gvisor.dev/gvisor@v0.0.0-20240520182842-f9d4d51c7e0f/test/syscalls/linux/getrandom.cc (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  #include <sys/syscall.h>
    16  #include <sys/types.h>
    17  #include <unistd.h>
    18  
    19  #include "gtest/gtest.h"
    20  #include "test/util/test_util.h"
    21  
    22  namespace gvisor {
    23  namespace testing {
    24  
    25  namespace {
    26  
    27  #ifndef SYS_getrandom
    28  #if defined(__x86_64__)
    29  #define SYS_getrandom 318
    30  #elif defined(__i386__)
    31  #define SYS_getrandom 355
    32  #elif defined(__aarch64__)
    33  #define SYS_getrandom 278
    34  #else
    35  #error "Unknown architecture"
    36  #endif
    37  #endif  // SYS_getrandom
    38  
    39  bool SomeByteIsNonZero(char* random_bytes, int length) {
    40    for (int i = 0; i < length; i++) {
    41      if (random_bytes[i] != 0) {
    42        return true;
    43      }
    44    }
    45    return false;
    46  }
    47  
    48  TEST(GetrandomTest, IsRandom) {
    49    // This test calls get_random and makes sure that the array is filled in with
    50    // something that is non-zero. Perhaps we get back \x00\x00\x00\x00\x00.... as
    51    // a random result, but it's so unlikely that we'll just ignore this.
    52    char random_bytes[64] = {};
    53    int n = syscall(SYS_getrandom, random_bytes, 64, 0);
    54    SKIP_IF(!IsRunningOnGvisor() && n < 0 && errno == ENOSYS);
    55    EXPECT_THAT(n, SyscallSucceeds());
    56    EXPECT_GT(n, 0);  // Some bytes should be returned.
    57    EXPECT_TRUE(SomeByteIsNonZero(random_bytes, n));
    58  }
    59  
    60  }  // namespace
    61  
    62  }  // namespace testing
    63  }  // namespace gvisor