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Add a helper to obtain a function's address in kernel32.dll
In particular, we are interested in the address of the CtrlRoutine and the ExitProcess functions. Since kernel32.dll is loaded first thing, the addresses will be the same for all processes (matching the CPU architecture, of course). This will help us with emulating SIGINT properly (by not sending signals to *all* processes attached to the same Console). Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,146 @@ | ||
| #include <stdio.h> | ||
| #include <windows.h> | ||
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| /** | ||
| * To determine the address of kernel32!CtrlRoutine, we need to use | ||
| * dbghelp.dll. But we want to avoid linking statically to that library because | ||
| * the normal operation of cygwin-console-helper.exe (i.e. to allocate a hidden | ||
| * Console) does not need it. | ||
| * | ||
| * Therefore, we declare the SYMBOL_INFOW structure here, load the dbghelp | ||
| * library via LoadLibraryExA() and obtain the SymInitialize(), SymFromAddrW() | ||
| * and SymCleanup() functions via GetProcAddr(). | ||
| */ | ||
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| #include <dbghelp.h> | ||
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| /* Avoid fprintf(), as it would try to reference '__getreent' */ | ||
| static void | ||
| output (BOOL error, const char *fmt, ...) | ||
| { | ||
| va_list ap; | ||
| char buffer[1024]; | ||
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| va_start (ap, fmt); | ||
| vsnprintf (buffer, sizeof(buffer) - 1, fmt, ap); | ||
| buffer[sizeof(buffer) - 1] = '\0'; | ||
| va_end (ap); | ||
| WriteFile (GetStdHandle(error ? STD_ERROR_HANDLE : STD_OUTPUT_HANDLE), | ||
| buffer, strlen (buffer), NULL, NULL); | ||
| } | ||
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| static WINAPI BOOL | ||
| ctrl_handler(DWORD ctrl_type) | ||
| { | ||
| unsigned short count; | ||
| void *address; | ||
| HANDLE process; | ||
| PSYMBOL_INFOW info; | ||
| DWORD64 displacement; | ||
|
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||
| count = CaptureStackBackTrace (1l /* skip this function */, | ||
| 1l /* return only one trace item */, | ||
| &address, NULL); | ||
| if (count != 1) | ||
| { | ||
| output (1, "Could not capture backtrace\n"); | ||
| return FALSE; | ||
| } | ||
|
|
||
| process = GetCurrentProcess (); | ||
| if (!SymInitialize (process, NULL, TRUE)) | ||
| { | ||
| output (1, "Could not initialize symbols\n"); | ||
| return FALSE; | ||
| } | ||
|
|
||
| info = (PSYMBOL_INFOW) | ||
| malloc (sizeof(*info) + MAX_SYM_NAME * sizeof(wchar_t)); | ||
| if (!info) | ||
| { | ||
| output (1, "Could not allocate symbol info structure\n"); | ||
| return FALSE; | ||
| } | ||
| info->SizeOfStruct = sizeof(*info); | ||
| info->MaxNameLen = MAX_SYM_NAME; | ||
|
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||
| if (!SymFromAddrW (process, (DWORD64)(intptr_t)address, &displacement, info)) | ||
| { | ||
| output (1, "Could not get symbol info\n"); | ||
| SymCleanup(process); | ||
| return FALSE; | ||
| } | ||
| output (0, "%p\n", (void *)(intptr_t)info->Address); | ||
| CloseHandle(GetStdHandle(STD_OUTPUT_HANDLE)); | ||
| SymCleanup(process); | ||
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||
| exit(0); | ||
| } | ||
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||
| int | ||
| main (int argc, char **argv) | ||
| { | ||
| char *end; | ||
|
|
||
| if (argc < 2) | ||
| { | ||
| output (1, "Need a function name\n"); | ||
| return 1; | ||
| } | ||
|
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||
| if (strcmp(argv[1], "CtrlRoutine")) | ||
| { | ||
| if (argc > 2) | ||
| { | ||
| output (1, "Unhandled option: %s\n", argv[2]); | ||
| return 1; | ||
| } | ||
|
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||
| HINSTANCE kernel32 = GetModuleHandle ("kernel32"); | ||
| if (!kernel32) | ||
| return 1; | ||
| void *address = (void *) GetProcAddress (kernel32, argv[1]); | ||
| if (!address) | ||
| return 1; | ||
| output (0, "%p\n", address); | ||
| return 0; | ||
| } | ||
|
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||
| /* Special-case kernel32!CtrlRoutine */ | ||
| if (argc == 3 && !strcmp ("--alloc-console", argv[2])) | ||
| { | ||
| if (!FreeConsole () && GetLastError () != ERROR_INVALID_PARAMETER) | ||
| { | ||
| output (1, "Could not detach from current Console: %d\n", | ||
| (int)GetLastError()); | ||
| return 1; | ||
| } | ||
| if (!AllocConsole ()) | ||
| { | ||
| output (1, "Could not allocate a new Console\n"); | ||
| return 1; | ||
| } | ||
| } | ||
| else if (argc > 2) | ||
| { | ||
| output (1, "Unhandled option: %s\n", argv[2]); | ||
| return 1; | ||
| } | ||
|
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||
| if (!SetConsoleCtrlHandler (ctrl_handler, TRUE)) | ||
| { | ||
| output (1, "Could not register Ctrl handler\n"); | ||
| return 1; | ||
| } | ||
|
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||
| if (!GenerateConsoleCtrlEvent(CTRL_BREAK_EVENT, 0)) | ||
| { | ||
| output (1, "Could not simulate Ctrl+Break\n"); | ||
| return 1; | ||
| } | ||
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||
| /* Give the event 1sec time to print out the address */ | ||
| Sleep(1000); | ||
| return 1; | ||
| } | ||
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