Thanks Glynn.
I tried to rectify the flaw and now I am getting the whole file contents 
from the zip file, ie., it is outputting the contents of the file stored 
in the zipfile.
But Actually, I wanted only to list the content of the zip file as 
zipinfo does.

Regards
Prasanta
Glynn Clements wrote:
> Prasanta Sadhukhan wrote:
>
>   
>> I have tried to create a ziptest code with the information found but 
>> when I tried to inflate the contents by calling inflate() [line68], I am 
>> getting Z_DATA_ERROR citing  input data is corrupted or not conforming 
>> to zlib format but I can do zipinfo or unzip on the attached ziptest.zip 
>> file successfully (and also the zip header is found to be valid by the 
>> header validity check done in the program)
>> Can anyone point me as to what should I being more to get rid of this 
>> problem?
>>     
>
> I've found 3 flaws:
>
> 1. You're not skipping over the variable-length fields (file name and
> extra field) at the end of the header; add:
>
> 	fseek(file, SH(&h[LOCFIL]), SEEK_CUR);
> 	fseek(file, SH(&h[LOCEXT]), SEEK_CUR);
>
> after reading the header but before calling inf().
>
> 2. You're trying to inflate() everything up to end-of-file, when you
> should be using the compressed length from the header (LOCSIZ) to
> determine how much compressed data is available (even with only one
> file, the central directory occurs at the end of the file).
>
> 3. This one wasn't obvious until I looked at the unzip source code. 
> You need to call inflateInit2(&strm, -15) rather than inflateInit(),
> in order to have it process "raw" data. zlib.h says:
>
>      windowBits can also be -8..-15 for raw inflate. In this case, -windowBits
>    determines the window size. inflate() will then process raw deflate data,
>    not looking for a zlib or gzip header, not generating a check value, and not
>    looking for any check values for comparison at the end of the stream. This
>    is for use with other formats that use the deflate compressed data format
>    such as zip. ...
>
> IOW, inflateInit() expects the data to be "wrapped" with a zlib or
> gzip header and trailer, but ZIP files don't have these.
>
> After fixing the above issues, I get C source code on stdout.
>
>