->uc_mcontext.pc += 4;
   101  }
   102  #endif
   103  
   104  }  // namespace testing
   105  }  // namespace gvisor
   106  
   107  #endif  // GVISOR_TEST_UTIL_SIGNAL_UTIL_H_