From c13fa82dec4b053f742ec240e9af892e2c01d831 Mon Sep 17 00:00:00 2001 From: Johannes Schindelin Date: Thu, 3 Dec 2020 22:44:24 +0100 Subject: [PATCH] win32: add a helper to run `git.exe` without a foreground window On Windows, there are two kinds of executables, console ones and non-console ones. Git's executables are all console ones. When launching the former e.g. in a scheduled task, a CMD window pops up. This is not what we want for the tasks installed via the `git maintenance` command. To work around this, let's introduce `headless-git.exe`, which is a non-console program that does _not_ pop up any window. All it does is to re-launch `git.exe`, suppressing that console window, passing through all command-line arguments as-are. Signed-off-by: Johannes Schindelin Signed-off-by: Derrick Stolee --- Makefile | 7 ++ compat/win32/headless.c | 114 ++++++++++++++++++++++++++++ config.mak.uname | 3 + contrib/buildsystems/CMakeLists.txt | 3 + 4 files changed, 127 insertions(+) create mode 100644 compat/win32/headless.c diff --git a/Makefile b/Makefile index f3dc217832..3275125aa6 100644 --- a/Makefile +++ b/Makefile @@ -2504,6 +2504,13 @@ compat/nedmalloc/nedmalloc.sp compat/nedmalloc/nedmalloc.o: EXTRA_CPPFLAGS = \ compat/nedmalloc/nedmalloc.sp: SP_EXTRA_FLAGS += -Wno-non-pointer-null endif +headless-git.o: compat/win32/headless.c + $(QUIET_CC)$(CC) $(ALL_CFLAGS) $(COMPAT_CFLAGS) \ + -fno-stack-protector -o $@ -c -Wall -Wwrite-strings $< + +headless-git$X: headless-git.o git.res + $(QUIET_LINK)$(CC) $(ALL_LDFLAGS) -mwindows $(COMPAT_CFLAGS) -o $@ $^ + git-%$X: %.o GIT-LDFLAGS $(GITLIBS) $(QUIET_LINK)$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS) diff --git a/compat/win32/headless.c b/compat/win32/headless.c new file mode 100644 index 0000000000..d04ddc0795 --- /dev/null +++ b/compat/win32/headless.c @@ -0,0 +1,114 @@ +/* + * headless Git - run Git without opening a console window on Windows + */ + +#define STRICT +#define WIN32_LEAN_AND_MEAN +#define UNICODE +#define _UNICODE +#include +#include +#include +#include + +/* + * If `dir` contains the path to a Git exec directory, extend `PATH` to + * include the corresponding `bin/` directory (which is where all those + * `.dll` files needed by `git.exe` are, on Windows). + */ +static int extend_path(wchar_t *dir, size_t dir_len) +{ + const wchar_t *suffix = L"\\libexec\\git-core"; + size_t suffix_len = wcslen(suffix); + wchar_t *env; + DWORD len; + + if (dir_len < suffix_len) + return 0; + + dir_len -= suffix_len; + if (memcmp(dir + dir_len, suffix, suffix_len * sizeof(wchar_t))) + return 0; + + len = GetEnvironmentVariableW(L"PATH", NULL, 0); + if (!len) + return 0; + + env = _alloca((dir_len + 5 + len) * sizeof(wchar_t)); + wcsncpy(env, dir, dir_len); + wcscpy(env + dir_len, L"\\bin;"); + if (!GetEnvironmentVariableW(L"PATH", env + dir_len + 5, len)) + return 0; + + SetEnvironmentVariableW(L"PATH", env); + return 1; +} + +int WINAPI wWinMain(HINSTANCE instance, HINSTANCE previous_instance, + wchar_t *command_line, int show) +{ + wchar_t git_command_line[32768]; + size_t size = sizeof(git_command_line) / sizeof(wchar_t); + const wchar_t *needs_quotes = L""; + int slash = 0, i; + + STARTUPINFO startup_info = { + .dwFlags = STARTF_USESHOWWINDOW, + .wShowWindow = SW_HIDE, + }; + PROCESS_INFORMATION process_info = { 0 }; + DWORD creation_flags = CREATE_UNICODE_ENVIRONMENT | + CREATE_NEW_CONSOLE | CREATE_NO_WINDOW; + DWORD exit_code; + + /* First, determine the full path of argv[0] */ + for (i = 0; _wpgmptr[i]; i++) + if (_wpgmptr[i] == L' ') + needs_quotes = L"\""; + else if (_wpgmptr[i] == L'\\') + slash = i; + + if (slash + 11 >= sizeof(git_command_line) / sizeof(wchar_t)) + return 127; /* Too long path */ + + /* If it is in Git's exec path, add the bin/ directory to the PATH */ + extend_path(_wpgmptr, slash); + + /* Then, add the full path of `git.exe` as argv[0] */ + i = swprintf_s(git_command_line, size, L"%ls%.*ls\\git.exe%ls", + needs_quotes, slash, _wpgmptr, needs_quotes); + if (i < 0) + return 127; /* Too long path */ + + if (*command_line) { + /* Now, append the command-line arguments */ + i = swprintf_s(git_command_line + i, size - i, + L" %ls", command_line); + if (i < 0) + return 127; + } + + startup_info.cb = sizeof(STARTUPINFO); + + startup_info.hStdInput = GetStdHandle(STD_INPUT_HANDLE); + startup_info.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE); + startup_info.hStdError = GetStdHandle(STD_ERROR_HANDLE); + + if (!CreateProcess(NULL, /* infer argv[0] from the command line */ + git_command_line, /* modified command line */ + NULL, /* inherit process handles? */ + NULL, /* inherit thread handles? */ + FALSE, /* handles inheritable? */ + creation_flags, + NULL, /* use this process' environment */ + NULL, /* use this process' working directory */ + &startup_info, &process_info)) + return 129; /* could not start */ + WaitForSingleObject(process_info.hProcess, INFINITE); + if (!GetExitCodeProcess(process_info.hProcess, &exit_code)) { + CloseHandle(process_info.hProcess); + return 130; /* Could not determine exit code? */ + } + + return (int)exit_code; +} diff --git a/config.mak.uname b/config.mak.uname index d204c20a64..c524d2b1f1 100644 --- a/config.mak.uname +++ b/config.mak.uname @@ -484,6 +484,8 @@ else endif X = .exe + EXTRA_PROGRAMS += headless-git$X + compat/msvc.o: compat/msvc.c compat/mingw.c GIT-CFLAGS endif ifeq ($(uname_S),Interix) @@ -625,6 +627,7 @@ ifneq (,$(findstring MINGW,$(uname_S))) RC = windres -O coff NATIVE_CRLF = YesPlease X = .exe + EXTRA_PROGRAMS += headless-git$X ifneq (,$(wildcard ../THIS_IS_MSYSGIT)) htmldir = doc/git/html/ prefix = diff --git a/contrib/buildsystems/CMakeLists.txt b/contrib/buildsystems/CMakeLists.txt index ac3dbc079a..1621dabc33 100644 --- a/contrib/buildsystems/CMakeLists.txt +++ b/contrib/buildsystems/CMakeLists.txt @@ -642,6 +642,9 @@ if(WIN32) else() message(FATAL_ERROR "Unhandled compiler: ${CMAKE_C_COMPILER_ID}") endif() + + add_executable(headless-git ${CMAKE_SOURCE_DIR}/compat/win32/headless.c) + target_link_options(headless-git PUBLIC /NOLOGO /ENTRY:wWinMainCRTStartup /SUBSYSTEM:WINDOWS) elseif(UNIX) target_link_libraries(common-main pthread rt) endif()