mirror of
https://github.com/jart/cosmopolitan.git
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e466dd0553
This change hardens the code for opening /zip/ files using the system call interface. Thread safety and signal safety has been improved for file descriptors in general. We now document fixed addresses that are needed for low level allocations.
102 lines
4 KiB
C
102 lines
4 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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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/calls/calls.h"
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#include "libc/calls/strace.internal.h"
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#include "libc/intrin/cmpxchg.h"
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#include "libc/intrin/pthread.h"
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#include "libc/macros.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/map.h"
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#include "libc/sysv/consts/o.h"
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#include "libc/sysv/consts/prot.h"
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#include "libc/zip.h"
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#include "libc/zipos/zipos.internal.h"
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static uint64_t __zipos_get_min_offset(const uint8_t *base,
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const uint8_t *cdir) {
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uint64_t i, n, c, r, o;
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c = GetZipCdirOffset(cdir);
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n = GetZipCdirRecords(cdir);
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for (r = c, i = 0; i < n; ++i, c += ZIP_CFILE_HDRSIZE(base + c)) {
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o = GetZipCfileOffset(base + c);
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if (o < r) r = o;
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}
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return r;
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}
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static void __zipos_munmap_unneeded(const uint8_t *base, const uint8_t *cdir,
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const uint8_t *map) {
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uint64_t n;
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n = __zipos_get_min_offset(base, cdir);
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n += base - map;
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n = ROUNDDOWN(n, FRAMESIZE);
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if (n) munmap(map, n);
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}
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/**
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* Returns pointer to zip central directory of current executable.
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* @asyncsignalsafe
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* @threadsafe
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*/
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struct Zipos *__zipos_get(void) {
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int fd;
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ssize_t size;
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const char *msg;
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static bool once;
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struct Zipos *res;
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const char *progpath;
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static struct Zipos zipos;
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uint8_t *map, *base, *cdir;
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if (!once) {
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__zipos_lock();
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progpath = GetProgramExecutableName();
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if ((fd = open(progpath, O_RDONLY)) != -1) {
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if ((size = getfiledescriptorsize(fd)) != -1ul &&
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(map = mmap(0, size, PROT_READ, MAP_SHARED, fd, 0)) != MAP_FAILED) {
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if ((base = FindEmbeddedApe(map, size))) {
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size -= base - map;
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} else {
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base = map;
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}
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if ((cdir = GetZipCdir(base, size)) && _cmpxchg(&zipos.map, 0, base)) {
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__zipos_munmap_unneeded(base, cdir, map);
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zipos.cdir = cdir;
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msg = "ok";
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} else {
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munmap(map, size);
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msg = "eocd not found";
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}
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} else {
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msg = "map failed";
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}
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close(fd);
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} else {
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msg = "open failed";
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}
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once = true;
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__zipos_unlock();
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STRACE("__zipos_get(%#s) → %s% m", progpath, msg);
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}
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if (zipos.cdir) {
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res = &zipos;
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} else {
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res = 0;
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}
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return res;
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}
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