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/*
* This file is part of pkg (SvarDOS)
* Copyright (C) 2012-2021 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 "kprintf.h"
#include "inf.h" /* INFLATE support */
#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) {
kitten_printf(2, 14, "libunzip"); /* "Out of memory! (%s)" */
puts("");
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 */
kitten_printf(8, 1, entrysig); /* "unknown zip sig: 0x%08lx" */
puts("");
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) {
#define buffsize (12 * 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;
unsigned char *buff;
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 */
/* allocate buffers for data I/O */
buff = malloc(buffsize);
if (buff == NULL) {
fclose(filefd);
unlink(fulldestfilename); /* remove the failed file once it is closed */
return(-6);
}
if (fseek(zipfd, curzipnode->dataoffset, SEEK_SET) != 0) { /* set the reading position inside the zip file */
free(buff);
fclose(filefd);
unlink(fulldestfilename); /* remove the failed file once it is closed */
return(-7);
}
extract_res = -255;
cksum = crc32_init(); /* 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(buff, toread, 1, zipfd) != 1) extract_res = -3; /* read a chunk of data */
crc32_feed(&cksum, buff, toread); /* update the crc32 checksum */
if (fwrite(buff, 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, buff, buffsize / 3, buff + (buffsize / 3), buffsize / 3 * 2, &cksum, curzipnode->compressedfilelen);
}
/* clean up memory, close the dst file and terminates crc32 */
free(buff);
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;
}