cosmopolitan/libc/stdio/nftw.c

/*-*- mode:c;indent-tabs-mode:t;c-basic-offset:8;tab-width:8;coding:utf-8   -*-│
│vi: set et ft=c ts=8 tw=8 fenc=utf-8                                       :vi│
╚──────────────────────────────────────────────────────────────────────────────╝
│                                                                              │
│  Musl Libc                                                                   │
│  Copyright © 2005-2014 Rich Felker, et al.                                   │
│                                                                              │
│  Permission is hereby granted, free of charge, to any person obtaining       │
│  a copy of this software and associated documentation files (the             │
│  "Software"), to deal in the Software without restriction, including         │
│  without limitation the rights to use, copy, modify, merge, publish,         │
│  distribute, sublicense, and/or sell copies of the Software, and to          │
│  permit persons to whom the Software is furnished to do so, subject to       │
│  the following conditions:                                                   │
│                                                                              │
│  The above copyright notice and this permission notice shall be              │
│  included in all copies or substantial portions of the Software.             │
│                                                                              │
│  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,             │
│  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF          │
│  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.      │
│  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY        │
│  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,        │
│  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE           │
│  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                      │
│                                                                              │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/calls/calls.h"
#include "libc/calls/struct/dirent.h"
#include "libc/calls/weirdtypes.h"
#include "libc/errno.h"
#include "libc/runtime/stack.h"
#include "libc/stdio/ftw.h"
#include "libc/str/str.h"
#include "libc/sysv/consts/o.h"
#include "libc/sysv/consts/s.h"
#include "libc/thread/thread.h"

#define PATH_MAXIMUS 4096

asm(".ident\t\"\\n\\n\
Musl libc (MIT License)\\n\
Copyright 2005-2014 Rich Felker, et. al.\"");
asm(".include \"libc/disclaimer.inc\"");
// clang-format off

struct history
{
	struct history *chain;
	dev_t dev;
	ino_t ino;
	int level;
	int base;
};

static int do_nftw(char *path,
		   int fn(const char *, const struct stat *, int, struct FTW *),
		   int fd_limit,
		   int flags,
		   struct history *h)
{
	size_t l = strlen(path), j = l && path[l-1]=='/' ? l-1 : l;
	struct stat st;
	struct history new;
	int type;
	int r;
	int dfd=-1;
	int err=0;
	struct FTW lev;

	if ((flags & FTW_PHYS) ? lstat(path, &st) : stat(path, &st) < 0) {
		if (!(flags & FTW_PHYS) && errno==ENOENT && !lstat(path, &st))
			type = FTW_SLN;
		else if (errno != EACCES) return -1;
		else type = FTW_NS;
	} else if (S_ISDIR(st.st_mode)) {
		if (flags & FTW_DEPTH) type = FTW_DP;
		else type = FTW_D;
	} else if (S_ISLNK(st.st_mode)) {
		if (flags & FTW_PHYS) type = FTW_SL;
		else type = FTW_SLN;
	} else {
		type = FTW_F;
	}

	if ((flags & FTW_MOUNT) && h && st.st_dev != h->dev)
		return 0;

	new.chain = h;
	new.dev = st.st_dev;
	new.ino = st.st_ino;
	new.level = h ? h->level+1 : 0;
	new.base = j+1;

	lev.level = new.level;
	if (h) {
		lev.base = h->base;
	} else {
		size_t k;
		for (k=j; k && path[k]=='/'; k--);
		for (; k && path[k-1]!='/'; k--);
		lev.base = k;
	}

	if (type == FTW_D || type == FTW_DP) {
		dfd = open(path, O_RDONLY | O_DIRECTORY);
		err = errno;
		if (dfd < 0 && err == EACCES) type = FTW_DNR;
		if (!fd_limit) close(dfd);
        }

	if (!(flags & FTW_DEPTH) && (r=fn(path, &st, type, &lev)))
		return r;

	for (; h; h = h->chain)
		if (h->dev == st.st_dev && h->ino == st.st_ino)
			return 0;

	if ((type == FTW_D || type == FTW_DP) && fd_limit) {
		if (dfd < 0) {
			errno = err;
			return -1;
		}
		DIR *d = fdopendir(dfd);
		if (d) {
			struct dirent *de;
			while ((de = readdir(d))) {
				if (de->d_name[0] == '.'
				 && (!de->d_name[1]
				  || (de->d_name[1]=='.'
				   && !de->d_name[2]))) continue;
				if (strlen(de->d_name) >= PATH_MAXIMUS-l) {
					errno = ENAMETOOLONG;
					closedir(d);
					return -1;
				}
				path[j]='/';
				strcpy(path+j+1, de->d_name);
				if ((r=do_nftw(path, fn, fd_limit-1, flags, &new))) {
					closedir(d);
					return r;
				}
			}
			closedir(d);
		} else {
			close(dfd);
			return -1;
		}
	}

	path[l] = 0;
	if ((flags & FTW_DEPTH) && (r=fn(path, &st, type, &lev)))
		return r;

	return 0;
}

/**
 * Walks file tree.
 *
 * @return 0 on success, -1 on error, or non-zero `fn` result
 * @see examples/walk.c for example
 * @threadsafe
 */
int nftw(const char *dirpath,
	 int fn(const char *fpath,
		const struct stat *st,
		int typeflag,
		struct FTW *ftwbuf),
	 int fd_limit,
	 int flags)
{
#pragma GCC push_options
#pragma GCC diagnostic ignored "-Wframe-larger-than="
	char pathbuf[PATH_MAXIMUS+1];
	CheckLargeStackAllocation(pathbuf, sizeof(pathbuf));
#pragma GCC pop_options
	int r, cs;
	size_t l;

	if (fd_limit <= 0) return 0;

	l = strlen(dirpath);
	if (l > PATH_MAXIMUS) {
		errno = ENAMETOOLONG;
		return -1;
	}
	memcpy(pathbuf, dirpath, l+1);

	pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &cs);
	r = do_nftw(pathbuf, fn, fd_limit, flags, NULL);
	pthread_setcancelstate(cs, 0);

	return r;
}