1#include <ftw.h>
  2#include <dirent.h>
  3#include <fcntl.h>
  4#include <sys/stat.h>
  5#include <errno.h>
  6#include <unistd.h>
  7#include <string.h>
  8#include <limits.h>
  9#include <pthread.h>
 10
 11struct history
 12{
 13	struct history *chain;
 14	dev_t dev;
 15	ino_t ino;
 16	int level;
 17	int base;
 18};
 19
 20#undef dirfd
 21#define dirfd(d) (*(int *)d)
 22
 23static int do_nftw(char *path, int (*fn)(const char *, const struct stat *, int, struct FTW *), int fd_limit, int flags, struct history *h)
 24{
 25	size_t l = strlen(path), j = l && path[l-1]=='/' ? l-1 : l;
 26	struct stat st;
 27	struct history new;
 28	int type;
 29	int r;
 30	int dfd;
 31	int err;
 32	struct FTW lev;
 33
 34	st.st_dev = st.st_ino = 0;
 35
 36	if ((flags & FTW_PHYS) ? lstat(path, &st) : stat(path, &st) < 0) {
 37		if (!(flags & FTW_PHYS) && errno==ENOENT && !lstat(path, &st))
 38			type = FTW_SLN;
 39		else if (errno != EACCES) return -1;
 40		else type = FTW_NS;
 41	} else if (S_ISDIR(st.st_mode)) {
 42		if (flags & FTW_DEPTH) type = FTW_DP;
 43		else type = FTW_D;
 44	} else if (S_ISLNK(st.st_mode)) {
 45		if (flags & FTW_PHYS) type = FTW_SL;
 46		else type = FTW_SLN;
 47	} else {
 48		type = FTW_F;
 49	}
 50
 51	if ((flags & FTW_MOUNT) && h && type != FTW_NS && st.st_dev != h->dev)
 52		return 0;
 53	
 54	new.chain = h;
 55	new.dev = st.st_dev;
 56	new.ino = st.st_ino;
 57	new.level = h ? h->level+1 : 0;
 58	new.base = j+1;
 59	
 60	lev.level = new.level;
 61	if (h) {
 62		lev.base = h->base;
 63	} else {
 64		size_t k;
 65		for (k=j; k && path[k]=='/'; k--);
 66		for (; k && path[k-1]!='/'; k--);
 67		lev.base = k;
 68	}
 69
 70	if (type == FTW_D || type == FTW_DP) {
 71		dfd = open(path, O_RDONLY);
 72		err = errno;
 73		if (dfd < 0 && err == EACCES) type = FTW_DNR;
 74		if (!fd_limit) close(dfd);
 75	}
 76
 77	if (!(flags & FTW_DEPTH) && (r=fn(path, &st, type, &lev)))
 78		return r;
 79
 80	for (; h; h = h->chain)
 81		if (h->dev == st.st_dev && h->ino == st.st_ino)
 82			return 0;
 83
 84	if ((type == FTW_D || type == FTW_DP) && fd_limit) {
 85		if (dfd < 0) {
 86			errno = err;
 87			return -1;
 88		}
 89		DIR *d = fdopendir(dfd);
 90		if (d) {
 91			struct dirent *de;
 92			while ((de = readdir(d))) {
 93				if (de->d_name[0] == '.'
 94				 && (!de->d_name[1]
 95				  || (de->d_name[1]=='.'
 96				   && !de->d_name[2]))) continue;
 97				if (strlen(de->d_name) >= PATH_MAX-l) {
 98					errno = ENAMETOOLONG;
 99					closedir(d);
100					return -1;
101				}
102				path[j]='/';
103				strcpy(path+j+1, de->d_name);
104				if ((r=do_nftw(path, fn, fd_limit-1, flags, &new))) {
105					closedir(d);
106					return r;
107				}
108			}
109			closedir(d);
110		} else {
111			close(dfd);
112			return -1;
113		}
114	}
115
116	path[l] = 0;
117	if ((flags & FTW_DEPTH) && (r=fn(path, &st, type, &lev)))
118		return r;
119
120	return 0;
121}
122
123int nftw(const char *path, int (*fn)(const char *, const struct stat *, int, struct FTW *), int fd_limit, int flags)
124{
125	int r, cs;
126	size_t l;
127	char pathbuf[PATH_MAX+1];
128
129	if (fd_limit <= 0) return 0;
130
131	l = strlen(path);
132	if (l > PATH_MAX) {
133		errno = ENAMETOOLONG;
134		return -1;
135	}
136	memcpy(pathbuf, path, l+1);
137	
138	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
139	r = do_nftw(pathbuf, fn, fd_limit, flags, NULL);
140	pthread_setcancelstate(cs, 0);
141	return r;
142}