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Single-file apps should not use copy-on-write mapping of the .exe on windows. #59033

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agocke merged 1 commit into from
Sep 16, 2021
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Single-file apps should not use copy-on-write mapping of the .exe on windows. #59033

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7 changes: 7 additions & 0 deletions src/native/corehost/bundle/info.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -108,7 +108,14 @@ char* info_t::config_t::map(const pal::string_t& path, const location_t* &locati
// * There is no performance limitation due to a larger sized mapping, since we actually only read the pages with relevant contents.
// * Files that are too large to be mapped (ex: that exhaust 32-bit virtual address space) are not supported.

#ifdef _WIN32
// Since we can't use in-situ parsing on Windows, as JSON data is encoded in
// UTF-8 and the host expects wide strings.
Comment on lines +112 to +113
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@am11 am11 Sep 16, 2021

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Is this part of the comment related to the code below on line 115 or above line 88?

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@agocke agocke Sep 16, 2021

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This is about 115 -- the RapidJson parser used in json_parser.cpp modifies the buffer on Linux, but not on Windows, so the CoW permissions are not useful on Windows.

// We do not need COW and read-only mapping will be enough.
char* addr = (char*)pal::mmap_read(app->m_bundle_path);
#else // _WIN32
char* addr = (char*)pal::mmap_copy_on_write(app->m_bundle_path);
#endif // _WIN32
if (addr == nullptr)
{
trace::error(_X("Failure processing application bundle."));
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