cosmopolitan/libc/calls/mkntpath.ncabi.c
Justine Tunney f4f4caab0e Add x86_64-linux-gnu emulator
I wanted a tiny scriptable meltdown proof way to run userspace programs
and visualize how program execution impacts memory. It helps to explain
how things like Actually Portable Executable works. It can show you how
the GCC generated code is going about manipulating matrices and more. I
didn't feel fully comfortable with Qemu and Bochs because I'm not smart
enough to understand them. I wanted something like gVisor but with much
stronger levels of assurances. I wanted a single binary that'll run, on
all major operating systems with an embedded GPL barrier ZIP filesystem
that is tiny enough to transpile to JavaScript and run in browsers too.

https://justine.storage.googleapis.com/emulator625.mp4
2020-08-25 04:43:42 -07:00

80 lines
3.6 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ This program is free software; you can redistribute it and/or modify │
│ it under the terms of the GNU General Public License as published by │
│ the Free Software Foundation; version 2 of the License. │
│ │
│ This program is distributed in the hope that it will be useful, but │
│ WITHOUT ANY WARRANTY; without even the implied warranty of │
│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
│ General Public License for more details. │
│ │
│ You should have received a copy of the GNU General Public License │
│ along with this program; if not, write to the Free Software │
│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
│ 02110-1301 USA │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/bits/pushpop.h"
#include "libc/bits/safemacros.h"
#include "libc/calls/hefty/ntspawn.h"
#include "libc/calls/internal.h"
#include "libc/conv/conv.h"
#include "libc/str/str.h"
#include "libc/str/tpdecode.h"
#include "libc/sysv/errfuns.h"
/**
* Copies path for Windows NT.
*
* This entails (1) UTF-8 to UTF-16 conversion; (2) replacing
* forward-slashes with backslashes; and (3) remapping several
* well-known paths (e.g. /dev/null → NUL) for convenience.
*
* @param path16 is shortened so caller can prefix, e.g. \\.\pipe\, and
* due to a plethora of special-cases throughout the Win32 API
* @param flags is used by open(), see fixntmagicpath2()
* @return short count excluding NUL on success, or -1 w/ errno
* @error ENAMETOOLONG
*/
forcealignargpointer textwindows int(mkntpath)(
const char *path, unsigned flags,
char16_t path16[hasatleast PATH_MAX - 16]) {
/*
* 1. Reserve +1 for NUL-terminator
* 2. Reserve +1 for UTF-16 overflow
* 3. Reserve ≥2 for SetCurrentDirectory trailing slash requirement
* 4. Reserve ≥10 for CreateNamedPipe "\\.\pipe\" prefix requirement
* 5. Reserve ≥13 for mkdir() i.e. 1+8+3+1, e.g. "\\ffffffff.xxx\0"
*/
int rc;
wint_t wc;
size_t i, j;
path = fixntmagicpath(path, flags);
i = 0;
j = 0;
for (;;) {
if ((rc = tpdecode(&path[i], &wc)) == -1) {
path16[0] = u'\0';
return -1;
}
if (!wc) break;
i += (size_t)rc;
if (wc == '/') wc = '\\';
if (j + 1 /* utf-16 */ + 1 /* chdir() */ + 1 /* NUL */ < PATH_MAX - 16) {
if ((rc = pututf16(&path16[j], 2, wc, false)) == -1) {
path16[0] = u'\0';
return -1;
}
j += (size_t)rc;
} else {
path16[0] = u'\0';
return enametoolong();
}
}
path16[j] = u'\0';
return j;
}