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-rw-r--r--src/dumm/cowfs.c913
1 files changed, 913 insertions, 0 deletions
diff --git a/src/dumm/cowfs.c b/src/dumm/cowfs.c
new file mode 100644
index 000000000..4c16c7c5d
--- /dev/null
+++ b/src/dumm/cowfs.c
@@ -0,0 +1,913 @@
+/*
+ * Copyright (C) 2007 Martin Willi
+ * Hochschule fuer Technik Rapperswil
+ * Copyright (C) 2001-2007 Miklos Szeredi
+ *
+ * Based on example shipped with FUSE.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ */
+
+
+#define FUSE_USE_VERSION 26
+#define _GNU_SOURCE
+
+#include <fuse.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <dirent.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <pthread.h>
+
+#include "cowfs.h"
+
+#include <library.h>
+#include <debug.h>
+
+/** define _XOPEN_SOURCE 500 fails when using libstrongswan, define popen */
+extern ssize_t pread(int fd, void *buf, size_t count, off_t offset);
+extern ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);
+
+typedef struct private_cowfs_t private_cowfs_t;
+
+struct private_cowfs_t {
+ /** public cowfs interface */
+ cowfs_t public;
+ /** fuse channel to mountpoint */
+ struct fuse_chan *chan;
+ /** fuse handle */
+ struct fuse *fuse;
+ /** mountpoint of cowfs FUSE */
+ char *mount;
+ /** master filesystem path */
+ char *master;
+ /** host filesystem path */
+ char *host;
+ /** overlay filesystem path */
+ char *over;
+ /** fd of read only master filesystem */
+ int master_fd;
+ /** copy on write overlay to master */
+ int host_fd;
+ /** optional COW overlay */
+ int over_fd;
+ /** thread processing FUSE */
+ pthread_t thread;
+};
+
+/**
+ * get this pointer stored in fuse context
+ */
+static private_cowfs_t *get_this()
+{
+ return (fuse_get_context())->private_data;
+}
+
+/**
+ * make a path relative
+ */
+static void rel(const char **path)
+{
+ if (**path == '/')
+ {
+ (*path)++;
+ }
+ if (**path == '\0')
+ {
+ *path = ".";
+ }
+}
+
+/**
+ * get the highest overlay in which path exists
+ */
+static int get_rd(const char *path)
+{
+ private_cowfs_t *this = get_this();
+
+ if (this->over_fd > 0 && faccessat(this->over_fd, path, F_OK, 0) == 0)
+ {
+ return this->over_fd;
+ }
+ if (faccessat(this->host_fd, path, F_OK, 0) == 0)
+ {
+ return this->host_fd;
+ }
+ return this->master_fd;
+}
+
+/**
+ * get the highest overlay available, to write something
+ */
+static int get_wr(const char *path)
+{
+ private_cowfs_t *this = get_this();
+ if (this->over_fd > 0)
+ {
+ return this->over_fd;
+ }
+ return this->host_fd;
+}
+
+/**
+ * create full "path" at "wr" the same way they exist at "rd"
+ */
+static bool clone_path(int rd, int wr, const char *path)
+{
+ char *pos, *full;
+ struct stat st;
+ full = strdupa(path);
+ pos = full;
+
+ while ((pos = strchr(pos, '/')))
+ {
+ *pos = '\0';
+ if (fstatat(wr, full, &st, 0) < 0)
+ {
+ /* TODO: handle symlinks!? */
+ if (fstatat(rd, full, &st, 0) < 0)
+ {
+ return FALSE;
+ }
+ if (mkdirat(wr, full, st.st_mode) < 0)
+ {
+ return FALSE;
+ }
+ }
+ *pos = '/';
+ pos++;
+ }
+ return TRUE;
+}
+
+/**
+ * copy a (special) file from a readonly to a read-write overlay
+ */
+static int copy(const char *path)
+{
+ char *buf[4096];
+ int len;
+ int rd, wr;
+ int from, to;
+ struct stat st;
+
+ rd = get_rd(path);
+ wr = get_wr(path);
+
+ if (rd == wr)
+ {
+ /* already writeable */
+ return wr;
+ }
+ if (fstatat(rd, path, &st, 0) < 0)
+ {
+ return -1;
+ }
+ if (!clone_path(rd, wr, path))
+ {
+ return -1;
+ }
+ if (mknodat(wr, path, st.st_mode, st.st_rdev) < 0)
+ {
+ return -1;
+ }
+ /* copy if no special file */
+ if (st.st_size)
+ {
+ from = openat(rd, path, O_RDONLY, st.st_mode);
+ if (from < 0)
+ {
+ return -1;
+ }
+ to = openat(wr, path, O_WRONLY , st.st_mode);
+ if (to < 0)
+ {
+ close(from);
+ return -1;
+ }
+ while ((len = read(from, buf, sizeof(buf))) > 0)
+ {
+ if (write(to, buf, len) < len)
+ {
+ /* TODO: only on len < 0 ? */
+ close(from);
+ close(to);
+ return -1;
+ }
+ }
+ close(from);
+ close(to);
+ if (len < 0)
+ {
+ return -1;
+ }
+ }
+ return wr;
+}
+
+/**
+ * FUSE getattr method
+ */
+static int cowfs_getattr(const char *path, struct stat *stbuf)
+{
+ rel(&path);
+
+ if (fstatat(get_rd(path), path, stbuf, AT_SYMLINK_NOFOLLOW) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE access method
+ */
+static int cowfs_access(const char *path, int mask)
+{
+ rel(&path);
+
+ if (faccessat(get_rd(path), path, mask, 0) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE readlink method
+ */
+static int cowfs_readlink(const char *path, char *buf, size_t size)
+{
+ int res;
+
+ rel(&path);
+
+ res = readlinkat(get_rd(path), path, buf, size - 1);
+ if (res < 0)
+ {
+ return -errno;
+ }
+ buf[res] = '\0';
+ return 0;
+}
+
+/**
+ * get a directory stream of two concatenated paths
+ */
+static DIR* get_dir(char *dir, const char *subdir)
+{
+ char *full;
+
+ if (dir == NULL)
+ {
+ return NULL;
+ }
+
+ full = alloca(strlen(dir) + strlen(subdir) + 1);
+ strcpy(full, dir);
+ strcat(full, subdir);
+
+ return opendir(full);
+}
+
+/**
+ * check if a directory stream contains a directory
+ */
+static bool contains_dir(DIR *d, char *dirname)
+{
+ if (d)
+ {
+ struct dirent *ent;
+
+ rewinddir(d);
+ while ((ent = readdir(d)))
+ {
+ if (streq(ent->d_name, dirname))
+ {
+ return TRUE;
+ }
+ }
+ }
+ return FALSE;
+}
+
+/**
+ * FUSE readdir method
+ */
+static int cowfs_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
+ off_t offset, struct fuse_file_info *fi)
+{
+ private_cowfs_t *this = get_this();
+ DIR *d1, *d2, *d3;
+ struct stat st;
+ struct dirent *ent;
+
+ memset(&st, 0, sizeof(st));
+
+ d1 = get_dir(this->master, path);
+ d2 = get_dir(this->host, path);
+ d3 = get_dir(this->over, path);
+
+ if (d1)
+ {
+ while ((ent = readdir(d1)))
+ {
+ if (!contains_dir(d2, ent->d_name) &&
+ !contains_dir(d3, ent->d_name))
+ {
+ st.st_ino = ent->d_ino;
+ st.st_mode = ent->d_type << 12;
+ filler(buf, ent->d_name, &st, 0);
+ }
+ }
+ closedir(d1);
+ }
+ if (d2)
+ {
+ rewinddir(d2);
+ while ((ent = readdir(d2)))
+ {
+ if (!contains_dir(d3, ent->d_name))
+ {
+ st.st_ino = ent->d_ino;
+ st.st_mode = ent->d_type << 12;
+ filler(buf, ent->d_name, &st, 0);
+ }
+ }
+ closedir(d2);
+ }
+ if (d3)
+ {
+ rewinddir(d3);
+ while ((ent = readdir(d3)))
+ {
+ st.st_ino = ent->d_ino;
+ st.st_mode = ent->d_type << 12;
+ filler(buf, ent->d_name, &st, 0);
+ }
+ closedir(d3);
+ }
+ return 0;
+}
+
+/**
+ * FUSE mknod method
+ */
+static int cowfs_mknod(const char *path, mode_t mode, dev_t rdev)
+{
+ int fd;
+ rel(&path);
+
+ fd = get_wr(path);
+ if (!clone_path(get_rd(path), fd, path))
+ {
+ return -errno;
+ }
+
+ if (mknodat(fd, path, mode, rdev) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE mkdir method
+ */
+static int cowfs_mkdir(const char *path, mode_t mode)
+{
+ int fd;
+ rel(&path);
+
+ fd = get_wr(path);
+ if (!clone_path(get_rd(path), fd, path))
+ {
+ return -errno;
+ }
+ if (mkdirat(fd, path, mode) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE unlink method
+ */
+static int cowfs_unlink(const char *path)
+{
+ rel(&path);
+
+ /* TODO: whiteout master */
+ if (unlinkat(get_wr(path), path, 0) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE rmdir method
+ */
+static int cowfs_rmdir(const char *path)
+{
+ rel(&path);
+
+ /* TODO: whiteout master */
+ if (unlinkat(get_wr(path), path, AT_REMOVEDIR) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE symlink method
+ */
+static int cowfs_symlink(const char *from, const char *to)
+{
+ int fd;
+ const char *fromrel = from;
+
+ rel(&to);
+ rel(&fromrel);
+
+ fd = get_wr(to);
+ if (!clone_path(get_rd(fromrel), fd, fromrel))
+ {
+ return -errno;
+ }
+ if (symlinkat(from, fd, to) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE rename method
+ */
+static int cowfs_rename(const char *from, const char *to)
+{
+ int fd;
+ private_cowfs_t *this = get_this();
+
+ rel(&from);
+ rel(&to);
+
+ fd = get_rd(from);
+ if (fd == this->master_fd)
+ {
+ fd = copy(from);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ }
+
+ if (renameat(fd, from, get_wr(to), to) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE link method
+ */
+static int cowfs_link(const char *from, const char *to)
+{
+ int rd, wr;
+
+ rel(&from);
+ rel(&to);
+
+ rd = get_rd(from);
+ wr = get_wr(to);
+
+ if (!clone_path(rd, wr, to))
+ {
+ DBG1("cloning path '%s' failed", to);
+ return -errno;
+ }
+ if (linkat(rd, from, wr, to, 0) < 0)
+ {
+ DBG1("linking '%s' to '%s' failed", from, to);
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE chmod method
+ */
+static int cowfs_chmod(const char *path, mode_t mode)
+{
+ int fd;
+ struct stat st;
+ private_cowfs_t *this = get_this();
+
+ rel(&path);
+ fd = get_rd(path);
+ if (fd == this->master_fd)
+ {
+ if (fstatat(fd, path, &st, 0) < 0)
+ {
+ return -errno;
+ }
+ if (st.st_mode == mode)
+ {
+ return 0;
+ }
+ fd = copy(path);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ }
+ if (fchmodat(fd, path, mode, 0) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE chown method
+ */
+static int cowfs_chown(const char *path, uid_t uid, gid_t gid)
+{
+ int fd;
+ struct stat st;
+ private_cowfs_t *this = get_this();
+
+ rel(&path);
+ fd = get_rd(path);
+ if (fd == this->master_fd)
+ {
+ if (fstatat(fd, path, &st, 0) < 0)
+ {
+ return -errno;
+ }
+ if (st.st_uid == uid && st.st_gid == gid)
+ {
+ return 0;
+ }
+ fd = copy(path);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ }
+ if (fchownat(fd, path, uid, gid, AT_SYMLINK_NOFOLLOW) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE truncate method
+ */
+static int cowfs_truncate(const char *path, off_t size)
+{
+ int fd;
+ struct stat st;
+
+ private_cowfs_t *this = get_this();
+
+ rel(&path);
+ fd = get_rd(path);
+ if (fd == this->master_fd)
+ {
+ if (fstatat(fd, path, &st, 0) < 0)
+ {
+ return -errno;
+ }
+ if (st.st_size == size)
+ {
+ return 0;
+ }
+ fd = copy(path);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ }
+ fd = openat(fd, path, O_WRONLY);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ if (ftruncate(fd, size) < 0)
+ {
+ close(fd);
+ return -errno;
+ }
+ close(fd);
+ return 0;
+}
+
+/**
+ * FUSE utimens method
+ */
+static int cowfs_utimens(const char *path, const struct timespec ts[2])
+{
+ struct timeval tv[2];
+ int fd;
+ private_cowfs_t *this = get_this();
+
+ rel(&path);
+ fd = get_rd(path);
+ if (fd == this->master_fd)
+ {
+ fd = copy(path);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ }
+
+ tv[0].tv_sec = ts[0].tv_sec;
+ tv[0].tv_usec = ts[0].tv_nsec / 1000;
+ tv[1].tv_sec = ts[1].tv_sec;
+ tv[1].tv_usec = ts[1].tv_nsec / 1000;
+
+ if (futimesat(fd, path, tv) < 0)
+ {
+ return -errno;
+ }
+ return 0;
+}
+
+/**
+ * FUSE open method
+ */
+static int cowfs_open(const char *path, struct fuse_file_info *fi)
+{
+ int fd;
+
+ rel(&path);
+ fd = get_rd(path);
+
+ fd = openat(fd, path, fi->flags);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ close(fd);
+ return 0;
+}
+
+/**
+ * FUSE read method
+ */
+static int cowfs_read(const char *path, char *buf, size_t size, off_t offset,
+ struct fuse_file_info *fi)
+{
+ int file, fd, res;
+
+ rel(&path);
+
+ fd = get_rd(path);
+
+ file = openat(fd, path, O_RDONLY);
+ if (file < 0)
+ {
+ return -errno;
+ }
+
+ res = pread(file, buf, size, offset);
+ if (res < 0)
+ {
+ res = -errno;
+ }
+ close(file);
+ return res;
+}
+
+/**
+ * FUSE write method
+ */
+static int cowfs_write(const char *path, const char *buf, size_t size,
+ off_t offset, struct fuse_file_info *fi)
+{
+ private_cowfs_t *this = get_this();
+ int file, fd, res;
+
+ rel(&path);
+
+ fd = get_rd(path);
+ if (fd == this->master_fd)
+ {
+ fd = copy(path);
+ if (fd < 0)
+ {
+ return -errno;
+ }
+ }
+ file = openat(fd, path, O_WRONLY);
+ if (file < 0)
+ {
+ return -errno;
+ }
+ res = pwrite(file, buf, size, offset);
+ if (res < 0)
+ {
+ res = -errno;
+ }
+ close(file);
+ return res;
+}
+
+/**
+ * FUSE statfs method
+ */
+static int cowfs_statfs(const char *path, struct statvfs *stbuf)
+{
+ private_cowfs_t *this = get_this();
+ int fd;
+
+ fd = this->host_fd;
+ if (this->over_fd > 0)
+ {
+ fd = this->over_fd;
+ }
+
+ if (fstatvfs(fd, stbuf) < 0)
+ {
+ return -errno;
+ }
+
+ return 0;
+}
+
+/**
+ * FUSE init method
+ */
+static void *cowfs_init(struct fuse_conn_info *conn)
+{
+ struct fuse_context *ctx;
+
+ ctx = fuse_get_context();
+
+ return ctx->private_data;
+}
+
+/**
+ * FUSE method vectors
+ */
+static struct fuse_operations cowfs_operations = {
+ .getattr = cowfs_getattr,
+ .access = cowfs_access,
+ .readlink = cowfs_readlink,
+ .readdir = cowfs_readdir,
+ .mknod = cowfs_mknod,
+ .mkdir = cowfs_mkdir,
+ .symlink = cowfs_symlink,
+ .unlink = cowfs_unlink,
+ .rmdir = cowfs_rmdir,
+ .rename = cowfs_rename,
+ .link = cowfs_link,
+ .chmod = cowfs_chmod,
+ .chown = cowfs_chown,
+ .truncate = cowfs_truncate,
+ .utimens = cowfs_utimens,
+ .open = cowfs_open,
+ .read = cowfs_read,
+ .write = cowfs_write,
+ .statfs = cowfs_statfs,
+ .init = cowfs_init,
+};
+
+/**
+ * Implementation of cowfs_t.set_overlay.
+ */
+static bool set_overlay(private_cowfs_t *this, char *path)
+{
+ if (this->over)
+ {
+ free(this->over);
+ this->over = NULL;
+ }
+ if (this->over_fd > 0)
+ {
+ close(this->over_fd);
+ this->over_fd = -1;
+ }
+ if (path)
+ {
+ this->over_fd = open(path, O_RDONLY | O_DIRECTORY);
+ if (this->over_fd < 0)
+ {
+ DBG1("failed to open overlay directory '%s': %m", path);
+ return FALSE;
+ }
+ this->over = strdup(path);
+ }
+ return TRUE;
+}
+
+/**
+ * stop, umount and destroy a cowfs FUSE filesystem
+ */
+static void destroy(private_cowfs_t *this)
+{
+ fuse_exit(this->fuse);
+ fuse_unmount(this->mount, this->chan);
+ pthread_join(this->thread, NULL);
+ fuse_destroy(this->fuse);
+ free(this->mount);
+ free(this->master);
+ free(this->host);
+ free(this->over);
+ close(this->master_fd);
+ close(this->host_fd);
+ if (this->over_fd > 0)
+ {
+ close(this->over_fd);
+ }
+ free(this);
+}
+
+/**
+ * creates a new cowfs fuse instance
+ */
+cowfs_t *cowfs_create(char *master, char *host, char *mount)
+{
+ struct fuse_args args = {0, NULL, 0};
+ private_cowfs_t *this = malloc_thing(private_cowfs_t);
+
+ this->public.set_overlay = (bool(*)(cowfs_t*, char *path))set_overlay;
+ this->public.destroy = (void(*)(cowfs_t*))destroy;
+
+ this->master_fd = open(master, O_RDONLY | O_DIRECTORY);
+ if (this->master_fd < 0)
+ {
+ DBG1("failed to open master filesystem '%s'", master);
+ free(this);
+ }
+ this->host_fd = open(host, O_RDONLY | O_DIRECTORY);
+ if (this->master_fd < 0)
+ {
+ DBG1("failed to open host filesystem '%s'", host);
+ close(this->master_fd);
+ free(this);
+ }
+ this->over_fd = -1;
+
+ this->chan = fuse_mount(mount, &args);
+ if (this->chan == NULL)
+ {
+ DBG1("mounting cowfs FUSE on '%s' failed", mount);
+ close(this->master_fd);
+ close(this->host_fd);
+ free(this);
+ return NULL;
+ }
+
+ this->fuse = fuse_new(this->chan, &args, &cowfs_operations,
+ sizeof(cowfs_operations), this);
+ if (this->fuse == NULL)
+ {
+ DBG1("creating cowfs FUSE handle failed");
+ close(this->master_fd);
+ close(this->host_fd);
+ fuse_unmount(mount, this->chan);
+ free(this);
+ return NULL;
+ }
+
+ this->mount = strdup(mount);
+ this->master = strdup(master);
+ this->host = strdup(host);
+ this->over = NULL;
+
+ if (pthread_create(&this->thread, NULL, (void*)fuse_loop, this->fuse) != 0)
+ {
+ DBG1("creating thread to handle FUSE failed");
+ fuse_unmount(mount, this->chan);
+ free(this->mount);
+ free(this->master);
+ free(this->host);
+ close(this->master_fd);
+ close(this->host_fd);
+ free(this);
+ return NULL;
+ }
+
+ return &this->public;
+}
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-10 09:46:45 +0000