git

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/*
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 * headless Git - run Git without opening a console window on Windows
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 */
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#define STRICT
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#define WIN32_LEAN_AND_MEAN
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#define UNICODE
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#define _UNICODE
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#include <windows.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <wchar.h>
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/*
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 * If `dir` contains the path to a Git exec directory, extend `PATH` to
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 * include the corresponding `bin/` directory (which is where all those
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 * `.dll` files needed by `git.exe` are, on Windows).
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 */
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static int extend_path(wchar_t *dir, size_t dir_len)
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{
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	const wchar_t *suffix = L"\\libexec\\git-core";
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	size_t suffix_len = wcslen(suffix);
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	wchar_t *env;
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	DWORD len;
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	if (dir_len < suffix_len)
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		return 0;
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	dir_len -= suffix_len;
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	if (memcmp(dir + dir_len, suffix, suffix_len * sizeof(wchar_t)))
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		return 0;
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	len = GetEnvironmentVariableW(L"PATH", NULL, 0);
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	if (!len)
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		return 0;
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	env = _alloca((dir_len + 5 + len) * sizeof(wchar_t));
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	wcsncpy(env, dir, dir_len);
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	wcscpy(env + dir_len, L"\\bin;");
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	if (!GetEnvironmentVariableW(L"PATH", env + dir_len + 5, len))
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		return 0;
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	SetEnvironmentVariableW(L"PATH", env);
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	return 1;
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}
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int WINAPI wWinMain(_In_ HINSTANCE instance,
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		    _In_opt_ HINSTANCE previous_instance,
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		    _In_ LPWSTR command_line, _In_ int show)
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{
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	wchar_t git_command_line[32768];
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	size_t size = sizeof(git_command_line) / sizeof(wchar_t);
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	const wchar_t *needs_quotes = L"";
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	int slash = 0, i;
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	STARTUPINFO startup_info = {
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		.cb = sizeof(STARTUPINFO),
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		.dwFlags = STARTF_USESHOWWINDOW,
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		.wShowWindow = SW_HIDE,
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	};
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	PROCESS_INFORMATION process_info = { 0 };
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	DWORD creation_flags = CREATE_UNICODE_ENVIRONMENT |
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		CREATE_NEW_CONSOLE | CREATE_NO_WINDOW;
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	DWORD exit_code;
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	/* First, determine the full path of argv[0] */
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	for (i = 0; _wpgmptr[i]; i++)
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		if (_wpgmptr[i] == L' ')
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			needs_quotes = L"\"";
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		else if (_wpgmptr[i] == L'\\')
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			slash = i;
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	if (slash >= size - 11)
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		return 127; /* Too long path */
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	/* If it is in Git's exec path, add the bin/ directory to the PATH */
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	extend_path(_wpgmptr, slash);
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	/* Then, add the full path of `git.exe` as argv[0] */
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	i = swprintf_s(git_command_line, size, L"%ls%.*ls\\git.exe%ls",
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		       needs_quotes, slash, _wpgmptr, needs_quotes);
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	if (i < 0)
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		return 127; /* Too long path */
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	if (*command_line) {
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		/* Now, append the command-line arguments */
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		i = swprintf_s(git_command_line + i, size - i,
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			       L" %ls", command_line);
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		if (i < 0)
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			return 127;
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	}
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	startup_info.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
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	startup_info.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
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	startup_info.hStdError = GetStdHandle(STD_ERROR_HANDLE);
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	if (!CreateProcess(NULL, /* infer argv[0] from the command line */
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			   git_command_line, /* modified command line */
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			   NULL, /* inherit process handles? */
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			   NULL, /* inherit thread handles? */
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			   FALSE, /* handles inheritable? */
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			   creation_flags,
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			   NULL, /* use this process' environment */
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			   NULL, /* use this process' working directory */
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			   &startup_info, &process_info))
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		return 129; /* could not start */
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	WaitForSingleObject(process_info.hProcess, INFINITE);
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	if (!GetExitCodeProcess(process_info.hProcess, &exit_code))
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		exit_code = 130; /* Could not determine exit code? */
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	CloseHandle(process_info.hProcess);
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	CloseHandle(process_info.hThread);
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	return (int)exit_code;
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}
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