关于path_alloc函数：：：：
http://www.cnblogs.com/xiaoliyu/archive/2009/03/08/1406448.html
#include <sys/stat.h>#include <dirent.h>#include <limits.h>#include <stdio.h>#include <stdlib.h>#include <string.h>/* function type that is called for each filename */typedefintMyfunc(const char *, const struct stat *, int);static Myfuncmyfunc;static intmyftw(char *, Myfunc *);static intdopath(Myfunc *);static longnreg, ndir, nblk, nchr, nfifo, nslink, nsock, ntot;char*path_alloc(int* size){char *p = NULL;if(!size) return NULL;p = malloc(256);if(p)*size = 256;else*size = 0;return p;}intmain(int argc, char *argv[]){intret;if (argc != 2)printf("usage: ftw <starting-pathname>");ret = myftw(argv[1], myfunc);/* does it all */ntot = nreg + ndir + nblk + nchr + nfifo + nslink + nsock;if (ntot == 0)ntot = 1;/* avoid divide by 0; print 0 for all counts */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("FIFOs = %7ld, %5.2f %%\n", nfifo, nfifo*100.0/ntot);printf("symbolic links = %7ld, %5.2f %%\n", nslink, nslink*100.0/ntot);printf("sockets = %7ld, %5.2f %%\n", nsock, nsock*100.0/ntot);exit(ret);}/* * Descend through the hierarchy, starting at "pathname". * The caller's func() is called for every file. */#defineFTW_F1/* file other than directory */#defineFTW_D2/* directory */#defineFTW_DNR3/* directory that can't be read */#defineFTW_NS4/* file that we can't stat */static char*fullpath;/* contains full pathname for every file */static int/* we return whatever func() returns */myftw(char *pathname, Myfunc *func){int len;fullpath = path_alloc(&len);/* malloc's for PATH_MAX+1 bytes *//* ({Prog pathalloc}) */strncpy(fullpath, pathname, len);/* protect against */fullpath[len-1] = 0;/* buffer overrun */return(dopath(func));}/* * Descend through the hierarchy, starting at "fullpath". * If "fullpath" is anything other than a directory, we lstat() it, * call func(), and return. For a directory, we call ourself * recursively for each name in the directory. */static int/* we return whatever func() returns */dopath(Myfunc* func){struct statstatbuf;struct dirent*dirp;DIR*dp;intret;char*ptr;if (lstat(fullpath, &statbuf) < 0)/* stat error */return(func(fullpath, &statbuf, FTW_NS));if (S_ISDIR(statbuf.st_mode) == 0)/* not a directory */return(func(fullpath, &statbuf, FTW_F));/* * It's a directory. First call func() for the directory, * then process each filename in the directory. */if ((ret = func(fullpath, &statbuf, FTW_D)) != 0)return(ret);ptr = fullpath + strlen(fullpath);/* point to end of fullpath */*ptr++ = '/';*ptr = 0;if ((dp = opendir(fullpath)) == NULL)/* can't read directory */return(func(fullpath, &statbuf, FTW_DNR));while ((dirp = readdir(dp)) != NULL) {if (strcmp(dirp->d_name, ".") == 0 || strcmp(dirp->d_name, "..") == 0)continue;/* ignore dot and dot-dot */strcpy(ptr, dirp->d_name);/* append name after slash */if ((ret = dopath(func)) != 0)/* recursive */break;/* time to leave */}ptr[-1] = 0;/* erase everything from slash onwards */if (closedir(dp) < 0)printf("can't close directory %s", fullpath);return(ret);}static intmyfunc(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:printf("for S_IFDIR for %s", pathname);/* directories should have type = FTW_D */}break;case FTW_D:ndir++;break;case FTW_DNR:printf("can't read directory %s", pathname);break;case FTW_NS:printf("stat error for %s", pathname);break;default:printf("unknown type %d for pathname %s", type, pathname);}return(0);}
