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MDEV-35891 mtr, Windows - fix multi-process append for stdout and stderr

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This backports https://github.com/mysql/mysql-server/commit/e2f685972985,
which works around perl issue https://github.com/Perl/perl5/issues/17570

MySQL fix  ensures that FILE_APPEND_DATA is used in redirected
stdout/stderr open flags, rather than FILE_GENERIC_WRITE. Only this gives
lossless append behavior, if multiple processes use the same file.
This commit is contained in:
Vladislav Vaintroub 2025-01-20 14:07:23 +01:00
parent d32ec7d48e
commit b056ed6d98
1 changed files with 21 additions and 0 deletions
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21
mysql-test/lib/My/SafeProcess/safe_process_win.cc
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@ -152,6 +152,24 @@ void handle_signal (int signal)
}
}
/**
Sets the append flag (FILE_APPEND_DATA) so that the handle inherited by the
child process will be in append mode.
Workaround for perl bug https://github.com/Perl/perl5/issues/17570
*/
static void fix_file_append_flag_inheritance(DWORD std_handle)
{
HANDLE old_handle = GetStdHandle(std_handle);
HANDLE new_handle = ReOpenFile(old_handle, FILE_APPEND_DATA,
FILE_SHARE_WRITE | FILE_SHARE_READ, 0);
if (new_handle != INVALID_HANDLE_VALUE)
{
SetHandleInformation(new_handle, HANDLE_FLAG_INHERIT, HANDLE_FLAG_INHERIT);
SetStdHandle(std_handle, new_handle);
CloseHandle(old_handle);
}
}
int main(int argc, const char** argv )
{
@ -270,6 +288,9 @@ int main(int argc, const char** argv )
SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOGPFAULTERRORBOX
| SEM_NOOPENFILEERRORBOX);
fix_file_append_flag_inheritance(STD_OUTPUT_HANDLE);
fix_file_append_flag_inheritance(STD_ERROR_HANDLE);
#if 0
/* Setup stdin, stdout and stderr redirect */
si.dwFlags= STARTF_USESTDHANDLES;