extrafld.c

给出了 zip 压缩算法的完整实现过程。

    c_ef += z->cext;


    if ( verbose ) {
        print_extra_info();
    }


    /**
    **
    **  Now add the local version of the field.
    **/
    make_extrafield_JLEE(l_ef);
    z->ext += EB_L_JLEE_SIZE;


    /**
    **
    **  Now add the central version of the field.
    **  It's identical to the local header. I wonder why ??
    *  the first two fields are in Intel little-endian format  */
    make_extrafield_JLEE(c_ef);
    z->cext += EB_C_JLEE_SIZE;

    return ZE_OK;
}



/*
* This is an implementation of Johnny Lee's extra field.
* I never saw Johnny Lee's code. My code is based on the extra-field
* definition mac (see latest appnote 1997-03-11)
* and on some experiments with Johnny Lee's Zip-app version 1.0, 1992
*
* Unfortunately I cannot agree with his extra-field layout.
*   - it wasted space
*   - and holds not all mac-specific information
*
* I coded this extra-field only for testing purposes.
* I don't want support this extra-field. Please use my implementation.
*
* This is old implementation of Johnny Lee's extra field.
* All native datas are in Motorola (=big-endian) format
*/

static void make_extrafield_JLEE(char *ef)
{

    Assert_it(ef, "make_extrafield_JLEE","")

    if (MacZip.isMacStatValid == false)
        {
        fprintf(stderr,"Internal Logic Error: [%d/%s] MacStat is out of sync !",
                        __LINE__,__FILE__);
        exit(-1);
        }


    /*  the first two fields are in Intel little-endian format  */
    *ef++ = 0xC8;                             /* tag for this extra block */
    *ef++ = 0x07;

    *ef++ = (char)(EB_L_JLEE_LEN);            /* total data size this block */
    *ef++ = (char)((EB_L_JLEE_LEN) >> 8);

     /*  the following fields are in motorola big-endian format  */
        *ef++ = 'J';                /* extra field signature:       4 Bytes */
        *ef++ = 'L';                /* the old style extra field */
        *ef++ = 'E';
        *ef++ = 'E';

                /* Start Macintosh Finder FInfo structure   16 Bytes overall */
                                    /* Type:                        4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType);

                                    /* Creator:                     4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator);

                                     /* file Finder Flags:                2 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdFlags >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdFlags);

                                     /* Finders Icon position of a file*/
                                     /* V/Y-Position:                2 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdLocation.v >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdLocation.v);
                                     /* H/X-Position:                2 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdLocation.h >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdLocation.h);

                               /* fdFldr Folder containing file    2 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdFldr >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdFldr);
                /* End Macintosh Finder FInfo structure */


                                                  /* Creation-time  4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlCrDat >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlCrDat >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlCrDat >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlCrDat);

                                              /* Modification-time  4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlMdDat >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlMdDat >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlMdDat >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlMdDat);

                                     /* info Bits                    4 Bytes */
    *ef++ = 0x00;
    *ef++ = 0x00;
    *ef++ = 0x00;
    if (MacZip.DataForkOnly)
        {          /* don't convert filename for unzipping */
                   /* 0x01 = data-fork; 0x00 = resource-fork */
        *ef++ = (char) (MacZip.CurrentFork == DataFork) | 2;
        }
    else
        {
        *ef++ = (char) (MacZip.CurrentFork == DataFork);
        }

                                  /* file's location folder ID  4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlParID >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlParID >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlParID >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlParID);
                                                          /* ============  */
                                                          /*     40 Bytes  */
}



/*
* Build and add the new mac extra field
* All native data are stored in Intel (=little-endian) format
*/

static int add_MAC3_ef( struct zlist far *z )
{
    char *l_ef        = NULL;
    char *c_ef        = NULL;
    char *attrbuff    = NULL;
    off_t attrsize    = (EB_L_MAC3_FINFO_LEN + EB_MAX_OF_VARDATA);
    char *compbuff    = NULL;
    unsigned compsize = 0;
    unsigned m3_compr;
    Boolean compress_data = true;

    Assert_it(z, "add_MAC3_ef","")

    UserStop();  /* do event handling and let the user stop */

    if( verbose ) {
        print_extra_info();
    }

    /* allocate temporary buffer to collect the Mac extra field info */
    attrbuff = (char *)malloc( (size_t)attrsize );
    if( attrbuff == NULL ) {
        return ZE_MEM;
    }

    /* fill the attribute buffer, to get its (uncompressed) size */
    attrsize = make_extrafield_MAC3(attrbuff);

    if (compress_data &&
        ((compbuff = (char *)malloc((size_t)attrsize + MEMCOMPRESS_OVERHEAD))
         != NULL))
        {
        /* Try compressing the data */
        compsize = memcompress( compbuff,
                                (size_t)attrsize + MEMCOMPRESS_OVERHEAD,
                                attrbuff,
                                (size_t)attrsize );
#ifdef MAC_EXTRAFLD_UNCMPR
        compsize = attrsize;
#endif
        }
    else
        {
        compsize = attrsize;
        }

    if ((compsize) < attrsize) {
        /* compression gained some space ... */
        free(attrbuff);         /* no longer needed ... */
        m3_compr = EB_M3_FL_COMPRESS;
    } else {
        /* compression does not help, store data in uncompressed mode */
        if (compbuff != NULL) free(compbuff);
        compbuff = attrbuff;
        compsize = attrsize;
        m3_compr = EB_M3_FL_UNCMPR;
    }

    /* Check to make sure we've got enough room in the extra fields. */
    if( z->ext + (EB_L_MAC3_SIZE + compsize) > EXTRAFLD_MAX ||
        z->cext + EB_C_MAC3_SIZE > EXTRAFLD_MAX ) {
        if (compbuff != NULL) free(compbuff);
        return ZE_MEM;
    }

    /* Allocate memory for the local extra fields. */
    if( z->extra && z->ext != 0 ) {
        l_ef = (char *)realloc( z->extra, z->ext +
                                EB_L_MAC3_SIZE + compsize);
    } else {
        l_ef = (char *)malloc( EB_L_MAC3_SIZE + compsize);
        z->ext = 0;
    }
    if( l_ef == NULL ) {
        return ZE_MEM;
    }
    z->extra = l_ef;
    l_ef += z->ext;

    /* Allocate memory for the  central extra fields. */
    if( z->cextra && z->cext != 0 ) {
        c_ef = (char *)realloc( z->cextra, z->cext + EB_C_MAC3_SIZE);
    } else {
        c_ef = (char *)malloc( EB_C_MAC3_SIZE );
        z->cext = 0;
    }
    if( c_ef == NULL ) {
        return ZE_MEM;
    }
    z->cextra = c_ef;
    c_ef += z->cext;

    /**
    **  Now add the local version of the field.
    **/
    l_ef = make_EF_Head_MAC3(l_ef, compsize, (ulg)attrsize, m3_compr);
    memcpy(l_ef, compbuff, (size_t)compsize);
    l_ef += compsize;
    z->ext += EB_L_MAC3_SIZE + compsize;
    free(compbuff);
    /* And the central version. */
    c_ef = make_EF_Head_MAC3(c_ef, 0, (ulg)attrsize, m3_compr);
    z->cext += EB_C_MAC3_SIZE;

    return ZE_OK;
}




/*
* Build the new mac local extra field header.
* It's identical with the central extra field.
* All native data are in Intel (=little-endian) format
*/
static char *make_EF_Head_MAC3(char *ef, unsigned compsize, ulg attrsize,
                               unsigned flag)
{
    unsigned info_flag = flag;

    Assert_it(ef, "make_EF_Head_MAC3","")

    /*  the first four fields are in Intel little-endian format  */
    *ef++ = 'M';         /* tag for this extra block               2 Bytes */
    *ef++ = '3';

                                  /* total data size this block    2 Bytes */
    *ef++ = (char) (EB_MAC3_HLEN + compsize);
    *ef++ = (char)((EB_MAC3_HLEN + compsize) >> 8);

    *ef++ = (char)(attrsize);
    *ef++ = (char)(attrsize >> 8);
    *ef++ = (char)(attrsize >> 16);
    *ef++ = (char)(attrsize >> 24);

                                   /* info Bits  (flags)           2 Bytes */

    if (MacZip.DataForkOnly)            info_flag |= (EB_M3_FL_DATFRK |
                                                      EB_M3_FL_NOCHANGE);
    if (MacZip.CurrentFork == DataFork) info_flag |= EB_M3_FL_DATFRK;
    if (!MacZip.HaveGMToffset)          info_flag |= EB_M3_FL_NOUTC;

    *ef++ = (char)info_flag;
    *ef++ = (char)0x00;            /* reserved at the moment */

 /* Note: Apple defined File-Type/-Creator as OSType ( =unsigned long,
          see Universal Headers 3.1). However, File-Type/-Creator are a
          unique four-character sequence. Therefore the byteorder of the
          File-Type/-Creator are NOT changed. The native format is used.  */

                                                       /* Type:    4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdType);

                                                       /* Creator: 4 Bytes */
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator >> 24);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator >> 16);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator >> 8);
    *ef++ = (char)(MacZip.fpb.hFileInfo.ioFlFndrInfo.fdCreator);