github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/test/util/file_descriptor.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_FILE_DESCRIPTOR_H_
    16  #define GVISOR_TEST_UTIL_FILE_DESCRIPTOR_H_
    17  
    18  #include <fcntl.h>
    19  #include <sys/stat.h>
    20  #include <sys/types.h>
    21  #include <unistd.h>
    22  
    23  #include <algorithm>
    24  #include <string>
    25  
    26  #include "gmock/gmock.h"
    27  #include "absl/strings/str_cat.h"
    28  #include "absl/strings/str_format.h"
    29  #include "test/util/logging.h"
    30  #include "test/util/posix_error.h"
    31  #include "test/util/save_util.h"
    32  
    33  namespace gvisor {
    34  namespace testing {
    35  
    36  // FileDescriptor is an RAII type class which takes ownership of a file
    37  // descriptor. It will close the FD when this object goes out of scope.
    38  class FileDescriptor {
    39   public:
    40    // Constructs an empty FileDescriptor (one that does not own a file
    41    // descriptor).
    42    FileDescriptor() = default;
    43  
    44    // Constructs a FileDescriptor that owns fd. If fd is negative, constructs an
    45    // empty FileDescriptor.
    46    explicit FileDescriptor(int fd) { set_fd(fd); }
    47  
    48    FileDescriptor(FileDescriptor&& orig) : fd_(orig.release()) {}
    49  
    50    FileDescriptor& operator=(FileDescriptor&& orig) {
    51      reset(orig.release());
    52      return *this;
    53    }
    54  
    55    PosixErrorOr<FileDescriptor> Dup() const {
    56      if (fd_ < 0) {
    57        return PosixError(EINVAL, "Attempting to Dup unset fd");
    58      }
    59  
    60      int fd = dup(fd_);
    61      if (fd < 0) {
    62        return PosixError(errno, absl::StrCat("dup ", fd_));
    63      }
    64      MaybeSave();
    65      return FileDescriptor(fd);
    66    }
    67  
    68    FileDescriptor(FileDescriptor const& other) = delete;
    69    FileDescriptor& operator=(FileDescriptor const& other) = delete;
    70  
    71    ~FileDescriptor() { reset(); }
    72  
    73    // If this object is non-empty, returns the owned file descriptor. (Ownership
    74    // is retained by the FileDescriptor.) Otherwise returns -1.
    75    int get() const { return fd_; }
    76  
    77    // If this object is non-empty, transfers ownership of the file descriptor to
    78    // the caller and returns it. Otherwise returns -1.
    79    int release() {
    80      int const fd = fd_;
    81      fd_ = -1;
    82      return fd;
    83    }
    84  
    85    // If this object is non-empty, closes the owned file descriptor (recording a
    86    // test failure if the close fails).
    87    void reset() { reset(-1); }
    88  
    89    // Like no-arg reset(), but the FileDescriptor takes ownership of fd after
    90    // closing its existing file descriptor.
    91    void reset(int fd) {
    92      if (fd_ >= 0) {
    93        TEST_PCHECK(close(fd_) == 0);
    94        MaybeSave();
    95      }
    96      set_fd(fd);
    97    }
    98  
    99   private:
   100    // Wrapper that coerces negative fd values other than -1 to -1 so that get()
   101    // etc. return -1.
   102    void set_fd(int fd) { fd_ = std::max(fd, -1); }
   103  
   104    int fd_ = -1;
   105  };
   106  
   107  // Wrapper around open(2) that returns a FileDescriptor.
   108  inline PosixErrorOr<FileDescriptor> Open(std::string const& path, int flags,
   109                                           mode_t mode = 0) {
   110    int fd = open(path.c_str(), flags, mode);
   111    if (fd < 0) {
   112      return PosixError(errno, absl::StrFormat("open(%s, %#x, %#o)", path.c_str(),
   113                                               flags, mode));
   114    }
   115    MaybeSave();
   116    return FileDescriptor(fd);
   117  }
   118  
   119  // Wrapper around openat(2) that returns a FileDescriptor.
   120  inline PosixErrorOr<FileDescriptor> OpenAt(int dirfd, std::string const& path,
   121                                             int flags, mode_t mode = 0) {
   122    int fd = openat(dirfd, path.c_str(), flags, mode);
   123    if (fd < 0) {
   124      return PosixError(errno, absl::StrFormat("openat(%d, %s, %#x, %#o)", dirfd,
   125                                               path, flags, mode));
   126    }
   127    MaybeSave();
   128    return FileDescriptor(fd);
   129  }
   130  
   131  }  // namespace testing
   132  }  // namespace gvisor
   133  
   134  #endif  // GVISOR_TEST_UTIL_FILE_DESCRIPTOR_H_