diff --git a/libstdc++-v3/src/filesystem/ops-common.h b/libstdc++-v3/src/filesystem/ops-common.h index 7c8d3a694e211b0d3829a70d24605c1ec7f5b757..901f166514f2e7aa9cc7582e1ae9ba528fe1a214 100644 --- a/libstdc++-v3/src/filesystem/ops-common.h +++ b/libstdc++-v3/src/filesystem/ops-common.h @@ -618,11 +618,16 @@ _GLIBCXX_BEGIN_NAMESPACE_FILESYSTEM if (sbout.is_open()) out.fd = -1; - if (from_st->st_size && !(std::ostream(&sbout) << &sbin)) - { - ec = std::make_error_code(std::errc::io_error); - return false; - } + // ostream::operator<<(streambuf*) fails if it extracts no characters, + // so don't try to use it for empty files. But from_st->st_size == 0 for + // some special files (e.g. procfs, see PR libstdc++/108178) so just try + // to read a character to decide whether there is anything to copy or not. + if (sbin.sgetc() != char_traits<char>::eof()) + if (!(std::ostream(&sbout) << &sbin)) + { + ec = std::make_error_code(std::errc::io_error); + return false; + } if (!sbout.close() || !sbin.close()) { diff --git a/libstdc++-v3/testsuite/27_io/filesystem/operations/copy_file_108178.cc b/libstdc++-v3/testsuite/27_io/filesystem/operations/copy_file_108178.cc new file mode 100644 index 0000000000000000000000000000000000000000..25135834e21e41dbfbc4e2a29fc45027423cf1ec --- /dev/null +++ b/libstdc++-v3/testsuite/27_io/filesystem/operations/copy_file_108178.cc @@ -0,0 +1,33 @@ +// { dg-do run { target c++17 } } +// { dg-require-filesystem-ts "" } + +// C++17 30.10.15.4 Copy [fs.op.copy_file] + +#include <filesystem> +#include <fstream> +#include <unistd.h> // getpid +#include <testsuite_fs.h> +#include <testsuite_hooks.h> + +namespace fs = std::filesystem; + +void +test_procfs() // PR libstdc++/108178 +{ + auto pid = ::getpid(); + std::string from = "/proc/" + std::to_string(pid) + "/status"; + if (fs::exists(from)) + { + auto to = __gnu_test::nonexistent_path(); + fs::copy_file(from, to); + std::ifstream f(to); + VERIFY(f.is_open()); + VERIFY(f.peek() != std::char_traits<char>::eof()); + fs::remove(to); + } +} + +int main() +{ + test_procfs(); +}