How to decompress a .zip file into folder using zlib.h library? - compression

Question

I have a .zip file to unzip which contain multiple sub-folders. I am using zlib.h library function to unzip the .zip file.
#include<stdio.h>
#include<zlib.h>
#define MAX_MOI_PATH 200
#define READ_BLOCK_SIZE 1024*16
BOOL DCompressFile(char *SourceFILENAME, char *DestinationFILENAME)
{
char buffer[READ_BLOCK_SIZE];
unsigned long dwBytesRead;
unsigned long numberOfBytesWritten;
Bool status = false;
char cFilename[MAX_MOI_PATH];
int pathIndex=0;
char FileMode[4] = "w";
gzFile * FileFd = (gzFile *)gzopen (SourceFILENAME, "rb");
if (FileFd)
{
FILE* handle = fopen(DestinationFILENAME, "wb");
if(handle != NULL)
{
status = true;
while (status)
{
dwBytesRead = gzread(FileFd, buffer, READ_BLOCK_SIZE-1);
buffer[dwBytesRead] = '\0';
if (dwBytesRead)
{
status = fwrite(buffer, 1 , sizeof(buffer) , handle );
if(!status)
status = false;
else if (dwBytesRead < READ_BLOCK_SIZE)
{
break;
status = false;
}
}
}
fclose(handle);
}
gzclose (FileFd);
}
return status;
}
int main()
{
DCompressFile("/home/vivek/zlib_test/1.zip","/home/vivek/zlib_test/1");
return 0;
}
problem with this source code is, it is creating again a zip file "1.zip" with same content, not decompressing the .zip file to folder.
please help what going wrong with this?

Answer 1

gzip is not zip. zip is not gzip. Completely different things. You need to find a library or class that handles zip files. zlib doesn't do this by itself.

Answer 2

I complete this task using libarchive
static int
copy_data(struct archive *ar, struct archive *aw)
{
int r;
const void *buff;
size_t size;
#if ARCHIVE_VERSION_NUMBER >= 3000000
int64_t offset;
#else
off_t offset;
#endif
for (;;) {
r = archive_read_data_block(ar, &buff, &size, &offset);
if (r == ARCHIVE_EOF)
return (ARCHIVE_OK);
if (r != ARCHIVE_OK)
return (r);
r = archive_write_data_block(aw, buff, size, offset);
if (r != ARCHIVE_OK) {
return (r);
}
}
}
static int
extract(const char *filename)
{
struct archive *a;
struct archive *ext;
struct archive_entry *entry;
int flags;
int r;
//Select which attributes we want to restore.
flags = ARCHIVE_EXTRACT_TIME;
flags |= ARCHIVE_EXTRACT_PERM;
flags |= ARCHIVE_EXTRACT_ACL;
flags |= ARCHIVE_EXTRACT_FFLAGS;
a = archive_read_new();
archive_read_support_filter_all(a);
archive_read_support_format_all(a);
ext = archive_write_disk_new();
archive_write_disk_set_options(ext, flags);
archive_write_disk_set_standard_lookup(ext);
if ((r = archive_read_open_filename(a, filename, 16384)))
{
printf("File name %s\n",filename);
return 1;
}
for (;;) {
r = archive_read_next_header(a, &entry);
printf("%s \n",archive_entry_pathname(entry));
if (r == ARCHIVE_EOF)
break;
if (r < ARCHIVE_OK)
{
fprintf(stderr, "%s\n", archive_error_string(a));
printf("Error1 : %s\n",archive_error_string(a));
if (r < ARCHIVE_WARN)
return 1;
}
r = archive_write_header(ext, entry);
if (r < ARCHIVE_OK){
fprintf(stderr, "%s\n", archive_error_string(ext));
printf("Error2 : %s\n",archive_error_string(ext));
}
else if (archive_entry_size(entry) > 0) {
r = copy_data(a, ext);
if (r < ARCHIVE_OK){
fprintf(stderr, "%s\n", archive_error_string(ext));
printf("Error3 : %s\n",archive_error_string(ext));
}
if (r < ARCHIVE_WARN)
return 1;
}
r = archive_write_finish_entry(ext);
if (r < ARCHIVE_OK){
fprintf(stderr, "%s\n", archive_error_string(ext));
printf("Error4 : %s\n",archive_error_string(ext));
}
if (r < ARCHIVE_WARN)
return 1;
}
archive_read_close(a);
archive_read_free(a);
archive_write_close(ext);
archive_write_free(ext);
return 0;
}
int main()
{
extract("/home/sanjay/zlib_test/FileDownload.zip");
return 0;
}