C++ SymbolTable::FindSymbol方法代码示例

void *ResolveSymbol(void *handle, const char *symbol)
{
    struct link_map *dlmap;
    struct stat dlstat;
    int dlfile;
    uintptr_t map_base;
    Elf32_Ehdr *file_hdr;
    Elf32_Shdr *sections, *shstrtab_hdr, *symtab_hdr, *strtab_hdr;
    Elf32_Sym *symtab;
    const char *shstrtab, *strtab;
    uint16_t section_count;
    uint32_t symbol_count;
    LibSymbolTable *libtable;
    SymbolTable *table;
    Symbol *symbol_entry;

    dlmap = (struct link_map *)handle;
    symtab_hdr = NULL;
    strtab_hdr = NULL;
    table = NULL;

    /* See if we already have a symbol table for this library */
    for (size_t i = 0; i < m_SymTables.Count(); i++)
    {
        libtable = m_SymTables[i];
        if (libtable->lib_base == dlmap->l_addr)
        {
            table = &libtable->table;
            break;
        }
    }

    /* If we don't have a symbol table for this library, then create one */
    if (table == NULL)
    {
        libtable = new LibSymbolTable();
        libtable->table.Initialize();
        libtable->lib_base = dlmap->l_addr;
        libtable->last_pos = 0;
        table = &libtable->table;
        m_SymTables.AddToTail(libtable);
    }

    /* See if the symbol is already cached in our table */
    symbol_entry = table->FindSymbol(symbol, strlen(symbol));
    if (symbol_entry != NULL)
    {
        return symbol_entry->address;
    }

    /* If symbol isn't in our table, then we have open the actual library */
    dlfile = open(dlmap->l_name, O_RDONLY);
    if (dlfile == -1 || fstat(dlfile, &dlstat) == -1)
    {
        close(dlfile);
        return NULL;
    }

    /* Map library file into memory */
    file_hdr = (Elf32_Ehdr *)mmap(NULL, dlstat.st_size, PROT_READ, MAP_PRIVATE, dlfile, 0);
    map_base = (uintptr_t)file_hdr;
    if (file_hdr == MAP_FAILED)
    {
        close(dlfile);
        return NULL;
    }
    close(dlfile);

    if (file_hdr->e_shoff == 0 || file_hdr->e_shstrndx == SHN_UNDEF)
    {
        munmap(file_hdr, dlstat.st_size);
        return NULL;
    }

    sections = (Elf32_Shdr *)(map_base + file_hdr->e_shoff);
    section_count = file_hdr->e_shnum;
    /* Get ELF section header string table */
    shstrtab_hdr = &sections[file_hdr->e_shstrndx];
    shstrtab = (const char *)(map_base + shstrtab_hdr->sh_offset);

    /* Iterate sections while looking for ELF symbol table and string table */
    for (uint16_t i = 0; i < section_count; i++)
    {
        Elf32_Shdr &hdr = sections[i];
        const char *section_name = shstrtab + hdr.sh_name;

        if (strcmp(section_name, ".symtab") == 0)
        {
            symtab_hdr = &hdr;
        }
        else if (strcmp(section_name, ".strtab") == 0)
        {
            strtab_hdr = &hdr;
        }
    }

    /* Uh oh, we don't have a symbol table or a string table */
    if (symtab_hdr == NULL || strtab_hdr == NULL)
    {
        munmap(file_hdr, dlstat.st_size);
//.........这里部分代码省略.........

//.........这里部分代码省略.........
		
		dlclose(h);
	}
	
	if (!dlbase)
	{
		/* Uh oh, we couldn't find a matching handle */
		return NULL;
	}
	
	/* See if we already have a symbol table for this library */
	for (size_t i = 0; i < m_SymTables.size(); i++)
	{
		libtable = m_SymTables[i];
		if (libtable->lib_base == dlbase)
		{
			table = &libtable->table;
			break;
		}
	}
	
	/* If we don't have a symbol table for this library, then create one */
	if (table == NULL)
	{
		libtable = new LibSymbolTable();
		libtable->table.Initialize();
		libtable->lib_base = dlbase;
		libtable->last_pos = 0;
		table = &libtable->table;
		m_SymTables.push_back(libtable);
	}
	
	/* See if the symbol is already cached in our table */
	symbol_entry = table->FindSymbol(symbol, strlen(symbol));
	if (symbol_entry != NULL)
	{
		return symbol_entry->address;
	}
	
	/* If symbol isn't in our table, then we have to locate it in memory */
	
	file_hdr = (struct mach_header *)dlbase;
	loadcmds = (struct load_command *)(dlbase + sizeof(struct mach_header));
	loadcmd_count = file_hdr->ncmds;
	
	/* Loop through load commands until we find the ones for the symbol table */
	for (uint32_t i = 0; i < loadcmd_count; i++)
	{
		if (loadcmds->cmd == LC_SEGMENT && !linkedit_hdr)
		{
			struct segment_command *seg = (struct segment_command *)loadcmds;
			if (strcmp(seg->segname, "__LINKEDIT") == 0)
			{
				linkedit_hdr = seg;
				if (symtab_hdr)
				{
					break;
				}
			}
		}
		else if (loadcmds->cmd == LC_SYMTAB)
		{
			symtab_hdr = (struct symtab_command *)loadcmds;
			if (linkedit_hdr)
			{
				break;

void *MemoryUtils::ResolveSymbol(void *handle, const char *symbol)
{
#if defined(WIN32)

	return GetProcAddress((HMODULE)handle, symbol);
	
#elif defined(__linux__)

	void *address = dlsym(handle, symbol);
	
	if (address != NULL)
	{
		return address;
	}

	struct link_map *dlmap;
	struct stat dlstat;
	int dlfile;
	uintptr_t map_base;
	Elf32_Ehdr *file_hdr;
	Elf32_Shdr *sections, *shstrtab_hdr, *symtab_hdr, *strtab_hdr;
	Elf32_Sym *symtab;
	const char *shstrtab, *strtab;
	uint16_t section_count;
	uint32_t symbol_count;
	LibSymbolTable *libtable;
	SymbolTable *table;
	Symbol *symbol_entry;

	dlmap = (struct link_map *)handle;
	symtab_hdr = NULL;
	strtab_hdr = NULL;
	table = NULL;
	
	/* See if we already have a symbol table for this library */
	for (size_t i = 0; i < m_SymTables.length(); i++)
	{
		libtable = m_SymTables[i];
		if (libtable->lib_base == dlmap->l_addr)
		{
			table = &libtable->table;
			break;
		}
	}

	/* If we don't have a symbol table for this library, then create one */
	if (table == NULL)
	{
		libtable = new LibSymbolTable();
		libtable->table.Initialize();
		libtable->lib_base = dlmap->l_addr;
		libtable->last_pos = 0;
		table = &libtable->table;
		m_SymTables.append(libtable);
	}

	/* See if the symbol is already cached in our table */
	symbol_entry = table->FindSymbol(symbol, strlen(symbol));
	if (symbol_entry != NULL)
	{
		return symbol_entry->address;
	}

	/* If symbol isn't in our table, then we have open the actual library */
	dlfile = open(dlmap->l_name, O_RDONLY);
	if (dlfile == -1 || fstat(dlfile, &dlstat) == -1)
	{
		close(dlfile);
		return NULL;
	}

	/* Map library file into memory */
	file_hdr = (Elf32_Ehdr *)mmap(NULL, dlstat.st_size, PROT_READ, MAP_PRIVATE, dlfile, 0);
	map_base = (uintptr_t)file_hdr;
	if (file_hdr == MAP_FAILED)
	{
		close(dlfile);
		return NULL;
	}
	close(dlfile);

	if (file_hdr->e_shoff == 0 || file_hdr->e_shstrndx == SHN_UNDEF)
	{
		munmap(file_hdr, dlstat.st_size);
		return NULL;
	}

	sections = (Elf32_Shdr *)(map_base + file_hdr->e_shoff);
	section_count = file_hdr->e_shnum;
	/* Get ELF section header string table */
	shstrtab_hdr = &sections[file_hdr->e_shstrndx];
	shstrtab = (const char *)(map_base + shstrtab_hdr->sh_offset);

	/* Iterate sections while looking for ELF symbol table and string table */
	for (uint16_t i = 0; i < section_count; i++)
	{
		Elf32_Shdr &hdr = sections[i];
		const char *section_name = shstrtab + hdr.sh_name;

		if (strcmp(section_name, ".symtab") == 0)
//.........这里部分代码省略.........