fileio.c

给出了 zip 压缩算法的完整实现过程。

int h;                  /* hour */
int m;                  /* minute */
int s;                  /* second */
/* Convert the date y/n/d and time h:m:s to a four byte DOS date and
   time (date in high two bytes, time in low two bytes allowing magnitude
   comparison). */
{
  return y < 1980 ? DOSTIME_MINIMUM /* dostime(1980, 1, 1, 0, 0, 0) */ :
        (((ulg)y - 1980) << 25) | ((ulg)n << 21) | ((ulg)d << 16) |
        ((ulg)h << 11) | ((ulg)m << 5) | ((ulg)s >> 1);
}


ulg unix2dostime(t)
time_t *t;              /* unix time to convert */
/* Return the Unix time t in DOS format, rounded up to the next two
   second boundary. */
{
  time_t t_even;
  struct tm *s;         /* result of localtime() */

  t_even = (time_t)(((unsigned long)(*t) + 1) & (~1));
                                /* Round up to even seconds. */
  s = localtime(&t_even);       /* Use local time since MSDOS does. */
  if (s == (struct tm *)NULL) {
      /* time conversion error; use current time as emergency value
         (assuming that localtime() does at least accept this value!) */
      t_even = (time_t)(((unsigned long)time(NULL) + 1) & (~1));
      s = localtime(&t_even);
  }
  return dostime(s->tm_year + 1900, s->tm_mon + 1, s->tm_mday,
                 s->tm_hour, s->tm_min, s->tm_sec);
}

int issymlnk(a)
ulg a;                  /* Attributes returned by filetime() */
/* Return true if the attributes are those of a symbolic link */
{
#ifndef QDOS
#ifdef S_IFLNK
#ifdef __human68k__
  int *_dos_importlnenv(void);

  if (_dos_importlnenv() == NULL)
    return 0;
#endif
  return ((a >> 16) & S_IFMT) == S_IFLNK;
#else /* !S_IFLNK */
  return (int)a & 0;    /* avoid warning on unused parameter */
#endif /* ?S_IFLNK */
#else
  return 0;
#endif
}

#endif /* !UTIL */


#if (!defined(UTIL) && !defined(ZP_NEED_GEN_D2U_TIME))
   /* There is no need for dos2unixtime() in the ZipUtils' code. */
#  define ZP_NEED_GEN_D2U_TIME
#endif
#if ((defined(OS2) || defined(VMS)) && defined(ZP_NEED_GEN_D2U_TIME))
   /* OS/2 and VMS use a special solution to handle time-stams of files. */
#  undef ZP_NEED_GEN_D2U_TIME
#endif
#if (defined(W32_STATROOT_FIX) && !defined(ZP_NEED_GEN_D2U_TIME))
   /* The Win32 stat()-bandaid to fix stat'ing root directories needs
    * dos2unixtime() to calculate the time-stamps. */
#  define ZP_NEED_GEN_D2U_TIME
#endif

#ifdef ZP_NEED_GEN_D2U_TIME

time_t dos2unixtime(dostime)
ulg dostime;            /* DOS time to convert */
/* Return the Unix time_t value (GMT/UTC time) for the DOS format (local)
 * time dostime, where dostime is a four byte value (date in most significant
 * word, time in least significant word), see dostime() function.
 */
{
  struct tm *t;         /* argument for mktime() */
  ZCONST time_t clock = time(NULL);

  t = localtime(&clock);
  t->tm_isdst = -1;     /* let mktime() determine if DST is in effect */
  /* Convert DOS time to UNIX time_t format */
  t->tm_sec  = (((int)dostime) <<  1) & 0x3e;
  t->tm_min  = (((int)dostime) >>  5) & 0x3f;
  t->tm_hour = (((int)dostime) >> 11) & 0x1f;
  t->tm_mday = (int)(dostime >> 16) & 0x1f;
  t->tm_mon  = ((int)(dostime >> 21) & 0x0f) - 1;
  t->tm_year = ((int)(dostime >> 25) & 0x7f) + 80;

  return mktime(t);
}

#undef ZP_NEED_GEN_D2U_TIME
#endif /* ZP_NEED_GEN_D2U_TIME */


#ifndef MACOS
int destroy(f)
char *f;                /* file to delete */
/* Delete the file *f, returning non-zero on failure. */
{
  return unlink(f);
}


int replace(d, s)
char *d, *s;            /* destination and source file names */
/* Replace file *d by file *s, removing the old *s.  Return an error code
   in the ZE_ class. This function need not preserve the file attributes,
   this will be done by setfileattr() later.
 */
{
  struct stat t;        /* results of stat() */
#if defined(CMS_MVS)
  /* cmsmvs.h defines FOPW_TEMP as memory(hiperspace).  Since memory is
   * lost at end of run, always do copy instead of rename.
   */
  int copy = 1;
#else
  int copy = 0;
#endif
  int d_exists;

#if defined(VMS) || defined(CMS_MVS)
  /* stat() is broken on VMS remote files (accessed through Decnet).
   * This patch allows creation of remote zip files, but is not sufficient
   * to update them or compress remote files */
  unlink(d);
#else /* !(VMS || CMS_MVS) */
  d_exists = (LSTAT(d, &t) == 0);
  if (d_exists)
  {
    /*
     * respect existing soft and hard links!
     */
    if (t.st_nlink > 1
# ifdef S_IFLNK
        || (t.st_mode & S_IFMT) == S_IFLNK
# endif
        )
       copy = 1;
    else if (unlink(d))
       return ZE_CREAT;                 /* Can't erase zip file--give up */
  }
#endif /* ?(VMS || CMS_MVS) */
#ifndef CMS_MVS
  if (!copy) {
      if (rename(s, d)) {               /* Just move s on top of d */
          copy = 1;                     /* failed ? */
#if !defined(VMS) && !defined(ATARI) && !defined(AZTEC_C)
#if !defined(CMS_MVS) && !defined(RISCOS) && !defined(QDOS)
    /* For VMS, ATARI, AMIGA Aztec, VM_CMS, MVS, RISCOS,
       always assume that failure is EXDEV */
          if (errno != EXDEV
#  ifdef THEOS
           && errno != EEXIST
#  else
#    ifdef ENOTSAM
           && errno != ENOTSAM /* Used at least on Turbo C */
#    endif
#  endif
              ) return ZE_CREAT;
#endif /* !CMS_MVS && !RISCOS */
#endif /* !VMS && !ATARI && !AZTEC_C */
      }
  }
#endif /* !CMS_MVS */

  if (copy) {
    FILE *f, *g;        /* source and destination files */
    int r;              /* temporary variable */

#ifdef RISCOS
    if (SWI_OS_FSControl_26(s,d,0xA1)!=NULL) {
#endif

    if ((f = fopen(s, FOPR)) == NULL) {
      fprintf(stderr," replace: can't open %s\n", s);
      return ZE_TEMP;
    }
    if ((g = fopen(d, FOPW)) == NULL)
    {
      fclose(f);
      return ZE_CREAT;
    }
    r = fcopy(f, g, (ulg)-1L);
    fclose(f);
    if (fclose(g) || r != ZE_OK)
    {
      unlink(d);
      return r ? (r == ZE_TEMP ? ZE_WRITE : r) : ZE_WRITE;
    }
    unlink(s);
#ifdef RISCOS
    }
#endif
  }
  return ZE_OK;
}
#endif /* !MACOS */


int getfileattr(f)
char *f;                /* file path */
/* Return the file attributes for file f or 0 if failure */
{
#ifdef __human68k__
  struct _filbuf buf;

  return _dos_files(&buf, f, 0xff) < 0 ? 0x20 : buf.atr;
#else
  struct stat s;

  return SSTAT(f, &s) == 0 ? (int) s.st_mode : 0;
#endif
}


int setfileattr(f, a)
char *f;                /* file path */
int a;                  /* attributes returned by getfileattr() */
/* Give the file f the attributes a, return non-zero on failure */
{
#if defined(TOPS20) || defined (CMS_MVS)
  return 0;
#else
#ifdef __human68k__
  return _dos_chmod(f, a) < 0 ? -1 : 0;
#else
  return chmod(f, a);
#endif
#endif
}

#ifndef VMS /* VMS-specific function is in VMS.C. */

char *tempname(zip)
char *zip;              /* path name of zip file to generate temp name for */

/* Return a temporary file name in its own malloc'ed space, using tempath. */
{
  char *t = zip;   /* malloc'ed space for name (use zip to avoid warning) */

#ifdef CMS_MVS
  if ((t = malloc(strlen(tempath)+L_tmpnam+2)) == NULL)
    return NULL;
#  ifdef VM_CMS
  tmpnam(t);
  /* Remove filemode and replace with tempath, if any. */
  /* Otherwise A-disk is used by default */
  *(strrchr(t, ' ')+1) = '\0';
  if (tempath!=NULL)
     strcat(t, tempath);
  return t;
#  else   /* !VM_CMS */
  /* For MVS */
  tmpnam(t);
  if (tempath != NULL)
  {
    int l1 = strlen(t);
    char *dot;
    if (*t == '\'' && *(t+l1-1) == '\'' && (dot = strchr(t, '.')))
    {
      /* MVS and not OE.  tmpnam() returns quoted string of 5 qualifiers.
       * First is HLQ, rest are timestamps.  User can only replace HLQ.
       */
      int l2 = strlen(tempath);
      if (strchr(tempath, '.') || l2 < 1 || l2 > 8)
        ziperr(ZE_PARMS, "On MVS and not OE, tempath (-b) can only be HLQ");
      memmove(t+1+l2, dot, l1+1-(dot-t));  /* shift dot ready for new hlq */
      memcpy(t+1, tempath, l2);            /* insert new hlq */
    }
    else
    {
      /* MVS and probably OE.  tmpnam() returns filename based on TMPDIR,
       * no point in even attempting to change it.  User should modify TMPDIR
       * instead.
       */
      zipwarn("MVS, assumed to be OE, change TMPDIR instead of option -b: ",
              tempath);
    }
  }
  return t;
#  endif  /* !VM_CMS */
#else /* !CMS_MVS */
#ifdef TANDEM
  char cur_subvol [FILENAME_MAX];
  char temp_subvol [FILENAME_MAX];
  char *zptr;
  char *ptr;
  char *cptr = &cur_subvol[0];
  char *tptr = &temp_subvol[0];
  short err;
  FILE *tempf;
  int attempts;

  t = (char *)malloc(NAMELEN); /* malloc here as you cannot free */
                               /* tmpnam allocated storage later */

  zptr = strrchr(zip, TANDEM_DELIMITER);

  if (zptr != NULL) {
    /* ZIP file specifies a Subvol so make temp file there so it can just
       be renamed at end */

    *tptr = *cptr = '\0';
    strcat(cptr, getenv("DEFAULTS"));

    strncat(tptr, zip, _min(FILENAME_MAX, (zptr - zip)) ); /* temp subvol */
    strncat(t, zip, _min(NAMELEN, ((zptr - zip) + 1)) );   /* temp stem   */

    err = chvol(tptr);
    ptr = t + strlen(t);  /* point to end of stem */
  }
  else
    ptr = t;

  /* If two zips are running in same subvol then we can get contention problems
     with the temporary filename.  As a work around we attempt to create
     the file here, and if it already exists we get a new temporary name */

  attempts = 0;
  do {
    attempts++;
    tmpnam(ptr);  /* Add filename */
    tempf = fopen(ptr, FOPW_TMP);    /* Attempt to create file */
  } while (tempf == NULL && attempts < 100);

  if (attempts >= 100) {
    ziperr(ZE_TEMP, "Could not get unique temp file name");
  }
  fclose(tempf);

  if (zptr != NULL) {
    err = chvol(cptr);  /* Put ourself back to where we came in */
  }

  return t;

#else /* !CMS_MVS && !TANDEM */
/*
 * Do something with TMPDIR, TMP, TEMP ????
 */
  if (tempath != NULL)
  {
    if ((t = malloc(strlen(tempath)+12)) == NULL)
      return NULL;
    strcpy(t, tempath);
#if (!defined(VMS) && !defined(TOPS20))
#  ifdef MSDOS
    {
      char c = (char)lastchar(t);
      if (c != '/' && c != ':' && c != '\\')
        strcat(t, "/");
    }
#  else
#    ifdef AMIGA
    {
      char c = (char)lastchar(t);
      if (c != '/' && c != ':')
        strcat(t, "/");
    }
#    else /* !AMIGA */
#      ifdef RISCOS
    if (lastchar(t) != '.')
      strcat(t, ".");
#      else /* !RISCOS */
#        ifdef QDOS
    if (lastchar(t) != '_')
      strcat(t, "_");
#        else
    if (lastchar(t) != '/')
      strcat(t, "/");
#        endif /* ?QDOS */
#      endif /* ?RISCOS */
#    endif  /* ?AMIGA */
#  endif /* ?MSDOS */
#endif /* !VMS && !TOPS20 */
  }
  else
  {
    if ((t = malloc(12)) == NULL)
      return NULL;
    *t = 0;
  }
#ifdef NO_MKTEMP
  {
    char *p = t + strlen(t);
    sprintf(p, "%08lx", (ulg)time(NULL));
    return t;
  }
#else
  strcat(t, "ziXXXXXX"); /* must use lowercase for Linux dos file system */
  return mktemp(t);
#endif /* NO_MKTEMP */
#endif /* TANDEM */
#endif /* CMS_MVS */
}

#endif /* !VMS */

int fcopy(f, g, n)
FILE *f, *g;            /* source and destination files */
ulg n;                  /* number of bytes to copy or -1 for all */
/* Copy n bytes from file *f to file *g, or until EOF if (long)n == -1.
   Return an error code in the ZE_ class. */
{
  char *b;              /* malloc'ed buffer for copying */
  extent k;             /* result of fread() */
  ulg m;                /* bytes copied so far */

  if ((b = malloc(CBSZ)) == NULL)
    return ZE_MEM;
  m = 0;
  while (n == (ulg)(-1L) || m < n)
  {
    if ((k = fread(b, 1, n == (ulg)(-1) ?
                   CBSZ : (n - m < CBSZ ? (extent)(n - m) : CBSZ), f)) == 0)
    {
      if (ferror(f))
      {
        free((zvoid *)b);
        return ZE_READ;
      }
      else
        break;
    }
    if (fwrite(b, 1, k, g) != k)
    {
      free((zvoid *)b);
      fprintf(stderr," fcopy: write error\n");
      return ZE_TEMP;
    }
    m += k;
  }
  free((zvoid *)b);
  return ZE_OK;
}

#ifdef NO_RENAME
int rename(from, to)
ZCONST char *from;
ZCONST char *to;
{
    unlink(to);
    if (link(from, to) == -1)
        return -1;
    if (unlink(from) == -1)
        return -1;
    return 0;
}

#endif /* NO_RENAME */


#ifdef ZMEM

/************************/
/*  Function memset()   */
/************************/

/*
 * memset - for systems without it
 *  bill davidsen - March 1990
 */

char *
memset(buf, init, len)
register char *buf;     /* buffer loc */
register int init;      /* initializer */
register unsigned int len;   /* length of the buffer */
{
    char *start;

    start = buf;
    while (len--) *(buf++) = init;
    return(start);
}


/************************/
/*  Function memcpy()   */
/************************/

char *
memcpy(dst,src,len)             /* v2.0f */
register char *dst, *src;
register unsigned int len;
{
    char *start;

    start = dst;
    while (len--)
        *dst++ = *src++;
    return(start);
}


/************************/
/*  Function memcmp()   */
/************************/

int
memcmp(b1,b2,len)                     /* [e-mail] -- 11/16/90 */
register char *b1, *b2;
register unsigned int len;
{

    if (len) do {       /* examine each byte (if any) */
      if (*b1++ != *b2++)
        return (*((uch *)b1-1) - *((uch *)b2-1));  /* exit when miscompare */
    } while (--len);

    return(0);          /* no miscompares, yield 0 result */
}

#endif  /* ZMEM */