cosmopolitan/tool/decode/elf.c
Jōshin 6e6fc38935
Apply clang-format update to repo (#1154)
Commit bc6c183 introduced a bunch of discrepancies between what files
look like in the repo and what clang-format says they should look like.
However, there were already a few discrepancies prior to that. Most of
these discrepancies seemed to be unintentional, but a few of them were
load-bearing (e.g., a #include that violated header ordering needing
something to have been #defined by a 'later' #include.)

I opted to take what I hope is a relatively smooth-brained approach: I
reverted the .clang-format change, ran clang-format on the whole repo,
reapplied the .clang-format change, reran clang-format again, and then
reverted the commit that contained the first run. Thus the full effect
of this PR should only be to apply the changed formatting rules to the
repo, and from skimming the results, this seems to be the case.

My work can be checked by applying the short, manual commits, and then
rerunning the command listed in the autogenerated commits (those whose
messages I have prefixed auto:) and seeing if your results agree.

It might be that the other diffs should be fixed at some point but I'm
leaving that aside for now.

fd '\.c(c|pp)?$' --print0| xargs -0 clang-format -i
2024-04-25 10:38:00 -07:00

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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/elf/elf.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/stat.h"
#include "libc/elf/def.h"
#include "libc/elf/elf.h"
#include "libc/elf/struct/rela.h"
#include "libc/elf/struct/shdr.h"
#include "libc/errno.h"
#include "libc/fmt/conv.h"
#include "libc/fmt/libgen.h"
#include "libc/intrin/safemacros.internal.h"
#include "libc/log/check.h"
#include "libc/log/log.h"
#include "libc/macros.internal.h"
#include "libc/mem/gc.h"
#include "libc/mem/mem.h"
#include "libc/runtime/runtime.h"
#include "libc/serialize.h"
#include "libc/stdio/stdio.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/auxv.h"
#include "libc/sysv/consts/map.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/prot.h"
#include "libc/x/xasprintf.h"
#include "tool/decode/lib/asmcodegen.h"
#include "tool/decode/lib/elfidnames.h"
#include "tool/decode/lib/flagger.h"
#include "tool/decode/lib/titlegen.h"
/**
* @fileoverview ELF executable metadata disassembler.
*/
static const char *path;
static struct stat st[1];
static Elf64_Ehdr *elf;
static void startfile(void) {
showtitle("αcτµαlly pδrταblε εxεcµταblε", "tool/decode/elf",
basename(gc(strdup(path))), NULL, &kModelineAsm);
printf("#include \"libc/elf.h\"\n\n", path);
}
static void printelfehdr(void) {
show(".ascii", format(b1, "%`'.*s", 4, (const char *)&elf->e_ident[0]),
"magic");
show(".byte",
firstnonnull(findnamebyid(&kElfClassNames[0], elf->e_ident[EI_CLASS]),
format(b1, "%d", elf->e_ident[EI_CLASS])),
"elf->e_ident[EI_CLASS]");
show(".byte",
firstnonnull(findnamebyid(kElfDataNames, elf->e_ident[EI_DATA]),
format(b1, "%d", elf->e_ident[EI_DATA])),
"elf->e_ident[EI_DATA]");
show(".byte", format(b1, "%d", elf->e_ident[EI_VERSION]),
"elf->e_ident[EI_VERSION]");
show(".byte",
firstnonnull(findnamebyid(kElfOsabiNames, elf->e_ident[EI_OSABI]),
format(b1, "%d", elf->e_ident[EI_OSABI])),
"elf->e_ident[EI_OSABI]");
show(".byte", format(b1, "%d", elf->e_ident[EI_ABIVERSION]),
"elf->e_ident[EI_ABIVERSION]");
show(".byte",
format(b1, "%d,%d,%d,%d,%d,%d,%d", elf->e_ident[EI_PAD + 0],
elf->e_ident[EI_PAD + 1], elf->e_ident[EI_PAD + 2],
elf->e_ident[EI_PAD + 3], elf->e_ident[EI_PAD + 4],
elf->e_ident[EI_PAD + 5], elf->e_ident[EI_PAD + 6]),
"padding");
show(".org", "0x10", NULL);
show(".short",
firstnonnull(findnamebyid(kElfTypeNames, elf->e_type),
format(b1, "%hd", elf->e_type)),
"elf->e_type");
show(".short",
firstnonnull(findnamebyid(kElfMachineNames, elf->e_machine),
format(b1, "%hd", elf->e_machine)),
"elf->e_machine");
show(".long", format(b1, "%d", elf->e_version), "elf->e_version");
show(".quad", format(b1, "%#x", elf->e_entry), "elf->e_entry");
show(".quad", format(b1, "%#x", elf->e_phoff), "elf->e_phoff");
show(".quad", format(b1, "%#x", elf->e_shoff), "elf->e_shoff");
show(".long", format(b1, "%#x", elf->e_flags), "elf->e_flags");
show(".short", format(b1, "%hd", elf->e_ehsize), "elf->e_ehsize");
show(".short", format(b1, "%hd", elf->e_phentsize), "elf->e_phentsize");
show(".short", format(b1, "%hd", elf->e_phnum), "elf->e_phnum");
show(".short", format(b1, "%hd", elf->e_shentsize), "elf->e_shentsize");
show(".short", format(b1, "%hd", elf->e_shnum), "elf->e_shnum");
show(".short", format(b1, "%hd", elf->e_shstrndx), "elf->e_shstrndx");
}
static void printelfsegmentheader(int i) {
Elf64_Phdr *phdr = GetElfProgramHeaderAddress(elf, st->st_size, i);
if (!phdr)
return;
printf("/\tElf64_Phdr *phdr = GetElfProgramHeaderAddress(elf, st->st_size, "
"%d)\n",
i);
printf(".Lph%d:", i);
show(".long",
firstnonnull(findnamebyid(kElfSegmentTypeNames, phdr->p_type),
format(b1, "%#x", phdr->p_type)),
"phdr->p_type");
show(".long", RecreateFlags(kElfSegmentFlagNames, phdr->p_flags),
"phdr->p_flags");
show(".quad", format(b1, "%#x", phdr->p_offset), "phdr->p_offset");
show(".quad", format(b1, "%#x", phdr->p_vaddr), "phdr->p_vaddr");
show(".quad", format(b1, "%#x", phdr->p_paddr), "phdr->p_paddr");
show(".quad", format(b1, "%#x", phdr->p_filesz), "phdr->p_filesz");
show(".quad", format(b1, "%#x", phdr->p_memsz), "phdr->p_memsz");
show(".quad", format(b1, "%#x", phdr->p_align), "phdr->p_align");
fflush(stdout);
}
static void printelfsegmentheaders(void) {
printf("\n");
printf("\t.org\t%#x\n", elf->e_phoff);
for (unsigned i = 0; i < elf->e_phnum; ++i)
printelfsegmentheader(i);
}
static void printelfsectionheader(int i, char *shstrtab) {
Elf64_Shdr *shdr;
shdr = GetElfSectionHeaderAddress(elf, st->st_size, i);
if (!shdr)
return;
printf("/\tElf64_Shdr *shdr = GetElfSectionHeaderAddress(elf, st->st_size, "
"%d)\n",
i);
printf(".Lsh%d:", i);
show(".long", format(b1, "%d", shdr->sh_name),
format(b2,
"%`'s == GetElfString(elf, st->st_size, shstrtab, shdr->sh_name)",
GetElfString(elf, st->st_size, shstrtab, shdr->sh_name)));
show(".long",
firstnonnull(findnamebyid(kElfSectionTypeNames, shdr->sh_type),
format(b1, "%d", shdr->sh_type)),
"shdr->sh_type");
show(".long", RecreateFlags(kElfSectionFlagNames, shdr->sh_flags),
"shdr->sh_flags");
show(".quad", format(b1, "%#x", shdr->sh_addr), "shdr->sh_addr");
show(".quad", format(b1, "%#x", shdr->sh_offset), "shdr->sh_offset");
show(".quad", format(b1, "%#x", shdr->sh_size), "shdr->sh_size");
show(".long", format(b1, "%#x", shdr->sh_link), "shdr->sh_link");
show(".long", format(b1, "%#x", shdr->sh_info), "shdr->sh_info");
show(".quad", format(b1, "%#x", shdr->sh_addralign), "shdr->sh_addralign");
show(".quad", format(b1, "%#x", shdr->sh_entsize), "shdr->sh_entsize");
fflush(stdout);
}
static void printelfsectionheaders(void) {
Elf64_Half i;
char *shstrtab;
const char *str;
Elf64_Shdr *shdr, *shshdr;
shshdr = GetElfSectionHeaderAddress(elf, st->st_size, elf->e_shstrndx);
shstrtab = GetElfSectionNameStringTable(elf, st->st_size);
if (!shshdr || !shstrtab)
return;
if (shstrtab) {
printf("\n");
printf("\t.org\t%#x\n", elf->e_shoff);
for (i = 0; i < elf->e_shnum; ++i) {
printelfsectionheader(i, shstrtab);
}
printf("\n/\t%s\n", "elf->e_shstrndx");
printf("\t.org\t%#x\n", shshdr->sh_offset);
for (i = 0; i < elf->e_shnum; ++i) {
shdr = GetElfSectionHeaderAddress(elf, st->st_size, i);
if (!shdr)
break;
str = GetElfString(elf, st->st_size, shstrtab, shdr->sh_name);
show(".asciz", format(b1, "%`'s", str), NULL);
}
}
}
static void printelfgroups(void) {
for (int i = 0; i < elf->e_shnum; ++i) {
Elf64_Shdr *shdr = GetElfSectionHeaderAddress(elf, st->st_size, i);
if (!shdr)
break;
if (shdr->sh_type == SHT_GROUP) {
const Elf64_Shdr *symhdr =
GetElfSectionHeaderAddress(elf, st->st_size, shdr->sh_link);
if (!symhdr)
break;
const Elf64_Shdr *strhdr =
GetElfSectionHeaderAddress(elf, st->st_size, symhdr->sh_link);
if (!strhdr)
break;
Elf64_Sym *syms = GetElfSectionAddress(elf, st->st_size, symhdr);
if (!syms)
break;
char *strs = GetElfSectionAddress(elf, st->st_size, strhdr);
if (!strs)
break;
printf("\n");
printf("//\t%s group\n",
GetElfString(elf, st->st_size, strs, syms[shdr->sh_info].st_name));
printf("\t.org\t%#x\n", shdr->sh_offset);
bool first = true;
for (char *p = (char *)elf + shdr->sh_offset;
p < (char *)elf + shdr->sh_offset + shdr->sh_size; p += 4) {
if (first) {
first = false;
if (READ32LE(p) == GRP_COMDAT) {
printf("\t.long\tGRP_COMDAT\n");
continue;
}
}
const Elf64_Shdr *section =
GetElfSectionHeaderAddress(elf, st->st_size, READ32LE(p));
printf("\t.long\t%#x\t\t\t# %s\n", READ32LE(p),
section ? GetElfString(
elf, st->st_size,
GetElfSectionNameStringTable(elf, st->st_size),
section->sh_name)
: 0);
}
}
}
}
static void printelfsymbolinfo(Elf64_Sym *sym) {
int bind = (sym->st_info >> 4) & 0xf;
const char *bindname = findnamebyid(kElfSymbolBindNames, bind);
int type = (sym->st_info >> 0) & 0xf;
const char *typename = findnamebyid(kElfSymbolTypeNames, type);
show(".byte",
format(b1, "%s%s%s", bindname ? format(b2, "%s<<4", bindname) : "",
bindname && typename ? "|" : "", firstnonnull(typename, "")),
"sym->st_info");
}
static void printelfsymbolother(Elf64_Sym *sym) {
int visibility = sym->st_other & 0x3;
const char *visibilityname =
findnamebyid(kElfSymbolVisibilityNames, visibility);
int other = sym->st_other & ~0x3;
show(".byte",
format(b1, "%s%s%s", firstnonnull(visibilityname, ""),
other && visibilityname ? "+" : "",
other ? format(b2, "%d", other) : ""),
"sym->st_other");
}
static void printelfsymbol(Elf64_Sym *sym, char *strtab, char *shstrtab) {
show(".long", format(b1, "%d", sym->st_name),
format(b2, "%`'s (sym->st_name)",
GetElfString(elf, st->st_size, strtab, sym->st_name)));
printelfsymbolinfo(sym);
printelfsymbolother(sym);
Elf64_Shdr *shdr =
GetElfSectionHeaderAddress(elf, st->st_size, sym->st_shndx);
show(".short", format(b1, "%d", sym->st_shndx),
format(b2, "%s sym->st_shndx",
sym->st_shndx < 0xff00
? format(b1, "%`'s",
shdr ? GetElfString(elf, st->st_size, shstrtab,
shdr->sh_name)
: 0)
: findnamebyid(kElfSpecialSectionNames, sym->st_shndx)));
show(".quad", format(b1, "%#x", sym->st_value), "sym->st_value");
show(".quad", format(b1, "%#x", sym->st_size), "sym->st_size");
}
static void printelfsymboltable(void) {
size_t i, symcount = 0;
Elf64_Sym *symtab = GetElfSymbols(elf, st->st_size, SHT_SYMTAB, &symcount);
if (!symtab)
return;
char *strtab = GetElfStringTable(elf, st->st_size, ".strtab");
char *shstrtab = GetElfSectionNameStringTable(elf, st->st_size);
printf("\n\n");
printf("\t.org\t%#x\n", (intptr_t)symtab - (intptr_t)elf);
for (i = 0; i < symcount; ++i) {
printf(".Lsym%d:\n", i);
if (strtab && shstrtab) {
printelfsymbol(&symtab[i], strtab, shstrtab);
}
}
}
static void printelfdynsymboltable(void) {
size_t i, symcount = 0;
Elf64_Sym *symtab = GetElfSymbols(elf, st->st_size, SHT_DYNSYM, &symcount);
if (!symtab)
return;
char *strtab = GetElfStringTable(elf, st->st_size, ".dynstr");
char *shstrtab = GetElfSectionNameStringTable(elf, st->st_size);
printf("\n\n");
printf("\t.org\t%#x\n", (intptr_t)symtab - (intptr_t)elf);
for (i = 0; i < symcount; ++i) {
printf(".Lsym%d:\n", i);
if (strtab && shstrtab) {
printelfsymbol(&symtab[i], strtab, shstrtab);
}
}
}
static char *getelfsymbolname(const Elf64_Ehdr *elf, size_t mapsize,
const char *strtab, const char *shstrtab,
const Elf64_Sym *sym) {
char *res;
const Elf64_Shdr *shdr;
if (elf && sym &&
((shstrtab && !sym->st_name &&
ELF64_ST_TYPE(sym->st_info) == STT_SECTION &&
(shdr = GetElfSectionHeaderAddress(elf, mapsize, sym->st_shndx)) &&
(res = GetElfString(elf, mapsize, shstrtab, shdr->sh_name))) ||
(strtab && (res = GetElfString(elf, mapsize, strtab, sym->st_name))))) {
return res;
} else {
return NULL;
}
}
static void printelfrelocations(void) {
int sym;
size_t i, j, count;
const Elf64_Sym *syms;
const Elf64_Rela *rela;
char *strtab, *shstrtab, *symbolname;
const Elf64_Shdr *shdr, *shdr2, *symtab;
strtab = GetElfStringTable(elf, st->st_size, ".strtab");
shstrtab = GetElfSectionNameStringTable(elf, st->st_size);
for (i = 0; i < elf->e_shnum; ++i) {
if ((shdr = GetElfSectionHeaderAddress(elf, st->st_size, i)) &&
shdr->sh_type == SHT_RELA &&
(rela = GetElfSectionAddress(elf, st->st_size, shdr))) {
printf("\n/\t%s\n", GetElfSectionName(elf, st->st_size, shdr));
printf("\t.org\t%#x\n", (intptr_t)rela - (intptr_t)elf);
for (j = 0; ((uintptr_t)rela + sizeof(Elf64_Rela) <=
min((uintptr_t)elf + st->st_size,
(uintptr_t)elf + shdr->sh_offset + shdr->sh_size));
++rela, ++j) {
symtab = GetElfSectionHeaderAddress(elf, st->st_size, shdr->sh_link);
if (!symtab)
continue;
count = symtab->sh_size / symtab->sh_entsize;
syms = GetElfSectionAddress(elf, st->st_size, symtab);
sym = ELF64_R_SYM(rela->r_info);
if (0 <= sym && sym < count) {
if (syms && strtab && shstrtab) {
symbolname = getelfsymbolname(elf, st->st_size, strtab, shstrtab,
syms + sym);
} else {
symbolname = xasprintf("evil-sym-%d", sym);
}
} else {
symbolname = xasprintf("bad-sym-%d", sym);
}
printf("/\t%s+%#lx → %s%c%#lx\n",
(shdr2 =
GetElfSectionHeaderAddress(elf, st->st_size, shdr->sh_info))
? GetElfString(elf, st->st_size, shstrtab, shdr2->sh_name)
: 0,
rela->r_offset, symbolname, rela->r_addend >= 0 ? '+' : '-',
ABS(rela->r_addend));
printf("%s_%zu_%zu:\n", ".Lrela", i, j);
show(".quad", format(b1, "%#lx", rela->r_offset), "rela->r_offset");
show(".long",
format(b1, "%s%s", "R_X86_64_",
findnamebyid(kElfNexgen32eRelocationNames,
ELF64_R_TYPE(rela->r_info))),
"ELF64_R_TYPE(rela->r_info)");
show(".long", format(b1, "%d", ELF64_R_SYM(rela->r_info)),
"ELF64_R_SYM(rela->r_info)");
show(".quad", format(b1, "%#lx", rela->r_addend), "rela->r_addend");
}
}
}
}
int main(int argc, char *argv[]) {
int fd;
ShowCrashReports();
if (argc != 2) {
fprintf(stderr, "usage: %s FILE\n", argv[0]);
return 1;
}
path = argv[1];
fd = open(path, O_RDONLY);
if (fd == -1) {
if (errno == ENOENT) {
fprintf(stderr, "error: %`s not found\n", path);
exit(1);
}
perror("open");
exit(1);
}
fstat(fd, st);
CHECK_NE(MAP_FAILED,
(elf = mmap(NULL, st->st_size, PROT_READ, MAP_SHARED, fd, 0)));
if (memcmp(elf->e_ident, ELFMAG, 4) != 0) {
fprintf(stderr, "error: not an elf executable: %'s\n", path);
exit(1);
}
startfile();
printelfehdr();
printelfsegmentheaders();
printelfsectionheaders();
printelfgroups();
printelfrelocations();
printelfsymboltable();
printelfdynsymboltable();
munmap(elf, st->st_size);
close(fd);
return 0;
}