iconv.c

/*
  fuse iconv module: file name charset conversion
  Copyright (C) 2007  Miklos Szeredi <miklos@szeredi.hu>

  This program can be distributed under the terms of the GNU LGPLv2.
  See the file COPYING.LIB
*/

#include <config.h>

#include <fuse.h>
#include <stdio.h>
#include <stdlib.h>
#include <stddef.h>
#include <string.h>
#include <errno.h>
#include <iconv.h>
#include <pthread.h>
#include <locale.h>
#include <langinfo.h>

struct iconv {
        struct fuse_fs *next;
        pthread_mutex_t lock;
        char *from_code;
        char *to_code;
        iconv_t tofs;
        iconv_t fromfs;
};

struct iconv_dh {
        struct iconv *ic;
        void *prev_buf;
        fuse_fill_dir_t prev_filler;
};

static struct iconv *iconv_get(void)
{
        return fuse_get_context()->private_data;
}

static int iconv_convpath(struct iconv *ic, const char *path, char **newpathp,
                          int fromfs)
{
        size_t pathlen;
        size_t newpathlen;
        char *newpath;
        size_t plen;
        char *p;
        size_t res;
        int err;

        if (path == NULL) {
                *newpathp = NULL;
                return 0;
        }

        pathlen = strlen(path);
        newpathlen = pathlen * 4;
        newpath = malloc(newpathlen + 1);
        if (!newpath)
                return -ENOMEM;

        plen = newpathlen;
        p = newpath;
        pthread_mutex_lock(&ic->lock);
        do {
                res = iconv(fromfs ? ic->fromfs : ic->tofs, (char **) &path,
                            &pathlen, &p, &plen);
                if (res == (size_t) -1) {
                        char *tmp;
                        size_t inc;

                        err = -EILSEQ;
                        if (errno != E2BIG)
                                goto err;

                        inc = (pathlen + 1) * 4;
                        newpathlen += inc;
                        tmp = realloc(newpath, newpathlen + 1);
                        err = -ENOMEM;
                        if (!tmp)
                                goto err;

                        p = tmp + (p - newpath);
                        plen += inc;
                        newpath = tmp;
                }
        } while (res == (size_t) -1);
        pthread_mutex_unlock(&ic->lock);
        *p = '\0';
        *newpathp = newpath;
        return 0;

err:
        iconv(fromfs ? ic->fromfs : ic->tofs, NULL, NULL, NULL, NULL);
        pthread_mutex_unlock(&ic->lock);
        free(newpath);
        return err;
}

static int iconv_getattr(const char *path, struct stat *stbuf,
                         struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_getattr(ic->next, newpath, stbuf, fi);
                free(newpath);
        }
        return err;
}

static int iconv_access(const char *path, int mask)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_access(ic->next, newpath, mask);
                free(newpath);
        }
        return err;
}

static int iconv_readlink(const char *path, char *buf, size_t size)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_readlink(ic->next, newpath, buf, size);
                if (!err) {
                        char *newlink;
                        err = iconv_convpath(ic, buf, &newlink, 1);
                        if (!err) {
                                strncpy(buf, newlink, size - 1);
                                buf[size - 1] = '\0';
                                free(newlink);
                        }
                }
                free(newpath);
        }
        return err;
}

static int iconv_opendir(const char *path, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_opendir(ic->next, newpath, fi);
                free(newpath);
        }
        return err;
}

static int iconv_dir_fill(void *buf, const char *name,
                          const struct stat *stbuf, off_t off,
                          enum fuse_fill_dir_flags flags)
{
        struct iconv_dh *dh = buf;
        char *newname;
        int res = 0;
        if (iconv_convpath(dh->ic, name, &newname, 1) == 0) {
                res = dh->prev_filler(dh->prev_buf, newname, stbuf, off, flags);
                free(newname);
        }
        return res;
}

static int iconv_readdir(const char *path, void *buf, fuse_fill_dir_t filler,
                         off_t offset, struct fuse_file_info *fi,
                         enum fuse_readdir_flags flags)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                struct iconv_dh dh;
                dh.ic = ic;
                dh.prev_buf = buf;
                dh.prev_filler = filler;
                err = fuse_fs_readdir(ic->next, newpath, &dh, iconv_dir_fill,
                                      offset, fi, flags);
                free(newpath);
        }
        return err;
}

static int iconv_releasedir(const char *path, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_releasedir(ic->next, newpath, fi);
                free(newpath);
        }
        return err;
}

static int iconv_mknod(const char *path, mode_t mode, dev_t rdev)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_mknod(ic->next, newpath, mode, rdev);
                free(newpath);
        }
        return err;
}

static int iconv_mkdir(const char *path, mode_t mode)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_mkdir(ic->next, newpath, mode);
                free(newpath);
        }
        return err;
}

static int iconv_unlink(const char *path)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_unlink(ic->next, newpath);
                free(newpath);
        }
        return err;
}

static int iconv_rmdir(const char *path)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_rmdir(ic->next, newpath);
                free(newpath);
        }
        return err;
}

static int iconv_symlink(const char *from, const char *to)
{
        struct iconv *ic = iconv_get();
        char *newfrom;
        char *newto;
        int err = iconv_convpath(ic, from, &newfrom, 0);
        if (!err) {
                err = iconv_convpath(ic, to, &newto, 0);
                if (!err) {
                        err = fuse_fs_symlink(ic->next, newfrom, newto);
                        free(newto);
                }
                free(newfrom);
        }
        return err;
}

static int iconv_rename(const char *from, const char *to, unsigned int flags)
{
        struct iconv *ic = iconv_get();
        char *newfrom;
        char *newto;
        int err = iconv_convpath(ic, from, &newfrom, 0);
        if (!err) {
                err = iconv_convpath(ic, to, &newto, 0);
                if (!err) {
                        err = fuse_fs_rename(ic->next, newfrom, newto, flags);
                        free(newto);
                }
                free(newfrom);
        }
        return err;
}

static int iconv_link(const char *from, const char *to)
{
        struct iconv *ic = iconv_get();
        char *newfrom;
        char *newto;
        int err = iconv_convpath(ic, from, &newfrom, 0);
        if (!err) {
                err = iconv_convpath(ic, to, &newto, 0);
                if (!err) {
                        err = fuse_fs_link(ic->next, newfrom, newto);
                        free(newto);
                }
                free(newfrom);
        }
        return err;
}

static int iconv_chmod(const char *path, mode_t mode,
                       struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_chmod(ic->next, newpath, mode, fi);
                free(newpath);
        }
        return err;
}

static int iconv_chown(const char *path, uid_t uid, gid_t gid,
                       struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_chown(ic->next, newpath, uid, gid, fi);
                free(newpath);
        }
        return err;
}

static int iconv_truncate(const char *path, off_t size,
                           struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_truncate(ic->next, newpath, size, fi);
                free(newpath);
        }
        return err;
}

static int iconv_utimens(const char *path, const struct timespec ts[2],
                         struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_utimens(ic->next, newpath, ts, fi);
                free(newpath);
        }
        return err;
}

static int iconv_create(const char *path, mode_t mode,
                        struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_create(ic->next, newpath, mode, fi);
                free(newpath);
        }
        return err;
}

static int iconv_open_file(const char *path, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_open(ic->next, newpath, fi);
                free(newpath);
        }
        return err;
}

static int iconv_read_buf(const char *path, struct fuse_bufvec **bufp,
                          size_t size, off_t offset, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_read_buf(ic->next, newpath, bufp, size, offset, fi);
                free(newpath);
        }
        return err;
}

static int iconv_write_buf(const char *path, struct fuse_bufvec *buf,
                           off_t offset, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_write_buf(ic->next, newpath, buf, offset, fi);
                free(newpath);
        }
        return err;
}

static int iconv_statfs(const char *path, struct statvfs *stbuf)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_statfs(ic->next, newpath, stbuf);
                free(newpath);
        }
        return err;
}

static int iconv_flush(const char *path, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_flush(ic->next, newpath, fi);
                free(newpath);
        }
        return err;
}

static int iconv_release(const char *path, struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_release(ic->next, newpath, fi);
                free(newpath);
        }
        return err;
}

static int iconv_fsync(const char *path, int isdatasync,
                       struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_fsync(ic->next, newpath, isdatasync, fi);
                free(newpath);
        }
        return err;
}

static int iconv_fsyncdir(const char *path, int isdatasync,
                          struct fuse_file_info *fi)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_fsyncdir(ic->next, newpath, isdatasync, fi);
                free(newpath);
        }
        return err;
}

static int iconv_setxattr(const char *path, const char *name,
                          const char *value, size_t size, int flags)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_setxattr(ic->next, newpath, name, value, size,
                                       flags);
                free(newpath);
        }
        return err;
}

static int iconv_getxattr(const char *path, const char *name, char *value,
                          size_t size)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_getxattr(ic->next, newpath, name, value, size);
                free(newpath);
        }
        return err;
}

static int iconv_listxattr(const char *path, char *list, size_t size)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_listxattr(ic->next, newpath, list, size);
                free(newpath);
        }
        return err;
}

static int iconv_removexattr(const char *path, const char *name)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_removexattr(ic->next, newpath, name);
                free(newpath);
        }
        return err;
}

static int iconv_lock(const char *path, struct fuse_file_info *fi, int cmd,
                      struct flock *lock)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_lock(ic->next, newpath, fi, cmd, lock);
                free(newpath);
        }
        return err;
}

static int iconv_flock(const char *path, struct fuse_file_info *fi, int op)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_flock(ic->next, newpath, fi, op);
                free(newpath);
        }
        return err;
}

static int iconv_bmap(const char *path, size_t blocksize, uint64_t *idx)
{
        struct iconv *ic = iconv_get();
        char *newpath;
        int err = iconv_convpath(ic, path, &newpath, 0);
        if (!err) {
                err = fuse_fs_bmap(ic->next, newpath, blocksize, idx);
                free(newpath);
        }
        return err;
}

static void *iconv_init(struct fuse_conn_info *conn,
                        struct fuse_config *cfg)
{
        struct iconv *ic = iconv_get();
        fuse_fs_init(ic->next, conn, cfg);
        /* Don't touch cfg->nullpath_ok, we can work with
           either */
        return ic;
}

static void iconv_destroy(void *data)
{
        struct iconv *ic = data;
        fuse_fs_destroy(ic->next);
        iconv_close(ic->tofs);
        iconv_close(ic->fromfs);
        pthread_mutex_destroy(&ic->lock);
        free(ic->from_code);
        free(ic->to_code);
        free(ic);
}

static const struct fuse_operations iconv_oper = {
        .destroy        = iconv_destroy,
        .init           = iconv_init,
        .getattr        = iconv_getattr,
        .access         = iconv_access,
        .readlink       = iconv_readlink,
        .opendir        = iconv_opendir,
        .readdir        = iconv_readdir,
        .releasedir     = iconv_releasedir,
        .mknod          = iconv_mknod,
        .mkdir          = iconv_mkdir,
        .symlink        = iconv_symlink,
        .unlink         = iconv_unlink,
        .rmdir          = iconv_rmdir,
        .rename         = iconv_rename,
        .link           = iconv_link,
        .chmod          = iconv_chmod,
        .chown          = iconv_chown,
        .truncate       = iconv_truncate,
        .utimens        = iconv_utimens,
        .create         = iconv_create,
        .open           = iconv_open_file,
        .read_buf       = iconv_read_buf,
        .write_buf      = iconv_write_buf,
        .statfs         = iconv_statfs,
        .flush          = iconv_flush,
        .release        = iconv_release,
        .fsync          = iconv_fsync,
        .fsyncdir       = iconv_fsyncdir,
        .setxattr       = iconv_setxattr,
        .getxattr       = iconv_getxattr,
        .listxattr      = iconv_listxattr,
        .removexattr    = iconv_removexattr,
        .lock           = iconv_lock,
        .flock          = iconv_flock,
        .bmap           = iconv_bmap,
};

static const struct fuse_opt iconv_opts[] = {
        FUSE_OPT_KEY("-h", 0),
        FUSE_OPT_KEY("--help", 0),
        { "from_code=%s", offsetof(struct iconv, from_code), 0 },
        { "to_code=%s", offsetof(struct iconv, to_code), 1 },
        FUSE_OPT_END
};

static void iconv_help(void)
{
        char *old = strdup(setlocale(LC_CTYPE, ""));
        char *charmap = strdup(nl_langinfo(CODESET));
        setlocale(LC_CTYPE, old);
        free(old);
        printf(
"    -o from_code=CHARSET   original encoding of file names (default: UTF-8)\n"
"    -o to_code=CHARSET     new encoding of the file names (default: %s)\n",
                charmap);
        free(charmap);
}

static int iconv_opt_proc(void *data, const char *arg, int key,
                          struct fuse_args *outargs)
{
        (void) data; (void) arg; (void) outargs;

        if (!key) {
                iconv_help();
                return -1;
        }

        return 1;
}

static struct fuse_fs *iconv_new(struct fuse_args *args,
                                 struct fuse_fs *next[])
{
        struct fuse_fs *fs;
        struct iconv *ic;
        char *old = NULL;
        const char *from;
        const char *to;

        ic = calloc(1, sizeof(struct iconv));
        if (ic == NULL) {
                fprintf(stderr, "fuse-iconv: memory allocation failed\n");
                return NULL;
        }

        if (fuse_opt_parse(args, ic, iconv_opts, iconv_opt_proc) == -1)
                goto out_free;

        if (!next[0] || next[1]) {
                fprintf(stderr, "fuse-iconv: exactly one next filesystem required\n");
                goto out_free;
        }

        from = ic->from_code ? ic->from_code : "UTF-8";
        to = ic->to_code ? ic->to_code : "";
        /* FIXME: detect charset equivalence? */
        if (!to[0])
                old = strdup(setlocale(LC_CTYPE, ""));
        ic->tofs = iconv_open(from, to);
        if (ic->tofs == (iconv_t) -1) {
                fprintf(stderr, "fuse-iconv: cannot convert from %s to %s\n",
                        to, from);
                goto out_free;
        }
        ic->fromfs = iconv_open(to, from);
        if (ic->tofs == (iconv_t) -1) {
                fprintf(stderr, "fuse-iconv: cannot convert from %s to %s\n",
                        from, to);
                goto out_iconv_close_to;
        }
        if (old) {
                setlocale(LC_CTYPE, old);
                free(old);
        }

        ic->next = next[0];
        fs = fuse_fs_new(&iconv_oper, sizeof(iconv_oper), ic);
        if (!fs)
                goto out_iconv_close_from;

        return fs;

out_iconv_close_from:
        iconv_close(ic->fromfs);
out_iconv_close_to:
        iconv_close(ic->tofs);
out_free:
        free(ic->from_code);
        free(ic->to_code);
        free(ic);
        if (old) {
                setlocale(LC_CTYPE, old);
                free(old);
        }
        return NULL;
}

FUSE_REGISTER_MODULE(iconv, iconv_new);