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Stop throwing in destructors

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When exception processing is unwinding the stack, any exception thrown
in destructors end up std::terminate()-in our process.

Since all workarounds to report errors from destructors seems an
overkill, and the only important place where we should notify the user
about a failure is the stdex::stream::cache::~cache() (data loss occurs
when failure happens here), and if we'd throw in stdex::stream::cache::
~cache(), our process would get terminated anyway so the data loss is
inevitable, let's just silence this for now and come up with a better
solution later if we get smarter anytime in the future.

Signed-off-by: Simon Rozman <simon@rozman.si>
This commit is contained in:
Simon Rozman 2025-03-06 22:09:50 +01:00
parent 69f2c639cd
commit bfd8aaff65
3 changed files with 33 additions and 25 deletions
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19
include/stdex/stream.hpp
View File

@ -86,7 +86,7 @@ namespace stdex
public:
basic(_In_ state_t state = state_t::ok) : m_state(state) {}
virtual ~basic() noexcept(false) {}
virtual ~basic() {}
///
/// Reads block of data from the stream
@ -1852,17 +1852,20 @@ namespace stdex
#endif
{}
virtual ~cache() noexcept(false)
virtual ~cache()
{
if (m_source) {
flush_cache();
if (!ok()) _Unlikely_
throw std::system_error(sys_error(), std::system_category(), "failed to flush cache"); // Data loss occurred
m_source->seekbeg(m_offset);
try {
flush_cache();
if (!ok()) _Unlikely_
throw std::system_error(sys_error(), std::system_category(), "failed to flush cache"); // Data loss occurred
m_source->seekbeg(m_offset);
#if SET_FILE_OP_TIMES
m_source->set_atime(m_atime);
m_source->set_mtime(m_mtime);
m_source->set_atime(m_atime);
m_source->set_mtime(m_mtime);
#endif
}
catch (...) {} // TODO: Never throw in destructors. If we'd throw here exception stack unwinding would std::terminate() our process anyway. Is there a way to catch this?
}
}

8
include/stdex/system.hpp
View File

@ -171,10 +171,12 @@ namespace stdex
return *this;
}
virtual ~basic_sys_object() noexcept(false)
virtual ~basic_sys_object()
{
if (m_h != TR::invalid_handle)
TR::close(m_h);
if (m_h != TR::invalid_handle) {
try { TR::close(m_h); }
catch (...) {} // Failure to close a handle should not be that devastating as throwing in a destructor may be.
}
}
///

31
include/stdex/zlib.hpp
View File

@ -61,20 +61,23 @@ namespace stdex
virtual ~zlib_writer()
{
m_zlib.avail_in = 0;
m_zlib.next_in = NULL;
do {
m_zlib.avail_out = m_block_size;
m_zlib.next_out = m_block.get();
throw_on_zlib_error(deflate(&m_zlib, Z_FINISH));
m_source->write(m_block.get(), m_block_size - m_zlib.avail_out);
if (!m_source->ok()) _Unlikely_
throw std::system_error(sys_error(), std::system_category(), "failed to flush compressed stream"); // Data loss occured
} while (m_zlib.avail_out == 0);
// m_zlib.avail_out = m_block_size;
// m_zlib.next_out = m_block.get();
// deflateReset(&m_zlib);
deflateEnd(&m_zlib);
try {
m_zlib.avail_in = 0;
m_zlib.next_in = NULL;
do {
m_zlib.avail_out = m_block_size;
m_zlib.next_out = m_block.get();
throw_on_zlib_error(deflate(&m_zlib, Z_FINISH));
m_source->write(m_block.get(), m_block_size - m_zlib.avail_out);
if (!m_source->ok()) _Unlikely_
throw std::system_error(sys_error(), std::system_category(), "failed to flush compressed stream"); // Data loss occured
} while (m_zlib.avail_out == 0);
// m_zlib.avail_out = m_block_size;
// m_zlib.next_out = m_block.get();
// deflateReset(&m_zlib);
deflateEnd(&m_zlib);
}
catch (...) {} // TODO: Never throw in destructors. If we'd throw here exception stack unwinding would std::terminate() our process anyway. Is there a way to catch this?
}
virtual _Success_(return != 0) size_t write(