Alien-TinyCC

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src/tccelf.c  view on Meta::CPAN

   found. */
ST_FUNC int find_elf_sym(Section *s, const char *name)
{
    ElfW(Sym) *sym;
    Section *hs;
    int nbuckets, sym_index, h;
    const char *name1;
    
    hs = s->hash;
    if (!hs)
        return 0;
    nbuckets = ((int *)hs->data)[0];
    h = elf_hash(name) % nbuckets;
    sym_index = ((int *)hs->data)[2 + h];
    while (sym_index != 0) {
        sym = &((ElfW(Sym) *)s->data)[sym_index];
        name1 = s->link->data + sym->st_name;
        if (!strcmp(name, name1))
            return sym_index;
        sym_index = ((int *)hs->data)[2 + nbuckets + sym_index];
    }
    return 0;
}

/* return elf symbol value, signal error if 'err' is nonzero */
ST_FUNC addr_t get_elf_sym_addr(TCCState *s, const char *name, int err)
{
    int sym_index;
    ElfW(Sym) *sym;

    sym_index = find_elf_sym(s->symtab, name);
    sym = &((ElfW(Sym) *)s->symtab->data)[sym_index];
    if (!sym_index || sym->st_shndx == SHN_UNDEF) {
        if (err)
            tcc_error("%s not defined", name);
        return 0;
    }
    return sym->st_value;
}

/* return elf symbol value */
LIBTCCAPI void *tcc_get_symbol(TCCState *s, const char *name)
{
    return (void*)(uintptr_t)get_elf_sym_addr(s, name, 0);
}

#ifdef TCC_IS_NATIVE
/* return elf symbol value or error */
ST_FUNC void* tcc_get_symbol_err(TCCState *s, const char *name)
{
    return (void*)get_elf_sym_addr(s, name, 1);
}
#endif

/* add an elf symbol : check if it is already defined and patch
   it. Return symbol index. NOTE that sh_num can be SHN_UNDEF. */
ST_FUNC int add_elf_sym(Section *s, addr_t value, unsigned long size,
                       int info, int other, int sh_num, const char *name)
{
    ElfW(Sym) *esym;
    int sym_bind, sym_index, sym_type, esym_bind;
    unsigned char sym_vis, esym_vis, new_vis;

    sym_bind = ELFW(ST_BIND)(info);
    sym_type = ELFW(ST_TYPE)(info);
    sym_vis = ELFW(ST_VISIBILITY)(other);
        
    if (sym_bind != STB_LOCAL) {
        /* we search global or weak symbols */
        sym_index = find_elf_sym(s, name);
        if (!sym_index)
            goto do_def;
        esym = &((ElfW(Sym) *)s->data)[sym_index];
        if (esym->st_shndx != SHN_UNDEF) {
            esym_bind = ELFW(ST_BIND)(esym->st_info);
            /* propagate the most constraining visibility */
            /* STV_DEFAULT(0)<STV_PROTECTED(3)<STV_HIDDEN(2)<STV_INTERNAL(1) */
            esym_vis = ELFW(ST_VISIBILITY)(esym->st_other);
            if (esym_vis == STV_DEFAULT) {
                new_vis = sym_vis;
            } else if (sym_vis == STV_DEFAULT) {
                new_vis = esym_vis;
            } else {
                new_vis = (esym_vis < sym_vis) ? esym_vis : sym_vis;
            }
            esym->st_other = (esym->st_other & ~ELFW(ST_VISIBILITY)(-1))
                             | new_vis;
            other = esym->st_other; /* in case we have to patch esym */
            if (sh_num == SHN_UNDEF) {
                /* ignore adding of undefined symbol if the
                   corresponding symbol is already defined */
            } else if (sym_bind == STB_GLOBAL && esym_bind == STB_WEAK) {
                /* global overrides weak, so patch */
                goto do_patch;
            } else if (sym_bind == STB_WEAK && esym_bind == STB_GLOBAL) {
                /* weak is ignored if already global */
            } else if (sym_bind == STB_WEAK && esym_bind == STB_WEAK) {
                /* keep first-found weak definition, ignore subsequents */
            } else if (sym_vis == STV_HIDDEN || sym_vis == STV_INTERNAL) {
                /* ignore hidden symbols after */
            } 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);
}

src/tccelf.c  view on Meta::CPAN

    p = (ElfW(Sym) *)s->data;
    for(i = 0; i < nb_syms; i++) {
        if (ELFW(ST_BIND)(p->st_info) != STB_LOCAL) {
            old_to_new_syms[i] = q - new_syms;
            *q++ = *p;
        }
        p++;
    }
    
    /* we copy the new symbols to the old */
    memcpy(s->data, new_syms, nb_syms * sizeof(ElfW(Sym)));
    tcc_free(new_syms);

    /* now we modify all the relocations */
    for(i = 1; i < s1->nb_sections; i++) {
        sr = s1->sections[i];
        if (sr->sh_type == SHT_RELX && sr->link == s) {
            rel_end = (ElfW_Rel *)(sr->data + sr->data_offset);
            for(rel = (ElfW_Rel *)sr->data;
                rel < rel_end;
                rel++) {
                sym_index = ELFW(R_SYM)(rel->r_info);
                type = ELFW(R_TYPE)(rel->r_info);
                sym_index = old_to_new_syms[sym_index];
                rel->r_info = ELFW(R_INFO)(sym_index, type);
            }
        }
    }
    
    tcc_free(old_to_new_syms);
}

/* relocate common symbols in the .bss section */
ST_FUNC void relocate_common_syms(void)
{
    ElfW(Sym) *sym, *sym_end;
    unsigned long offset, align;
    
    sym_end = (ElfW(Sym) *)(symtab_section->data + symtab_section->data_offset);
    for(sym = (ElfW(Sym) *)symtab_section->data + 1; 
        sym < sym_end;
        sym++) {
        if (sym->st_shndx == SHN_COMMON) {
            /* align symbol */
            align = sym->st_value;
            offset = bss_section->data_offset;
            offset = (offset + align - 1) & -align;
            sym->st_value = offset;
            sym->st_shndx = bss_section->sh_num;
            offset += sym->st_size;
            bss_section->data_offset = offset;
        }
    }
}

/* relocate symbol table, resolve undefined symbols if do_resolve is
   true and output error if undefined symbol. */
ST_FUNC void relocate_syms(TCCState *s1, int do_resolve)
{
    ElfW(Sym) *sym, *esym, *sym_end;
    int sym_bind, sh_num, sym_index;
    const char *name;

    sym_end = (ElfW(Sym) *)(symtab_section->data + symtab_section->data_offset);
    for(sym = (ElfW(Sym) *)symtab_section->data + 1; 
        sym < sym_end;
        sym++) {
        sh_num = sym->st_shndx;
        if (sh_num == SHN_UNDEF) {
            name = strtab_section->data + sym->st_name;
            if (do_resolve) {
#if defined TCC_IS_NATIVE && !defined _WIN32
                void *addr;
                name = symtab_section->link->data + sym->st_name;
                addr = resolve_sym(s1, name);
                if (addr) {
                    sym->st_value = (addr_t)addr;
                    goto found;
                }
#endif
            } else if (s1->dynsym) {
                /* if dynamic symbol exist, then use it */
                sym_index = find_elf_sym(s1->dynsym, name);
                if (sym_index) {
                    esym = &((ElfW(Sym) *)s1->dynsym->data)[sym_index];
                    sym->st_value = esym->st_value;
                    goto found;
                }
            }
            /* XXX: _fp_hw seems to be part of the ABI, so we ignore
               it */
            if (!strcmp(name, "_fp_hw"))
                goto found;
            /* only weak symbols are accepted to be undefined. Their
               value is zero */
            sym_bind = ELFW(ST_BIND)(sym->st_info);
            if (sym_bind == STB_WEAK) {
                sym->st_value = 0;
            } else {
                tcc_error_noabort("undefined symbol '%s'", name);
            }
        } else if (sh_num < SHN_LORESERVE) {
            /* add section base */
            sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
        }
    found: ;
    }
}

#ifdef TCC_HAS_RUNTIME_PLTGOT
#ifdef TCC_TARGET_X86_64
#define JMP_TABLE_ENTRY_SIZE 14
static addr_t add_jmp_table(TCCState *s1, addr_t val)
{
    char *p = s1->runtime_plt_and_got + s1->runtime_plt_and_got_offset;
    s1->runtime_plt_and_got_offset += JMP_TABLE_ENTRY_SIZE;
    /* jmp *0x0(%rip) */
    p[0] = 0xff;
    p[1] = 0x25;
    *(int *)(p + 2) = 0;
    *(addr_t *)(p + 6) = val;
    return (addr_t)p;
}

static addr_t add_got_table(TCCState *s1, addr_t val)
{
    addr_t *p = (addr_t *)(s1->runtime_plt_and_got + s1->runtime_plt_and_got_offset);
    s1->runtime_plt_and_got_offset += sizeof(addr_t);
    *p = val;
    return (addr_t)p;
}
#elif defined TCC_TARGET_ARM
#define JMP_TABLE_ENTRY_SIZE 8
static addr_t add_jmp_table(TCCState *s1, int val)
{
    uint32_t *p = (uint32_t *)(s1->runtime_plt_and_got + s1->runtime_plt_and_got_offset);
    s1->runtime_plt_and_got_offset += JMP_TABLE_ENTRY_SIZE;
    /* ldr pc, [pc, #-4] */
    p[0] = 0xE51FF004;
    p[1] = val;
    return (addr_t)p;
}
#endif
#endif /* def TCC_HAS_RUNTIME_PLTGOT */

/* relocate a given section (CPU dependent) */
ST_FUNC void relocate_section(TCCState *s1, Section *s)
{
    Section *sr;
    ElfW_Rel *rel, *rel_end, *qrel;
    ElfW(Sym) *sym;
    int type, sym_index;
    unsigned char *ptr;
    addr_t val, addr;
#if defined TCC_TARGET_I386 || defined TCC_TARGET_X86_64
    int esym_index;
#endif

src/tccelf.c  view on Meta::CPAN

/* load a '.a' file */
ST_FUNC int tcc_load_archive(TCCState *s1, int fd)
{
    ArchiveHeader hdr;
    char ar_size[11];
    char ar_name[17];
    char magic[8];
    int size, len, i;
    unsigned long file_offset;

    /* skip magic which was already checked */
    read(fd, magic, sizeof(magic));
    
    for(;;) {
        len = read(fd, &hdr, sizeof(hdr));
        if (len == 0)
            break;
        if (len != sizeof(hdr)) {
            tcc_error_noabort("invalid archive");
            return -1;
        }
        memcpy(ar_size, hdr.ar_size, sizeof(hdr.ar_size));
        ar_size[sizeof(hdr.ar_size)] = '\0';
        size = strtol(ar_size, NULL, 0);
        memcpy(ar_name, hdr.ar_name, sizeof(hdr.ar_name));
        for(i = sizeof(hdr.ar_name) - 1; i >= 0; i--) {
            if (ar_name[i] != ' ')
                break;
        }
        ar_name[i + 1] = '\0';
        //        printf("name='%s' size=%d %s\n", ar_name, size, ar_size);
        file_offset = lseek(fd, 0, SEEK_CUR);
        /* align to even */
        size = (size + 1) & ~1;
        if (!strcmp(ar_name, "/")) {
            /* coff symbol table : we handle it */
            if(s1->alacarte_link)
                return tcc_load_alacarte(s1, fd, size);
        } else if (!strcmp(ar_name, "//") ||
                   !strcmp(ar_name, "__.SYMDEF") ||
                   !strcmp(ar_name, "__.SYMDEF/") ||
                   !strcmp(ar_name, "ARFILENAMES/")) {
            /* skip symbol table or archive names */
        } else {
            if (tcc_load_object_file(s1, fd, file_offset) < 0)
                return -1;
        }
        lseek(fd, file_offset + size, SEEK_SET);
    }
    return 0;
}

#ifndef TCC_TARGET_PE
/* load a DLL and all referenced DLLs. 'level = 0' means that the DLL
   is referenced by the user (so it should be added as DT_NEEDED in
   the generated ELF file) */
ST_FUNC int tcc_load_dll(TCCState *s1, int fd, const char *filename, int level)
{ 
    ElfW(Ehdr) ehdr;
    ElfW(Shdr) *shdr, *sh, *sh1;
    int i, j, nb_syms, nb_dts, sym_bind, ret;
    ElfW(Sym) *sym, *dynsym;
    ElfW(Dyn) *dt, *dynamic;
    unsigned char *dynstr;
    const char *name, *soname;
    DLLReference *dllref;
    
    read(fd, &ehdr, sizeof(ehdr));

    /* test CPU specific stuff */
    if (ehdr.e_ident[5] != ELFDATA2LSB ||
        ehdr.e_machine != EM_TCC_TARGET) {
        tcc_error_noabort("bad architecture");
        return -1;
    }

    /* read sections */
    shdr = load_data(fd, ehdr.e_shoff, sizeof(ElfW(Shdr)) * ehdr.e_shnum);

    /* load dynamic section and dynamic symbols */
    nb_syms = 0;
    nb_dts = 0;
    dynamic = NULL;
    dynsym = NULL; /* avoid warning */
    dynstr = NULL; /* avoid warning */
    for(i = 0, sh = shdr; i < ehdr.e_shnum; i++, sh++) {
        switch(sh->sh_type) {
        case SHT_DYNAMIC:
            nb_dts = sh->sh_size / sizeof(ElfW(Dyn));
            dynamic = load_data(fd, sh->sh_offset, sh->sh_size);
            break;
        case SHT_DYNSYM:
            nb_syms = sh->sh_size / sizeof(ElfW(Sym));
            dynsym = load_data(fd, sh->sh_offset, sh->sh_size);
            sh1 = &shdr[sh->sh_link];
            dynstr = load_data(fd, sh1->sh_offset, sh1->sh_size);
            break;
        default:
            break;
        }
    }
    
    /* compute the real library name */
    soname = tcc_basename(filename);
        
    for(i = 0, dt = dynamic; i < nb_dts; i++, dt++) {
        if (dt->d_tag == DT_SONAME) {
            soname = dynstr + dt->d_un.d_val;
        }
    }

    /* if the dll is already loaded, do not load it */
    for(i = 0; i < s1->nb_loaded_dlls; i++) {
        dllref = s1->loaded_dlls[i];
        if (!strcmp(soname, dllref->name)) {
            /* but update level if needed */
            if (level < dllref->level)
                dllref->level = level;
            ret = 0;
            goto the_end;
        }
    }
    
    //    printf("loading dll '%s'\n", soname);

    /* add the dll and its level */
    dllref = tcc_mallocz(sizeof(DLLReference) + strlen(soname));
    dllref->level = level;
    strcpy(dllref->name, soname);
    dynarray_add((void ***)&s1->loaded_dlls, &s1->nb_loaded_dlls, dllref);

    /* add dynamic symbols in dynsym_section */
    for(i = 1, sym = dynsym + 1; i < nb_syms; i++, sym++) {
        sym_bind = ELFW(ST_BIND)(sym->st_info);
        if (sym_bind == STB_LOCAL)
            continue;
        name = dynstr + sym->st_name;
        add_elf_sym(s1->dynsymtab_section, sym->st_value, sym->st_size,
                    sym->st_info, sym->st_other, sym->st_shndx, name);
    }

    /* load all referenced DLLs */
    for(i = 0, dt = dynamic; i < nb_dts; i++, dt++) {
        switch(dt->d_tag) {
        case DT_NEEDED:
            name = dynstr + dt->d_un.d_val;
            for(j = 0; j < s1->nb_loaded_dlls; j++) {
                dllref = s1->loaded_dlls[j];
                if (!strcmp(name, dllref->name))
                    goto already_loaded;
            }
            if (tcc_add_dll(s1, name, AFF_REFERENCED_DLL) < 0) {
                tcc_error_noabort("referenced dll '%s' not found", name);
                ret = -1;
                goto the_end;
            }
        already_loaded:
            break;
        }
    }
    ret = 0;
 the_end:
    tcc_free(dynstr);
    tcc_free(dynsym);
    tcc_free(dynamic);
    tcc_free(shdr);
    return ret;
}

#define LD_TOK_NAME 256
#define LD_TOK_EOF  (-1)

/* return next ld script token */
static int ld_next(TCCState *s1, char *name, int name_size)
{
    int c;
    char *q;

 redo:
    switch(ch) {
    case ' ':
    case '\t':
    case '\f':
    case '\v':
    case '\r':
    case '\n':
        inp();
        goto redo;
    case '/':
        minp();
        if (ch == '*') {
            file->buf_ptr = parse_comment(file->buf_ptr);
            ch = file->buf_ptr[0];
            goto redo;
        } else {