vms_im.c

给出了 zip 压缩算法的完整实现过程。

/*
  Copyright (c) 1990-2005 Info-ZIP.  All rights reserved.

  See the accompanying file LICENSE, version 2004-May-22 or later
  (the contents of which are also included in zip.h) for terms of use.
  If, for some reason, both of these files are missing, the Info-ZIP license
  also may be found at:  ftp://ftp.info-zip.org/pub/infozip/license.html
*/
/*
 *  vms_im.c (zip) by Igor Mandrichenko    Version 2.2-2
 *
 *  Revision history:
 *  ...
 *  2.1-1       16-feb-1993     I.Mandrichenko
 *      Get file size from XABFHC and check bytes rest in file before
 *      reading.
 *  2.1-2       2-mar-1993      I.Mandrichenko
 *      Make code more standard
 *  2.2         21-jun-1993     I.Mandrichenko
 *      Free all allocated space, use more static storage.
 *      Use memcompress() from bits.c (deflation) for block compression.
 *      To revert to old compression method #define OLD_COMPRESS
 *  2.2-2       28-sep-1995     C.Spieler
 *      Reorganized code for easier maintance of the two incompatible
 *      flavours (IM style and PK style) VMS attribute support.
 *      Generic functions (common to both flavours) are now collected
 *      in a `wrapper' source file that includes one of the VMS attribute
 *      handlers.
 *  3.0         23-Oct-2004     Steven Schweda
 *      Changed to maintain compatibility with VMS_PK.C.  Note that
 *      reading with sys$read() prevents getting any data past EOF,
 *      regardless of appearances.  Moved the VMS_PK_EXTRA test into
 *      here from VMS.C to allow more general automatic dependency
 *      generation.
 */

#ifdef VMS                      /* For VMS only ! */

#ifndef VMS_PK_EXTRA

#define OLD_COMPRESS            /*To use old compression method define it.*/

#ifdef VMS_ZIP
#undef VMS_ZIP                  /* do NOT include PK style Zip definitions */
#endif

#include "vms.h"

#ifndef __LIB$ROUTINES_LOADED
#include <lib$routines.h>
#endif

#ifndef UTIL

#define RET_ERROR 1
#define RET_SUCCESS 0
#define RET_EOF 0

#define Kbyte 1024

typedef struct XAB *xabptr;

/*
 *   Block sizes
 */

#define EXTL0   ((FABL + EXTHL)+        \
                (XFHCL + EXTHL)+        \
                (XPROL + EXTHL)+        \
                (XDATL + EXTHL)+        \
                (XRDTL + EXTHL))

#ifdef OLD_COMPRESS
#define PAD     sizeof(uch)
#else
#define PAD     10*sizeof(ush)          /* Two extra bytes for compr. header */
#endif

#define PAD0    (5*PAD)                 /* Reserve space for the case when
                                         *  compression fails */
static int _compress(uch *from, uch *to, int size);
#ifdef DEBUG
static void dump_rms_block(uch *p);
#endif /* DEBUG */

/********************************
 *   Function set_extra_field   *
 ********************************/
/*
 |   2004-11-11 SMS.
 |   Changed to use separate storage for ->extra and ->cextra.  Zip64
 |   processing may move (reallocate) one and not the other.
 */

static uch *_compress_block(register struct IZ_block *to,
                            uch *from, int size, char *sig);
static int get_vms_version(char *verbuf, int len);

int set_extra_field(z, z_utim)
  struct zlist far *z;
  iztimes *z_utim;
/*
 *      Get file VMS file attributes and store them into extent fields.
 *      Store VMS version also.
 *      On error leave z intact.
 */
{
    int status;
    uch *xtra;
    uch *cxtra;
    uch *scan;
    extent extra_l;
    static struct FAB fab;
    static struct XABSUM xabsum;
    static struct XABFHC xabfhc;
    static struct XABDAT xabdat;
    static struct XABPRO xabpro;
    static struct XABRDT xabrdt;
    xabptr x = (xabptr)NULL, xab_chain = (xabptr)NULL, last_xab = (xabptr)NULL;
    int nk, na;
    int i;
    int rc=RET_ERROR;
    char verbuf[80];
    int verlen = 0;

    if (!vms_native)
    {
#ifdef USE_EF_UT_TIME
       /*
        *  A `portable' zipfile entry is created. Create an "UT" extra block
        *  containing UNIX style modification time stamp in UTC, which helps
        *  maintaining the `real' "last modified" time when the archive is
        *  transfered across time zone boundaries.
        */
#  ifdef IZ_CHECK_TZ
        if (!zp_tz_is_valid)
            return ZE_OK;       /* skip silently if no valid TZ info */
#  endif
        if ((xtra = (uch *) malloc( EB_HEADSIZE+ EB_UT_LEN( 1))) == NULL)
            return ZE_MEM;

        if ((cxtra = (uch *) malloc( EB_HEADSIZE+ EB_UT_LEN( 1))) == NULL)
            return ZE_MEM;

        /* Fill xtra[] with data. */
        xtra[ 0] = 'U';
        xtra[ 1] = 'T';
        xtra[ 2] = EB_UT_LEN(1);        /* length of data part of e.f. */
        xtra[ 3] = 0;
        xtra[ 4] = EB_UT_FL_MTIME;
        xtra[ 5] = (uch) (z_utim->mtime);
        xtra[ 6] = (uch) (z_utim->mtime >> 8);
        xtra[ 7] = (uch) (z_utim->mtime >> 16);
        xtra[ 8] = (uch) (z_utim->mtime >> 24);

        /* Copy xtra[] data into cxtra[]. */
        memcpy( cxtra, xtra, (EB_HEADSIZE+ EB_UT_LEN( 1)));

        /* Set sizes and pointers. */
        z->cext = z->ext = (EB_HEADSIZE+ EB_UT_LEN( 1));
        z->extra = (char *) xtra;
        z->cextra = (char *) cxtra;

#endif /* USE_EF_UT_TIME */

        return RET_SUCCESS;
    }

    /*
     *  Initialize RMS control blocks and link them
     */

    fab =    cc$rms_fab;
    xabsum = cc$rms_xabsum;
    xabdat = cc$rms_xabdat;
    xabfhc = cc$rms_xabfhc;
    xabpro = cc$rms_xabpro;
    xabrdt = cc$rms_xabrdt;


    fab.fab$l_xab = (char*)&xabsum;
    /*
     *  Open the file and read summary information.
     */
    fab.fab$b_fns = strlen(z->name);
    fab.fab$l_fna = z->name;

    status = sys$open(&fab);
    if (ERR(status))
    {
#ifdef DEBUG
        printf("set_extra_field: sys$open for file %s:\n  error status = %d\n",
               z->name, status);
#endif
        goto err_exit;
    }

    nk = xabsum.xab$b_nok;
    na = xabsum.xab$b_noa;
#ifdef DEBUG
    printf("%d keys, %d alls\n", nk, na);
#endif

    /*
     *  Allocate XABKEY and XABALL blocks and link them
     */

    xabfhc.xab$l_nxt = (char*)&xabdat;
    xabdat.xab$l_nxt = (char*)&xabpro;
    xabpro.xab$l_nxt = (char*)&xabrdt;
    xabrdt.xab$l_nxt = NULL;

    xab_chain = (xabptr)(&xabfhc);
    last_xab  = (xabptr)(&xabrdt);

#define INIT(ptr,size,type,init)     \
        if ( (ptr = (type *)malloc(size)) == NULL )     \
        {                                               \
              printf( "set_extra_field: Insufficient memory.\n" );   \
                      goto err_exit;                    \
        }                                               \
        *(ptr) = (init);
    /*
     *  Allocate and initialize all needed XABKEYs and XABALLs
     */
    for (i = 0; i < nk; i++)
    {
        struct XABKEY *k;
        INIT(k, XKEYL, struct XABKEY, cc$rms_xabkey);
        k->xab$b_ref = i;
        if (last_xab != NULL)
            last_xab->xab$l_nxt = (char*)k;
        last_xab = (xabptr)k;
    }
    for (i = 0; i < na; i++)
    {
        struct XABALL *a;
        INIT(a, XALLL, struct XABALL, cc$rms_xaball);
        a->xab$b_aid = i;
        if (last_xab != NULL)
            last_xab->xab$l_nxt = (char*)a;
        last_xab = (xabptr)a;
    }

    fab.fab$l_xab = (char*)xab_chain;
#ifdef DEBUG
    printf("Dump of XAB chain before $DISPLAY:\n");
    for (x = xab_chain; x != NULL; x = x->xab$l_nxt)
        dump_rms_block((uch *)x);
#endif
    /*
     *  Get information on the file structure etc.
     */
    status = sys$display(&fab, 0, 0);
    if (ERR(status))
    {
#ifdef DEBUG
        printf("set_extra_field: sys$display for file %s:\n  error status = %d\n",
               z->name, status);
#endif
        goto err_exit;
    }

#ifdef DEBUG
    printf("\nDump of XAB chain after $DISPLAY:\n");
    for (x = xab_chain; x != NULL; x = x->xab$l_nxt)
        dump_rms_block((uch *)x);
#endif

    fab.fab$l_xab = NULL;  /* Keep XABs */
    status = sys$close(&fab);
    if (ERR(status))
    {
#ifdef DEBUG
        printf("set_extra_field: sys$close for file %s:\n  error status = %d\n",
               z->name, status);
#endif
        goto err_exit;
    }

    extra_l = EXTL0 + nk * (XKEYL + EXTHL) + na * (XALLL + EXTHL);
#ifndef OLD_COMPRESS
    extra_l += PAD0 + (nk+na) * PAD;
#endif

    if ( (verlen = get_vms_version(verbuf, sizeof(verbuf))) > 0 )
    {
        extra_l += verlen + EXTHL;
#ifndef OLD_COMPRESS
        extra_l += PAD;
#endif
    }

    if ((scan = xtra = (uch *) malloc( extra_l)) == (uch*)NULL)
    {
#ifdef DEBUG
        printf(
         "set_extra_field: Insufficient memory to allocate extra L buffer\n");
#endif
        goto err_exit;
    }

    if ((cxtra = (uch *) malloc( extra_l)) == (uch*)NULL)
    {
#ifdef DEBUG
        printf(
         "set_extra_field: Insufficient memory to allocate extra C buffer\n");
#endif
        goto err_exit;
    }

    if (verlen > 0)
        scan = _compress_block((struct IZ_block *)scan, (uch *)verbuf,
                               verlen, VERSIG);

    /*
     *  Zero all unusable fields to improve compression
     */
    fab.fab$b_fns = fab.fab$b_shr = fab.fab$b_dns = fab.fab$b_fac = 0;
    fab.fab$w_ifi = 0;
    fab.fab$l_stv = fab.fab$l_sts = fab.fab$l_ctx = 0;
    fab.fab$l_fna = NULL;
    fab.fab$l_nam = NULL;
    fab.fab$l_xab = NULL;
    fab.fab$l_dna = NULL;

#ifdef DEBUG
    dump_rms_block( (uch *)&fab );
#endif
    scan = _compress_block((struct IZ_block *)scan, (uch *)&fab, FABL, FABSIG);
    for (x = xab_chain; x != NULL;)
    {
        int bln;
        char *sig;
        xabptr next;

        next = (xabptr)(x->xab$l_nxt);
        x->xab$l_nxt = 0;

        switch (x->xab$b_cod)
        {
            case XAB$C_ALL:
                bln = XALLL;
                sig = XALLSIG;
                break;
            case XAB$C_KEY:
                bln = XKEYL;
                sig = XKEYSIG;
                break;
            case XAB$C_PRO:
                bln = XPROL;
                sig = XPROSIG;
                break;
            case XAB$C_FHC:
                bln = XFHCL;
                sig = XFHCSIG;
                break;
            case XAB$C_DAT:
                bln = XDATL;
                sig = XDATSIG;
                break;
            case XAB$C_RDT:
                bln = XRDTL;
                sig = XRDTSIG;
                break;
            default:
                bln = 0;
                sig = 0L;
                break;
        }
        if (bln > 0)
            scan = _compress_block((struct IZ_block *)scan, (uch *)x,
                                   bln, sig);
        x = next;
    }

    /* Copy xtra[] data into cxtra[]. */
    memcpy( cxtra, xtra, (scan - xtra));

    /* Set sizes and pointers. */
    z->cext = z->ext = scan - xtra;
    z->extra = (char*) xtra;
    z->cextra = (char*) cxtra;

    rc = RET_SUCCESS;

err_exit:
    /*
     *  Give up all allocated blocks
     */
    for (x = (struct XAB *)xab_chain; x != NULL; )
    {
        struct XAB *next;
        next = (xabptr)(x->xab$l_nxt);
        if (x->xab$b_cod == XAB$C_ALL || x->xab$b_cod == XAB$C_KEY)
            free(x);
        x = next;
    }
    return rc;
}

static int get_vms_version(verbuf, len)
char *verbuf;
int len;
{
    int i = SYI$_VERSION;
    int verlen = 0;
    struct dsc$descriptor version;
    char *m;

    version.dsc$a_pointer = verbuf;
    version.dsc$w_length  = len - 1;
    version.dsc$b_dtype   = DSC$K_DTYPE_B;
    version.dsc$b_class   = DSC$K_CLASS_S;

    if (ERR(lib$getsyi(&i, 0, &version, &verlen, 0, 0)) || verlen == 0)
        return 0;

    /* Cut out trailing spaces "V5.4-3   " -> "V5.4-3" */
    for (m = verbuf + verlen, i = verlen - 1; i > 0 && verbuf[i] == ' '; --i)
        --m;
    *m = 0;

    /* Cut out release number "V5.4-3" -> "V5.4" */
    if ((m = strrchr(verbuf, '-')) != NULL)
        *m = 0;