git/compat/win32/headless.c
Johannes Schindelin 4b8a2717bb 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.

Helped-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
Helped-by: Yuyi Wang <Strawberry_Str@hotmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-08-09 13:58:13 -07:00

115 lines
3.2 KiB
C

/*
* headless Git - run Git without opening a console window on Windows
*/
#define STRICT
#define WIN32_LEAN_AND_MEAN
#define UNICODE
#define _UNICODE
#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <wchar.h>
/*
* 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(_In_ HINSTANCE instance,
_In_opt_ HINSTANCE previous_instance,
_In_ LPWSTR command_line, _In_ 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 = {
.cb = sizeof(STARTUPINFO),
.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 >= size - 11)
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.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))
exit_code = 130; /* Could not determine exit code? */
CloseHandle(process_info.hProcess);
CloseHandle(process_info.hThread);
return (int)exit_code;
}