zipcloak.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 2005-Feb-10 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
*/
#define __ZIPCLOAK_C

#ifndef UTIL
#define UTIL
#endif
#include "zip.h"
#define DEFCPYRT        /* main module: enable copyright string defines! */
#include "revision.h"
#include "crypt.h"
#include "ttyio.h"
#include <signal.h>
#ifndef NO_STDLIB_H
#  include <stdlib.h>
#endif

#if CRYPT       /* defined (as TRUE or FALSE) in crypt.h */

int main OF((int argc, char **argv));

local void handler OF((int sig));
local void license OF((void));
local void help OF((void));
local void version_info OF((void));

/* Temporary zip file name and file pointer */
local char *tempzip;
local FILE *tempzf;

/* Pointer to CRC-32 table (used for decryption/encryption) */
#if (!defined(USE_ZLIB) || defined(USE_OWN_CRCTAB))
ZCONST ulg near *crc_32_tab;
#else
ZCONST uLongf *crc_32_tab;
#endif

/***********************************************************************
 * Issue a message for the error, clean up files and memory, and exit.
 */
void ziperr(code, msg)
    int code;               /* error code from the ZE_ class */
    ZCONST char *msg;       /* message about how it happened */
{
    if (PERR(code)) perror("zipcloak error");
    fprintf(stderr, "zipcloak error: %s (%s)\n", ziperrors[code-1], msg);
    if (tempzf != NULL) fclose(tempzf);
    if (tempzip != NULL) {
        destroy(tempzip);
        free((zvoid *)tempzip);
    }
    if (zipfile != NULL) free((zvoid *)zipfile);
    EXIT(code);
}

/***********************************************************************
 * Print a warning message to stderr and return.
 */
void zipwarn(msg1, msg2)
    ZCONST char *msg1, *msg2;   /* message strings juxtaposed in output */
{
    fprintf(stderr, "zipcloak warning: %s%s\n", msg1, msg2);
}


/***********************************************************************
 * Upon getting a user interrupt, turn echo back on for tty and abort
 * cleanly using ziperr().
 */
local void handler(sig)
    int sig;                  /* signal number (ignored) */
{
#if (!defined(MSDOS) && !defined(__human68k__) && !defined(RISCOS))
    echon();
    putc('\n', stderr);
#endif
    ziperr(ZE_ABORT +sig-sig, "aborting");
    /* dummy usage of sig to avoid compiler warnings */
}


/***********************************************************************
 * Print license information to stdout.
 */
local void license()
{
    extent i;

    for (i = 0; i < sizeof(swlicense)/sizeof(char *); i++)
        puts(swlicense[i]);
    putchar('\n');
}


static ZCONST char *help_info[] = {
"",
"ZipCloak %s (%s)",
#ifdef VM_CMS
"Usage:  zipcloak [-dq] [-b fm] zipfile",
#else
"Usage:  zipcloak [-dq] [-b path] zipfile",
#endif
"  the default action is to encrypt all unencrypted entries in the zip file",
"  -d   decrypt--decrypt encrypted entries (copy if given wrong password)",
#ifdef VM_CMS
"  -b   use \"fm\" as the filemode for the temporary zip file",
#else
"  -b   use \"path\" for the temporary zip file",
#endif
"  -q   quieter operation, suppress some informational messages",
"  -h   show this help    -v   show version info    -L   show software license"
  };

/***********************************************************************
 * Print help (along with license info) to stdout.
 */
local void help()
{
    extent i;             /* counter for help array */

    for (i = 0; i < sizeof(help_info)/sizeof(char *); i++) {
        printf(help_info[i], VERSION, REVDATE);
        putchar('\n');
    }
}


local void version_info()
/* Print verbose info about program version and compile time options
   to stdout. */
{
  extent i;             /* counter in text arrays */

  /* Options info array */
  static ZCONST char *comp_opts[] = {
#ifdef DEBUG
    "DEBUG",
#endif
#if CRYPT && defined(PASSWD_FROM_STDIN)
    "PASSWD_FROM_STDIN",
#endif /* CRYPT && PASSWD_FROM_STDIN */
    NULL
  };

  for (i = 0; i < sizeof(copyright)/sizeof(char *); i++)
  {
    printf(copyright[i], "zipcloak");
    putchar('\n');
  }

  for (i = 0; i < sizeof(versinfolines)/sizeof(char *); i++)
  {
    printf(versinfolines[i], "ZipCloak", VERSION, REVDATE);
    putchar('\n');
  }

  version_local();

  puts("ZipCloak special compilation options:");
  for (i = 0; (int)i < (int)(sizeof(comp_opts)/sizeof(char *) - 1); i++)
  {
    printf("\t%s\n",comp_opts[i]);
  }
  printf("\t[encryption, version %d.%d%s of %s]\n",
            CR_MAJORVER, CR_MINORVER, CR_BETA_VER, CR_VERSION_DATE);

  for (i = 0; i < sizeof(cryptnote)/sizeof(char *); i++)
      puts(cryptnote[i]);
}


/***********************************************************************
 * Encrypt or decrypt all of the entries in a zip file.  See the command
 * help in help() above.
 */

int main(argc, argv)
    int argc;                   /* number of tokens in command line */
    char **argv;                /* command line tokens */
{
    int attr;                   /* attributes of zip file */
    ulg start_offset;           /* start of central directory */
    int decrypt;                /* decryption flag */
    int temp_path;              /* 1 if next argument is path for temp files */
    char passwd[IZ_PWLEN+1];    /* password for encryption or decryption */
    char verify[IZ_PWLEN+1];    /* password for encryption or decryption */
    char *q;                    /* steps through option arguments */
    int r;                      /* arg counter */
    int res;                    /* result code */
    ulg length;                 /* length of central directory */
    FILE *inzip, *outzip;       /* input and output zip files */
    struct zlist far *z;        /* steps through zfiles linked list */

#ifdef THEOS
    setlocale(LC_CTYPE, "I");
#endif

    /* If no args, show help */
    if (argc == 1) {
        help();
        EXIT(ZE_OK);
    }

    /* Informational messages are written to stdout. */
    mesg = stdout;

    init_upper();               /* build case map table */

    crc_32_tab = get_crc_table();
                                /* initialize crc table for crypt */

    /* Go through args */
    zipfile = tempzip = NULL;
    tempzf = NULL;
#ifdef SIGINT
    signal(SIGINT, handler);
#endif
#ifdef SIGTERM                  /* Some don't have SIGTERM */
    signal(SIGTERM, handler);
#endif
#ifdef SIGABRT
    signal(SIGABRT, handler);
#endif
#ifdef SIGBREAK
    signal(SIGBREAK, handler);
#endif
#ifdef SIGBUS
    signal(SIGBUS, handler);
#endif
#ifdef SIGILL
    signal(SIGILL, handler);
#endif
#ifdef SIGSEGV
    signal(SIGSEGV, handler);
#endif
    temp_path = decrypt = 0;
    for (r = 1; r < argc; r++) {
        if (*argv[r] == '-') {
            if (!argv[r][1]) ziperr(ZE_PARMS, "zip file cannot be stdin");
            for (q = argv[r]+1; *q; q++) {
                switch (*q) {
                case 'b':   /* Specify path for temporary file */
                    if (temp_path) {
                        ziperr(ZE_PARMS, "use -b before zip file name");
                    }
                    temp_path = 1;          /* Next non-option is path */
                    break;
                case 'd':
                    decrypt = 1;  break;
                case 'h':   /* Show help */
                    help();
                    EXIT(ZE_OK);
                case 'l': case 'L':  /* Show copyright and disclaimer */
                    license();
                    EXIT(ZE_OK);
                case 'q':   /* Quiet operation, suppress info messages */
                    noisy = 0;  break;
                case 'v':   /* Show version info */
                    version_info();
                    EXIT(ZE_OK);
                default:
                    ziperr(ZE_PARMS, "unknown option");
                } /* switch */
            } /* for */

        } else if (temp_path == 0) {
            if (zipfile != NULL) {
                ziperr(ZE_PARMS, "can only specify one zip file");

            } else if ((zipfile = ziptyp(argv[r])) == NULL) {
                ziperr(ZE_MEM, "was processing arguments");
            }
        } else {
            tempath = argv[r];
            temp_path = 0;
        } /* if */
    } /* for */

    if (zipfile == NULL) ziperr(ZE_PARMS, "need to specify zip file");

    /* Read zip file */
    if ((res = readzipfile()) != ZE_OK) ziperr(res, zipfile);
    if (zfiles == NULL) ziperr(ZE_NAME, zipfile);

    /* Check for something to do */
    for (z = zfiles; z != NULL; z = z->nxt) {
        if (decrypt ? z->flg & 1 : !(z->flg & 1)) break;
    }
    if (z == NULL) {
        ziperr(ZE_NONE, decrypt ? "no encrypted files"
                       : "all files encrypted already");
    }

    /* Before we get carried away, make sure zip file is writeable */
    if ((inzip = fopen(zipfile, "a")) == NULL) ziperr(ZE_CREAT, zipfile);
    fclose(inzip);
    attr = getfileattr(zipfile);

    /* Open output zip file for writing */
    if ((tempzf = outzip = fopen(tempzip = tempname(zipfile), FOPW)) == NULL) {
        ziperr(ZE_TEMP, tempzip);
    }

    /* Get password */
    if (getp("Enter password: ", passwd, IZ_PWLEN+1) == NULL)
        ziperr(ZE_PARMS,
               "stderr is not a tty (you may never see this message!)");

    if (decrypt == 0) {
        if (getp("Verify password: ", verify, IZ_PWLEN+1) == NULL)
               ziperr(ZE_PARMS,
                      "stderr is not a tty (you may never see this message!)");

        if (strcmp(passwd, verify))
               ziperr(ZE_PARMS, "password verification failed");

        if (*passwd == '\0')
               ziperr(ZE_PARMS, "zero length password not allowed");
    }

    /* Open input zip file again, copy preamble if any */
    if ((inzip = fopen(zipfile, FOPR)) == NULL) ziperr(ZE_NAME, zipfile);

    if (zipbeg && (res = fcopy(inzip, outzip, zipbeg)) != ZE_OK) {
        ziperr(res, res == ZE_TEMP ? tempzip : zipfile);
    }
    tempzn = zipbeg;

    /* Go through local entries, copying, encrypting, or decrypting */
    for (z = zfiles; z != NULL; z = z->nxt) {
        if (decrypt && (z->flg & 1)) {
            printf("decrypting: %s", z->zname);
            fflush(stdout);
            if ((res = zipbare(z, inzip, outzip, passwd)) != ZE_OK) {
                if (res != ZE_MISS) ziperr(res, "was decrypting an entry");
                printf(" (wrong password--just copying)");
            }
            putchar('\n');

        } else if ((!decrypt) && !(z->flg & 1)) {
            printf("encrypting: %s\n", z->zname);
            fflush(stdout);
            if ((res = zipcloak(z, inzip, outzip, passwd)) != ZE_OK) {
                ziperr(res, "was encrypting an entry");
            }
        } else {
            printf("   copying: %s\n", z->zname);
            fflush(stdout);
            if ((res = zipcopy(z, inzip, outzip)) != ZE_OK) {
                ziperr(res, "was copying an entry");
            }
        } /* if */
    } /* for */
    fclose(inzip);

    /* Write central directory and end of central directory */

    /* get start of central */
    if ((start_offset = (ulg)ftell(outzip)) == (ulg)-1L)
        ziperr(ZE_TEMP, tempzip);

    for (z = zfiles; z != NULL; z = z->nxt) {
        if ((res = putcentral(z, outzip)) != ZE_OK) ziperr(res, tempzip);
    }

    /* get end of central */
    if ((length = (ulg)ftell(outzip)) == (ulg)-1L)
        ziperr(ZE_TEMP, tempzip);

    length -= start_offset;               /* compute length of central */
    if ((res = putend((int)zcount, length, start_offset, zcomlen,
                       zcomment, outzip)) != ZE_OK) {
        ziperr(res, tempzip);
    }
    tempzf = NULL;
    if (fclose(outzip)) ziperr(ZE_TEMP, tempzip);
    if ((res = replace(zipfile, tempzip)) != ZE_OK) {
        zipwarn("new zip file left as: ", tempzip);
        free((zvoid *)tempzip);
        tempzip = NULL;
        ziperr(res, "was replacing the original zip file");
    }
    free((zvoid *)tempzip);
    tempzip = NULL;
    setfileattr(zipfile, attr);
#ifdef RISCOS
    /* Set the filetype of the zipfile to &DDC */
    setfiletype(zipfile, 0xDDC);
#endif
    free((zvoid *)zipfile);
    zipfile = NULL;

    /* Done! */
    RETURN(0);
}
#else /* !CRYPT */

int main OF((void));

void zipwarn(msg1, msg2)
ZCONST char  *msg1, *msg2;
{
    /* Tell picky compilers to shut up about unused variables */
    msg1 = msg1; msg2 = msg2;
}

void ziperr(c, h)
int  c;
ZCONST char *h;
{
    /* Tell picky compilers to shut up about unused variables */
    c = c; h = h;
}

int main()
{
    fprintf(stderr, "\
This version of ZipCloak does not support encryption.  Get the current Zip\n\
source distribution and recompile ZipCloak after you have added an option to\n\
define the symbol USE_CRYPT to the C compiler's command arguments.\n");
    RETURN(1);
}

#endif /* ?CRYPT */