commit a93e4ab988faad1117f8c2b2e385961e328abdd3
Author: dan <dan>
Date:   Thu Jul 9 00:42:07 2020 +0200

    Initial commit

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..f8012f7
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+tagfs
+zdir
diff --git a/makefile b/makefile
new file mode 100644
index 0000000..10bf897
--- /dev/null
+++ b/makefile
@@ -0,0 +1,20 @@
+.POSIX:
+.PHONY: clean install
+
+PREFIX=/usr/local
+
+CC=gcc
+CFLAGS=-Wall -Wextra -Wshadow -Wpedantic -std=c11 -O0 -g -Wno-unused-parameter
+LDFLAGS=$(shell pkg-config --libs --cflags fuse3)
+
+SRC=$(wildcard src/*.c)
+
+tagfs: $(SRC)
+	$(CC) $(LDFLAGS) $? $(CFLAGS) -o $@
+
+clean:
+	rm tagfs
+
+install: tagfs
+	cp $? $(PREFIX)/bin/
+
diff --git a/shell/tagfs.sh b/shell/tagfs.sh
new file mode 100644
index 0000000..edb77d7
--- /dev/null
+++ b/shell/tagfs.sh
@@ -0,0 +1,101 @@
+tagfs_nofs()
+{
+	echo "No tagfs filesystem found in `pwd`"
+}
+
+tagfs_exists()
+{
+	[ -d .tagfs ] && return 1 || return 0
+}
+
+tagfs_clear_filter()
+{
+	rm .tagfs/filters/$$ 2> /dev/null
+	return 0
+}
+
+tagfs_list_filter()
+{
+	cat .tagfs/filters/$$ 2> /dev/null
+	return 0
+}
+
+tagfs_list_tags()
+{
+	/bin/ls -1 .tagfs/tags/
+}
+
+tagfs_is_tag()
+{
+	[ -n "$(echo $1 | egrep '^[-+]')" ] && return 1 || return 0
+}
+
+filter()
+{
+	tagfs_exists
+	[ $? -eq 0 ] && tagfs_nofs && return
+	[ $# -eq 1 ] && [ "$1" = "-" ] && tagfs_clear_filter && return
+
+	filter_file=".tagfs/filters/$$"
+	tmp_file=".tagfs/filters/tmp_$$"
+	for t in "$@"; do
+		case "$(echo $t | cut -b1)" in
+		+) [ -z "$(fgrep $t $filter_file 2> /dev/null)" ] && echo "${t#+}" >> $filter_file ;;
+		-) sed -e "/${t#-}/d" $filter_file > $tmp_file && mv $tmp_file $filter_file 
+		echo nigga;;
+		esac
+	done
+	
+	tagfs_list_filter
+}
+
+tags()
+{
+	tagfs_exists
+	[ $? -eq 0 ] && tagfs_nofs && return
+	[ $# -eq 0 ] && tagfs_list_tags && return
+
+	tagfs_is_tag "$1"
+	if [ $? -eq 1 ]; then
+		for tag in "$@"; do
+			[ "$tag" = "-" ] && continue
+			
+			case "$(echo $tag | cut -b1)" in
+			+) mkdir .tagfs/tags/${tag#+} ;;
+			-) rm -r .tagfs/tags/${tag#-} ;;
+			esac
+		done
+	else
+		for tag in "$@"; do
+			[ "$tag" = "$1" ] && continue
+			[ "$tag" = "-" ] && rm $(find -name "$1") && continue
+
+			case "$(echo $tag | cut -b1)" in
+			+) ln -s ../../../"$1" .tagfs/tags/"${tag#+}"/"$1" ;;
+			-) rm .tagfs/tags/"${tag#-}"/"$1" ;;
+			esac
+		done
+	fi
+}
+
+# Bash completion
+# _filter_completion()
+# {
+# 	filter_file=".tagfs/filters/$$"
+# 	list=""
+# 	
+# 	for t in $(cat $filter_file 2> /dev/null); do
+# 		list+="-$t "
+# 	done
+# 
+# 	for t in $(ls .tagfs/tags/); do
+# 		[ -n "$(fgrep $t $filter_file 2> /dev/null)" ] && continue
+# 		list+="+$(basename $t) "
+# 	done
+# 
+# 	COMPREPLY=($(compgen -W "$list" -- "${COMP_WORDS[$COMP_CWORD]}"))
+# }
+# 
+# complete -F _filter_completion filter
+#
+
diff --git a/src/defs.h b/src/defs.h
new file mode 100644
index 0000000..8c210c9
--- /dev/null
+++ b/src/defs.h
@@ -0,0 +1,19 @@
+#ifndef H_DEFS
+#define H_DEFS
+
+/* fusefs version */
+#define FUSE_USE_VERSION 39
+
+/* posix */
+#define _POSIX_C_SOURCE 200809
+
+/* path constants */
+#define TAGFS_DIR ".tagfs"
+#define TAGFS_TAG_DIR TAGFS_DIR "/tags"
+#define TAGFS_FILTER_DIR TAGFS_DIR "/filters"
+
+/* size constants */
+#define TAG_MAX (32)
+
+#endif
+
diff --git a/src/dirinfo.h b/src/dirinfo.h
new file mode 100644
index 0000000..75e99b9
--- /dev/null
+++ b/src/dirinfo.h
@@ -0,0 +1,67 @@
+#ifndef H_DIRINFO
+#define H_DIRINFO
+
+#include <sys/stat.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+
+struct dirinfo
+{
+	int fd;
+	DIR* dp;
+	struct stat stat;
+};
+
+static inline void
+close_dirinfo(struct dirinfo* dirinfo)
+{
+	if (dirinfo->fd > 0)
+		close(dirinfo->fd);
+
+	if (dirinfo->dp)
+		closedir(dirinfo->dp);
+}
+
+static inline int
+openat_dirinfo(int dirfd, const char* path, struct dirinfo* dirinfo)
+{
+	if ((dirinfo->fd = openat(dirfd, path, O_DIRECTORY|O_RDONLY)) == -1)
+		goto err;
+
+	if ((dirinfo->dp = fdopendir(dirinfo->fd)) == NULL)
+		goto err;
+
+	if (fstat(dirinfo->fd, &dirinfo->stat) == -1)
+		goto err;
+
+	return 1;
+
+err:
+	close_dirinfo(dirinfo);
+
+	return 0;
+}
+
+static inline int
+open_dirinfo(const char* path, struct dirinfo* dirinfo)
+{
+	if ((dirinfo->fd = open(path, O_DIRECTORY|O_RDONLY)) == -1)
+		goto err;
+
+	if ((dirinfo->dp = fdopendir(dirinfo->fd)) == NULL)
+		goto err;
+
+	if (fstat(dirinfo->fd, &dirinfo->stat) == -1)
+		goto err;
+
+	return 1;
+
+err:
+	close_dirinfo(dirinfo);
+
+	return 0;
+}
+
+#endif
+
diff --git a/src/filter.h b/src/filter.h
new file mode 100644
index 0000000..a16286f
--- /dev/null
+++ b/src/filter.h
@@ -0,0 +1,238 @@
+#ifndef H_FILTER
+#define H_FILTER
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <dirent.h>
+#include <string.h>
+#include <limits.h>
+
+#define MIN(a, b) (a > b? b : a)
+#define MAX(a, b) (a > b? a : b)
+
+struct filter
+{
+	struct {
+		char** ptr;
+		size_t len;
+	} tags;
+
+	struct {
+		struct {
+			char** ptr;
+			int* in;
+			size_t len;
+		} included;
+		struct {
+			char** ptr;
+			size_t len;
+		} excluded;
+	} files;
+};
+
+static inline int
+filter_include_count(struct filter* filter)
+{
+	int count = 0;
+	
+	for (size_t i = 0; i < filter->tags.len; ++i) {
+		if (filter->tags.ptr[i][0] != '@')
+			count++;
+	}
+	
+	return count;
+}
+
+static inline int
+filter_exclude_count(struct filter* filter)
+{
+	int count = 0;
+	
+	for (size_t i = 0; i < filter->tags.len; ++i) {
+		if (filter->tags.ptr[i][0] == '@')
+			count++;
+	}
+	
+	return count;
+}
+
+static inline void
+filter_free(struct filter* filter)
+{
+	if (filter->tags.ptr) {
+		for (size_t i = 0; i < filter->tags.len; ++i) {
+			free(filter->tags.ptr[i]);
+		}
+		free(filter->tags.ptr);
+	}
+
+	if (filter->files.included.ptr) {
+		for (size_t i = 0; i < filter->files.included.len; ++i) {
+			free(filter->files.included.ptr[i]);
+		}
+		free(filter->files.included.ptr);
+		free(filter->files.included.in);
+	}
+
+	if (filter->files.excluded.ptr) {
+		for (size_t i = 0; i < filter->files.excluded.len; ++i) {
+			free(filter->files.excluded.ptr[i]);
+		}
+		free(filter->files.excluded.ptr);
+	}
+}
+
+static inline int
+load_filter_files(struct filter* filter, struct dirinfo* tagdir)
+{
+	memset(&filter->files, 0, sizeof filter->files);
+
+	for (size_t i = 0; i < filter->tags.len; ++i) {
+		const char* tag = filter->tags.ptr[i];
+
+		int excluded = (*tag == '@');
+		int fd = openat(tagdir->fd, tag + (excluded? 1 : 0), O_DIRECTORY|O_RDONLY);
+
+		if (fd == -1)
+			return 0;
+
+		DIR* dp = fdopendir(fd);
+		struct dirent* ent;
+		while ((ent = readdir(dp))) {
+			if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
+				continue;
+			
+			char name[PATH_MAX];
+			if (readlinkat(fd, ent->d_name, name, sizeof name) == -1) {
+				closedir(dp);
+				close(fd);
+				return 0;
+			}
+
+			const char* p = strrchr(name, '/') + 1;
+				
+			if (excluded) {
+				size_t size = ++filter->files.excluded.len * sizeof *filter->files.excluded.ptr;
+				void* ptr = realloc(filter->files.excluded.ptr, size);
+
+				if (ptr == NULL) {
+					closedir(dp);
+					close(fd);
+					return 0;
+				}
+
+				filter->files.excluded.ptr = ptr;
+
+				char** str = &filter->files.excluded.ptr[filter->files.excluded.len - 1];
+				size = MIN(strlen(p), NAME_MAX);
+				*str = malloc(size + 1);
+
+				if (*str == NULL) {
+					closedir(dp);
+					close(fd);
+					return 0;
+				}
+
+				strncpy(*str, p, size);
+				(*str)[size] = '\0';
+			}
+			else {
+				int skip = 0;
+
+				for (size_t j = 0; j < filter->files.included.len; ++j) {
+					if (strcmp(filter->files.included.ptr[j], p) == 0) {
+						skip = 1;
+						filter->files.included.in[j] += 1;
+					}
+				}
+
+				if (skip)
+					continue;
+				
+				size_t size = ++filter->files.included.len * sizeof *filter->files.included.ptr;
+				void* ptr = realloc(filter->files.included.ptr, size);
+
+				if (ptr == NULL) {
+					closedir(dp);
+					close(fd);
+					return 0;
+				}
+
+				filter->files.included.ptr = ptr;
+
+				size = filter->files.included.len * sizeof *filter->files.included.in;
+				ptr = realloc(filter->files.included.in, size);
+
+				if (ptr == NULL) {
+					closedir(dp);
+					close(fd);
+					return 0;
+				}
+
+				filter->files.included.in = ptr;
+				filter->files.included.in[filter->files.included.len - 1] = 1;
+
+				char** str = &filter->files.included.ptr[filter->files.included.len - 1];
+				size = MIN(strlen(p), NAME_MAX);
+				*str = malloc(size + 1);
+
+				if (*str == NULL) {
+					closedir(dp);
+					close(fd);
+					return 0;
+				}
+
+				strncpy(*str, p, size);
+				(*str)[size] = '\0';
+			}
+		}
+
+		closedir(dp);
+		close(fd);
+	}
+
+	return 1;
+}
+
+static inline int
+load_filter_tags(int fd, struct filter* filter)
+{
+	FILE* fp = fdopen(fd, "r");
+	char tag[TAG_MAX + 1];
+		
+	memset(&filter->tags, 0, sizeof filter->tags);
+
+	while (fgets(tag, sizeof tag, fp)) {
+		size_t size = ++filter->tags.len * sizeof *filter->tags.ptr;
+		void* ptr = realloc(filter->tags.ptr, size);
+		
+		if (ptr == NULL) {
+			fclose(fp);
+			return 0;
+		}
+
+		filter->tags.ptr = ptr;
+
+		char** str = &filter->tags.ptr[filter->tags.len - 1];
+		size = MIN(strlen(tag), TAG_MAX);
+		*str = malloc(size + 1);
+
+		if (*str == NULL) {
+			fclose(fp);
+			return 0;
+		}
+
+		if (tag[size - 1] == '\n')
+			tag[size - 1] = '\0';
+
+		strncpy(*str, tag, size);
+		(*str)[size] = '\0';
+	}
+
+	fclose(fp);
+	return 1;
+}
+
+#endif
+
diff --git a/src/proc.h b/src/proc.h
new file mode 100644
index 0000000..28dd478
--- /dev/null
+++ b/src/proc.h
@@ -0,0 +1,49 @@
+#ifndef H_PROC
+#define H_PROC
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <alloca.h>
+#include <limits.h>
+
+static inline int
+is_pid_alive(unsigned pid)
+{
+	char path[PATH_MAX];
+	snprintf(path, sizeof path, "/proc/%u", pid);
+
+	return access(path, F_OK) == 0;
+}
+
+static inline int 
+proc_get_ppid(unsigned pid)
+{
+	char path[PATH_MAX];
+	snprintf(path, sizeof path, "/proc/%u/stat", pid);
+	
+	FILE* fp;
+	if ((fp = fopen(path, "r")) == NULL)
+		goto err;
+
+	char stat[4096];
+
+	if (fread(stat, sizeof(char), sizeof stat, fp) == 0)
+		goto err;
+
+	fclose(fp);
+
+	char unused;
+	int ppid;
+	sscanf(strrchr(stat, ')') + 1, " %c %d", &unused, &ppid);
+
+	return ppid;
+
+err:
+	if (fp)	fclose(fp);
+
+	return -1;
+}
+
+#endif
+
diff --git a/src/tagfs.c b/src/tagfs.c
new file mode 100644
index 0000000..36e3877
--- /dev/null
+++ b/src/tagfs.c
@@ -0,0 +1,450 @@
+#include "defs.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <err.h>
+#include <errno.h>
+#include <unistd.h>
+
+#include "proc.h"
+#include "dirinfo.h"
+#include <fuse.h>
+#include <fuse_log.h>
+#include "filter.h"
+
+struct tagfs_private_data
+{
+	struct dirinfo mntdir;
+	struct dirinfo fsdir;
+	struct dirinfo tagdir;
+	struct dirinfo filterdir;
+};
+
+#define TAGFS_DATA ((struct tagfs_private_data*)fuse_get_context()->private_data)
+
+int
+tagfs_op_open(const char* path, struct fuse_file_info* fi) 
+{
+	fuse_log(FUSE_LOG_DEBUG, "open(%s)\n", path);
+
+	if (*path == '\0')
+		return -EACCES;
+
+	int fd;
+	
+	if ((fd = openat(TAGFS_DATA->mntdir.fd, path + 1, fi->flags)) == -1)
+		return -errno;
+
+	fi->fh = fd;
+
+	return 0;
+}
+
+int
+tagfs_op_create(const char* path, mode_t mode, struct fuse_file_info* fi)
+{
+	fuse_log(FUSE_LOG_DEBUG, "create(%s)\n", path);
+
+	int fd = -1;
+	int flags = O_CREAT|O_RDWR;
+	
+	if (strrchr(path, '/') == path) {
+		fd = openat(TAGFS_DATA->mntdir.fd, path + 1, flags, mode);
+	}
+	else if (strncmp(path, "/" TAGFS_FILTER_DIR, sizeof("/" TAGFS_FILTER_DIR) - 1) == 0) {
+		const char* p = strrchr(path, '/');
+		fd = openat(TAGFS_DATA->filterdir.fd, p + 1, flags, 0644);
+	}
+
+	if (fd == -1)
+		return -1;
+
+	fi->fh = fd;
+	
+	return 0;
+}
+
+int
+tagfs_op_rename(const char* oldpath, const char* newpath, unsigned int flags)
+{
+	(void) flags;
+
+	return renameat(TAGFS_DATA->mntdir.fd, oldpath + 1, TAGFS_DATA->mntdir.fd, newpath + 1);
+}
+
+int
+tagfs_op_mkdir(const char* path, mode_t mode)
+{
+	fuse_log(FUSE_LOG_DEBUG, "mkdir(%s)\n", path);
+	
+	if (strncmp(path, "/" TAGFS_TAG_DIR, sizeof("/" TAGFS_TAG_DIR) - 1) != 0)
+		return -1;
+
+	const char* p = strrchr(path, '/');
+	return mkdirat(TAGFS_DATA->tagdir.fd, p + 1, mode);
+}
+
+int
+tagfs_op_rmdir(const char* path)
+{
+	fuse_log(FUSE_LOG_DEBUG, "rmdir(%s)\n", path);
+	
+	if (strncmp(path, "/" TAGFS_TAG_DIR, sizeof("/" TAGFS_TAG_DIR) - 1) != 0)
+		return -1;
+
+	const char* p = strrchr(path, '/');
+	return unlinkat(TAGFS_DATA->tagdir.fd, p + 1, AT_REMOVEDIR);
+}
+
+int
+tagfs_op_release(const char* path, struct fuse_file_info* fi)
+{
+	fuse_log(FUSE_LOG_DEBUG, "release(%s)\n", path);
+
+	if (fi) 
+		close(fi->fh);
+
+	return 0;
+}
+
+int
+tagfs_op_read(const char* path, char* buf, size_t size, off_t off, struct fuse_file_info* fi)
+{
+	fuse_log(FUSE_LOG_DEBUG, "read(%s)\n", path);
+
+	ssize_t r = pread(fi->fh, buf, size, off);
+	
+	return r;
+}
+
+int
+tagfs_op_write(const char* path, const char* buf, size_t size, off_t off, struct fuse_file_info* fi)
+{
+	fuse_log(FUSE_LOG_DEBUG, "write(%s)\n", path);
+
+	ssize_t r = pwrite(fi->fh, buf, size, off);
+	
+	return r;
+}
+
+void
+remove_from_tags(const char* name)
+{
+	rewinddir(TAGFS_DATA->tagdir.dp);
+
+	struct dirent* tagent;
+	while ((tagent = readdir(TAGFS_DATA->tagdir.dp))) {
+		int fd = openat(TAGFS_DATA->tagdir.fd, tagent->d_name, O_DIRECTORY|O_RDONLY);
+		if (fd == -1)
+			continue;
+
+		DIR* dp = fdopendir(fd);
+		struct dirent* ent;
+		while ((ent = readdir(dp))) {
+			if (strcmp(name, ent->d_name) == 0)
+				unlinkat(fd, ent->d_name, 0);
+		}
+
+		closedir(dp);
+		close(fd);
+	}
+}
+
+int
+tagfs_op_unlink(const char* path)
+{
+	fuse_log(FUSE_LOG_DEBUG, "unlink(%s)\n", path);
+
+	if (strrchr(path, '/') == path) {
+		remove_from_tags(path + 1);
+	}
+
+	unlinkat(TAGFS_DATA->mntdir.fd, path + 1, 0);
+
+	return 0;
+}
+
+void
+fill_readdir(struct dirinfo* dir, void* buf, fuse_fill_dir_t filler, int skip_dirs)
+{
+	rewinddir(dir->dp);
+
+	struct dirent* ent;
+	while ((ent = readdir(dir->dp))) {
+		struct stat stbuf;
+
+		if (fstatat(dir->fd, ent->d_name, &stbuf, 0) == 0 && skip_dirs) {
+			if ((stbuf.st_mode & S_IFDIR) == S_IFDIR)
+				continue;
+		}
+
+		filler(buf, ent->d_name, &stbuf, 0, 0);
+	}
+}
+
+/* Removes filter files for dead processes, run at access and readdir */
+void
+remove_dead_filters(void)
+{
+	DIR* dp = TAGFS_DATA->filterdir.dp;
+	rewinddir(dp);
+	
+	struct dirent* ent;
+	while ((ent = readdir(dp))) {
+		char* end;
+		int pid = strtol(ent->d_name, &end, 10);
+
+		if (end && *end == 0 && !is_pid_alive(pid)) {
+			unlinkat(TAGFS_DATA->filterdir.fd, ent->d_name, 0);
+		}
+	}
+}
+
+int
+open_process_filter(unsigned pid)
+{
+	char path[PATH_MAX];
+	snprintf(path, sizeof path, "%u", pid);
+
+	return openat(TAGFS_DATA->filterdir.fd, path, O_RDONLY);
+}
+
+int
+fill_readdir_filtered(int filterfd, void* buf, fuse_fill_dir_t filler)
+{
+	struct filter filter = { 0 };
+	
+	if (!load_filter_tags(filterfd, &filter)) {
+		fuse_log(FUSE_LOG_DEBUG, "load_tags failed\n");
+		filter_free(&filter);
+		return 0;
+	}
+
+	if (!load_filter_files(&filter, &TAGFS_DATA->tagdir)) {
+		fuse_log(FUSE_LOG_DEBUG, "load_files failed\n");
+		filter_free(&filter);
+		return 0;
+	}
+
+	int include_count = filter_include_count(&filter);
+	int exclude_count = filter_exclude_count(&filter);
+
+	if (include_count > 0) {
+		for (size_t i = 0; i < filter.files.included.len; ++i) {
+			fuse_log(FUSE_LOG_DEBUG, "- %s\n", filter.files.included.ptr[i]);
+
+			if (filter.files.included.in[i] != include_count)
+				continue;
+
+			int skip = 0;
+			for (size_t j = 0; j < filter.files.excluded.len; ++j) {
+				skip = strcmp(filter.files.included.ptr[i], filter.files.excluded.ptr[j]) == 0;
+			}
+
+			if (skip)
+				continue;
+
+			filler(buf, filter.files.included.ptr[i], NULL, 0, 0);
+		}
+	}
+	else if (exclude_count > 0) {
+		int fd = TAGFS_DATA->mntdir.fd;
+		DIR* dp = TAGFS_DATA->mntdir.dp;
+		rewinddir(dp);
+		struct dirent* ent;
+		while ((ent = readdir(dp))) {
+			struct stat stbuf;
+			if (fstatat(fd, ent->d_name, &stbuf, 0) == 0 && (stbuf.st_mode & S_IFDIR) == S_IFDIR)
+				continue;
+			
+			int skip = 0;
+			for (size_t i = 0; i < filter.files.excluded.len; ++i) {
+				if ((skip = strcmp(ent->d_name, filter.files.excluded.ptr[i]) == 0))
+					break;
+			}
+
+			if (skip)
+				continue;
+
+			filler(buf, ent->d_name, NULL, 0, 0);
+		}
+	}
+
+	filter_free(&filter);
+
+	return 1;
+}
+
+int
+tagfs_op_readdir(const char* path, void* buf, fuse_fill_dir_t filler, off_t off, struct fuse_file_info* fi, enum fuse_readdir_flags flags)
+{
+	fuse_log(FUSE_LOG_DEBUG, "readdir(%s)\n", path);
+	
+	remove_dead_filters();
+	
+	if (strcmp(path, "/") == 0)
+	{
+		unsigned pid = fuse_get_context()->pid;
+		int fd = open_process_filter(pid);
+
+		while (fd == -1 && pid != 1) {
+			pid = proc_get_ppid(pid);
+			fd = open_process_filter(pid);
+		}
+
+		if (fd == -1) {
+			filler(buf, TAGFS_DIR, NULL, 0, 0);
+			fill_readdir(&TAGFS_DATA->mntdir, buf, filler, 1);
+		}
+		else {
+			filler(buf, TAGFS_DIR, NULL, 0, 0);
+			if (!fill_readdir_filtered(fd, buf, filler))
+				close(fd);
+		}
+	}
+	else if (strcmp(path, "/" TAGFS_DIR) == 0)
+	{
+		fill_readdir(&TAGFS_DATA->fsdir, buf, filler, 0);
+	}
+	else if (strcmp(path, "/" TAGFS_TAG_DIR) == 0)
+	{
+		fill_readdir(&TAGFS_DATA->tagdir, buf, filler, 0);
+	}
+	else if (strncmp(path, "/" TAGFS_TAG_DIR, sizeof("/" TAGFS_TAG_DIR) - 1) == 0)
+	{
+		const char* rpath = strrchr(path, '/') + 1;
+		int fd = openat(TAGFS_DATA->tagdir.fd, rpath, O_DIRECTORY|O_RDONLY);
+		if (fd == -1)
+			return -1;
+
+		DIR* dp = fdopendir(fd);
+		struct dirinfo dir = { fd, dp, (struct stat){0} };
+		fill_readdir(&dir, buf, filler, 0);
+
+		closedir(dp);
+		close(fd);
+	}
+	else if (strcmp(path, "/" TAGFS_FILTER_DIR) == 0)
+	{
+		fill_readdir(&TAGFS_DATA->filterdir, buf, filler, 0);
+	}
+
+	return 0;
+}
+
+int
+tagfs_op_readlink(const char* path, char* buf, size_t length)
+{
+	fuse_log(FUSE_LOG_DEBUG, "readlink(%s)\n", path);
+
+	if (strncmp(path, "/" TAGFS_TAG_DIR, sizeof("/" TAGFS_TAG_DIR) - 1) != 0)
+		return -1;
+
+	const char* rpath = &path[sizeof("/" TAGFS_TAG_DIR)];
+	fuse_log(FUSE_LOG_DEBUG, "- rpath(%s)\n", rpath);
+
+	readlinkat(TAGFS_DATA->tagdir.fd, rpath, buf, length);
+
+	return 0; 
+}
+
+int
+tagfs_op_symlink(const char* target, const char* path)
+{
+	fuse_log(FUSE_LOG_DEBUG, "symlink(%s, %s)\n", target, path);
+
+	if (strncmp(path, "/" TAGFS_TAG_DIR, sizeof("/" TAGFS_TAG_DIR) - 1) != 0)
+		return -1;
+
+	const char* rpath = &path[sizeof("/" TAGFS_TAG_DIR)];
+	symlinkat(target, TAGFS_DATA->tagdir.fd, rpath);
+
+	return 0;
+}
+
+int
+tagfs_op_getattr(const char* path, struct stat* st, struct fuse_file_info* fi)
+{
+	fuse_log(FUSE_LOG_DEBUG, "getattr(%s)\n", path);
+
+	if (strcmp(path, "/") == 0) {
+		*st = TAGFS_DATA->mntdir.stat;
+		return 0;
+	}
+
+	struct stat stbuf;
+	if (fstatat(TAGFS_DATA->mntdir.fd, path + 1, &stbuf, 0) == -1)
+		return -errno;
+
+	*st = stbuf;
+
+	return 0;
+}
+
+int
+tagfs_op_access(const char* path, int mask)
+{
+	fuse_log(FUSE_LOG_DEBUG, "access(%s)\n", path);
+
+	if (strcmp(path, "/") == 0) {
+		return faccessat(TAGFS_DATA->mntdir.fd, ".", mask, 0);
+		
+	}
+	
+	return faccessat(TAGFS_DATA->mntdir.fd, path + 1, mask, 0);
+}
+
+void
+init_tagfs_dir(int dirfd)
+{
+	mode_t mode = 0774;
+	mkdirat(dirfd, TAGFS_DIR, mode);
+	mkdirat(dirfd, TAGFS_TAG_DIR, mode);
+	mkdirat(dirfd, TAGFS_FILTER_DIR, mode);
+}
+
+int
+main(int argc, char** argv)
+{
+	struct fuse_operations tagfs_ops = {
+		.open    = tagfs_op_open,
+		.release = tagfs_op_release,
+		.read    = tagfs_op_read,
+		.write   = tagfs_op_write,
+		.create  = tagfs_op_create,
+		.rename  = tagfs_op_rename,
+		.mkdir   = tagfs_op_mkdir,
+		.rmdir   = tagfs_op_rmdir,
+		.unlink  = tagfs_op_unlink,
+		.readdir = tagfs_op_readdir,
+		.readlink= tagfs_op_readlink,
+		.symlink = tagfs_op_symlink,
+		/*.chmod   = tagfs_op_chmod,
+		.chown   = tagfs_op_chown,*/
+		.access  = tagfs_op_access,
+		.getattr = tagfs_op_getattr,
+	};
+	
+	const char* mntpoint = argv[argc - 1];
+	struct tagfs_private_data data;
+
+	if (!open_dirinfo(mntpoint, &data.mntdir))
+		err(1, "open_dirinfo(mntpoint)");
+
+	init_tagfs_dir(data.mntdir.fd);
+
+	if (!openat_dirinfo(data.mntdir.fd, TAGFS_DIR, &data.fsdir))
+		err(1, "openat_dirinfo(fsdir)");
+
+	if (!openat_dirinfo(data.mntdir.fd, TAGFS_TAG_DIR, &data.tagdir))
+		err(1, "openat_dirinfo(tagdir)");
+
+	if (!openat_dirinfo(data.mntdir.fd, TAGFS_FILTER_DIR, &data.filterdir))
+		err(1, "openat_dirinfo(filterdir)");
+
+	// FIXME: check if mount point is availeble, otherwise exit
+	fuse_main(argc, argv, &tagfs_ops, &data);
+
+	return 0;
+}
+