bool ElfFile::load_tables() {
assert(m_file, "file not open");
assert(!NullDecoder::is_error(m_status), "already in error");
// read elf file header
if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
if (!is_elf_file(m_elfHdr)) {
m_status = NullDecoder::file_invalid;
return false;
}
// walk elf file's section headers, and load string tables
Elf_Shdr shdr;
if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
if (NullDecoder::is_error(m_status)) return false;
for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
// string table
if (shdr.sh_type == SHT_STRTAB) {
ElfStringTable* table = new (std::nothrow) ElfStringTable(m_file, shdr, index);
if (table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
add_string_table(table);
} else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr);
if (table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
add_symbol_table(table);
}
}
}
return true;
}
lib_info* add_lib_info_fd(struct ps_prochandle* ph, const char* libname, int fd, uintptr_t base) {
lib_info* newlib;
print_debug("add_lib_info_fd %s\n", libname);
if ( (newlib = (lib_info*) calloc(1, sizeof(struct lib_info))) == NULL) {
print_debug("can't allocate memory for lib_info\n");
return NULL;
}
strncpy(newlib->name, libname, sizeof(newlib->name));
newlib->base = base;
if (fd == -1) {
if ( (newlib->fd = pathmap_open(newlib->name)) < 0) {
print_debug("can't open shared object %s\n", newlib->name);
free(newlib);
return NULL;
}
} else {
newlib->fd = fd;
}
#ifdef __APPLE__
// check whether we have got an Macho file.
if (is_macho_file(newlib->fd) == false) {
close(newlib->fd);
free(newlib);
print_debug("not a mach-o file\n");
return NULL;
}
#else
// check whether we have got an ELF file. /proc/<pid>/map
// gives out all file mappings and not just shared objects
if (is_elf_file(newlib->fd) == false) {
close(newlib->fd);
free(newlib);
return NULL;
}
#endif // __APPLE__
newlib->symtab = build_symtab(newlib->fd);
if (newlib->symtab == NULL) {
print_debug("symbol table build failed for %s\n", newlib->name);
} else {
print_debug("built symbol table for %s\n", newlib->name);
}
// even if symbol table building fails, we add the lib_info.
// This is because we may need to read from the ELF file or MachO file for core file
// address read functionality. lookup_symbol checks for NULL symtab.
if (ph->libs) {
ph->lib_tail->next = newlib;
ph->lib_tail = newlib;
} else {
ph->libs = ph->lib_tail = newlib;
}
ph->num_libs++;
return newlib;
}
BOOL
ElfLoader::read_header()
{
// read ELF header
_file->read(&_eh, sizeof(Elf_Ehdr), 0);
// check ELF Magic.
if (!is_elf_file()) {
DPRINTF((TEXT("not a ELF file.\n")));
return FALSE;
}
// Windows CE is 32bit little-endian only.
if (_eh.e_ident[EI_DATA] != ELFDATA2LSB ||
_eh.e_ident[EI_CLASS] != ELFCLASS32) {
DPRINTF((TEXT("invalid class/data(%d/%d)\n"),
_eh.e_ident[EI_CLASS], _eh.e_ident[EI_DATA]));
return FALSE;
}
// Is native architecture?
switch(_eh.e_machine) {
ELF32_MACHDEP_ID_CASES;
default:
DPRINTF((TEXT("not a native architecture. machine = %d\n"),
_eh.e_machine));
return FALSE;
}
// Check object type
if (_eh.e_type != ET_EXEC) {
DPRINTF((TEXT("not a executable file. type = %d\n"),
_eh.e_type));
return FALSE;
}
if (_eh.e_phoff == 0 || _eh.e_phnum == 0 || _eh.e_phnum > 16 ||
_eh.e_phentsize != sizeof(Elf_Phdr)) {
DPRINTF((TEXT("invalid program header information.\n")));
return FALSE;
}
return TRUE;
}
bool ElfFile::load_tables() {
assert(m_file, "file not open");
assert(!NullDecoder::is_error(m_status), "already in error");
// read elf file header
if (fread(&m_elfHdr, sizeof(m_elfHdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
if (!is_elf_file(m_elfHdr)) {
m_status = NullDecoder::file_invalid;
return false;
}
// walk elf file's section headers, and load string tables
Elf_Shdr shdr;
if (!fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
if (NullDecoder::is_error(m_status)) return false;
for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
if (shdr.sh_type == SHT_STRTAB) {
// string tables
ElfStringTable* table = new (std::nothrow) ElfStringTable(m_file, shdr, index);
if (table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
add_string_table(table);
} else if (shdr.sh_type == SHT_SYMTAB || shdr.sh_type == SHT_DYNSYM) {
// symbol tables
ElfSymbolTable* table = new (std::nothrow) ElfSymbolTable(m_file, shdr);
if (table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
add_symbol_table(table);
}
}
#if defined(PPC64) && !defined(ABI_ELFv2)
// Now read the .opd section wich contains the PPC64 function descriptor table.
// The .opd section is only available on PPC64 (see for example:
// http://refspecs.linuxfoundation.org/LSB_3.1.1/LSB-Core-PPC64/LSB-Core-PPC64/specialsections.html)
// so this code should do no harm on other platforms but because of performance reasons we only
// execute it on PPC64 platforms.
// Notice that we can only find the .opd section after we have successfully read in the string
// tables in the previous loop, because we need to query the name of each section which is
// contained in one of the string tables (i.e. the one with the index m_elfHdr.e_shstrndx).
// Reset the file pointer
if (fseek(m_file, m_elfHdr.e_shoff, SEEK_SET)) {
m_status = NullDecoder::file_invalid;
return false;
}
for (int index = 0; index < m_elfHdr.e_shnum; index ++) {
if (fread((void*)&shdr, sizeof(Elf_Shdr), 1, m_file) != 1) {
m_status = NullDecoder::file_invalid;
return false;
}
if (m_elfHdr.e_shstrndx != SHN_UNDEF && shdr.sh_type == SHT_PROGBITS) {
ElfStringTable* string_table = get_string_table(m_elfHdr.e_shstrndx);
if (string_table == NULL) {
m_status = NullDecoder::file_invalid;
return false;
}
char buf[8]; // '8' is enough because we only want to read ".opd"
if (string_table->string_at(shdr.sh_name, buf, sizeof(buf)) && !strncmp(".opd", buf, 4)) {
m_funcDesc_table = new (std::nothrow) ElfFuncDescTable(m_file, shdr, index);
if (m_funcDesc_table == NULL) {
m_status = NullDecoder::out_of_memory;
return false;
}
break;
}
}
}
#endif
}
return true;
}
