Subversion Repositories SvarDOS

/*

 * This file is part of pkg (SvarDOS)

 * Copyright (C) 2012-2024 Mateusz Viste.

 *

 * Simple library providing functions to unzip files from zip archives.

 */

#include <stdio.h>     /* printf(), FILE, fclose()... */

#include <stdlib.h>    /* NULL */

#include <string.h>    /* memset() */

#include <time.h>      /* mktime() */

#include <utime.h>     /* utime() */

#include <unistd.h>   /* unlink() */

#include "crc32.h"

#include "helpers.h"

#include "inf.h"   /* INFLATE support */

#include "svarlang.lib/svarlang.h"

#include "libunzip.h"  /* include self for control */

/* converts a "DOS format" timestamp into unix timestamp. The DOS timestamp is constructed an array of 4 bytes, that contains following data at the bit level:

 * HHHHHMMM MMMSSSSS YYYYYYYM MMMDDDDD

 *  where:

 * day of month is always within 1-31 range;

 * month is always within 1-12 range;

 * year starts from 1980 and continues for 127 years

 * seconds are actually not 0-59 but rather 0-29 as there are only 32 possible values – to get actual seconds multiply this field by 2;

 * minutes are always within 0-59 range;

 * hours are always within 0-23 range.     */

static time_t dostime2unix(const unsigned char *buff) {

  struct tm curtime;

  time_t result;

  memset(&curtime, 0, sizeof(curtime)); /* make sure to set everything in curtime to 0's */

  curtime.tm_sec = (buff[0] & 31) << 1; /* seconds (0..60) */

  curtime.tm_min = (((buff[1] << 8) | buff[0]) >> 5) & 63 ; /* minutes after the hour (0..59) */

  curtime.tm_hour = (buff[1] >> 3); /* hours since midnight (0..23) */

  curtime.tm_mday = buff[2] & 31; /* day of the month (1..31) */

  curtime.tm_mon = ((((buff[3] << 8) | buff[2]) >> 5) & 15) - 1; /* months since January (0, 11) */

  curtime.tm_year = (buff[3] >> 1) + 80; /* years since 1900 */

  curtime.tm_wday = 0; /* days since Sunday (0..6) - leave 0, mktime() will set it */

  curtime.tm_yday = 0; /* days since January 1 (0..365]) - leave 0, mktime() will set it */

  curtime.tm_isdst = -1; /* Daylight Saving Time flag. Positive if DST is in effect, zero if not and negative if no information is available */

  result = mktime(&curtime);

  if (result == (time_t)-1) return(0);

  return(result);

}

/* opens a zip file and provides the list of files in the archive.

   returns a pointer to a ziplist (linked list) with all records, or NULL on error.

   The ziplist is allocated automatically, and must be freed via zip_freelist. */

struct ziplist *zip_listfiles(FILE *fd) {

  struct ziplist *reslist = NULL;

  struct ziplist *newentry;

  unsigned long entrysig;

  unsigned short filenamelen, extrafieldlen, filecommentlen;

  unsigned long compfilelen;

  int centraldirectoryfound = 0;

  unsigned int ux;

  unsigned char hdrbuff[64];

  rewind(fd);  /* make sure the file cursor is at the very beginning of the file */

  for (;;) { /* read entry after entry */

    int x, eofflag;

    long longbuff;

    entrysig = 0;

    eofflag = 0;

    /* read the entry signature first */

    for (x = 0; x < 32; x += 8) {

      if ((longbuff = fgetc(fd)) == EOF) {

        eofflag = 1;

        break;

      }

      entrysig |= (longbuff << x);

    }

    if (eofflag != 0) break;

    /* printf("sig: 0x%08x\n", entrysig); */

    if (entrysig == 0x04034b50ul) { /* local file */

      unsigned int generalpurposeflags;

      /* read and parse the zip header */

      fread(hdrbuff, 1, 26, fd);

      /* read filename's length so I can allocate the proper amound of mem */

      filenamelen = hdrbuff[23];

      filenamelen <<= 8;

      filenamelen |= hdrbuff[22];

      /* create new entry and link it into the list */

      newentry = calloc(sizeof(struct ziplist) + filenamelen, 1);

      if (newentry == NULL) {

        outputnl(svarlang_str(2,14)); /* Out of memory! */

        zip_freelist(&reslist);

        break;

      }

      newentry->nextfile = reslist;

      newentry->flags = 0;

      reslist = newentry;

      /* read further areas of the header, and fill zip entry */

      generalpurposeflags = hdrbuff[3];  /* parse the general */

      generalpurposeflags <<= 8;         /* purpose flags and */

      generalpurposeflags |= hdrbuff[2]; /* save them for later */

      newentry->compmethod = hdrbuff[4] | (hdrbuff[5] << 8);

      newentry->timestamp = dostime2unix(&hdrbuff[6]);

      newentry->crc32 = 0;

      for (x = 13; x >= 10; x--) {

        newentry->crc32 <<= 8;

        newentry->crc32 |= hdrbuff[x];

      }

      newentry->compressedfilelen = 0;

      for (x = 17; x >= 14; x--) {

        newentry->compressedfilelen <<= 8;

        newentry->compressedfilelen |= hdrbuff[x];

      }

      newentry->filelen = 0;

      for (x = 21; x >= 18; x--) {

        newentry->filelen <<= 8;

        newentry->filelen |= hdrbuff[x];

      }

      extrafieldlen = hdrbuff[25];

      extrafieldlen <<= 8;

      extrafieldlen |= hdrbuff[24];

      /* printf("Filename len: %d / extrafield len: %d / compfile len: %ld / filelen: %ld\n", filenamelen, extrafieldlen, newentry->compressedfilelen, newentry->filelen); */

      /* check general purpose flags */

      if ((generalpurposeflags & 1) != 0) newentry->flags |= ZIP_FLAG_ENCRYPTED;

      /* parse the filename */

      for (ux = 0; ux < filenamelen; ux++) newentry->filename[ux] = fgetc(fd); /* store filename */

      if (newentry->filename[filenamelen - 1] == '/') newentry->flags |= ZIP_FLAG_ISADIR; /* if filename ends with / it's a dir. Note that ZIP forbids the usage of '\' in ZIP paths anyway */

      /* printf("Filename: %s (%ld bytes compressed)\n", newentry->filename, newentry->compressedfilelen); */

      newentry->dataoffset = ftell(fd) + extrafieldlen;

      /* skip rest of fields and data */

      fseek(fd, (extrafieldlen + newentry->compressedfilelen), SEEK_CUR);

    } else if (entrysig == 0x02014b50ul) { /* central directory */

      centraldirectoryfound = 1;

      /* parse header now */

      fread(hdrbuff, 1, 42, fd);

      filenamelen = hdrbuff[22] | (hdrbuff[23] << 8);

      extrafieldlen = hdrbuff[24] | (hdrbuff[25] << 8);

      filecommentlen = hdrbuff[26] | (hdrbuff[27] << 8);

      compfilelen = 0;

      for (x = 17; x >= 14; x--) {

        compfilelen <<= 8;

        compfilelen |= hdrbuff[x];

      }

      /* printf("central dir\n"); */

      /* skip rest of fields and data */

      fseek(fd, (filenamelen + extrafieldlen + compfilelen + filecommentlen), SEEK_CUR);

    } else if (entrysig == 0x08074b50ul) { /* Data descriptor header */

      /* no need to read the header we just have to skip it */

      fseek(fd, 12, SEEK_CUR); /* the header is 3x4 bytes (CRC + compressed len + uncompressed len) */

    } else { /* unknown sig */

      zip_freelist(&reslist);

      break;

    }

  }

  /* if we got no central directory record, the file is incomplete */

  if (centraldirectoryfound == 0) zip_freelist(&reslist);

  return(reslist);

}

/* unzips a file. zipfd points to the open zip file, curzipnode to the entry to extract, and fulldestfilename is the destination file where to unzip it. returns 0 on success, non-zero otherwise. */

int zip_unzip(FILE *zipfd, struct ziplist *curzipnode, const char *fulldestfilename, unsigned char *buff15k) {

  #define buffsize (15 * 1024) /* bigger buffer is better, but pkg has to work on a 256K PC so let's not get too crazy with RAM */

  FILE *filefd;

  unsigned long cksum;

  int extract_res;

  struct utimbuf filetimestamp;

  /* first of all, check we support the compression method */

  switch (curzipnode->compmethod) {

    case ZIP_METH_STORE:

    case ZIP_METH_DEFLATE:

      break;

    default: /* unsupported compression method, sorry */

      return(-1);

      break;

  }

  /* open the dst file */

  filefd = fopen(fulldestfilename, "wb");

  if (filefd == NULL) return(-2);  /* failed to open the dst file */

  if (fseek(zipfd, curzipnode->dataoffset, SEEK_SET) != 0) { /* set the reading position inside the zip file */

    fclose(filefd);

    unlink(fulldestfilename); /* remove the failed file once it is closed */

    return(-7);

  }

  extract_res = -255;

  cksum = CRC32_INITVAL; /* init the crc32 */

  if (curzipnode->compmethod == 0) { /* if the file is stored, copy it over */

    long i, toread;

    extract_res = 0;   /* assume we will succeed */

    for (i = 0; i < curzipnode->filelen;) {

      toread = curzipnode->filelen - i;

      if (toread > buffsize) toread = buffsize;

      if (fread(buff15k, toread, 1, zipfd) != 1) extract_res = -3;   /* read a chunk of data */

      crc32_feed(&cksum, buff15k, toread); /* update the crc32 checksum */

      if (fwrite(buff15k, toread, 1, filefd) != 1) extract_res = -4; /* write data chunk to dst file */

      i += toread;

    }

  } else if (curzipnode->compmethod == 8) {  /* if the file is deflated, inflate it */

    /* use 1/3 of my buffer as input and 2/3 as output */

    extract_res = inf(zipfd, filefd, buff15k, buffsize / 3, buff15k + (buffsize / 3), buffsize / 3 * 2, &cksum, curzipnode->compressedfilelen);

  }

  /* clean up memory, close the dst file and terminates crc32 */

  fclose(filefd);   /* close the dst file */

  crc32_finish(&cksum);

  /* printf("extract_res=%d / cksum_expected=%08lX / cksum_obtained=%08lX\n", extract_res, curzipnode->crc32, cksum); */

  if (extract_res != 0) {  /* was the extraction process successful? */

    unlink(fulldestfilename); /* remove the failed file */

    return(extract_res);

  }

  if (cksum != curzipnode->crc32) { /* is the crc32 ok after extraction? */

    unlink(fulldestfilename); /* remove the failed file */

    return(-9);

  }

  /* Set the timestamp of the new file to what was set in the zip file */

  filetimestamp.actime  = curzipnode->timestamp;

  filetimestamp.modtime = curzipnode->timestamp;

  utime(fulldestfilename, &filetimestamp);

  return(0);

#undef buffsize

}

/* Call this to free a ziplist computed by zip_listfiles() */

void zip_freelist(struct ziplist **ziplist) {

  struct ziplist *zipentrytobefreed;

  while (*ziplist != NULL) { /* iterate through the linked list and free all nodes */

    zipentrytobefreed = *ziplist;

    *ziplist = zipentrytobefreed->nextfile;

    /* free the node entry */

    free(zipentrytobefreed);

  }

  *ziplist = NULL;

}