using libzip to extract files

libzip_simple.c

/* Copyright (C) 2011 rocenting#gmail.com */
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/resource.h>
#include <dirent.h>
#include <limits.h>
#include <unistd.h>
#include <dirent.h>
#include <fcntl.h>
#include <limits.h>
#include <zip.h>
const char *prg;
 
static void safe_create_dir(const char *dir)
{
    if (mkdir(dir, 0755) < 0) {
        if (errno != EEXIST) {
            perror(dir);
            exit(1);
        }
    }
}
 
int main(int argc, char *argv[])
{
    const char *archive;
    struct zip *za;
    struct zip_file *zf;
    struct zip_stat sb;
    char buf[100];
    int err;
    int i, len;
    int fd;
    long long sum;
    prg = argv[0];
    if (argc != 2) {
        fprintf(stderr, "usage: %s archive\n", prg);
        return 1;
    }
 
    archive = argv[1];
    if ((za = zip_open(archive, 0, &err)) == NULL) {
        zip_error_to_str(buf, sizeof(buf), err, errno);
        fprintf(stderr, "%s: can't open zip archive `%s': %s/n", prg,
            archive, buf);
        return 1;
    }
 
    for (i = 0; i < zip_get_num_entries(za, 0); i++) {
        if (zip_stat_index(za, i, 0, &sb) == 0) {
            printf("==================/n");
            len = strlen(sb.name);
            printf("Name: [%s], ", sb.name);
            printf("Size: [%llu], ", sb.size);
            printf("mtime: [%u]/n", (unsigned int)sb.mtime);
            if (sb.name[len - 1] == '/') {
                safe_create_dir(sb.name);
            } else {
                zf = zip_fopen_index(za, i, 0);
                if (!zf) {
                    fprintf(stderr, "boese, boese/n");
                    exit(100);
                }
 
                fd = open(sb.name, O_RDWR | O_TRUNC | O_CREAT, 0644);
                if (fd < 0) {
                    fprintf(stderr, "boese, boese/n");
                    exit(101);
                }
 
                sum = 0;
                while (sum != sb.size) {
                    len = zip_fread(zf, buf, 100);
                    if (len < 0) {
                        fprintf(stderr, "boese, boese/n");
                        exit(102);
                    }
                    write(fd, buf, len);
                    sum += len;
                }
                close(fd);
                zip_fclose(zf);
            }
        } else {
            printf("File[%s] Line[%d]/n", __FILE__, __LINE__);
        }
    }   
 
    if (zip_close(za) == -1) {
        fprintf(stderr, "%s: can't close zip archive `%s'/n", prg, archive);
        return 1;
    }
 
    return 0;
}

gcc  libzip_simple.c  -lzip -o  libzip_simple.out

Windows O_BINARY is required. Or binary file as zip inside zip become corrupted.

fd = open(sb.name, O_RDWR | O_TRUNC | O_CREAT | O_BINARY, 0644);

if you wish to unzip a password protected zip file, you just need to add this before the for loop
int iRetPassword = zip_set_default_password(za, "the_password"); printf("password: %i", iRetPassword);

I've made a C++/Qt implementation that deals with password. It's available here on my github

What C environment uses "/n" rather than "\n"

Ouch the duplicate includes.
Also hello Google Search.