mirror of
https://github.com/jart/cosmopolitan.git
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95 lines
4.1 KiB
C
95 lines
4.1 KiB
C
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/*-*- 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 2022 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/bits/bits.h"
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#include "libc/calls/calls.h"
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#include "libc/calls/internal.h"
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#include "libc/elf/scalar.h"
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#include "libc/elf/struct/ehdr.h"
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#include "libc/elf/struct/shdr.h"
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#include "libc/elf/struct/sym.h"
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#include "libc/log/libfatal.internal.h"
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#include "libc/runtime/runtime.h"
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#include "libc/sysv/consts/auxv.h"
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#define LAZY_RHEL7_RELOCATION 0xfffff
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#define GetStr(tab, rva) ((char *)(tab) + (rva))
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#define GetSection(e, s) ((void *)((intptr_t)(e) + (size_t)(s)->sh_offset))
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#define GetShstrtab(e) GetSection(e, GetShdr(e, (e)->e_shstrndx))
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#define GetSectionName(e, s) GetStr(GetShstrtab(e), (s)->sh_name)
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#define GetPhdr(e, i) \
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((Elf64_Phdr *)((intptr_t)(e) + (e)->e_phoff + \
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(size_t)(e)->e_phentsize * (i)))
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#define GetShdr(e, i) \
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((Elf64_Shdr *)((intptr_t)(e) + (e)->e_shoff + \
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(size_t)(e)->e_shentsize * (i)))
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static char *GetDynamicStringTable(Elf64_Ehdr *e, size_t *n) {
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char *name;
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Elf64_Half i;
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Elf64_Shdr *shdr;
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for (i = 0; i < e->e_shnum; ++i) {
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shdr = GetShdr(e, i);
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name = GetSectionName(e, GetShdr(e, i));
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if (shdr->sh_type == SHT_STRTAB) {
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name = GetSectionName(e, GetShdr(e, i));
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if (name && READ64LE(name) == READ64LE(".dynstr")) {
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if (n) *n = shdr->sh_size;
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return GetSection(e, shdr);
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}
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}
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}
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return 0;
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}
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static Elf64_Sym *GetDynamicSymbolTable(Elf64_Ehdr *e, Elf64_Xword *n) {
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Elf64_Half i;
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Elf64_Shdr *shdr;
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for (i = e->e_shnum; i > 0; --i) {
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shdr = GetShdr(e, i - 1);
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if (shdr->sh_type == SHT_DYNSYM) {
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if (shdr->sh_entsize != sizeof(Elf64_Sym)) continue;
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if (n) *n = shdr->sh_size / shdr->sh_entsize;
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return GetSection(e, shdr);
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}
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}
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return 0;
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}
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/**
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* Returns Linux Kernel Virtual Dynamic Shared Object function address.
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*/
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void *__vdsofunc(const char *name) {
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size_t m;
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char *names;
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Elf64_Ehdr *ehdr;
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Elf64_Xword i, n;
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Elf64_Sym *symtab, *sym;
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if ((ehdr = (Elf64_Ehdr *)getauxval(AT_SYSINFO_EHDR)) &&
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(names = GetDynamicStringTable(ehdr, &m)) &&
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(symtab = GetDynamicSymbolTable(ehdr, &n))) {
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for (i = 0; i < n; ++i) {
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if (!__strcmp(names + symtab[i].st_name, name)) {
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return (char *)ehdr + (symtab[i].st_value & LAZY_RHEL7_RELOCATION);
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}
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}
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}
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return 0;
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}
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