List files in a zip archive

lszip.c

#include <stdio.h>
#include <stdint.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>

int main(int argc, const char *argv[]) {
    struct stat st;
    int fd;
    void *filebuf, *eof_addr, *eof_entry, *central_dir;
    uint32_t fsize, fcde_offset;
    uint16_t records;
    
    if(argc < 2) {
        printf("Specify a file\n");
        return -1;
    }
    
    if(stat(argv[1], &st) != 0) {
        printf("File not found.\n");
        return -1;
    }
    
    fsize = st.st_size;
    
    fd = open(argv[1], O_RDONLY);
    filebuf = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
    
    if(*(uint32_t *)filebuf != 0x04034b50) {
        printf("File isn't zip.\n");
        munmap(filebuf, fsize);
        close(fd);
        return -1;
    }
    
    eof_addr = (filebuf+fsize);
    eof_entry = (eof_addr - 22);
    records = (uint16_t)*((char *)eof_entry + 10);
    
    fcde_offset = *(uint32_t *)(eof_entry+16);
    
    central_dir = (void *)(filebuf + fcde_offset);
    
    int i;
    for(i=0;i<records;++i) {
        uint32_t magic = *(uint32_t *)central_dir;
        while(magic != 0x02014b50) {
            central_dir += 1;
            magic = *(uint32_t *)central_dir;
        }
        
        void *cdentry = (void *)central_dir;
        short x = *(short *)(cdentry+28);
       
        char namebuf[x+1];
        namebuf[x] = 0;
        
        memcpy((void *)namebuf, cdentry+46, x);
        
        printf("[%d] %s\n", i, namebuf);
        
        central_dir += 1;
    }
    
    munmap(filebuf, fsize);
    close(fd);
    
    return 0;
}