Re: code to list contents of zip files

[Prasanta Sadhukhan <Prasanta.Sadhukhan@Sun.COM>]

[-- Attachment #1: Type: text/plain, Size: 821 bytes --]

Thanks for the information.
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?

Thanks in advance
Prasanta
Glynn Clements wrote:
> Prasanta Sadhukhan wrote:
>
>   
>> Can anyone point me as to how to list the contents of zip file using ANSI c?
>> Any pointers will be appreciated
>>     
>
> Look at the source code for Unzip:
>
> 	http://sourceforge.net/projects/infozip/files/
>
>   


[-- Attachment #2: ziptest.c --]
[-- Type: text/plain, Size: 5051 bytes --]

#include <stdio.h>
#include <string.h>
#include <malloc.h>
#include <zlib.h>
#include <errno.h>
#include <assert.h>

#define CHUNK 16384

/* PKZIP header definitions */
#define ZIPMAG 0x4b50           /* two-byte zip lead-in */
#define LOCREM 0x0403           /* remaining two bytes in zip signature */
#define LOCSIG 0x04034b50L      /* full signature */
#define LOCFLG 4                /* offset of bit flag */
#define  CRPFLG 1               /*  bit for encrypted entry */
#define  EXTFLG 8               /*  bit for extended local header */
#define LOCHOW 6                /* offset of compression method */
#define LOCTIM 8                /* file mod time (for decryption) */
#define LOCCRC 12               /* offset of crc */
#define LOCSIZ 16               /* offset of compressed size */
#define LOCLEN 20               /* offset of uncompressed length */
#define LOCFIL 24               /* offset of file name field length */
#define LOCEXT 26               /* offset of extra field length */
#define LOCHDR 28               /* size of local header, including LOCREM */
#define EXTHDR 16               /* size of extended local header, inc sig */

#define SH(p) ((unsigned short)(unsigned char)((p)[0]) | ((unsigned short)(unsigned char)((p)[1]) << 8))

int inf(FILE *source, FILE *dest)
{
    int ret;
    unsigned have;
    z_stream strm;
    unsigned char in[CHUNK];
    unsigned char out[CHUNK];
	unsigned char dict;

    /* allocate inflate state */
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.avail_in = 0;
    strm.next_in = Z_NULL;
    ret = inflateInit(&strm);
    if (ret != Z_OK) {
		printf("inflateInit failed\n");
        return ret;
	}

		printf("inflateInit succeeded\n");
    /* decompress until deflate stream ends or end of file */
    do {
        strm.avail_in = fread(in, 1, CHUNK, source);
        if (ferror(source)) {
			printf("fread failed\n");
            (void)inflateEnd(&strm);
            return Z_ERRNO;
        }
		printf("fread succeeded\n");
        if (strm.avail_in == 0)
            break;
        strm.next_in = in;

        /* run inflate() on input until output buffer not full */
        do {
            strm.avail_out = CHUNK;
            strm.next_out = out;
            ret = inflate(&strm, Z_NO_FLUSH);
			printf("inflate returned errcode %d\n",ret);	
            assert(ret != Z_STREAM_ERROR);  /* state not clobbered */
            switch (ret) {
            case Z_NEED_DICT:
		printf("inflate returned Z_NEED_DICT\n");
                ret = Z_DATA_ERROR;     /* and fall through */
            case Z_DATA_ERROR:
		printf("inflate returned Z_DATA_ERROR\n");
            case Z_MEM_ERROR:
		printf("inflate returned Z_MEM_ERROR\n");
                (void)inflateEnd(&strm);
                return ret;
            }
		printf("inflate succeeded\n");
            have = CHUNK - strm.avail_out;
            if (fwrite(out, 1, have, dest) != have || ferror(dest)) {
		printf("fwrite failed\n");
                (void)inflateEnd(&strm);
                return Z_ERRNO;
            }
        } while (strm.avail_out == 0);

        /* done when inflate() says it's done */
    } while (ret != Z_STREAM_END);

    /* clean up and return */
    (void)inflateEnd(&strm);
	printf("inf ret %d\n", ret);
    return ret == Z_STREAM_END ? Z_OK : Z_DATA_ERROR;
}

/* report a zlib or i/o error */
void zerr(int ret)
{
    fputs("ziptest: ", stderr);
    switch (ret) {
    case Z_ERRNO:
        if (ferror(stdin))
            fputs("error reading stdin\n", stderr);
        if (ferror(stdout))
            fputs("error writing stdout\n", stderr);
        break;
    case Z_STREAM_ERROR:
        fputs("invalid compression level\n", stderr);
        break;
    case Z_DATA_ERROR:
        fputs("invalid or incomplete deflate data\n", stderr);
        break;
    case Z_MEM_ERROR:
        fputs("out of memory\n", stderr);
        break;
    case Z_VERSION_ERROR:
        fputs("zlib version mismatch!\n", stderr);
    }
}

int main(char *argc, char **argv)
{
	char str[] = "./ziptest.zip";
	char *substr = strcasestr(str, ".zip");
	char *loc;
	int errnum;
	unsigned short n;
	unsigned char h[LOCHDR];
	int ret;

	if (substr == NULL) {
		printf("zip not found\n");
		substr = strcasestr(substr, ".jar");
		if (substr == NULL) 
			printf("jar not found\n");
		else
			printf("jar found at location: %s\n",substr);
		return;
	}
	else
		printf("zip found at location: %s\n",substr);
	loc = (char*)malloc(substr-str+4);
	strncpy(loc, str, substr-str+4);
	printf("zip path = %s\n",loc);
	errno = 0;
	FILE* file = fopen(loc, "r");
	if (file == (FILE*)NULL)
		printf("cannot open zipfile. errno %d\n",errno);
	else 
		printf("file %p\n", file);

	n = getc(file);
	n |= getc(file) << 8;
	printf("getc returns n = 0x%x, errno %d\n", n, errno);
	if (n == ZIPMAG)
	{
		if (fread((char *)h, 1, LOCHDR, file) != LOCHDR || SH(h) != LOCREM) {
			printf("invalid zipfile");
		}
	} else
		printf("input not a zip file\n");

	ret = inf(file, stdout);
	if (ret != Z_OK)
		zerr(ret);
}

[-- Attachment #3: ziptest.zip --]
[-- Type: application/x-zip-compressed, Size: 1909 bytes --]