1 // Copyright 2014 The Android Open Source Project 2 // 3 // This software is licensed under the terms of the GNU General Public 4 // License version 2, as published by the Free Software Foundation, and 5 // may be copied, distributed, and modified under those terms. 6 // 7 // This program is distributed in the hope that it will be useful, 8 // but WITHOUT ANY WARRANTY; without even the implied warranty of 9 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 10 // GNU General Public License for more details. 11 12 #ifndef ANDROID_BASE_SCOPED_FD_H 13 #define ANDROID_BASE_SCOPED_FD_H 14 15 #include "android/base/Compiler.h" 16 17 #include <errno.h> 18 #include <unistd.h> 19 20 namespace android { 21 namespace base { 22 23 // Helper class to hold an integer file descriptor, and have the 'close' 24 // function called automatically on scope exit, unless the 'release' 25 // method was called previously. 26 class ScopedFd { 27 public: 28 // Default constructor will hold an invalid descriptor. ScopedFd()29 ScopedFd() : fd_(-1) {} 30 31 // Constructor takes ownership of |fd|. ScopedFd(int fd)32 explicit ScopedFd(int fd) : fd_(fd) {} 33 34 // Destructor calls close(). ~ScopedFd()35 ~ScopedFd() { close(); } 36 37 // Return the file descriptor value, does _not_ transfer ownership. get()38 int get() const { return fd_; } 39 40 // Return the file descriptor value, transfers ownership to the caller. release()41 int release() { 42 int fd = fd_; 43 fd_ = -1; 44 return fd; 45 } 46 47 // Return true iff the file descriptor is valid. valid()48 bool valid() const { return fd_ >= 0; } 49 50 // Close the file descriptor (and make the wrapped value invalid). close()51 void close() { 52 if (fd_ != -1) { 53 int save_errno = errno; 54 ::close(fd_); 55 fd_ = -1; 56 errno = save_errno; 57 } 58 } 59 60 // Swap two ScopedFd instances. swap(ScopedFd * other)61 void swap(ScopedFd* other) { 62 int fd = fd_; 63 fd_ = other->fd_; 64 other->fd_ = fd; 65 } 66 67 private: 68 DISALLOW_COPY_AND_ASSIGN(ScopedFd); 69 70 int fd_; 71 }; 72 73 } // namespace base 74 } // namespace android 75 76 #endif // ANDROID_BASE_SCOPED_FD_H 77