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https://github.com/jart/cosmopolitan.git
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f4f4caab0e
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
69 lines
3.3 KiB
C
69 lines
3.3 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=8 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#ifndef COSMOPOLITAN_LIBC_DOSENVIRON_H_
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#define COSMOPOLITAN_LIBC_DOSENVIRON_H_
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#ifndef __STRICT_ANSI__
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#include "libc/bits/safemacros.h"
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#include "libc/str/appendchar.h"
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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/**
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* Transcodes NT environment variable block from UTF-16 to UTF-8.
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*
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* @param env is a double NUL-terminated block of key=values
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* @param buf is the new environment
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* @param size is the byte capacity of buf
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* @param envp stores NULL-terminated string pointer list
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* @param max is the pointer count capacity of envp
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* @return number of variables decoded, excluding NULL-terminator
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*/
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static inline int getdosenviron(const char16_t *env, char *buf, size_t size,
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char **envp, size_t max) {
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const char16_t *s = env;
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size_t envc = 0;
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if (size) {
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wint_t wc;
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char *p = buf;
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char *pe = buf + size - 1;
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if (p < pe) {
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s += getutf16(s, &wc);
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while (wc) {
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if (++envc < max) {
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envp[envc - 1] = p < pe ? p : NULL;
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}
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bool endstring;
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do {
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AppendChar(&p, pe, wc);
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endstring = !wc;
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s += getutf16(s, &wc);
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} while (!endstring);
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buf[min(p - buf, size - 2)] = u'\0';
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}
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}
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AppendChar(&p, pe, '\0');
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buf[min(p - buf, size - 1)] = u'\0';
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}
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if (max) envp[min(envc, max - 1)] = NULL;
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return envc;
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}
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* !ANSI */
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#endif /* COSMOPOLITAN_LIBC_DOSENVIRON_H_ */
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