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
97 lines
4.5 KiB
C
97 lines
4.5 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=2 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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#include "libc/bits/safemacros.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/hefty/spawn.h"
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#include "libc/fmt/fmt.h"
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#include "libc/log/gdb.h"
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#include "libc/log/log.h"
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#include "libc/nexgen32e/vendor.h"
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#include "libc/paths.h"
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#include "libc/runtime/runtime.h"
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#include "libc/runtime/symbols.h"
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#include "libc/stdio/stdio.h"
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#include "libc/sysv/consts/fileno.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/w.h"
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/**
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* Launches GDB debugger GUI for current process.
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*
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* This function abstracts the toilsome details of configuring the best
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* possible UX for debugging your app, for varying levels of available
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* information, on most of the various platforms.
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*
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* Before calling this function, consider placing showcrashreports() in
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* your main function and calling DebugBreak() wherever you want; it's
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* safer. Also note the "GDB" environment variable can be set to empty
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* string, as a fail-safe for disabling this behavior.
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*
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* @param continuetoaddr can be a code address, 0, or -1 for auto
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* @return gdb pid if continuing, 0 if detached, or -1 w/ errno
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* @note this is called via eponymous spinlock macro wrapper
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*/
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relegated int(attachdebugger)(intptr_t continuetoaddr) {
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int ttyin, ttyout;
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struct StackFrame *bp;
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char pidstr[11], breakcmd[40];
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const char *se, *elf, *gdb, *rewind, *layout;
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if (IsGenuineCosmo() || !(gdb = GetGdbPath()) ||
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(ttyin = ttyout = open(_PATH_TTY, O_RDWR, 0)) == -1) {
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return -1;
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}
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snprintf(pidstr, sizeof(pidstr), "%u", getpid());
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layout = "layout asm";
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if ((elf = finddebugbinary())) {
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se = "-se";
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if (fileexists(__FILE__)) layout = "layout src";
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} else {
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se = "-q";
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elf = "-q";
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}
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if (continuetoaddr) {
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if (continuetoaddr == -1) {
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bp = __builtin_frame_address(0);
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continuetoaddr = bp->addr;
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}
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rewind = "-ex";
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snprintf(breakcmd, sizeof(breakcmd), "%s *%#p", "break", continuetoaddr);
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} else {
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rewind = NULL;
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breakcmd[0] = '\0';
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}
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return spawnve(0, (int[3]){ttyin, ttyout, STDERR_FILENO}, gdb,
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(char *const[]){
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"gdb", "--tui",
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"-p", pidstr,
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se, elf,
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"-ex", "set osabi GNU/Linux",
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"-ex", "set complaints 0",
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"-ex", "set confirm off",
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"-ex", layout,
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"-ex", "layout reg",
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"-ex", "set var g_gdbsync = 1",
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"-q", rewind,
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breakcmd, "-ex",
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"c", NULL,
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},
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environ);
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}
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