procutil: make stream detection in make_line_buffered more correct and strict
In make_line_buffered(), we don’t want to wrap the stream if we know that lines
get flushed to the underlying raw stream already.
Previously, the heuristic was too optimistic. It assumed that any stream which
is not an instance of io.BufferedIOBase doesn’t need wrapping. However, there
are buffered streams that aren’t instances of io.BufferedIOBase, like
Mercurial’s own winstdout.
The new logic is different in two ways:
First, only for the check, if unwraps any combination of WriteAllWrapper and
winstdout.
Second, it skips wrapping the stream only if it is an instance of io.RawIOBase
(or already wrapped). If it is an instance of io.BufferedIOBase, it gets
wrapped. In any other case, the function raises an exception. This ensures
that, if an unknown stream is passed or we add another wrapper in the future,
we don’t wrap the stream if it’s already line buffered or not wrap the stream
if it’s not line buffered. In fact, this was already helpful during development
of this change. Without it, I possibly would have forgot that WriteAllWrapper
needs to be ignored for the check, leading to unnecessary wrapping if stdout is
unbuffered.
The alternative would have been to always wrap unknown streams. However, I
don’t think that anyone would benefit from being less strict. We can expect
streams from the standard library to be subclassing either io.RawIOBase or
io.BufferedIOBase, so running Mercurial in the standard way should not regress
by this change. Py2exe might replace sys.stdout and sys.stderr, but that
currently breaks Mercurial anyway and also these streams don’t claim to be
interactive, so this function is not called for them.
/*
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;
}