Alien-TinyCC

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src/tccelf.c  view on Meta::CPAN

            } else if (esym->st_shndx == SHN_COMMON
                    && (sh_num < SHN_LORESERVE || sh_num == SHN_COMMON)) {
                /* gr: Happens with 'tcc ... -static tcctest.c' on e.g. Ubuntu 6.01
                   No idea if this is the correct solution ... */
                goto do_patch;
            } else if (s == tcc_state->dynsymtab_section) {
                /* we accept that two DLL define the same symbol */
            } else {
#if 0
                printf("new_bind=%x new_shndx=%x new_vis=%x old_bind=%x old_shndx=%x old_vis=%x\n",
                       sym_bind, sh_num, new_vis, esym_bind, esym->st_shndx, esym_vis);
#endif
                tcc_error_noabort("'%s' defined twice", name);
            }
        } else {
        do_patch:
            esym->st_info = ELFW(ST_INFO)(sym_bind, sym_type);
            esym->st_shndx = sh_num;
            new_undef_sym = 1;
            esym->st_value = value;
            esym->st_size = size;
            esym->st_other = other;
        }
    } else {
    do_def:
        sym_index = put_elf_sym(s, value, size, 
                                ELFW(ST_INFO)(sym_bind, sym_type), other, 
                                sh_num, name);
    }
    return sym_index;
}

/* put relocation */
ST_FUNC void put_elf_reloc(Section *symtab, Section *s, unsigned long offset,
                          int type, int symbol)
{
    char buf[256];
    Section *sr;
    ElfW_Rel *rel;

    sr = s->reloc;
    if (!sr) {
        /* if no relocation section, create it */
        snprintf(buf, sizeof(buf), REL_SECTION_FMT, s->name);
        /* if the symtab is allocated, then we consider the relocation
           are also */
        sr = new_section(tcc_state, buf, SHT_RELX, symtab->sh_flags);
        sr->sh_entsize = sizeof(ElfW_Rel);
        sr->link = symtab;
        sr->sh_info = s->sh_num;
        s->reloc = sr;
    }
    rel = section_ptr_add(sr, sizeof(ElfW_Rel));
    rel->r_offset = offset;
    rel->r_info = ELFW(R_INFO)(symbol, type);
#ifdef TCC_TARGET_X86_64
    rel->r_addend = 0;
#endif
}

/* put stab debug information */

ST_FUNC void put_stabs(const char *str, int type, int other, int desc,
                      unsigned long value)
{
    Stab_Sym *sym;

    sym = section_ptr_add(stab_section, sizeof(Stab_Sym));
    if (str) {
        sym->n_strx = put_elf_str(stabstr_section, str);
    } else {
        sym->n_strx = 0;
    }
    sym->n_type = type;
    sym->n_other = other;
    sym->n_desc = desc;
    sym->n_value = value;
}

ST_FUNC void put_stabs_r(const char *str, int type, int other, int desc, 
                        unsigned long value, Section *sec, int sym_index)
{
    put_stabs(str, type, other, desc, value);
    put_elf_reloc(symtab_section, stab_section, 
                  stab_section->data_offset - sizeof(unsigned int),
                  R_DATA_32, sym_index);
}

ST_FUNC void put_stabn(int type, int other, int desc, int value)
{
    put_stabs(NULL, type, other, desc, value);
}

ST_FUNC void put_stabd(int type, int other, int desc)
{
    put_stabs(NULL, type, other, desc, 0);
}

/* In an ELF file symbol table, the local symbols must appear below
   the global and weak ones. Since TCC cannot sort it while generating
   the code, we must do it after. All the relocation tables are also
   modified to take into account the symbol table sorting */
static void sort_syms(TCCState *s1, Section *s)
{
    int *old_to_new_syms;
    ElfW(Sym) *new_syms;
    int nb_syms, i;
    ElfW(Sym) *p, *q;
    ElfW_Rel *rel, *rel_end;
    Section *sr;
    int type, sym_index;

    nb_syms = s->data_offset / sizeof(ElfW(Sym));
    new_syms = tcc_malloc(nb_syms * sizeof(ElfW(Sym)));
    old_to_new_syms = tcc_malloc(nb_syms * sizeof(int));

    /* first pass for local symbols */
    p = (ElfW(Sym) *)s->data;
    q = new_syms;
    for(i = 0; i < nb_syms; i++) {
        if (ELFW(ST_BIND)(p->st_info) == STB_LOCAL) {

src/tccelf.c  view on Meta::CPAN

            saved_dynamic_data_offset = dynamic->data_offset;
            dynamic->data_offset += sizeof(ElfW(Dyn)) * EXTRA_RELITEMS;
        } else {
            /* still need to build got entries in case of static link */
            build_got_entries(s1);
        }
    }

    memset(&ehdr, 0, sizeof(ehdr));

    /* we add a section for symbols */
    strsec = new_section(s1, ".shstrtab", SHT_STRTAB, 0);
    put_elf_str(strsec, "");
    
    /* compute number of sections */
    shnum = s1->nb_sections;

    /* this array is used to reorder sections in the output file */
    section_order = tcc_malloc(sizeof(int) * shnum);
    section_order[0] = 0;
    sh_order_index = 1;
    
    /* compute number of program headers */
    switch(file_type) {
    default:
    case TCC_OUTPUT_OBJ:
        phnum = 0;
        break;
    case TCC_OUTPUT_EXE:
        if (!s1->static_link)
            phnum = 4 + HAVE_PHDR;
        else
            phnum = 2;
        break;
    case TCC_OUTPUT_DLL:
        phnum = 3;
        break;
    }

    /* allocate strings for section names and decide if an unallocated
       section should be output */
    /* NOTE: the strsec section comes last, so its size is also
       correct ! */
    for(i = 1; i < s1->nb_sections; i++) {
        s = s1->sections[i];
        s->sh_name = put_elf_str(strsec, s->name);
#if 0 /* gr */
        printf("section: f=%08x t=%08x i=%08x %s %s\n", 
               s->sh_flags, 
               s->sh_type, 
               s->sh_info, 
               s->name, 
               s->reloc ? s->reloc->name : "n"
               ); 
#endif
        /* when generating a DLL, we include relocations but we may
           patch them */
        if (file_type == TCC_OUTPUT_DLL && 
            s->sh_type == SHT_RELX && 
            !(s->sh_flags & SHF_ALLOC)) {
            /* //gr: avoid bogus relocs for empty (debug) sections */
            if (s1->sections[s->sh_info]->sh_flags & SHF_ALLOC)
                prepare_dynamic_rel(s1, s);
            else if (s1->do_debug)
                s->sh_size = s->data_offset;
        } else if (s1->do_debug ||
            file_type == TCC_OUTPUT_OBJ || 
            (s->sh_flags & SHF_ALLOC) ||
            i == (s1->nb_sections - 1)) {
            /* we output all sections if debug or object file */
            s->sh_size = s->data_offset;
        }
    }

    /* allocate program segment headers */
    phdr = tcc_mallocz(phnum * sizeof(ElfW(Phdr)));
        
    if (s1->output_format == TCC_OUTPUT_FORMAT_ELF) {
        file_offset = sizeof(ElfW(Ehdr)) + phnum * sizeof(ElfW(Phdr));
    } else {
        file_offset = 0;
    }
    if (phnum > 0) {
        /* compute section to program header mapping */
        if (s1->has_text_addr) { 
            int a_offset, p_offset;
            addr = s1->text_addr;
            /* we ensure that (addr % ELF_PAGE_SIZE) == file_offset %
               ELF_PAGE_SIZE */
            a_offset = (int) (addr & (s1->section_align - 1));
            p_offset = file_offset & (s1->section_align - 1);
            if (a_offset < p_offset) 
                a_offset += s1->section_align;
            file_offset += (a_offset - p_offset);
        } else {
            if (file_type == TCC_OUTPUT_DLL)
                addr = 0;
            else
                addr = ELF_START_ADDR;
            /* compute address after headers */
            addr += (file_offset & (s1->section_align - 1));
        }
        
        /* dynamic relocation table information, for .dynamic section */
        rel_size = 0;
        rel_addr = 0;

#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
        bss_addr = bss_size = 0;
#endif
        /* leave one program header for the program interpreter */
        ph = &phdr[0];
        if (interp)
            ph += 1 + HAVE_PHDR;

        for(j = 0; j < 2; j++) {
            ph->p_type = PT_LOAD;
            if (j == 0)
                ph->p_flags = PF_R | PF_X;
            else
                ph->p_flags = PF_R | PF_W;
            ph->p_align = s1->section_align;
            
            /* we do the following ordering: interp, symbol tables,
               relocations, progbits, nobits */
            /* XXX: do faster and simpler sorting */
            for(k = 0; k < 5; k++) {
                for(i = 1; i < s1->nb_sections; i++) {
                    s = s1->sections[i];
                    /* compute if section should be included */

src/tccelf.c  view on Meta::CPAN

                    }
#elif defined(TCC_TARGET_ARM)
                    int x;
                    x=s1->got->sh_addr - s1->plt->sh_addr - 12;
                    p += 16;
                    while (p < p_end) {
                        if (get32(p) == 0x46c04778) /* PLT Thumb stub present */
                            p += 4;
                        put32(p + 12, x + get32(p + 12) + s1->plt->data - p);
                        p += 16;
                    }
#elif defined(TCC_TARGET_C67)
                    /* XXX: TODO */
#else
#error unsupported CPU
#endif
                }
            }

            /* relocate symbols in .dynsym */
            sym_end = (ElfW(Sym) *)(s1->dynsym->data + s1->dynsym->data_offset);
            for(sym = (ElfW(Sym) *)s1->dynsym->data + 1; 
                sym < sym_end;
                sym++) {
                if (sym->st_shndx == SHN_UNDEF) {
                    /* relocate to the PLT if the symbol corresponds
                       to a PLT entry */
                    if (sym->st_value)
                        sym->st_value += s1->plt->sh_addr;
                } else if (sym->st_shndx < SHN_LORESERVE) {
                    /* do symbol relocation */
                    sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
                }
            }

            /* put dynamic section entries */
            dynamic->data_offset = saved_dynamic_data_offset;
            put_dt(dynamic, DT_HASH, s1->dynsym->hash->sh_addr);
            put_dt(dynamic, DT_STRTAB, dynstr->sh_addr);
            put_dt(dynamic, DT_SYMTAB, s1->dynsym->sh_addr);
            put_dt(dynamic, DT_STRSZ, dynstr->data_offset);
            put_dt(dynamic, DT_SYMENT, sizeof(ElfW(Sym)));
#ifdef TCC_TARGET_X86_64
            put_dt(dynamic, DT_RELA, rel_addr);
            put_dt(dynamic, DT_RELASZ, rel_size);
            put_dt(dynamic, DT_RELAENT, sizeof(ElfW_Rel));
#else
#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
            put_dt(dynamic, DT_PLTGOT, s1->got->sh_addr);
            put_dt(dynamic, DT_PLTRELSZ, rel_size);
            put_dt(dynamic, DT_JMPREL, rel_addr);
            put_dt(dynamic, DT_PLTREL, DT_REL);
            put_dt(dynamic, DT_REL, bss_addr);
            put_dt(dynamic, DT_RELSZ, bss_size);
#else
            put_dt(dynamic, DT_REL, rel_addr);
            put_dt(dynamic, DT_RELSZ, rel_size);
            put_dt(dynamic, DT_RELENT, sizeof(ElfW_Rel));
#endif
#endif
            if (s1->do_debug)
                put_dt(dynamic, DT_DEBUG, 0);
            put_dt(dynamic, DT_NULL, 0);
        }

        ehdr.e_phentsize = sizeof(ElfW(Phdr));
        ehdr.e_phnum = phnum;
        ehdr.e_phoff = sizeof(ElfW(Ehdr));
    }

    /* all other sections come after */
    for(i = 1; i < s1->nb_sections; i++) {
        s = s1->sections[i];
        if (phnum > 0 && (s->sh_flags & SHF_ALLOC))
            continue;
        section_order[sh_order_index++] = i;
        
        file_offset = (file_offset + s->sh_addralign - 1) & 
            ~(s->sh_addralign - 1);
        s->sh_offset = file_offset;
        if (s->sh_type != SHT_NOBITS)
            file_offset += s->sh_size;
    }
    
    /* if building executable or DLL, then relocate each section
       except the GOT which is already relocated */
    if (file_type != TCC_OUTPUT_OBJ) {
        relocate_syms(s1, 0);

        if (s1->nb_errors != 0) {
        fail:
            ret = -1;
            goto the_end;
        }

        /* relocate sections */
        /* XXX: ignore sections with allocated relocations ? */
        for(i = 1; i < s1->nb_sections; i++) {
            s = s1->sections[i];
            if (s->reloc && s != s1->got)
                relocate_section(s1, s);
        }

        /* relocate relocation entries if the relocation tables are
           allocated in the executable */
        for(i = 1; i < s1->nb_sections; i++) {
            s = s1->sections[i];
            if ((s->sh_flags & SHF_ALLOC) &&
                s->sh_type == SHT_RELX) {
                relocate_rel(s1, s);
            }
        }

        /* get entry point address */
        if (file_type == TCC_OUTPUT_EXE)
            ehdr.e_entry = get_elf_sym_addr(s1, "_start", 1);
        else
            ehdr.e_entry = text_section->sh_addr; /* XXX: is it correct ? */
    }
    if (file_type == TCC_OUTPUT_EXE && s1->static_link)
        fill_got(s1);

src/tccelf.c  view on Meta::CPAN

                sh->sh_name = s->sh_name;
                sh->sh_type = s->sh_type;
                sh->sh_flags = s->sh_flags;
                sh->sh_entsize = s->sh_entsize;
                sh->sh_info = s->sh_info;
                if (s->link)
                    sh->sh_link = s->link->sh_num;
                sh->sh_addralign = s->sh_addralign;
                sh->sh_addr = s->sh_addr;
                sh->sh_offset = s->sh_offset;
                sh->sh_size = s->sh_size;
            }
            fwrite(sh, 1, sizeof(ElfW(Shdr)), f);
        }
    } else {
        tcc_output_binary(s1, f, section_order);
    }
    fclose(f);

    ret = 0;
 the_end:
    tcc_free(s1->symtab_to_dynsym);
    tcc_free(section_order);
    tcc_free(phdr);
    tcc_free(s1->sym_attrs);
    return ret;
}

LIBTCCAPI int tcc_output_file(TCCState *s, const char *filename)
{
    int ret;
#ifdef TCC_TARGET_PE
    if (s->output_type != TCC_OUTPUT_OBJ) {
        ret = pe_output_file(s, filename);
    } else
#endif
    {
        ret = elf_output_file(s, filename);
    }
    return ret;
}

static void *load_data(int fd, unsigned long file_offset, unsigned long size)
{
    void *data;

    data = tcc_malloc(size);
    lseek(fd, file_offset, SEEK_SET);
    read(fd, data, size);
    return data;
}

typedef struct SectionMergeInfo {
    Section *s;            /* corresponding existing section */
    unsigned long offset;  /* offset of the new section in the existing section */
    uint8_t new_section;       /* true if section 's' was added */
    uint8_t link_once;         /* true if link once section */
} SectionMergeInfo;

/* load an object file and merge it with current files */
/* XXX: handle correctly stab (debug) info */
ST_FUNC int tcc_load_object_file(TCCState *s1, 
                                int fd, unsigned long file_offset)
{ 
    ElfW(Ehdr) ehdr;
    ElfW(Shdr) *shdr, *sh;
    int size, i, j, offset, offseti, nb_syms, sym_index, ret;
    unsigned char *strsec, *strtab;
    int *old_to_new_syms;
    char *sh_name, *name;
    SectionMergeInfo *sm_table, *sm;
    ElfW(Sym) *sym, *symtab;
    ElfW_Rel *rel, *rel_end;
    Section *s;

    int stab_index;
    int stabstr_index;

    stab_index = stabstr_index = 0;

    if (read(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
        goto fail1;
    if (ehdr.e_ident[0] != ELFMAG0 ||
        ehdr.e_ident[1] != ELFMAG1 ||
        ehdr.e_ident[2] != ELFMAG2 ||
        ehdr.e_ident[3] != ELFMAG3)
        goto fail1;
    /* test if object file */
    if (ehdr.e_type != ET_REL)
        goto fail1;
    /* test CPU specific stuff */
    if (ehdr.e_ident[5] != ELFDATA2LSB ||
        ehdr.e_machine != EM_TCC_TARGET) {
    fail1:
        tcc_error_noabort("invalid object file");
        return -1;
    }
    /* read sections */
    shdr = load_data(fd, file_offset + ehdr.e_shoff, 
                     sizeof(ElfW(Shdr)) * ehdr.e_shnum);
    sm_table = tcc_mallocz(sizeof(SectionMergeInfo) * ehdr.e_shnum);
    
    /* load section names */
    sh = &shdr[ehdr.e_shstrndx];
    strsec = load_data(fd, file_offset + sh->sh_offset, sh->sh_size);

    /* load symtab and strtab */
    old_to_new_syms = NULL;
    symtab = NULL;
    strtab = NULL;
    nb_syms = 0;
    for(i = 1; i < ehdr.e_shnum; i++) {
        sh = &shdr[i];
        if (sh->sh_type == SHT_SYMTAB) {
            if (symtab) {
                tcc_error_noabort("object must contain only one symtab");
            fail:
                ret = -1;
                goto the_end;
            }
            nb_syms = sh->sh_size / sizeof(ElfW(Sym));