[Bug libstdc++/97731] New: terminate called in std::experimental::filesystem::recursive_directory_iterator
torsten.hilbrich at secunet dot com
gcc-bugzilla@gcc.gnu.org
Thu Nov 5 13:51:46 GMT 2020
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97731
Bug ID: 97731
Summary: terminate called in
std::experimental::filesystem::recursive_directory_ite
rator
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: libstdc++
Assignee: unassigned at gcc dot gnu.org
Reporter: torsten.hilbrich at secunet dot com
Target Milestone: ---
Created attachment 49506
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=49506&action=edit
Reproducer for the problem
The recursive_directory_iterator causes a call to terminate when an I/O error
is happening on the directory to iterate. It originally occured in an
environment where access to a directory was no longer possible and caused EIO
reported through a linux device-mapper target. In the test program this
behaviour is simulated by replacing the readdir function with a mockup always
failing with errno set to EIO.
We initially found this problem with libstdc++ as provided with gcc 8.3.0. But
I also checked the version from gcc 10.2 and could reproduce the problem.
The testing code test.cpp is attached to this ticket.
Here is an example session:
$ g++ -o test test.cpp -lstdc++fs
$ ./test
terminate called after throwing an instance of
'std::experimental::filesystem::v1::__cxx11::filesystem_error'
what(): filesystem error: directory iterator cannot advance: Input/output
error
Aborted (core dumped)
I already looked at the code and thing I found the culprit.
In recursive_directory_iterator(const path&, directory_options options,
error_code*) (dir.cc:199) the following method call is found:
if (sp->top().advance(ec))
This calls the method "bool advance(bool skip_permission_denied = false)"
within _Dir, implicitly converting the std::error_code* to bool.
This way, we get roughly the following stack trace:
#0 std::filesystem::_Dir_base::advance (this=0x55555559a050,
skip_permission_denied=true, ec=...)
at dir-common.h:110
#1 0x000055555555eb39 in
std::experimental::filesystem::v1::__cxx11::_Dir::advance (
this=0x55555559a050, skip_permission_denied=true, ec=...) at dir.cc:65
#2 0x000055555555ed39 in
std::experimental::filesystem::v1::__cxx11::_Dir::advance (
this=0x55555559a050, skip_permission_denied=true) at dir.cc:87
#3 0x000055555555d110 in
std::experimental::filesystem::v1::__cxx11::recursive_directory_iterator::recursive_directory_iterator
(this=0x7fffffffdd90, p=filesystem::path "/tmp" = {...},
options=std::experimental::filesystem::v1::directory_options::none,
ec=0x7fffffffdd60) at dir.cc:199
#4 0x000055555555c07c in
std::experimental::filesystem::v1::__cxx11::recursive_directory_iterator::recursive_directory_iterator
(this=0x7fffffffdd90, __p=filesystem::path "/tmp" = {...}, __ec=...)
at /usr/include/c++/9/experimental/bits/fs_dir.h:280
#5 0x000055555555bb5d in main () at ./test.cpp:17
and finally, an exception is thrown via a method declared noexcept, causing the
termination of the program.
Torsten
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