view mercurial/exewrapper.c @ 41987:c1d83d916e85

revert: option to choose what to keep, not what to discard

I know the you (the reader) are probably tired of discussing how `hg
revert -i -r .` should behave and so am I. And I know I'm one of the
people who argued that showing the diff from the working copy to the
parent was confusing. I think it is less confusing now that we show
the diff from the parent to the working copy, but I still find it
confusing. I think showing the diff of hunks to keep might make it
easier to understand. So that's what this patch provides an option
for.

One argument doing it this way is that most people seem to find `hg
split` natural. I suspect that is because it shows the forward diff
(from parent commit to the commit) and asks you what to put in the
first commit. I think the new "keep" mode for revert (this patch)
matches that.

In "keep" mode, all the changes are still selected by default. That
means that `hg revert -i` followed by 'A' (keep all) (or 'c' in
curses) will be different from `hg revert -a`. That's mostly because
that was simplest. It can also be argued that it's safest. But it can
also be argued that it should be consistent with `hg revert -a`.

Note that in this mode, you can edit the hunks and it will do what you
expect (e.g. add new lines to your file if you added a new lines when
editing). The test case shows that that works.

Differential Revision: https://phab.mercurial-scm.org/D6125

/*
 exewrapper.c - wrapper for calling a python script on Windows

 Copyright 2012 Adrian Buehlmann <[e-mail]> and others

 This software may be used and distributed according to the terms of the
 GNU General Public License version 2 or any later version.
*/

#include <Python.h>
#include <stdio.h>
#include <tchar.h>
#include <windows.h>

#include "hgpythonlib.h"

#ifdef __GNUC__
int strcat_s(char *d, size_t n, const char *s)
{
	return !strncat(d, s, n);
}
int strcpy_s(char *d, size_t n, const char *s)
{
	return !strncpy(d, s, n);
}

#define _tcscpy_s strcpy_s
#define _tcscat_s strcat_s
#define _countof(array) (sizeof(array) / sizeof(array[0]))
#endif

static TCHAR pyscript[MAX_PATH + 10];
static TCHAR pyhome[MAX_PATH + 10];
static TCHAR pydllfile[MAX_PATH + 10];

int _tmain(int argc, TCHAR *argv[])
{
	TCHAR *p;
	int ret;
	int i;
	int n;
	TCHAR **pyargv;
	WIN32_FIND_DATA fdata;
	HANDLE hfind;
	const char *err;
	HMODULE pydll;
	void(__cdecl * Py_SetPythonHome)(TCHAR * home);
	int(__cdecl * Py_Main)(int argc, TCHAR *argv[]);

#if PY_MAJOR_VERSION >= 3
	Py_LegacyWindowsStdioFlag = 1;
#endif

	if (GetModuleFileName(NULL, pyscript, _countof(pyscript)) == 0) {
		err = "GetModuleFileName failed";
		goto bail;
	}

	p = _tcsrchr(pyscript, '.');
	if (p == NULL) {
		err = "malformed module filename";
		goto bail;
	}
	*p = 0; /* cut trailing ".exe" */
	_tcscpy_s(pyhome, _countof(pyhome), pyscript);

	hfind = FindFirstFile(pyscript, &fdata);
	if (hfind != INVALID_HANDLE_VALUE) {
		/* pyscript exists, close handle */
		FindClose(hfind);
	} else {
		/* file pyscript isn't there, take <pyscript>exe.py */
		_tcscat_s(pyscript, _countof(pyscript), _T("exe.py"));
	}

	pydll = NULL;

	p = _tcsrchr(pyhome, _T('\\'));
	if (p == NULL) {
		err = "can't find backslash in module filename";
		goto bail;
	}
	*p = 0; /* cut at directory */

	/* check for private Python of HackableMercurial */
	_tcscat_s(pyhome, _countof(pyhome), _T("\\hg-python"));

	hfind = FindFirstFile(pyhome, &fdata);
	if (hfind != INVALID_HANDLE_VALUE) {
		/* Path .\hg-python exists. We are probably in HackableMercurial
		scenario, so let's load python dll from this dir. */
		FindClose(hfind);
		_tcscpy_s(pydllfile, _countof(pydllfile), pyhome);
		_tcscat_s(pydllfile, _countof(pydllfile),
		          _T("\\") _T(HGPYTHONLIB) _T(".dll"));
		pydll = LoadLibrary(pydllfile);
		if (pydll == NULL) {
			err = "failed to load private Python DLL " HGPYTHONLIB
			      ".dll";
			goto bail;
		}
		Py_SetPythonHome =
		    (void *)GetProcAddress(pydll, "Py_SetPythonHome");
		if (Py_SetPythonHome == NULL) {
			err = "failed to get Py_SetPythonHome";
			goto bail;
		}
		Py_SetPythonHome(pyhome);
	}

	if (pydll == NULL) {
		pydll = LoadLibrary(_T(HGPYTHONLIB) _T(".dll"));
		if (pydll == NULL) {
			err = "failed to load Python DLL " HGPYTHONLIB ".dll";
			goto bail;
		}
	}

	Py_Main = (void *)GetProcAddress(pydll, "Py_Main");
	if (Py_Main == NULL) {
		err = "failed to get Py_Main";
		goto bail;
	}

	/*
	Only add the pyscript to the args, if it's not already there. It may
	already be there, if the script spawned a child process of itself, in
	the same way as it got called, that is, with the pyscript already in
	place. So we optionally accept the pyscript as the first argument
	(argv[1]), letting our exe taking the role of the python interpreter.
	*/
	if (argc >= 2 && _tcscmp(argv[1], pyscript) == 0) {
		/*
		pyscript is already in the args, so there is no need to copy
		the args and we can directly call the python interpreter with
		the original args.
		*/
		return Py_Main(argc, argv);
	}

	/*
	Start assembling the args for the Python interpreter call. We put the
	name of our exe (argv[0]) in the position where the python.exe
	canonically is, and insert the pyscript next.
	*/
	pyargv = malloc((argc + 5) * sizeof(TCHAR *));
	if (pyargv == NULL) {
		err = "not enough memory";
		goto bail;
	}
	n = 0;
	pyargv[n++] = argv[0];
	pyargv[n++] = pyscript;

	/* copy remaining args from the command line */
	for (i = 1; i < argc; i++)
		pyargv[n++] = argv[i];
	/* argv[argc] is guaranteed to be NULL, so we forward that guarantee */
	pyargv[n] = NULL;

	ret = Py_Main(n, pyargv); /* The Python interpreter call */

	free(pyargv);
	return ret;

bail:
	fprintf(stderr, "abort: %s\n", err);
	return 255;
}