exer4.11.c(done)

//第一次把apue的课后习题做出来了，以作纪念。 PS：这个程序的运行时间比figure4.22的运行时间多，大概是由于切换当前工作目录引起的吧

#include "apue.h"

#include <dirent.h>

#include <limits.h>

  

 

//line9-54 is copied from figure2.15

#ifdef        PATH_MAX

static int  pathmax = PATH_MAX;

#else

static int  pathmax = 0;

#endif

 

#define SUSV3 200112L

 

static long        posix_version = 0;

 

/* If PATH_MAX is indeterminate, no guarantee this is adequate */

#define     PATH_MAX_GUESS  1024

 

char *

path_alloc(int *sizep) /* also return allocated size, if nonnull */

{

  char      *ptr;

  int         size;

 

  if (posix_version == 0)

    posix_version = sysconf(_SC_VERSION);

 

  if (pathmax == 0) {                 /* first time through */

    errno = 0;

    if ((pathmax = pathconf("/", _PC_PATH_MAX)) < 0) {

      if (errno == 0)

         pathmax = PATH_MAX_GUESS;       /* it's indeterminate */

      else

         err_sys("pathconf error for _PC_PATH_MAX");

    } else {

      pathmax++;          /* add one since it's relative to root */

    }

  }

  if (posix_version < SUSV3)

    size = pathmax + 1;

  else

    size = pathmax;

 

  if ((ptr = malloc(size)) == NULL)

    err_sys("malloc error for pathname");

 

  if (sizep != NULL)

    *sizep = size;

  return(ptr);

}

 

 

typedef int Myfunc(const char *, const struct stat *, int);

 

static Myfunc myfunc;

static int myftw(char *, Myfunc *);

 

static long nreg, ndir, nblk, nchr, nfifo, nslink, nsock, ntot;

 

int

main(int argc, char *argv[]){

  int ret;

 

  if(argc != 2)

    err_quit("usage: %s <starting-pathname>", argv[0]);

 

  ret = myftw(argv[1], myfunc);

 

  ntot = nreg+ ndir+ nblk+ nchr+ nfifo+ nslink+ nsock;

 

  if(ntot == 0)

    ntot == 1;

 

  printf("regular files = %7ld, %5.2f %%\n", nreg, nreg*100.0/ntot);

  printf("directories   = %7ld, %5.2f %%\n", ndir, ndir*100.0/ntot);

  printf("block special = %7ld, %5.2f %%\n", nblk, nblk*100.0/ntot);

  printf("char special  = %7ld, %5.2f %%\n", nchr, nchr*100.0/ntot);

  printf("symbolic links= %7ld, %5.2f %%\n", nslink, nslink*100.0/ntot);

  printf("FIFOs         = %7ld, %5.2f %%\n", nfifo, nfifo*100.0/ntot);

  printf("sockets       = %7ld, %5.2f %%\n", nsock, nsock*100.0/ntot);

 

  exit(ret);

}

 

#define FTW_F 1

#define FTW_D 2

#define FTW_DNR 3

#define FTW_NS 4

 

static int myftw(char *pathname, Myfunc *func){

  struct stat statbuf;

  struct dirent *dirp;

  DIR *dp;

  int ret;

  char *ptr;

 

  if(lstat(pathname, &statbuf) < 0)

    return(func(pathname, &statbuf, FTW_NS));

  if(S_ISDIR(statbuf.st_mode) == 0)

    return(func(pathname, &statbuf, FTW_F));

 

  if((ret = func(pathname, &statbuf, FTW_D)) < 0)

    return(ret);

 

  if(chdir(pathname) < 0)

    err_sys("chdir to %s error", pathname);

 

  if((dp = opendir(".")) == NULL)       //access deny

    return(func(pathname, &statbuf, FTW_DNR));

 

  while((dirp = readdir(dp)) != NULL){

    if(strcmp(dirp->d_name, ".") == 0 || strcmp(dirp->d_name, "..") == 0)

      continue;

    if((ret = myftw(dirp->d_name, func)) != 0)

      break;

  } 

 

  chdir("..");

 

  if(closedir(dp) < 0)

    err_ret("can't close directory %s", pathname);

  return(ret);

}

 

 

static int

myfunc(const char *pathname, const struct stat *statptr, int type){

  switch(type){

  case FTW_F:

    switch(statptr->st_mode & S_IFMT){

    case S_IFREG: nreg++; break;

    case S_IFBLK: nblk++; break;

    case S_IFCHR: nchr++; break;

    case S_IFIFO: nfifo++; break;

    case S_IFLNK: nslink++; break;

    case S_IFSOCK: nsock++; break;

    case S_IFDIR:

      err_dump("for S_IFDIR for %s", pathname);

    }

    break;

  case FTW_D:

    ndir++;

    break;

  case FTW_DNR:

    err_ret("can't read directory %s", pathname);

    break;

  case FTW_NS:

    err_ret("stat error for %s", pathname);

    break;

  default:

    err_dump("unknown type %d for pathname %s", type, pathname);

  }

 

  return(0);

}