diff options
Diffstat (limited to 'libcxx/src/filesystem/operations.cpp')
| -rw-r--r-- | libcxx/src/filesystem/operations.cpp | 172 |
1 files changed, 139 insertions, 33 deletions
diff --git a/libcxx/src/filesystem/operations.cpp b/libcxx/src/filesystem/operations.cpp index d771f20..bd37c5a 100644 --- a/libcxx/src/filesystem/operations.cpp +++ b/libcxx/src/filesystem/operations.cpp @@ -15,6 +15,7 @@ #include <filesystem> #include <iterator> #include <string_view> +#include <system_error> #include <type_traits> #include <vector> @@ -32,11 +33,16 @@ # include <dirent.h> # include <sys/stat.h> # include <sys/statvfs.h> +# include <sys/types.h> # include <unistd.h> #endif #include <fcntl.h> /* values for fchmodat */ #include <time.h> +// since Linux 4.5 and FreeBSD 13, but the Linux libc wrapper is only provided by glibc and musl +#if (defined(__linux__) && (defined(__GLIBC__) || _LIBCPP_HAS_MUSL_LIBC)) || defined(__FreeBSD__) +# define _LIBCPP_FILESYSTEM_USE_COPY_FILE_RANGE +#endif #if __has_include(<sys/sendfile.h>) # include <sys/sendfile.h> # define _LIBCPP_FILESYSTEM_USE_SENDFILE @@ -44,10 +50,18 @@ # include <copyfile.h> # define _LIBCPP_FILESYSTEM_USE_COPYFILE #else -# include <fstream> # define _LIBCPP_FILESYSTEM_USE_FSTREAM #endif +// sendfile and copy_file_range need to fall back +// to the fstream implementation for special files +#if (defined(_LIBCPP_FILESYSTEM_USE_SENDFILE) || defined(_LIBCPP_FILESYSTEM_USE_COPY_FILE_RANGE) || \ + defined(_LIBCPP_FILESYSTEM_USE_FSTREAM)) && \ + _LIBCPP_HAS_LOCALIZATION +# include <fstream> +# define _LIBCPP_FILESYSTEM_NEED_FSTREAM +#endif + #if defined(__ELF__) && defined(_LIBCPP_LINK_RT_LIB) # pragma comment(lib, "rt") #endif @@ -178,9 +192,83 @@ void __copy(const path& from, const path& to, copy_options options, error_code* namespace detail { namespace { +#if defined(_LIBCPP_FILESYSTEM_NEED_FSTREAM) +bool copy_file_impl_fstream(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { + ifstream in; + in.__open(read_fd.fd, ios::binary); + if (!in.is_open()) { + // This assumes that __open didn't reset the error code. + ec = capture_errno(); + return false; + } + read_fd.fd = -1; + ofstream out; + out.__open(write_fd.fd, ios::binary); + if (!out.is_open()) { + ec = capture_errno(); + return false; + } + write_fd.fd = -1; + + if (in.good() && out.good()) { + using InIt = istreambuf_iterator<char>; + using OutIt = ostreambuf_iterator<char>; + InIt bin(in); + InIt ein; + OutIt bout(out); + copy(bin, ein, bout); + } + if (out.fail() || in.fail()) { + ec = make_error_code(errc::io_error); + return false; + } + + ec.clear(); + return true; +} +#endif + +#if defined(_LIBCPP_FILESYSTEM_USE_COPY_FILE_RANGE) +bool copy_file_impl_copy_file_range(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { + size_t count = read_fd.get_stat().st_size; + // a zero-length file is either empty, or not copyable by this syscall + // return early to avoid the syscall cost + if (count == 0) { + ec = {EINVAL, generic_category()}; + return false; + } + // do not modify the fd positions as copy_file_impl_sendfile may be called after a partial copy + off_t off_in = 0; + off_t off_out = 0; + do { + ssize_t res; + + if ((res = ::copy_file_range(read_fd.fd, &off_in, write_fd.fd, &off_out, count, 0)) == -1) { + ec = capture_errno(); + return false; + } + count -= res; + } while (count > 0); + + ec.clear(); + + return true; +} +#endif + #if defined(_LIBCPP_FILESYSTEM_USE_SENDFILE) -bool copy_file_impl(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { +bool copy_file_impl_sendfile(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { size_t count = read_fd.get_stat().st_size; + // a zero-length file is either empty, or not copyable by this syscall + // return early to avoid the syscall cost + // however, we can't afford this luxury in the no-locale build, + // as we can't utilize the fstream impl to copy empty files +# if _LIBCPP_HAS_LOCALIZATION + if (count == 0) { + ec = {EINVAL, generic_category()}; + return false; + } +# endif do { ssize_t res; if ((res = ::sendfile(write_fd.fd, read_fd.fd, nullptr, count)) == -1) { @@ -194,6 +282,54 @@ bool copy_file_impl(FileDescriptor& read_fd, FileDescriptor& write_fd, error_cod return true; } +#endif + +#if defined(_LIBCPP_FILESYSTEM_USE_COPY_FILE_RANGE) || defined(_LIBCPP_FILESYSTEM_USE_SENDFILE) +// If we have copy_file_range or sendfile, try both in succession (if available). +// If both fail, fall back to using fstream. +bool copy_file_impl(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { +# if defined(_LIBCPP_FILESYSTEM_USE_COPY_FILE_RANGE) + if (copy_file_impl_copy_file_range(read_fd, write_fd, ec)) { + return true; + } + // EINVAL: src and dst are the same file (this is not cheaply + // detectable from userspace) + // EINVAL: copy_file_range is unsupported for this file type by the + // underlying filesystem + // ENOTSUP: undocumented, can arise with old kernels and NFS + // EOPNOTSUPP: filesystem does not implement copy_file_range + // ETXTBSY: src or dst is an active swapfile (nonsensical, but allowed + // with normal copying) + // EXDEV: src and dst are on different filesystems that do not support + // cross-fs copy_file_range + // ENOENT: undocumented, can arise with CIFS + // ENOSYS: unsupported by kernel or blocked by seccomp + if (ec.value() != EINVAL && ec.value() != ENOTSUP && ec.value() != EOPNOTSUPP && ec.value() != ETXTBSY && + ec.value() != EXDEV && ec.value() != ENOENT && ec.value() != ENOSYS) { + return false; + } + ec.clear(); +# endif + +# if defined(_LIBCPP_FILESYSTEM_USE_SENDFILE) + if (copy_file_impl_sendfile(read_fd, write_fd, ec)) { + return true; + } + // EINVAL: unsupported file type + if (ec.value() != EINVAL) { + return false; + } + ec.clear(); +# endif + +# if defined(_LIBCPP_FILESYSTEM_NEED_FSTREAM) + return copy_file_impl_fstream(read_fd, write_fd, ec); +# else + // since iostreams are unavailable in the no-locale build, just fail after a failed sendfile + ec.assign(EINVAL, std::system_category()); + return false; +# endif +} #elif defined(_LIBCPP_FILESYSTEM_USE_COPYFILE) bool copy_file_impl(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { struct CopyFileState { @@ -217,37 +353,7 @@ bool copy_file_impl(FileDescriptor& read_fd, FileDescriptor& write_fd, error_cod } #elif defined(_LIBCPP_FILESYSTEM_USE_FSTREAM) bool copy_file_impl(FileDescriptor& read_fd, FileDescriptor& write_fd, error_code& ec) { - ifstream in; - in.__open(read_fd.fd, ios::binary); - if (!in.is_open()) { - // This assumes that __open didn't reset the error code. - ec = capture_errno(); - return false; - } - read_fd.fd = -1; - ofstream out; - out.__open(write_fd.fd, ios::binary); - if (!out.is_open()) { - ec = capture_errno(); - return false; - } - write_fd.fd = -1; - - if (in.good() && out.good()) { - using InIt = istreambuf_iterator<char>; - using OutIt = ostreambuf_iterator<char>; - InIt bin(in); - InIt ein; - OutIt bout(out); - copy(bin, ein, bout); - } - if (out.fail() || in.fail()) { - ec = make_error_code(errc::io_error); - return false; - } - - ec.clear(); - return true; + return copy_file_impl_fstream(read_fd, write_fd, ec); } #else # error "Unknown implementation for copy_file_impl" |