mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-07-07 03:38:31 +00:00
Invent tool for renaming ELF object symbols
This commit is contained in:
Justine Tunney
parent
5fd7b07fac
commit
3bf95ae7ec
2 changed files with 370 additions and 58 deletions
341
tool/build/resymbol.c
Normal file
341
tool/build/resymbol.c
Normal file
|
|
@ -0,0 +1,341 @@
|
|||
// Copyright 2024 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/calls/calls.h"
|
||||
#include "libc/elf/def.h"
|
||||
#include "libc/elf/scalar.h"
|
||||
#include "libc/elf/struct/ehdr.h"
|
||||
#include "libc/elf/struct/shdr.h"
|
||||
#include "libc/elf/struct/sym.h"
|
||||
#include "libc/errno.h"
|
||||
#include "libc/runtime/runtime.h"
|
||||
#include "libc/serialize.h"
|
||||
#include "libc/stdio/sysparam.h"
|
||||
#include "libc/str/str.h"
|
||||
#include "libc/sysv/consts/o.h"
|
||||
#include "third_party/getopt/getopt.internal.h"
|
||||
|
||||
bool FLAG_quiet;
|
||||
const char *FLAG_prefix;
|
||||
const char *FLAG_suffix;
|
||||
const char *path;
|
||||
|
||||
wontreturn void PrintUsage(int fd, int exitcode) {
|
||||
tinyprint(fd, "\n\
|
||||
NAME\n\
|
||||
\n\
|
||||
Cosmopolitan Symbol Renamer\n\
|
||||
\n\
|
||||
SYNOPSIS\n\
|
||||
\n\
|
||||
",
|
||||
path, " -s SUFFIX OBJECT...\n\
|
||||
\n\
|
||||
DESCRIPTION\n\
|
||||
\n\
|
||||
This program rewrites ELF objects (i.e. foo.o files) so that an\n\
|
||||
arbitrary string is appended to each public symbol's name.\n\
|
||||
\n\
|
||||
FLAGS\n\
|
||||
\n\
|
||||
-h show help\n\
|
||||
-q quiet mode\n\
|
||||
-p PREFIX specifies symbol prefix\n\
|
||||
-s SUFFIX specifies symbol suffix\n\
|
||||
\n\
|
||||
",
|
||||
NULL);
|
||||
exit(exitcode);
|
||||
}
|
||||
|
||||
wontreturn void Die(const char *reason) {
|
||||
tinyprint(2, path, ": ", reason, "\n", NULL);
|
||||
exit(1);
|
||||
}
|
||||
|
||||
wontreturn void DieSys(const char *func) {
|
||||
tinyprint(2, path, ": ", func, " failed with ", strerror(errno), "\n", NULL);
|
||||
exit(1);
|
||||
}
|
||||
|
||||
wontreturn void DieOom(void) {
|
||||
Die("out of memory");
|
||||
}
|
||||
|
||||
struct {
|
||||
char *last;
|
||||
size_t used;
|
||||
union {
|
||||
char memory[1024 * 1024 * 1024];
|
||||
size_t align;
|
||||
};
|
||||
} heap;
|
||||
|
||||
void *Malloc(size_t need) {
|
||||
if (need <= sizeof(heap.memory)) {
|
||||
int align = sizeof(size_t);
|
||||
size_t base = heap.used;
|
||||
base += align - 1;
|
||||
base &= -align;
|
||||
size_t toto = base + sizeof(size_t) + need;
|
||||
if (toto >= heap.used && toto <= sizeof(heap.memory)) {
|
||||
char *res = heap.memory + base;
|
||||
*(size_t *)res = need;
|
||||
heap.used = toto;
|
||||
return res + sizeof(size_t);
|
||||
}
|
||||
}
|
||||
DieOom();
|
||||
}
|
||||
|
||||
void *Realloc(void *ptr, size_t need) {
|
||||
if (ptr == heap.last) {
|
||||
heap.used = (char *)ptr - heap.memory;
|
||||
return Malloc(need);
|
||||
} else {
|
||||
void *res = Malloc(need);
|
||||
size_t size = *(size_t *)((char *)ptr - sizeof(size_t));
|
||||
memcpy(res, ptr, MIN(need, size));
|
||||
return res;
|
||||
}
|
||||
}
|
||||
|
||||
void ProcessFile(void) {
|
||||
|
||||
// open file
|
||||
int fildes;
|
||||
if ((fildes = open(path, O_RDWR)) == -1)
|
||||
DieSys("open");
|
||||
|
||||
// read elf header
|
||||
ssize_t got;
|
||||
Elf64_Ehdr ehdr;
|
||||
if ((got = pread(fildes, &ehdr, sizeof(ehdr), 0)) == -1)
|
||||
DieSys("pread");
|
||||
if (got != sizeof(ehdr))
|
||||
DieSys("file too small");
|
||||
if (READ32LE(ehdr.e_ident) != READ32LE(ELFMAG))
|
||||
DieSys("file doesn't have elf magic");
|
||||
if (ehdr.e_ident[EI_CLASS] == ELFCLASS32)
|
||||
DieSys("32-bit elf isn't supported");
|
||||
if (ehdr.e_shentsize != sizeof(Elf64_Shdr))
|
||||
Die("unsupported e_shentsize");
|
||||
if (!ehdr.e_shnum)
|
||||
Die("elf has no section headers");
|
||||
|
||||
// read elf section headers
|
||||
ssize_t need = ehdr.e_shnum * sizeof(Elf64_Shdr);
|
||||
Elf64_Shdr *shdrs = Malloc(need);
|
||||
if ((got = pread(fildes, shdrs, need, ehdr.e_shoff)) == -1)
|
||||
DieSys("pread");
|
||||
if (got != need)
|
||||
Die("found truncated elf section headers");
|
||||
|
||||
// find elf symbol table
|
||||
char *stab;
|
||||
Elf64_Xword stablen;
|
||||
Elf64_Sym *syms = 0;
|
||||
Elf64_Xword sym0 = 0;
|
||||
Elf64_Xword symcount = 0;
|
||||
Elf64_Off fixoff_symtab_offset = 0;
|
||||
Elf64_Off fixoff_strtab_offset = 0;
|
||||
Elf64_Off fixoff_strtab_size = 0;
|
||||
for (int i = 0; i < ehdr.e_shnum; ++i) {
|
||||
if (shdrs[i].sh_type == SHT_SYMTAB) {
|
||||
|
||||
// read elf symbol table
|
||||
if (!shdrs[i].sh_size)
|
||||
Die("elf symbol table empty");
|
||||
if (shdrs[i].sh_entsize != sizeof(Elf64_Sym))
|
||||
Die("unsupported sht_symtab sh_entsize");
|
||||
need = shdrs[i].sh_size;
|
||||
syms = Malloc(need);
|
||||
if ((got = pread(fildes, syms, need, shdrs[i].sh_offset)) == -1)
|
||||
DieSys("pread");
|
||||
if (got != need)
|
||||
Die("truncated elf symbol table");
|
||||
symcount = need / sizeof(Elf64_Sym);
|
||||
sym0 = shdrs[i].sh_info;
|
||||
|
||||
// read elf string table
|
||||
if (!(0 <= shdrs[i].sh_link && shdrs[i].sh_link < ehdr.e_shnum))
|
||||
Die("out of range section index");
|
||||
int j = shdrs[i].sh_link;
|
||||
if (shdrs[j].sh_type != SHT_STRTAB)
|
||||
Die("invalid string table reference");
|
||||
stablen = shdrs[j].sh_size;
|
||||
stab = Malloc(stablen + 1);
|
||||
stab[stablen] = 0;
|
||||
if ((got = pread(fildes, stab, stablen, shdrs[j].sh_offset)) == -1)
|
||||
DieSys("pread");
|
||||
if (got != stablen)
|
||||
Die("truncated elf symbol table");
|
||||
|
||||
// save file offsets of fields we're going to mutate later
|
||||
fixoff_symtab_offset = ehdr.e_shoff + i * sizeof(Elf64_Shdr) +
|
||||
offsetof(Elf64_Shdr, sh_offset);
|
||||
fixoff_strtab_offset = ehdr.e_shoff + j * sizeof(Elf64_Shdr) +
|
||||
offsetof(Elf64_Shdr, sh_offset);
|
||||
fixoff_strtab_size = (ehdr.e_shoff + j * sizeof(Elf64_Shdr) +
|
||||
offsetof(Elf64_Shdr, sh_size));
|
||||
break;
|
||||
}
|
||||
}
|
||||
if (!syms)
|
||||
Die("elf sht_symtab section not found");
|
||||
|
||||
// make better names for non-local symbols
|
||||
int renamed = 0;
|
||||
size_t prefixlen = strlen(FLAG_prefix);
|
||||
size_t suffixlen = strlen(FLAG_suffix);
|
||||
for (Elf64_Xword i = sym0; i < symcount; ++i) {
|
||||
if (syms[i].st_shndx == SHN_ABS)
|
||||
continue;
|
||||
if (syms[i].st_shndx == SHN_UNDEF)
|
||||
continue;
|
||||
if (syms[i].st_name >= stablen)
|
||||
Die("out of bounds symbol name");
|
||||
if (!strlen(stab + syms[i].st_name))
|
||||
Die("found function with empty string as its name");
|
||||
Elf64_Word name = syms[i].st_name;
|
||||
size_t namelen = strlen(stab + name);
|
||||
if (ELF64_ST_TYPE(syms[i].st_info) != STT_FUNC) {
|
||||
// resymbol is intended for compiling mathematical objects
|
||||
// multiple times, for all the cpu microarchitectures. any
|
||||
// global variables should be moved to a different object.
|
||||
const char *kind = "non-function symbol";
|
||||
if (ELF64_ST_TYPE(syms[i].st_info) == STT_OBJECT ||
|
||||
ELF64_ST_TYPE(syms[i].st_info) == STT_COMMON)
|
||||
kind = "global variable";
|
||||
else if (ELF64_ST_TYPE(syms[i].st_info) == STT_TLS)
|
||||
kind = "tls global variable";
|
||||
else if (ELF64_ST_TYPE(syms[i].st_info) == STT_GNU_IFUNC)
|
||||
kind = "ifunc or target_clones";
|
||||
tinyprint(2, path, ": resymbol won't rewrite object with ", kind, ": ",
|
||||
stab + name, "\n", NULL);
|
||||
exit(2);
|
||||
}
|
||||
size_t len = prefixlen + namelen + suffixlen;
|
||||
size_t newname = stablen;
|
||||
if (newname + len > 0x7fffffff)
|
||||
Die("elf string table too long");
|
||||
stablen += len + 1;
|
||||
stab = Realloc(stab, stablen);
|
||||
char *p = stab + newname;
|
||||
if (prefixlen)
|
||||
p = mempcpy(p, FLAG_prefix, prefixlen);
|
||||
p = mempcpy(p, stab + name, namelen);
|
||||
p = mempcpy(p, FLAG_suffix, suffixlen + 1);
|
||||
syms[i].st_name = newname;
|
||||
if (!FLAG_quiet)
|
||||
tinyprint(1, stab + name, " ", stab + newname, "\n", NULL);
|
||||
++renamed;
|
||||
}
|
||||
if (!renamed)
|
||||
Die("object doesn't have any non-local symbols");
|
||||
|
||||
// get size of object file
|
||||
ssize_t filesize;
|
||||
if ((filesize = lseek(fildes, 0, SEEK_END)) == -1)
|
||||
DieSys("lseek");
|
||||
|
||||
// write out new symbol table
|
||||
ssize_t wrote;
|
||||
Elf64_Off symtaboff = (filesize + 63) & -64;
|
||||
Elf64_Xword symtablen = symcount * sizeof(Elf64_Sym);
|
||||
if ((wrote = pwrite(fildes, syms, symtablen, symtaboff)) == -1)
|
||||
DieSys("pwrite");
|
||||
if (wrote != symtablen)
|
||||
Die("write truncated");
|
||||
filesize = symtaboff + symtablen;
|
||||
|
||||
// write out new string table
|
||||
Elf64_Off staboff = (filesize + 63) & -64;
|
||||
if ((wrote = pwrite(fildes, stab, stablen, staboff)) == -1)
|
||||
DieSys("pwrite");
|
||||
if (wrote != stablen)
|
||||
Die("write truncated");
|
||||
filesize = staboff + stablen;
|
||||
|
||||
// write new symbol table offset to elf section header
|
||||
if ((wrote = pwrite(fildes, &symtaboff, sizeof(symtaboff),
|
||||
fixoff_symtab_offset)) == -1)
|
||||
DieSys("pwrite");
|
||||
if (wrote != sizeof(symtaboff))
|
||||
Die("write truncated");
|
||||
|
||||
// write new string table offset to elf section header
|
||||
if ((wrote = pwrite(fildes, &staboff, sizeof(staboff),
|
||||
fixoff_strtab_offset)) == -1)
|
||||
DieSys("pwrite");
|
||||
if (wrote != sizeof(staboff))
|
||||
Die("write truncated");
|
||||
|
||||
// write new string table size to elf section header
|
||||
if ((wrote = pwrite(fildes, &stablen, sizeof(stablen), //
|
||||
fixoff_strtab_size)) == -1)
|
||||
DieSys("pwrite");
|
||||
if (wrote != sizeof(staboff))
|
||||
Die("write truncated");
|
||||
|
||||
// finish work
|
||||
if (close(fildes))
|
||||
DieSys("close");
|
||||
}
|
||||
|
||||
int main(int argc, char *argv[]) {
|
||||
|
||||
// get program name
|
||||
if (!(path = argv[0]))
|
||||
path = "resymbol";
|
||||
|
||||
// parse flags
|
||||
int opt;
|
||||
while ((opt = getopt(argc, argv, "p:s:qh")) != -1) {
|
||||
switch (opt) {
|
||||
case 'q':
|
||||
FLAG_quiet = true;
|
||||
break;
|
||||
case 'p':
|
||||
if (strchr(optarg, ' '))
|
||||
Die("symbols with space character unsupported");
|
||||
FLAG_prefix = optarg;
|
||||
break;
|
||||
case 's':
|
||||
if (strchr(optarg, ' '))
|
||||
Die("symbols with space character unsupported");
|
||||
FLAG_suffix = optarg;
|
||||
break;
|
||||
case 'h':
|
||||
PrintUsage(1, 0);
|
||||
default:
|
||||
PrintUsage(2, 1);
|
||||
}
|
||||
}
|
||||
if (optind == argc)
|
||||
Die("missing operand");
|
||||
if (!FLAG_prefix && !FLAG_suffix)
|
||||
Die("missing name mangling flag");
|
||||
if (!FLAG_prefix)
|
||||
FLAG_prefix = "";
|
||||
if (!FLAG_suffix)
|
||||
FLAG_suffix = "";
|
||||
|
||||
// process arguments
|
||||
for (int i = optind; i < argc; ++i) {
|
||||
path = argv[i];
|
||||
ProcessFile();
|
||||
}
|
||||
}
|
||||
Loading…
Add table
Add a link
Reference in a new issue