infback9.c

gcc的组建

                break;
            case 3:
                strm->msg = (char *)"invalid block type";
                mode = BAD;
            }
            DROPBITS(2);
            break;

        case STORED:
            /* get and verify stored block length */
            BYTEBITS();                         /* go to byte boundary */
            NEEDBITS(32);
            if ((hold & 0xffff) != ((hold >> 16) ^ 0xffff)) {
                strm->msg = (char *)"invalid stored block lengths";
                mode = BAD;
                break;
            }
            length = (unsigned)hold & 0xffff;
            Tracev((stderr, "inflate:       stored length %lu\n",
                    length));
            INITBITS();

            /* copy stored block from input to output */
            while (length != 0) {
                copy = length;
                PULL();
                ROOM();
                if (copy > have) copy = have;
                if (copy > left) copy = left;
                zmemcpy(put, next, copy);
                have -= copy;
                next += copy;
                left -= copy;
                put += copy;
                length -= copy;
            }
            Tracev((stderr, "inflate:       stored end\n"));
            mode = TYPE;
            break;

        case TABLE:
            /* get dynamic table entries descriptor */
            NEEDBITS(14);
            state->nlen = BITS(5) + 257;
            DROPBITS(5);
            state->ndist = BITS(5) + 1;
            DROPBITS(5);
            state->ncode = BITS(4) + 4;
            DROPBITS(4);
            if (state->nlen > 286) {
                strm->msg = (char *)"too many length symbols";
                mode = BAD;
                break;
            }
            Tracev((stderr, "inflate:       table sizes ok\n"));

            /* get code length code lengths (not a typo) */
            state->have = 0;
            while (state->have < state->ncode) {
                NEEDBITS(3);
                state->lens[order[state->have++]] = (unsigned short)BITS(3);
                DROPBITS(3);
            }
            while (state->have < 19)
                state->lens[order[state->have++]] = 0;
            state->next = state->codes;
            lencode = (code const FAR *)(state->next);
            lenbits = 7;
            ret = inflate_table9(CODES, state->lens, 19, &(state->next),
                                &(lenbits), state->work);
            if (ret) {
                strm->msg = (char *)"invalid code lengths set";
                mode = BAD;
                break;
            }
            Tracev((stderr, "inflate:       code lengths ok\n"));

            /* get length and distance code code lengths */
            state->have = 0;
            while (state->have < state->nlen + state->ndist) {
                for (;;) {
                    this = lencode[BITS(lenbits)];
                    if ((unsigned)(this.bits) <= bits) break;
                    PULLBYTE();
                }
                if (this.val < 16) {
                    NEEDBITS(this.bits);
                    DROPBITS(this.bits);
                    state->lens[state->have++] = this.val;
                }
                else {
                    if (this.val == 16) {
                        NEEDBITS(this.bits + 2);
                        DROPBITS(this.bits);
                        if (state->have == 0) {
                            strm->msg = (char *)"invalid bit length repeat";
                            mode = BAD;
                            break;
                        }
                        len = (unsigned)(state->lens[state->have - 1]);
                        copy = 3 + BITS(2);
                        DROPBITS(2);
                    }
                    else if (this.val == 17) {
                        NEEDBITS(this.bits + 3);
                        DROPBITS(this.bits);
                        len = 0;
                        copy = 3 + BITS(3);
                        DROPBITS(3);
                    }
                    else {
                        NEEDBITS(this.bits + 7);
                        DROPBITS(this.bits);
                        len = 0;
                        copy = 11 + BITS(7);
                        DROPBITS(7);
                    }
                    if (state->have + copy > state->nlen + state->ndist) {
                        strm->msg = (char *)"invalid bit length repeat";
                        mode = BAD;
                        break;
                    }
                    while (copy--)
                        state->lens[state->have++] = (unsigned short)len;
                }
            }

            /* handle error breaks in while */
            if (mode == BAD) break;

            /* build code tables */
            state->next = state->codes;
            lencode = (code const FAR *)(state->next);
            lenbits = 9;
            ret = inflate_table9(LENS, state->lens, state->nlen,
                            &(state->next), &(lenbits), state->work);
            if (ret) {
                strm->msg = (char *)"invalid literal/lengths set";
                mode = BAD;
                break;
            }
            distcode = (code const FAR *)(state->next);
            distbits = 6;
            ret = inflate_table9(DISTS, state->lens + state->nlen,
                            state->ndist, &(state->next), &(distbits),
                            state->work);
            if (ret) {
                strm->msg = (char *)"invalid distances set";
                mode = BAD;
                break;
            }
            Tracev((stderr, "inflate:       codes ok\n"));
            mode = LEN;

        case LEN:
            /* get a literal, length, or end-of-block code */
            for (;;) {
                this = lencode[BITS(lenbits)];
                if ((unsigned)(this.bits) <= bits) break;
                PULLBYTE();
            }
            if (this.op && (this.op & 0xf0) == 0) {
                last = this;
                for (;;) {
                    this = lencode[last.val +
                            (BITS(last.bits + last.op) >> last.bits)];
                    if ((unsigned)(last.bits + this.bits) <= bits) break;
                    PULLBYTE();
                }
                DROPBITS(last.bits);
            }
            DROPBITS(this.bits);
            length = (unsigned)this.val;

            /* process literal */
            if (this.op == 0) {
                Tracevv((stderr, this.val >= 0x20 && this.val < 0x7f ?
                        "inflate:         literal '%c'\n" :
                        "inflate:         literal 0x%02x\n", this.val));
                ROOM();
                *put++ = (unsigned char)(length);
                left--;
                mode = LEN;
                break;
            }

            /* process end of block */
            if (this.op & 32) {
                Tracevv((stderr, "inflate:         end of block\n"));
                mode = TYPE;
                break;
            }

            /* invalid code */
            if (this.op & 64) {
                strm->msg = (char *)"invalid literal/length code";
                mode = BAD;
                break;
            }

            /* length code -- get extra bits, if any */
            extra = (unsigned)(this.op) & 31;
            if (extra != 0) {
                NEEDBITS(extra);
                length += BITS(extra);
                DROPBITS(extra);
            }
            Tracevv((stderr, "inflate:         length %lu\n", length));

            /* get distance code */
            for (;;) {
                this = distcode[BITS(distbits)];
                if ((unsigned)(this.bits) <= bits) break;
                PULLBYTE();
            }
            if ((this.op & 0xf0) == 0) {
                last = this;
                for (;;) {
                    this = distcode[last.val +
                            (BITS(last.bits + last.op) >> last.bits)];
                    if ((unsigned)(last.bits + this.bits) <= bits) break;
                    PULLBYTE();
                }
                DROPBITS(last.bits);
            }
            DROPBITS(this.bits);
            if (this.op & 64) {
                strm->msg = (char *)"invalid distance code";
                mode = BAD;
                break;
            }
            offset = (unsigned)this.val;

            /* get distance extra bits, if any */
            extra = (unsigned)(this.op) & 15;
            if (extra != 0) {
                NEEDBITS(extra);
                offset += BITS(extra);
                DROPBITS(extra);
            }
            if (offset > WSIZE - (wrap ? 0: left)) {
                strm->msg = (char *)"invalid distance too far back";
                mode = BAD;
                break;
            }
            Tracevv((stderr, "inflate:         distance %lu\n", offset));

            /* copy match from window to output */
            do {
                ROOM();
                copy = WSIZE - offset;
                if (copy < left) {
                    from = put + copy;
                    copy = left - copy;
                }
                else {
                    from = put - offset;
                    copy = left;
                }
                if (copy > length) copy = length;
                length -= copy;
                left -= copy;
                do {
                    *put++ = *from++;
                } while (--copy);
            } while (length != 0);
            break;

        case DONE:
            /* inflate stream terminated properly -- write leftover output */
            ret = Z_STREAM_END;
            if (left < WSIZE) {
                if (out(out_desc, window, (unsigned)(WSIZE - left)))
                    ret = Z_BUF_ERROR;
            }
            goto inf_leave;

        case BAD:
            ret = Z_DATA_ERROR;
            goto inf_leave;

        default:                /* can't happen, but makes compilers happy */
            ret = Z_STREAM_ERROR;
            goto inf_leave;
        }

    /* Return unused input */
  inf_leave:
    strm->next_in = next;
    strm->avail_in = have;
    return ret;
}

int ZEXPORT inflateBack9End(strm)
z_stream FAR *strm;
{
    if (strm == Z_NULL || strm->state == Z_NULL || strm->zfree == (free_func)0)
        return Z_STREAM_ERROR;
    ZFREE(strm, strm->state);
    strm->state = Z_NULL;
    Tracev((stderr, "inflate: end\n"));
    return Z_OK;
}