Mercurial > hg
view mercurial/exewrapper.c @ 50336:cf4d2f31660d stable
chg: populate CHGHG if not set
Normally, chg determines which `hg` executable to use by first consulting the
`$CHGHG` and `$HG` environment variables, and if neither are present defaults
to the `hg` found in the user's `$PATH`. If built with the `HGPATHREL` compiler
flag, chg will instead assume that there exists an `hg` executable in the same
directory as the `chg` binary and attempt to use that.
This can cause problems in situations where there are multiple actively-used
Mercurial installations on the same system. When a `chg` client connects to a
running command server, the server process performs some basic validation to
determine whether a new command server needs to be spawned. These checks include
things like checking certain "sensitive" environment variables and config
sections, as well as checking whether the mtime of the extensions, hg's
`__version__.py` module, and the Python interpreter have changed.
Crucially, the command server doesn't explicitly check whether the executable it
is running from matches the executable that the `chg` client would have
otherwise invoked had there been no existing command server process. Without
`HGPATHREL`, this still gets implicitly checked during the validation step,
because the only way to specify an alternate hg executable (apart from `$PATH`)
is via the `$CHGHG` and `$HG` environment variables, both of which are checked.
With `HGPATHREL`, however, the command server has no way of knowing which hg
executable the client would have run. This means that a client located at
`/version_B/bin/chg` will happily connect to a command server running
`/version_A/bin/hg` instead of `/version_B/bin/hg` as expected. A simple
solution is to have the client set `$CHGHG` itself, which then allows the
command server's environment validation to work as intended.
I have tested this manually using two locally built hg installations and it
seems to work with no ill effects. That said, I'm not sure how to write an
automated test for this since the `chg` available to the tests isn't even built
with the `HGPATHREL` compiler flag to begin with.
author | Arun Kulshreshtha <akulshreshtha@janestreet.com> |
---|---|
date | Mon, 27 Mar 2023 17:30:14 -0400 |
parents | 2ec5fbe26659 |
children |
line wrap: on
line source
/* exewrapper.c - wrapper for calling a python script on Windows Copyright 2012 Adrian Buehlmann <adrian@cadifra.com> 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 _wputenv(L"PYTHONLEGACYWINDOWSSTDIO=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; }