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

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?

zlib can’t decompress ZIP files; it decompresses `gzip` streams. You would be better off with libarchive. — Stephen Kitt, Oct 06 '17 at 09:13

score 1 · Answer 1 · answered Oct 08 '17 at 01:02

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.

answered Oct 08 '17 at 01:02

Mark Adler

101,978
13
118
158

score 1 · Answer 2 · answered Oct 09 '17 at 11:18

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;
}

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

2 Answers2