#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <sys/fcntl.h>
#include <sys/stat.h>
#include <errno.h>
#ifdef HAVE_LIBGEN_H
#include <libgen.h>
#endif

#ifndef HAVE_LIBGEN_H
char *basename(char *filename)
{
  char *slash = filename;

  while (*filename) {
    if (*filename == '/') {
      slash = filename;
    }
    filename++;
  }
  if(*slash == '/'){
    slash++;
  }
  return slash;
}
#endif

void usage(char *progname){
  printf("%s filename...\n", progname);
  exit(1);
}

int main(argc, argv)
  int argc;
  char *argv[];
{
  int filecount;
  int i, j;
  struct stat fbuf;
  char *fmem, *stmem;
  char fname[13];
  int fflag;
  unsigned long int fpnt;
  int ffp;
  int i1f = 0x1f;
  int i8b = 0x8b;
  int i08 = 0x08;

  stmem = NULL;

  if(argc < 2)
    usage(argv[0]);
  filecount = argc - 1;
  for(i=0;i<filecount;i++){
    printf("\n");
    if(stat(argv[i+1], &fbuf) == -1){
      printf("%s stat error[%d]\n", argv[i+1], errno);
      continue;
    }
    printf("%s file size:%d\n",argv[i+1], fbuf.st_size);

    if(!(fbuf.st_mode & S_IFREG)){
      if(fbuf.st_mode & S_IFDIR){
        printf("%s is directory\n", argv[i+1]);
      } else {
        printf("%s is not regular file\n", argv[i+1]);
      }
      continue;
    }

    if(fbuf.st_size < 10){
      printf("%s is too short[%d]\n", argv[i+1], fbuf.st_size);
      continue;
    }

    if((ffp=open(argv[i+1], O_RDONLY)) < 0 ){
      printf("%s open error[%d]\n", argv[i+1], errno);
      continue;
    }

    fmem = realloc(stmem, fbuf.st_size + 1);
    stmem = fmem;
    if(fmem == NULL){
      printf("memory allocate error[%d]\n", errno);
      close(ffp);
      continue;
    }

    if(read(ffp, fmem, fbuf.st_size) == -1 ){
      printf("%s read error[%d]\n", argv[i+1], errno);
      close(ffp);
      continue;
    }

    if(!memchr(fmem, 0x1f, fbuf.st_size - 1)){
      printf("can't find gzip header\n");
      close(ffp);
      continue;
    }

    memset(fname, 0, sizeof(fname));
    snprintf(fname, 13, "%s             ", basename(argv[i+1]));
    fflag = 0;
    for(fpnt = 0; fpnt < fbuf.st_size - 2; fpnt++, fmem++){
      if( (*fmem == i1f) && ((0xff & *(fmem+1)) == i8b) 
                         && ((0xff & *(fmem+2)) == i08) ){
        printf("%8s ",fname);
        if(fpnt < 4){
          printf("%08x(%10d)          ",fpnt,fpnt);
        } else {
          printf("%08x(%10d) %02x %02x %02x-",fpnt,fpnt,
                  0xff & *(fmem-3), 0xff & *(fmem-2), 0xff & *(fmem-1));
        }
        j = 0;
        while(j < 8){
          if(fpnt + j > fbuf.st_size - 1){
            printf("   ");
          } else {
            printf("%02x ",0xff & *(fmem+j));
          }
          j++;
        }
        if( (fpnt + 20 < fbuf.st_size) && (8 & (0xff & *(fmem+3))) ){
        j = 10;
          while((0xff & *(fmem+j)) > 0x1f && (0xff & *(fmem+j)) < 0x7f 
                                          && j < 20){
            printf("%c",*(fmem+j));
            j++;
          }
        }
        printf("\n");
        fflag = 1;
      }
    }
    if(!fflag)
      printf("can't find gzip header\n");
    close(ffp);
  }
}