mirror of
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
292 lines
10 KiB
C
292 lines
10 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/weaken.h"
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#include "libc/conv/conv.h"
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#include "libc/fmt/fmt.h"
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#include "libc/mem/mem.h"
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#include "libc/runtime/runtime.h"
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#include "libc/str/str.h"
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#include "libc/str/tpdecodecb.h"
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#include "libc/sysv/errfuns.h"
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/**
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* String / file / stream decoder.
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*
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* This scanf implementation is able to tokenize strings containing
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* 8-bit through 128-bit integers (with validation), floating point
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* numbers, etc. It can also be used to convert UTF-8 to UTF-16/32.
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*
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* - `%d` parses integer
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* - `%ms` parses string allocating buffer assigning pointer
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*
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* @param callback supplies UTF-8 characters using -1 sentinel
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* @param fmt is a computer program embedded inside a c string, written
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* in a domain-specific programming language that, by design, lacks
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* Turing-completeness
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* @param va points to the variadic argument state
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* @see libc/fmt/pflink.h (dynamic memory is not a requirement)
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*/
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int vcscanf(int callback(void *), void *arg, const char *fmt, va_list va) {
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struct FreeMe {
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struct FreeMe *next;
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void *ptr;
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} *freeme = NULL;
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const unsigned char *p = (const unsigned char *)fmt;
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unsigned i = 0;
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int items = 0;
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int c = callback(arg);
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while (c != -1) {
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switch (p[i++]) {
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case '\0':
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return items;
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case ' ':
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case '\t':
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case '\n':
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case '\r':
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case '\v':
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while (isspace(c)) c = callback(arg);
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break;
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case '%': {
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uintmax_t number;
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void *buf;
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size_t bufsize;
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unsigned width = 0;
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unsigned char bits = 32;
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unsigned char charbytes = sizeof(char);
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unsigned char diglet;
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unsigned char base;
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unsigned char prefix;
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bool rawmode = false;
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bool issigned = false;
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bool ismalloc = false;
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bool isneg = false;
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bool thousands = false;
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bool discard = false;
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for (;;) {
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switch (p[i++]) {
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case '%': /* %% → % */
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goto NonDirectiveCharacter;
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case '0':
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case '1':
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case '2':
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case '3':
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case '4':
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case '5':
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case '6':
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case '7':
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case '8':
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case '9':
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width *= 10;
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width += p[i - 1] - '0';
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break;
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case '*':
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discard = true;
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break;
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case 'm':
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ismalloc = true;
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break;
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case 'c':
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rawmode = true;
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if (!width) width = 1;
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/* εpsilon transition */
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case 's':
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goto DecodeString;
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case '\'':
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thousands = true;
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break;
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case 'j': /* 128-bit */
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bits = sizeof(intmax_t) * 8;
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break;
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case 'l': /* long */
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case 'L': /* loooong */
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charbytes = sizeof(wchar_t);
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/* fallthrough */
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case 't': /* ptrdiff_t */
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case 'Z': /* size_t */
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case 'z': /* size_t */
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bits = 64;
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break;
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case 'h': /* short and char */
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charbytes = sizeof(char16_t);
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bits >>= 1;
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break;
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case 'b': /* binary */
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base = 2;
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prefix = 'b';
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goto ConsumeBasePrefix;
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case 'p': /* pointer (NexGen32e) */
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bits = 48;
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/* fallthrough */
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case 'x':
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case 'X': /* hexadecimal */
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base = 16;
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prefix = 'x';
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goto ConsumeBasePrefix;
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case 'o': /* octal */
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base = 8;
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goto DecodeNumber;
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case 'd': /* decimal */
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case 'n': /* TODO(jart): flexidecimal */
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issigned = true;
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if (c == '+' || (isneg = c == '-')) {
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c = callback(arg);
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}
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/* εpsilon transition */
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case 'u':
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base = 10;
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goto DecodeNumber;
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default:
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items = einval();
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goto Done;
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}
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}
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ConsumeBasePrefix:
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if (c == '0') {
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c = callback(arg);
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if (c == prefix || c == prefix + ('a' - 'A')) {
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c = callback(arg);
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}
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}
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DecodeNumber:
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if (c != -1) {
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number = 0;
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do {
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diglet = kBase36[(unsigned char)c];
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if (1 <= diglet && diglet <= base) {
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number *= base;
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number += diglet - 1;
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} else if (thousands && diglet == ',') {
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/* ignore */
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} else {
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break;
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}
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} while ((c = callback(arg)) != -1);
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if (!discard) {
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uintmax_t bane = (uintmax_t)1 << (bits - 1);
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if (!(number & ~((bane - 1) | (issigned ? 0 : bane))) ||
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(issigned && number == bane /* two's complement bane */)) {
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++items;
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} else {
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items = erange();
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goto Done;
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}
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if (issigned && isneg) {
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number = ~number + 1;
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}
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void *out = va_arg(va, void *);
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switch (bits) {
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case sizeof(uintmax_t) * CHAR_BIT:
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*(uintmax_t *)out = number;
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break;
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case 48:
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case 64:
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*(uint64_t *)out = (uint64_t)number;
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break;
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case 32:
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*(uint32_t *)out = (uint32_t)number;
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break;
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case 16:
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*(uint16_t *)out = (uint16_t)number;
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break;
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case 8:
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default:
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*(uint8_t *)out = (uint8_t)number;
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break;
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}
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}
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}
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continue;
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DecodeString:
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bufsize = !width ? 32 : rawmode ? width : width + 1;
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if (discard) {
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buf = NULL;
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} else if (ismalloc) {
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buf = weaken(malloc)(bufsize * charbytes);
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struct FreeMe *entry;
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if (buf && (entry = weaken(calloc)(1, sizeof(struct FreeMe)))) {
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entry->ptr = buf;
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entry->next = freeme;
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freeme = entry;
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}
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} else {
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buf = va_arg(va, void *);
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}
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if (buf) {
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size_t j = 0;
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for (;;) {
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if (ismalloc && !width && j + 2 + 1 >= bufsize &&
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!weaken(grow)(&buf, &bufsize, charbytes, 0)) {
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width = bufsize - 1;
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}
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if (c != -1 && j + !rawmode < bufsize && (rawmode || !isspace(c))) {
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if (charbytes == 1) {
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((unsigned char *)buf)[j++] = (unsigned char)c;
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c = callback(arg);
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} else if (tpdecodecb((wint_t *)&c, c, (void *)callback, arg) !=
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-1) {
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if (charbytes == sizeof(char16_t)) {
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j += abs(pututf16(&((char16_t *)buf)[j], bufsize - j - 1, c,
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false));
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} else {
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((wchar_t *)buf)[j++] = (wchar_t)c;
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}
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c = callback(arg);
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}
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} else {
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if (!rawmode && j < bufsize) {
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if (charbytes == sizeof(char)) {
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((unsigned char *)buf)[j] = '\0';
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} else if (charbytes == sizeof(char16_t)) {
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((char16_t *)buf)[j] = u'\0';
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} else if (charbytes == sizeof(wchar_t)) {
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((wchar_t *)buf)[j] = L'\0';
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}
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}
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break;
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}
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}
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++items;
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if (ismalloc) {
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*va_arg(va, char **) = buf;
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}
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} else {
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do {
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if (isspace(c)) break;
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} while ((c = callback(arg)) != -1);
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}
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break;
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}
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default:
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NonDirectiveCharacter:
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c = (c == p[i - 1]) ? callback(arg) : -1;
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break;
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}
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}
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Done:
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while (freeme) {
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struct FreeMe *entry = freeme;
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freeme = entry->next;
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if (items == -1) {
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weaken(free_s)((void **)&entry->ptr);
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}
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weaken(free_s)((void **)&entry);
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}
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return items;
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}
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