C++ elf_version函数代码示例

int
nlist(const char *filename, struct nlist *nl) {
    int result = -1;
    unsigned oldver;
    Elf *elf;
    int fd;

    if ((oldver = elf_version(EV_CURRENT)) != EV_NONE) {
	if ((fd = open(filename, O_RDONLY)) != -1) {
	    if ((elf = elf_begin(fd, ELF_C_READ, NULL))) {
		result = _elf_nlist(elf, nl);
		elf_end(elf);
	    }
	    close(fd);
	}
	elf_version(oldver);
    }
    if (result) {
	while (nl->n_name && *nl->n_name) {
	    nl->n_value = 0;
	    nl++;
	}
    }
    return result;
}

int
pkg_analyse_files(struct pkgdb *db, struct pkg *pkg)
{
	struct pkg_file *file = NULL;
	int ret = EPKG_OK;
	const char *fpath;
	bool shlibs = false;
	bool autodeps = false;
	bool developer = false;
	int (*action)(void *, struct pkg *, const char *, const char *, bool);

	pkg_config_bool(PKG_CONFIG_SHLIBS, &shlibs);
	pkg_config_bool(PKG_CONFIG_AUTODEPS, &autodeps);
	pkg_config_bool(PKG_CONFIG_DEVELOPER_MODE, &developer);

	if (!autodeps && !shlibs && !developer)
		return (EPKG_OK);

	if (elf_version(EV_CURRENT) == EV_NONE)
		return (EPKG_FATAL);

	if (autodeps)
		action = test_depends;
	else if (shlibs)
		action = add_shlibs_to_pkg;
	else
		action = do_nothing;

	if (autodeps || shlibs) {
		shlib_list_init();

		ret = shlib_list_from_elf_hints(_PATH_ELF_HINTS);
		if (ret != EPKG_OK)
			goto cleanup;
	}

	/* Assume no architecture dependence, for contradiction */
	if (developer)
		pkg->flags &= ~(PKG_CONTAINS_ELF_OBJECTS |
				PKG_CONTAINS_STATIC_LIBS |
				PKG_CONTAINS_H_OR_LA);

	while (pkg_files(pkg, &file) == EPKG_OK) {
		fpath = pkg_file_path(file);
		ret = analyse_elf(pkg, fpath, action, db);
		if (developer) {
			if (ret != EPKG_OK && ret != EPKG_END)
				goto cleanup;
			analyse_fpath(pkg, fpath);
		}
	}

	ret = EPKG_OK;

cleanup:
	if (autodeps || shlibs)
		shlib_list_free();

	return (ret);
}

static Elf *
get_elf (const gchar *file,
         gint        *fd)
{
  Elf *elf;

  if (elf_version (EV_CURRENT) == EV_NONE )
    return NULL;

  *fd = g_open (file, O_RDONLY, 0);
  if (*fd < 0)
    return NULL;

  elf = elf_begin (*fd, ELF_C_READ, NULL);
  if (elf == NULL)
    {
      g_close (*fd, NULL);
      *fd = -1;
      return NULL;
    }

  if (elf_kind (elf) != ELF_K_ELF)
    {
      g_close (*fd, NULL);
      *fd = -1;
      return NULL;
    }

  return elf;
}

void
get_syms(char *filename, mod_info_t *mi)
{
	int		fd;
	Elf		*elf;

	if ((fd = open(filename, O_RDONLY)) == -1) {
		perror(filename);
		exit(ERR_SYSCALL);
	}

	if (elf_version(EV_CURRENT) == EV_NONE) {
		(void) fprintf(stderr, "%s: libelf out of date\n", cmdname);
		exit(ERR_ELF);
	}

	if ((elf = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
		(void) fprintf(stderr, "%s: elf_begin failed\n", cmdname);
		exit(ERR_ELF);
	}

	if (gelf_getclass(elf) != ELFCLASS64) {
		(void) fprintf(stderr, "%s: unsupported mon.out format for "
				    "this class of object\n", cmdname);
		exit(ERR_ELF);
	}

	mi->txt_origin = get_txtorigin(elf, filename);

	fetch_symtab(elf, filename, mi);
}

/*
 * get_elf_class - get the target executable elf class
 *                 i.e. ELFCLASS64 or ELFCLASS32.
 */
static int
get_elf_class(char *filename)
{
	int	elfclass = -1;
	int	elffd = get_executable(filename);
	Elf	*elf;
	size_t	size;
	char	*ident;
	GElf_Ehdr	ehdr;

	if (elffd < 0)
		return (elfclass);
	if (elf_version(EV_CURRENT) == EV_NONE) {
		(void) close(elffd);
		return (elfclass);
	}
	elf = elf_begin(elffd, ELF_C_READ, (Elf *) 0);
	/*
	 * verify information in file header
	 */
	if (gelf_getehdr(elf, &ehdr) == (GElf_Ehdr *) 0) {
		close(elffd);
		return (elfclass);
	}
	ident = elf_getident(elf, &size);
	if (ident[EI_CLASS] == ELFCLASS32)
		elfclass = ELFCLASS32;
	if (ident[EI_CLASS] == ELFCLASS64)
		elfclass = ELFCLASS64;
	close(elffd);
	return (elfclass);
}

/* Below code adapted from libelf tutorial example */
static u32 extract_functions_internal (const char *str, func_entry *func_list) {
    Elf *e;
    Elf_Kind ek;
    Elf_Scn *scn;
    Elf_Data *edata;
    u32 fd, i, symbol_count;
    GElf_Sym sym;
    GElf_Shdr shdr;
    u32 func_count = 0;

    if(elf_version(EV_CURRENT) == EV_NONE) {
        printf("Error initializing ELF: %s\n", elf_errmsg(-1));
        return -1;
    }

    if ((fd = open(str, O_RDONLY, 0)) < 0) {
        printf("Unable to open %s\n", str);
        return -1;
    }

    if ((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL) {
        printf("elf_begin failed: %s\n", elf_errmsg(-1));
    }

    ek = elf_kind(e);
    if(ek != ELF_K_ELF) {
        printf("not an ELF object");
    } else {
        scn = NULL;
        edata = NULL;
        while((scn = elf_nextscn(e, scn)) != NULL) {
            gelf_getshdr(scn, &shdr);
            if(shdr.sh_type == SHT_SYMTAB) {
                edata = elf_getdata(scn, edata);
                symbol_count = shdr.sh_size / shdr.sh_entsize;
                for(i = 0; i < symbol_count; i++) {
                    gelf_getsym(edata, i, &sym);
                    if(ELF32_ST_TYPE(sym.st_info) != STT_FUNC) {
                        check_for_end_marker(elf_strptr(e, shdr.sh_link, sym.st_name), sym.st_value);
                        continue;
                    }
                    if(sym.st_size == 0) continue;

                    func_list[func_count].offset = sym.st_value;
                    func_list[func_count++].func_name = strdup(elf_strptr(e, shdr.sh_link, sym.st_name));

                    if(func_count >= MAXFNS) {
                        printf("Func limit (%"PRId32") reached, please increase MAXFNS & rebuild\n", MAXFNS);
                        raise(SIGABRT);
                    }
                    //                    printf("%08x %08x\t%s\n", sym.st_value, sym.st_size, elf_strptr(e, shdr.sh_link, sym.st_name));
                }
            }
        }
    }

    elf_end(e);
    close(fd);
    return func_count;
}

int
pkg_register_shlibs(struct pkg *pkg)
{
	struct pkg_file        *file = NULL;
	bool			shlibs;

	pkg_config_bool(PKG_CONFIG_SHLIBS, &shlibs);

	pkg_list_free(pkg, PKG_SHLIBS_REQUIRED);

	if (!shlibs)
		return (EPKG_OK);

	if (elf_version(EV_CURRENT) == EV_NONE)
		return (EPKG_FATAL);

	shlib_list_init();
	if (shlib_list_from_elf_hints(_PATH_ELF_HINTS) != EPKG_OK) {
		shlib_list_free();
		return (EPKG_FATAL);
	}

	while(pkg_files(pkg, &file) == EPKG_OK)
		analyse_elf(pkg, pkg_file_path(file), add_shlibs_to_pkg, NULL);

	shlib_list_free();
	return (EPKG_OK);
}

int exec_open( NAME_LIST *fnames, Elf32_Half machine,
               int code_size, int data_size )
{
    if (!fnames)
    {
        yyerror("No output file specified");
    }
    else if (fnames->next)
    {
        yyerror("Multiple output files specified");
    }
    else if (elf_version(EV_CURRENT) == EV_NONE)
    {
        yyerror( "Elf library is out of date" );
    }
    else
    {
        outfile_init( fnames->name, machine, TRUE,
                      code_size, data_size );
        out_file_machine = machine;
        out_file_name = strdup( fnames->name );
        if ( !fixup_code_map( machine, &fixup_code ) )
        {
            yyerror( "Relocations for this machine type are not supported" );
            return FALSE;
        }
        return TRUE;
    }
    return FALSE;
}

bool ElfWriter::initElfHeader() {
  if (elf_version(EV_CURRENT) == EV_NONE) {
    logError("ELF library initialization failed");
    return false;
  }

  m_elf = elf_begin(m_fd, ELF_C_WRITE, 0);
  if (!m_elf) {
    logError("Unable to create elf with elf_begin()");
    return false;
  }

  m_ehdr = elf64_newehdr(m_elf);
  if (!m_ehdr) {
    logError("Unable to create elf header with elf64_newehdr()");
    return false;
  }

  m_ehdr->e_ident[EI_MAG0] = ELFMAG0;
  m_ehdr->e_ident[EI_MAG1] = ELFMAG1;
  m_ehdr->e_ident[EI_MAG2] = ELFMAG2;
  m_ehdr->e_ident[EI_MAG3] = ELFMAG3;
  m_ehdr->e_ident[EI_CLASS] = ELFCLASS64;
  m_ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
  m_ehdr->e_ident[EI_VERSION] = EV_CURRENT;
  m_ehdr->e_machine = EM_X86_64;
  m_ehdr->e_type = ET_EXEC;
  m_ehdr->e_version = EV_CURRENT;

  return true;
}

static struct bpf_object *
__bpf_object__open(const char *path, void *obj_buf, size_t obj_buf_sz)
{
	struct bpf_object *obj;
	int err;

	if (elf_version(EV_CURRENT) == EV_NONE) {
		pr_warning("failed to init libelf for %s\n", path);
		return ERR_PTR(-LIBBPF_ERRNO__LIBELF);
	}

	obj = bpf_object__new(path, obj_buf, obj_buf_sz);
	if (IS_ERR(obj))
		return obj;

	CHECK_ERR(bpf_object__elf_init(obj), err, out);
	CHECK_ERR(bpf_object__check_endianness(obj), err, out);
	CHECK_ERR(bpf_object__elf_collect(obj), err, out);
	CHECK_ERR(bpf_object__collect_reloc(obj), err, out);
	CHECK_ERR(bpf_object__validate(obj), err, out);

	bpf_object__elf_finish(obj);
	return obj;
out:
	bpf_object__close(obj);
	return ERR_PTR(err);
}

static int perf_session__list_build_ids(void)
{
	struct perf_session *session;

	elf_version(EV_CURRENT);

	session = perf_session__new(input_name, O_RDONLY, force, false,
				    &build_id__mark_dso_hit_ops);
	if (session == NULL)
		return -1;

	/*
	 * See if this is an ELF file first:
	 */
	if (filename__fprintf_build_id(session->filename, stdout))
		goto out;

	if (with_hits)
		perf_session__process_events(session, &build_id__mark_dso_hit_ops);

	perf_session__fprintf_dsos_buildid(session, stdout, with_hits);
out:
	perf_session__delete(session);
	return 0;
}

std::string get_embedded_repo() {
  GElf_Shdr shdr;
  size_t shstrndx;
  char *name;
  Elf_Scn *scn;

  if (elf_version(EV_CURRENT) == EV_NONE) return "";

  int fd = open("/proc/self/exe", O_RDONLY, 0);
  if (fd < 0) return "";
  Elf* e = elf_begin(fd, ELF_C_READ, nullptr);

  if (!e ||
      elf_kind(e) != ELF_K_ELF ||
      !elf_getshstrndx(e, &shstrndx)) {
    return "";
  }
  scn = nullptr;
  while ((scn = elf_nextscn(e, scn)) != nullptr) {
    if (gelf_getshdr(scn, &shdr) != &shdr ||
        !(name = elf_strptr(e, shstrndx , shdr.sh_name))) {
      return "";
    }
    if (!strcmp("repo", name)) {
      GElf_Shdr ghdr;
      if (gelf_getshdr(scn, &ghdr) != &ghdr) return "";
      char buf[512];
      sprintf(buf, "/proc/self/exe:%lu:%lu", ghdr.sh_offset, ghdr.sh_size);
      sqlite3_embedded_initialize(nullptr, true);
      return buf;
    }
  }
  return "";
}

int binary_diff(int fd1, int fd2, char *sections, int verbose) {
  Elf *elf1, *elf2;
  Elf_Kind kind1, kind2;

  if (elf_version(EV_CURRENT) == EV_NONE) {
    if (verbose) fprintf(stderr, "elfdiff: ELF Version mismatch\n");
    return ED_ELFFAIL;
  }

  if ((elf1 = elf_begin(fd1, ELF_C_READ, NULL)) != NULL) {
    kind1 = elf_kind(elf1);
    elf_end(elf1);
  } else {
    if (verbose) fprintf(stderr, "elfdiff: Error reading ELF information from first input file.\n");  
    return ED_NOELF1;
  }

  if ((elf2 = elf_begin(fd2, ELF_C_READ, NULL)) != NULL) {
    kind2 = elf_kind(elf2);
    elf_end(elf2);
  } else {
    if (verbose) fprintf(stderr, "elfdiff: Error reading ELF information from second input file.\n");  
    return ED_NOELF2;
  }

  if ((kind1 == ELF_K_ELF) && (kind2 == ELF_K_ELF)){ 
    return elf_diff (fd1, fd2, sections, verbose);
  } else if ((kind1 == ELF_K_AR) && (kind2 == ELF_K_AR)) {
    return ar_diff (fd1, fd2, sections, verbose);
  } else {
    if (verbose) fprintf(stderr, "elfdiff: The specified files are not of matching/supported types.\n");
    return ED_ELFFAIL;
  }
}

int ELF_initial(char *input_file){
    if(elf_version(EV_CURRENT) == EV_NONE){
        fprintf(stderr, "ELF library initialization failed: %s.\n",
                elf_errmsg(-1));
        exit(1);
    }
    if((fd = open(input_file, O_RDONLY, 0)) < 0){
        fprintf(stderr, "Open \"%s\" failed.\n", input_file);
        exit(1);
    }
    if((e = elf_begin(fd, ELF_C_READ, NULL)) == NULL){
        fprintf(stderr, "elf_begin() failed: %s.\n", elf_errmsg(-1));
        exit(1);
    }
    if(elf_kind(e) != ELF_K_ELF){
        fprintf(stderr, "\"%s\" is not an ELF object.\n", input_file);
        exit(1);
    }
    if(gelf_getehdr(e, &ehdr) == NULL){
        fprintf(stderr, "getehdr() failed: %s.\n",
                elf_errmsg(-1));
        exit(1);
    }
    if(ehdr.e_flags != 2){
        fprintf(stderr, "\"%s\" is not an execution file.\n", input_file);
        exit(1);
    }

    phdr_index = 0;

    // printf("Entry point: 0x%jx\n", ehdr.e_entry);
    // printf("Flags: %d\n", ehdr.e_flags);
    return 0;
}

int find_symbol(char *fn, struct lsym *lsym, unsigned long baseaddr)
{
	struct lsym *ls;
	int num = 0;
	for (ls = lsym; ls->name; ls++)
		num++;

	elf_version(EV_CURRENT);
	int fd = open(fn, O_RDONLY);
	if (fd < 0)
		return -1;

	long ret = -1;
	Elf *elf = elf_begin(fd, ELF_C_READ, NULL);
	if (elf == NULL)
		goto out;

	GElf_Ehdr header;
	if (!gelf_getehdr(elf, &header))
		goto out_elf;

	Elf_Scn *section = NULL;
	int found = 0;
	while (found < num && (section = elf_nextscn(elf, section)) != 0) {
		GElf_Shdr shdr, *sh;
		sh = gelf_getshdr(section, &shdr);

		if (sh->sh_type == SHT_SYMTAB || sh->sh_type == SHT_DYNSYM) {
			Elf_Data *data = elf_getdata(section, NULL);
			GElf_Sym *sym, symbol;
			int j;

			unsigned numsym = sh->sh_size / sh->sh_entsize;
			for (j = 0; j < numsym; j++) {
				sym = gelf_getsymshndx(data, NULL, j, &symbol, NULL);
				char *symname = elf_strptr(elf, shdr.sh_link, sym->st_name);
				for (ls = lsym; ls->name; ls++) {
					if (!strcmp(symname, ls->name)) {
						Elf_Scn *oscn = elf_getscn(elf, sym->st_shndx);
						GElf_Shdr oshdr, *osh;
						osh = gelf_getshdr(oscn, &oshdr);
						ls->addr = (sym->st_value - osh->sh_addr) + osh->sh_offset + baseaddr;
						found++;
						if (found == num)
							break;
					}
				}
			}
		}
	}
	if (found == num)
		ret = 0;

out_elf:
	elf_end(elf);

out:
	close(fd);
	return ret;
}