| 60 | |
| 61 | |
| 62 | std::unique_ptr<FileDescriptorInfo> FileDescriptorInfo::CreateFromFd(int fd, fail_fn_t fail_fn) { |
| 63 | struct stat f_stat; |
| 64 | // This should never happen; the zygote should always have the right set |
| 65 | // of permissions required to stat all its open files. |
| 66 | if (TEMP_FAILURE_RETRY(fstat(fd, &f_stat)) == -1) { |
| 67 | fail_fn(android::base::StringPrintf("Unable to stat %d: %s", fd, strerror(errno))); |
| 68 | return {}; |
| 69 | } |
| 70 | if (S_ISSOCK(f_stat.st_mode)) { |
| 71 | return std::unique_ptr<FileDescriptorInfo>(new FileDescriptorInfo(fd)); |
| 72 | } |
| 73 | // We only handle allowlisted regular files and character devices. Allowlisted |
| 74 | // character devices must provide a guarantee of sensible behaviour when |
| 75 | // reopened. |
| 76 | // |
| 77 | // S_ISDIR : Not supported. (We could if we wanted to, but it's unused). |
| 78 | // S_ISLINK : Not supported. |
| 79 | // S_ISBLK : Not supported. |
| 80 | // S_ISFIFO : Not supported. Note that the Zygote and USAPs use pipes to |
| 81 | // communicate with the child processes across forks but those should have been |
| 82 | // added to the redirection exemption list. |
| 83 | if (!S_ISCHR(f_stat.st_mode) && !S_ISREG(f_stat.st_mode)) { |
| 84 | std::string mode = "Unknown"; |
| 85 | if (S_ISDIR(f_stat.st_mode)) { |
| 86 | mode = "DIR"; |
| 87 | } else if (S_ISLNK(f_stat.st_mode)) { |
| 88 | mode = "LINK"; |
| 89 | } else if (S_ISBLK(f_stat.st_mode)) { |
| 90 | mode = "BLOCK"; |
| 91 | } else if (S_ISFIFO(f_stat.st_mode)) { |
| 92 | mode = "FIFO"; |
| 93 | } |
| 94 | fail_fn(android::base::StringPrintf("Unsupported st_mode for FD %d: %d(%s)", fd, f_stat.st_mode, mode.c_str())); |
| 95 | return {}; |
| 96 | } |
| 97 | std::string file_path; |
| 98 | const std::string fd_path = android::base::StringPrintf("/proc/self/fd/%d", fd); |
| 99 | if (!android::base::Readlink(fd_path, &file_path)) { |
| 100 | fail_fn(android::base::StringPrintf("Could not read fd link %s: %s", |
| 101 | fd_path.c_str(), |
| 102 | strerror(errno))); |
| 103 | return {}; |
| 104 | } |
| 105 | // File descriptor flags : currently on FD_CLOEXEC. We can set these |
| 106 | // using F_SETFD - we're single threaded at this point of execution so |
| 107 | // there won't be any races. |
| 108 | const int fd_flags = TEMP_FAILURE_RETRY(fcntl(fd, F_GETFD)); |
| 109 | if (fd_flags == -1) { |
| 110 | fail_fn(android::base::StringPrintf("Failed fcntl(%d, F_GETFD) (%s): %s", |
| 111 | fd, |
| 112 | file_path.c_str(), |
| 113 | strerror(errno))); |
| 114 | return {}; |
| 115 | } |
| 116 | // File status flags : |
| 117 | // - File access mode : (O_RDONLY, O_WRONLY...) we'll pass these through |
| 118 | // to the open() call. |
| 119 | // |
nothing calls this directly
no test coverage detected